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Sample records for lanthanum compounds

  1. Process for obtaining cobalt and lanthanum nickelate

    International Nuclear Information System (INIS)

    Tapcov, V.; Samusi, N.; Gulea, A.; Horosun, I.; Stasiuc, V.; Petrenco, P.

    1999-01-01

    The invention relates to the process for obtaining polycrystalline ceramics of cobalt and lanthanum nickelate with the perovskite structure from coordinative hetero metallic compounds. The obtained products can be utilized in the industry in the capacity of catalysts. Summary of the invention consists in obtaining polycrystalline ceramics LaCoO 3 and LaNiO 3 with the perovskite structure by pyrolysis of the parent compounds, namely, the coordinative hetero metallic compounds of the lanthanum cobalt or lanthanum nickel. The pyrolysis of the parent compound runs during one hour at 800 C. The technical result of the invention consists in lowering the temperature of the parent compound pyrolysis containing the precise ratio of metals necessary for ceramics obtaining

  2. Calcium and lanthanum solid base catalysts for transesterification

    Science.gov (United States)

    Ng, K. Y. Simon; Yan, Shuli; Salley, Steven O.

    2015-07-28

    In one aspect, a heterogeneous catalyst comprises calcium hydroxide and lanthanum hydroxide, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g. In another aspect, a heterogeneous catalyst comprises a calcium compound and a lanthanum compound, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g, and a total basicity of about 13.6 mmol/g. In further another aspect, a heterogeneous catalyst comprises calcium oxide and lanthanum oxide, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g. In still another aspect, a process for preparing a catalyst comprises introducing a base precipitant, a neutral precipitant, and an acid precipitant to a solution comprising a first metal ion and a second metal ion to form a precipitate. The process further comprises calcining the precipitate to provide the catalyst.

  3. Microwave-assisted synthesis of lanthanum conversion coating on Mg-Li alloy and its corrosion resistance

    International Nuclear Information System (INIS)

    Song Dalei; Jing Xiaoyan; Wang Jun; Lu Shanshan; Yang Piaoping; Wang Yanli; Zhang Milin

    2011-01-01

    Graphical abstract: Highlights: → The method of microwave is used to synthesize lanthanum conversion coating. → Lanthanum conversion coating on Mg-Li alloy was studied. → Different conditions between room temperature and microwave were compared. → The corrosion behavior of lanthanum conversion coatings was studied. → The corrosion mechanism of lanthanum conversion coatings was studied. - Abstract: Lanthanum-based conversion coating on Mg-Li alloy has been prepared by a microwave-assisted method. X-ray diffractions (XRD) indicate that the intermetallic compounds of lanthanum are formed on Mg-Li alloy surface. Scanning electron microscopy (SEM) images show that the coating has different morphologies and special structures. The corrosion resistance was assessed by means of potentiodynamic polarization curves and electrochemical impedance spectra (EIS). The results indicate that this coating significantly reduces the corrosion rate of Mg-Li alloy in NaCl solution. A comparing experiment indicates that the coating prepared by microwave-assisted process has superior corrosion resistance to the coating obtained at room temperature.

  4. Encephalopathy caused by lanthanum carbonate.

    Science.gov (United States)

    Fraile, Pilar; Cacharro, Luis Maria; Garcia-Cosmes, Pedro; Rosado, Consolacion; Tabernero, Jose Matias

    2011-06-01

    Lanthanum carbonate is a nonaluminum, noncalcium phosphate-binding agent, which is widely used in patients with end-stage chronic kidney disease. Until now, no significant side-effects have been described for the clinical use of lanthanum carbonate, and there are no available clinical data regarding its tissue stores. Here we report the case of a 59-year-old patient who was admitted with confusional syndrome. The patient received 3750 mg of lanthanum carbonate daily. Examinations were carried out, and the etiology of the encephalopathy of the patient could not be singled out. The lanthanum carbonate levels in serum and cerebrospinal fluid were high, and the syndrome eased after the drug was removed. The results of our study confirm that, in our case, the lanthanum carbonate did cross the blood-brain barrier (BBB). Although lanthanum carbonate seems a safe drug with minimal absorption, this work reveals the problem derived from the increase of serum levels of lanthanum carbonate, and the possibility that it may cross the BBB. Further research is required on the possible pathologies that increase serum levels of lanthanum carbonate, as well as the risks and side-effects derived from its absorption.

  5. Preparation of lanthanum ferrite powder at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Andoulsi, R.; Horchani-Naifer, K.; Ferid, M., E-mail: karima_horchani@yahoo.com [Physical Chemistry Laboratory of Mineral Materials and their Applications, Hammam-Lif (Tunisia)

    2012-01-15

    Single lanthanum ferrite phase was successfully prepared at low processing temperature using the polymerizable complex method. To implement this work, several techniques such as differential scanning calorimetry, X-ray diffraction, Fourier Transform Infrared Spectroscopy, scanning electron microscopy and BET surface area measurements were used. Throw the obtained results, it was shown that steps of preparing the powder precursor and temperature of its calcination are critical parameters for avoiding phase segregation and obtaining pure lanthanum ferrite compound. Thus, a single perovskite phase was obtained at 600 deg C. At this temperature, the powder was found to be fine and homogeneous with an average crystallite size of 13 nm and a specific surface area of 12.5 m{sup 2}.g{sup -1}. (author)

  6. XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referencing and peak fitting procedures

    International Nuclear Information System (INIS)

    Sunding, M.F.; Hadidi, K.; Diplas, S.; Lovvik, O.M.; Norby, T.E.; Gunnaes, A.E.

    2011-01-01

    Highlights: → Gold particles deposited in vacuum as energy reference for insulating samples in XPS. → Separation of La 3d and MNN peaks in XP spectra acquired with Al Kα radiation. → We describe the spectral differences between lanthanum oxide and lanthanum hydroxide. → A doublet in O 1s of La 2 O 3 is ascribed to two distinct oxygen sites in the crystal. - Abstract: A technique is described for deposition of gold nanoparticles under vacuum, enabling consistent energy referencing of X-ray photoelectron spectra obtained from lanthanum hydroxide La(OH) 3 and in situ treated lanthanum oxide La 2 O 3 powders. A method is also presented for the separation of the overlapping lanthanum 3d and MNN peaks in X-ray photoelectron spectra acquired with Al Kα radiation. The lower satellite intensity in La(OH) 3 compared to La 2 O 3 is related to the higher ionicity of the La-O bond in the former compared to the latter compound. The presence of an additional peak in the valence band spectrum of the hydroxide compared to the oxide is attributed to the O-H bond as indicated by density functional theory based calculations. A doublet in the O 1s peak of lanthanum oxide is associated to the presence of two distinct oxygen sites in the crystal structure of this compound.

  7. Management of hyperphosphatemia in patients with end-stage renal disease: focus on lanthanum carbonate

    Directory of Open Access Journals (Sweden)

    Veerle P Persy

    2009-04-01

    Full Text Available Veerle P Persy, Geert J Behets, Marc E De Broe, Patrick C D’HaeseLaboratory of Pathophysiology, University of Antwerp, BelgiumAbstract: Elevated serum phosphate levels as a consequence of chronic kidney disease (CKD contribute to the increased cardiovascular risk observed in dialysis patients. Protein restriction and dialysis fail to adequately prevent hyperphosphatemia, and in general treatment with oral phosphate binding agents is necessary in patients with advanced CKD. Phosphate plays a pivotal role in the development of vascular calcification, one of the factors contributing to increased cardiovascular risk in CKD patients. Treatment of hyperphosphatemia with standard calcium-based phosphate binders and vitamin D compounds can induce hypercalcemic episodes, increase the Ca × PO4 product and thus add to the risk of ectopic mineralization. In this review, recent clinical as well as experimental data on lanthanum carbonate, a novel, non-calcium, non-resin phosphate binding agent are summarized. Although lanthanum is a metal cation no aluminium-like toxicity is observed since the bioavailability of lanthanum is extremely low and its metabolism differs from that of aluminium. Clinical studies now document the absence of toxic effects of lanthanum for up to 6 years of follow-up. The effects of lanthanum on bone, vasculature and brain are discussed and put in perspective with lanthanum pharmacokinetics.Keywords: lanthanum carbonate, phosphate binding, chronic kidney disease

  8. XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referencing and peak fitting procedures

    Energy Technology Data Exchange (ETDEWEB)

    Sunding, M.F., E-mail: m.f.sunding@fys.uio.no [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Hadidi, K. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Diplas, S. [Department of Chemistry and Centre for Material Science and Nanotechnology (SMN), University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo (Norway); SINTEF Materials and Chemistry, P.O. Box 124 Blindern, NO-0314 Oslo (Norway); Lovvik, O.M. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); SINTEF Materials and Chemistry, P.O. Box 124 Blindern, NO-0314 Oslo (Norway); Norby, T.E. [Department of Chemistry and Centre for Material Science and Nanotechnology (SMN), University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo (Norway); Gunnaes, A.E. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway)

    2011-07-15

    Highlights: {yields} Gold particles deposited in vacuum as energy reference for insulating samples in XPS. {yields} Separation of La 3d and MNN peaks in XP spectra acquired with Al K{alpha} radiation. {yields} We describe the spectral differences between lanthanum oxide and lanthanum hydroxide. {yields} A doublet in O 1s of La{sub 2}O{sub 3} is ascribed to two distinct oxygen sites in the crystal. - Abstract: A technique is described for deposition of gold nanoparticles under vacuum, enabling consistent energy referencing of X-ray photoelectron spectra obtained from lanthanum hydroxide La(OH){sub 3} and in situ treated lanthanum oxide La{sub 2}O{sub 3} powders. A method is also presented for the separation of the overlapping lanthanum 3d and MNN peaks in X-ray photoelectron spectra acquired with Al K{alpha} radiation. The lower satellite intensity in La(OH){sub 3} compared to La{sub 2}O{sub 3} is related to the higher ionicity of the La-O bond in the former compared to the latter compound. The presence of an additional peak in the valence band spectrum of the hydroxide compared to the oxide is attributed to the O-H bond as indicated by density functional theory based calculations. A doublet in the O 1s peak of lanthanum oxide is associated to the presence of two distinct oxygen sites in the crystal structure of this compound.

  9. Lanthanum additions and the toughness of ultra-high strength steels and the determination of appropriate lanthanum additions

    International Nuclear Information System (INIS)

    Garrison, Warren M.; Maloney, James L.

    2005-01-01

    Studies of commercial heats of AF1410 steel suggest that under appropriate conditions additions of rare-earth elements can significantly enhance fracture toughness. This improvement in toughness is not due to an extremely low inclusion volume fraction but is apparently due to the formation of larger and more widely spaced inclusions. The purpose of this work is to discuss our experience in using rare-earth additions to laboratory scale vacuum induction melted and subsequently vacuum arc remelted heats of ultra-high strength steels to achieve inclusion distributions similar to those observed in commercial heats modified with lanthanum additions. The results indicate that lanthanum additions of 0.015 wt.% to low sulfur steels which have been well deoxidized using carbon-vacuum deoxidation can result in lanthanum rich inclusions which are similar in size, volume fraction and spacing to those obtained in commercially produced heats of ultra-high strength steel to which lanthanum has been added. The heat of steel to which lanthanum additions of 0.015 wt.% were made had significantly higher toughness than did the heat of the same steel in which the sulfur had been gettered as small and closely spaced particles of MnS and which had an inclusion volume fraction similar to that of the heat modified by the addition of 0.015 wt.% lanthanum. This improvement in toughness was attributed to an increase in inclusion spacing. An addition of 0.06 wt.% lanthanum was excessive. Such an addition of lanthanum resulted in a huge volume fraction of large cuboidal inclusions which primarily contain lanthanum and oxygen and which are extremely detrimental to toughness

  10. Lanthanum and yttrium oxysulfides activated by europium: (Ln1-x Eux)2 O2 S - Synthesis and characterization

    International Nuclear Information System (INIS)

    Luiz, J.M.

    1989-01-01

    The synthesis of lanthanum and yttrium oxysulfides activated by europium were obtained by thermal decomposition of lanthanum and yttrium oxalates doped with europium, under an argon and sulphur atmosphere. The thermal decomposition of these compounds is studied by differential thermal analysis (DTA). The characterization of these oxysulfides were made by chemical analyses, infrared spectroscopy, X-ray diffraction, scanning electron microscopy and emission spectroscopy. (M.V.M.)

  11. Lanthanum

    Science.gov (United States)

    ... levels of phosphate in the blood can cause bone problems. Lanthanum is in a clsas of medications ... to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in ...

  12. Lanthanum Containing Polymer's Modification to PP

    Institute of Scientific and Technical Information of China (English)

    Dai Shaojun; Zhang Ming

    2004-01-01

    Polypropylene (PP)'s low impact strength limits its usages. Adding some a rare earth polymer can enhance PP's tensile strength and impact strength. Acrylic lanthanum was prepared by the reaction between lanthanum oxide and acrylic acid. The IR spectrum prove that and optimum reacting conditions are that the bulk ratio of La(AA) 3 and MMA is not less than one and temperature is about 80 ℃. Lanthanum containing Polymer were added into PP. When percent of addition only was 3%, strength were enhanced 10% , and impact strength 40%. SEM shows the compatibility of rare earth polymer and PP; lanthanum containing polymer can form physical crosslinking between PP's molecules, then every particle's surface connect with several PP molecules and the PP mechanical property were enhanced.

  13. Corrosion and electrochemical properties of lanthanum

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Matveeva, T.V.

    The kinetics of the corrosion rate of lanthanum at 25 0 in air of different relative humidities, distilled water, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, potassium hydroxide of different concentrations and at 100 0 C in distilled water and potassium hydroxide have been studied. In air at 22--100% relative humidity, the corrosion rate of lanthanum increases with time and with increasing humidity. In distilled water and in potassium hydroxide solutions, the corrosion rate of lanthanum increases with time and decreasees when the concentration of alkali exceeds 20%. With increasing concentration of the acids, the corrosion rate of lanthanum increases in hydrochloric acid and nitric acid and passes through a maximum in sulfuric acid (20%) and phosphoric acid (60%). The values of the corrosion rates of lanthanum in 40% nitric acid, 35% hydrochloric acid, 20% sulfuric acid, 60% phosphoric acid, and 40% hydrofluoric acid are 8 x 10 5 ; 4.4 x 10 4 ; 1.3 x 10 3 ; 9 g/m 2 h respectively

  14. Effect of lanthanum substitution on dielectric relaxation, impedance response, conducting and magnetic properties of strontium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Want, Basharat, E-mail: bawant@kashmiruniversity.ac.in; Bhat, Bilal Hamid; Ahmad, Bhat Zahoor

    2015-04-05

    Highlights: • The substitution of La affects the dielectric and magnetic properties of strontium hexaferrite. • The electric behaviour of the compound follows the Koop’s phenomenological theory. • The impedance study shows the role of grain boundaries to the electric properties of the compound. • The substitution of La to strontium hexaferrite reduces the resistive nature of grain boundaries. - Abstract: Lanthanum strontium hexaferrite Sr{sub 1−x}La{sub x}Fe{sub 12}O{sub 19} (x = 0, 0.08, 0.13 , 0.18) has been successfully synthesized by using citrate-precursor method and characterized by different techniques. The X-ray diffraction results revealed that the sample is crystalline in nature and is of single phase with the space group P63/mmc. The dielectric, conducting and impedance related studies have been carried out as a function of frequency and concentration of lanthanum in the frequency ranges of 20 Hz–3 MHz. Impedance studies were performed in the frequency domain to distinguish between bulk and grain boundary contributions of the material to the overall dielectric response. The electric response of the material was also modeled by an equivalent circuit and different circuit parameters were calculated. Magnetic characterization of the material was also performed and the effect of lanthanum concentration was studied. The hysteresis loop obtained from the magnetometer showed that with the increase of lanthanum concentration, the saturation magnetisation decreases while as coercivity increases.

  15. Complexometric determination of lanthanum and calcium in lanthanum chromite

    International Nuclear Information System (INIS)

    Novoselova, I.M.

    1989-01-01

    Methods of complexometric determination of lanthanum and calcium in lanthanum chromite, based on sequential titration of La and Ca by EDTA solution, where as an indicator eriochrome brack T with NaCl mixture in the ratio of 1:100 is used, are determined. Cr (3) effect was removed by its oxidation up to Cr (6) with perchloric acid; at first La was determined in presence of urotropine buffer, then Ca at pH 9.5-10 in presence of ammonia buffer. For reaction acceleration method of back titration of EDTA excess by zinc salt solution was used. Standard deviation in La and Ca determination is not over 0.2 and 0.1 % respectively

  16. Lanthanum (samarium) nitrate-4-aminoantipyrine nitrate-water systems

    International Nuclear Information System (INIS)

    Starikova, L.I.; Zhuravlev, E.F.

    1985-01-01

    Using the isothermal method of cross-sections at 50 deg C systems lanthanum nitrate-4-aminoantipyrine nitrate-water (1), samarium nitrate-4-aminoantipyrine nitrate-water (2), are studied. Isotherms of system 1 consist of two crystallization branches of initial salt components. In system 2 formation of congruently soluble compounds of the composition Sm(No) 3 ) 3 xC 11 H 13 ON 3 xHNO 3 is established. Analytical, X-ray phase and thermogravimetric analysis of the isolated binary salt are carried out

  17. Separation of lanthanum from samarium on solid aluminum electrode in LiCl-KCl eutectic melts

    International Nuclear Information System (INIS)

    De-Bin Ji; Mi-Lin Zhang; Xing Li; Xiao-Yan Jing; Wei Han; Yong-De Yan; Yun Xue; Zhi-Jian Zhang; Harbin Engineering University, Harbin

    2015-01-01

    This paper presents an electrochemical study on the separation of lanthanum from samarium on aluminum electrode at 773 K. The results from different electrochemical methods showed that Sm(III) and La(III) formed Al-Sm and Al-La intermetallic compounds on an aluminum electrode at electrode potential around -1.67 and -1.46 V, respectively. The electrochemical separation of lanthanum was carried out in LiCl-KCl-LaCl 3 -SmCl 3 melts on solid aluminum electrodes at 773 K by potentiostatic electrolysis at -1.45 V for 40 h and the separation efficiency was 99.1 %. (author)

  18. Oriented growing and anisotropy of emission properties of lanthanum hexaboride single crystals

    International Nuclear Information System (INIS)

    Lazorenko, V.I.; Lotsko, D.V.; Platonov, V.F.; Kovalev, A.V.; Galasun, A.P.; Matvienko, A.A.; Klinkov, A.E.

    1987-01-01

    Single crystals of lanthanum hexaboride with preset crystallographic orientation are grown by the method of crucible-free zone melting. It is shown that oriented growing of single crystals of the given compound is possible only when using seed crystals of the required orientation because no predominant orientation of the LaB 6 growth is found in case of spontaneous crystallization. Orientation of spontaneously growing LaB 6 crystals does not depend on their growth rate, degree of the melt diffusion annealing, purity of the inital powder. Anisotropy of the electronic work function for single crystal lanthanum hexaboride is confirmed. Its value grows as (100)<(110)<(111). Conditions of the preliminary thermovacuum purification of the surface are shown to affect the measured work function

  19. Eucalyptus tolerance mechanisms to lanthanum and cerium: subcellular distribution, antioxidant system and thiol pools.

    Science.gov (United States)

    Shen, Yichang; Zhang, Shirong; Li, Sen; Xu, Xiaoxun; Jia, Yongxia; Gong, Guoshu

    2014-12-01

    Guanglin 9 (Eucalyptus grandis × Eucalyptus urophlla) and Eucalyptus grandis 5 are two eucalyptus species which have been found to grow normally in soils contaminated with lanthanum and cerium, but the tolerance mechanisms are not clear yet. In this study, a pot experiment was conducted to investigate the tolerance mechanisms of the eucalyptus to lanthanum and cerium. Cell walls stored 45.40-63.44% of the metals under lanthanum or cerium stress. Peroxidase and catalase activities enhanced with increasing soil La or Ce concentrations up to 200 mg kg(-1), while there were no obvious changes in glutathione and ascorbate concentrations. Non-protein thiols concentrations increased with increasing treatment levels up to 200 mg kg(-1), and then decreased. Phytochelatins concentrations continued to increase under La or Ce stress. Therefore, the two eucalyptus species are La and Ce tolerant plants, and the tolerance mechanisms include cell wall deposition, antioxidant system response, and thiol compound synthesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Thermoelectric properties of non-stoichiometric lanthanum sulfides

    International Nuclear Information System (INIS)

    Shapiro, E.; Danielson, L.R.

    1983-01-01

    The lanthanum sulfides are promising candidate materials for high-efficiency thermoelectric applications at temperatures up to 1300 0 C. The nonstoichiometric lanthanum sulfides (LaS /SUB x/ , where 1.33 2 //rho/ can be chosen. The thermal conductivity remains approximately constant with stoichiometry, so a material with an optimum value of α 2 //rho/ should possess the optimum figure-of-merit. Data for the Seebeck coefficient and electrical resistivity of non-stoichiometric lanthanum sulfides is presented, together with structural properties of these materials

  1. Preparation and characterization of perovskite structure lanthanum gallate and lanthanum aluminate based oxides

    OpenAIRE

    Li, Shuai

    2009-01-01

    The present work was initiated to study the synthesis and properties of lanthanum gallate based oxides as intermediate temperature electrolyte for solid oxide fuel cells. The wet chemical method, polymer complexing route, was used to prepare the precursor powders. To further investigate the polymer complexing method, it was also applied to the preparation of lanthanum aluminate based oxides.   Single perovskite phase La0.8Sr0.2Ga0.83Mg0.17O2.815 can be prepared by the polymer complexing meth...

  2. The systems lanthanum (cerium, samarium) nitrate-tetramethyl-ammonium nitrate-water

    International Nuclear Information System (INIS)

    Zhuravlev, E.F.; Khisaeva, D.A.; Semenova, Eh.B.

    1984-01-01

    The method of cross sections at 25 and 50 deg C has been applied to study solubility in the systems lanthanum nitrate-tetramethyl ammonium nitrate-water (1), cesium (3) nitrate-tetramethyl ammonium nitrate-water (2) and samarium nitrate-tetramethyl ammonium nitrate-water (3). Crystallization fields of congruently dissolving compounds with 1:3 ratio of salt components (in system 1) and 1:2 ratio (in systems 2 and 3) are found in the systems. New solid phases are separated preparatively and subjected to chemical, differential thermal and IR spectroscopic analyses. Compositions of formed compounds are compared with the compositions known for nitrates of other representatives of light lanthanides

  3. Adsorption of lithium-lanthanum films on the (100) tungsten face

    International Nuclear Information System (INIS)

    Gupalo, M.S.; Smereka, T.P.; Babkin, G.V.; Palyukh, B.M.

    1982-01-01

    The method of contact potential difference is used to investigate combined adsorption of lithium-lanthanum on the (100) tungsten face. The data on work functions and thermal stability of mixed lithium-lanthanum films are obtained. The presence of lanthanum on the W(100) surface leads to appearance of minimum of work functions unobserved for the Li-W(100) system, minimum work functions and optimum lithium concentration in a mixed film are decreased at initial lanthanum coating increase. The presence of lanthanum on the W(100) face leads to lithium adsorption heat decrease

  4. Synthesis of calcium doped lanthanum manganite by mechanosynthesis

    International Nuclear Information System (INIS)

    Bolarin, A.M.; Sanchez, F.; Palomares, S.; Aguilar, J.A.; Torres-Villasenor, G.

    2007-01-01

    Lanthanum manganite doped with calcium, Ca 1/3 La 2/3 MnO 3-δ , was prepared by a high-energy ball milling. The precursors used were Mn 2 O 3 , La 2 O 3 and CaO, mixed in the stoichiometric ratio to obtain this manganite. The mechano-chemical process was performed at room temperature in a SPEX 8000D mixer/mill, using hardened steel balls and stainless steel vials, in air atmosphere. X-ray diffraction was used to elucidate the phase transformation as a function of the milling time. The Rietveld refinement was used in order to characterize structurally the manganites. The morphology and particle size of powder compound obtained were characterized by scanning electron microscope. The particle size of this powder material was measured with zeta size analyzer, and selected area electron diffraction (SAED) from TEM was used to elucidate the crystalline structure of this powder compound. The results showed that it is possible to obtain calcium doped lanthanum manganite by mechano-synthesis, using a weight ratio of ball to powder of 12:1, after 3 h of milling. The evolution of the phase transformation during the milling time is reported. Increases in milling time produce exponential decrease in the particle size, up to 680 nm after 1 h of milling. After the milling process it is obtained a powder compound with an orthorhombic structure (S.G. Pbnm). A prolonged milling time (>9 h) produce an important reduction in the particle size but this is accompanied with a high iron contamination caused by metallic residues originated from vial and balls and also, after 9 h of milling time, it was found an important distortion in orthorhombic structure, obtaining two types of parameters

  5. Nanoscale assembly of lanthanum silica with dense and porous interfacial structures.

    Science.gov (United States)

    Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R; Smart, Simon; Diniz da Costa, João C

    2015-02-03

    This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate.

  6. Lanthanum deposition corresponds to white lesions in the stomach.

    Science.gov (United States)

    Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Kawano, Seiji; Kawahara, Yoshiro; Kimoto, Katsuhiko; Okada, Hiroyuki

    2018-05-23

    Although lanthanum deposition in the stomach has been most frequently reported to occur as white lesions, no study has investigated whether the white lesions observed during esophagogastroduodenoscopy are truly lanthanum-related. Here, we retrospectively investigated the amount of lanthanum in endoscopic biopsy specimens. We reviewed four patients showing gastric white spots or annular whitish mucosa in the gastric white lesions (Bw) and peripheral mucosa where the white substance was not endoscopically observed (Bp) during biopsy. We also reviewed three patients with diffuse whitish mucosa and three patients with no whitish lesions. We performed scanning electron microscopy and energy dispersive X-ray spectrometry to quantify the lanthanum elements (wt%) in the biopsy specimens. The amount of lanthanum in the Bw ranged from 0.15-0.31 wt%, whereas that of Bp was 0.00-0.13 wt%. The difference was statistically significant (P < 0.05). The amount of lanthanum in the Bw, endoscopically presented with white spots or annular whitish mucosa, was significantly higher than that of no whitish lesions (0.05-0.14 wt%, P < 0.05). The amount of lanthanum was also higher in the diffuse whitish mucosa (0.21-0.23 wt%) compared with no whitish lesions (P < 0.01). This study is the first to reveal that pathological lanthanum deposition corresponds to the endoscopically observed white lesions in the gastric mucosa. Therefore, during esophagogastroduodenoscopy, physicians should pay attention to possible presence of white lesions in patients treated with oral lanthanum carbonate to ensure prompt identification of associated issues. Copyright © 2018 Elsevier GmbH. All rights reserved.

  7. Mechanical properties of dense to porous alumina/lanthanum hexaaluminate composite ceramics

    International Nuclear Information System (INIS)

    Negahdari, Zahra; Willert-Porada, Monika; Pfeiffer, Carolin

    2010-01-01

    For development of new composite materials based on lanthanum hexaaluminate and alumina ceramics, a better understanding of the microstructure-properties relationship is essential. In this paper, attention was focused on the evaluation of mechanical properties of lanthanum hexaaluminate/alumina particulate composite. It was found out that the lanthanum hexaaluminate content plays a critical role in determination of the microstructure and mechanical properties of the composite ceramics. In situ formation of plate-like lanthanum hexaaluminate in the ceramic matrix was accompanied with formation of pores so that the microstructure shifted from dense to porous. Increasing the lanthanum hexaaluminate content up to a certain value enhanced the fracture toughness, increased the hardness, and increased the elastic modulus of the composite materials. Further increase in the lanthanum hexaaluminate content degraded the hardness as well as the elastic modulus of composite ceramics. The influence of lanthanum hexaaluminate on mechanical properties was described by means of microstructure, porosity, and intrinsic characteristics of lanthanum hexaaluminate.

  8. Electrochemical properties of lanthanum nitride with calcium nitride additions

    International Nuclear Information System (INIS)

    Lesunova, R.P.; Fishman, L.S.

    1986-01-01

    This paper reports on the electrochemical properties of lanthanum nitride with calcium nitride added. The lanthanum nitride was obtained by nitriding metallic lanthanum at 870 K in an ammonia stream. The product contained Cl, Pr, Nd, Sm, Fe, Ca, Cu, Mo, Mg, Al, Si, and Be. The calcium nitride was obtained by nitriding metallic calcium in a nitrogen stream. The conductivity on the LaN/C 3 N 2 system components are shown as a function of temperature. A table shows the solid solutions to be virtually electronic conductors and the lanthanum nitride a mixed conductor

  9. Preparation and Characterization of Lanthanum Carbonate Octahydrate for the Treatment of Hyperphosphatemia

    Directory of Open Access Journals (Sweden)

    Anqi He

    2013-01-01

    Full Text Available We proposed a new approach to prepare lanthanum carbonate via reactions between lanthanum chloride and NaHCO3. In the reaction, small amount of NaHCO3 solution was firstly added to the acidic lanthanum chloride solution to generate lanthanum carbonate nuclei and then NaHCO3 is added to the lanthanum chloride at a constant speed. This approach makes both precipitation reaction and neutralization reaction take place simultaneously. Consequently, lanthanum carbonate is produced at low pH environment (pH below 4.0 so that the risk of generating lanthanum carbonate hydroxide is reduced. The product of the above reaction is validated by EDTA titration, elemental analysis, and XRD characterization. In addition, we established a FTIR spectroscopic method to identify La(OHCO3 from La2(CO32·8H2O. Lanthanum carbonate exhibits considerable ability to bind phosphate.

  10. Near fifty percent sodium substituted lanthanum manganites—A potential magnetic refrigerant for room temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Sethulakshmi, N.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Al-Omari, I. A. [Department of Physics, Sultan Qaboos University, PC 123 Muscat, Sultanate of Oman (Oman); Suresh, K. G. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2014-03-03

    Nearly half of lanthanum sites in lanthanum manganites were substituted with monovalent ion-sodium and the compound possessed distorted orthorhombic structure. Ferromagnetic ordering at 300 K and the magnetic isotherms at different temperature ranges were analyzed for estimating magnetic entropy variation. Magnetic entropy change of 1.5 J·kg{sup −1}·K{sup −1} was observed near 300 K. An appreciable magnetocaloric effect was also observed for a wide range of temperatures near 300 K for small magnetic field variation. Heat capacity was measured for temperatures lower than 300 K and the adiabatic temperature change increases with increase in temperature with a maximum of 0.62 K at 280 K.

  11. Preparation of lanthanum sulfide nanoparticles by thermal decomposition of lanthanum complex

    Institute of Scientific and Technical Information of China (English)

    LI Peisen; LI Huanyong; JIE Wanqi

    2011-01-01

    γ-La2S3 nanoparticles were successfully prepared by thermal decomposition of lanthanum complex La(Et2S2CN)3·phen at low temperature. The obtained sample was characterized by the X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and element analysis. The decomposition mechanism of lanthanum complex was studied by thermogravimetric analyses (TGA). The results showed that the obtained samples were cubic phase particles with uniform sizes among 10-30 nm and γ-La2S3 was prepared by decomposition of La(Et2S2CN)3 phen via La4(Et2S2CN)3 as an intermediate product. The band gap of γ-La2S3 was 2.97 eV, which was bigger than bulk crystal because of pronounced quantum confinement effect.

  12. Synthesis and investigation of saturated vapor pressure of lanthanum, praseodymium and neodymium tris-isopropylcyclopentadienyls

    International Nuclear Information System (INIS)

    Devyatykh, G.G.; Chernyaev, N.P.; Zverev, Yu.B.; Gavrishchuk, E.M.; Runovskaya, I.V.; Krupnova, Eh.F.; Chesnokova, S.G.

    1980-01-01

    Lanthanum, praseodymium and neodymium tris-isopropylcyclopentadienyls are synthesized with corresponding unhydrous chlorides in tetrahydrofuran solution. Saturated vapour pressure of substances obtained is studied in the 150-262 deg C range by the statistic method using a compensation zero-manometer. Vapour pressure of the compounds in question is shown to increase with the growth of the rare earth element number [ru

  13. Impact of Annealing Temperature on the Physical Properties of the Lanthanum Deficiency Manganites

    Directory of Open Access Journals (Sweden)

    Skini Ridha

    2017-10-01

    Full Text Available The lanthanum deficiency manganites La0.8-x□xCa0.2MnO3 (x = 0, 0.1 and 0.2, where □ is a lanthanum vacancy, were prepared using the classic ceramic methods with different thermal treatments (1373 K and 973 K. The structural, magnetic, and magnetocaloric properties of these compounds were studied as a function of annealing temperature. It was noted that the annealing temperature did not affect the crystal structure of our samples (orthorhombic structure with Pnma space group. Nevertheless, a change in the variation of the unit cell volume V, the average bond length dMn–O, and the average bond angles θMn–O–Mn were observed. Magnetization versus temperature study has shown that all samples exhibited a magnetic transition from ferromagnetic (FM to paramagnetic (PM phase with increasing temperature. However, it can be clearly seen that the annealing at 973 K induced an increase of the magnetization. In addition, the magnetocaloric effect (MCE as well as the relative cooling power (RCP were estimated. As an important result, the values of MCE and RCP in our Lanthanum-deficiency manganites are reported to be near to those found in gadolinium, considered as magnetocaloric reference material.

  14. Fuel cells with doped lanthanum gallate electrolyte

    Science.gov (United States)

    Feng, Man; Goodenough, John B.; Huang, Keqin; Milliken, Christopher

    Single cells with doped lanthanum gallate electrolyte material were constructed and tested from 600 to 800°C. Both ceria and the electrolyte material were mixed with NiO powder respectively to form composite anodes. Doped lanthanum cobaltite was used exclusively as the cathode material. While high power density from the solid oxide fuel cells at 800°C was achieved. our results clearly indicate that anode overpotential is the dominant factor in the power loss of the cells. Better anode materials and anode processing methods need to be found to fully utilize the high ionic conductivity of the doped lanthanum galiate and achieve higher power density at 800°C from solid oxide fuel cells.

  15. Fuel cells with doped lanthanum gallate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Feng Man [Texas Univ., Austin, TX (United States). Center for Materials Science and Engineering; Goodenough, J.B. [Texas Univ., Austin, TX (United States). Center for Materials Science and Engineering; Huang Keqin [Texas Univ., Austin, TX (United States). Center for Materials Science and Engineering; Milliken, C. [Cerematec, Inc., Salt Lake City, UT (United States)

    1996-11-01

    Single cells with doped lanthanum gallate electrolyte material were constructed and tested from 600 to 800 C. Both ceria and the electrolyte material were mixed with NiO powder respectively to form composite anodes. Doped lanthanum cobaltite was used exclusively as the cathode material. While high power density from the solid oxide fuel cells at 800 C was achieved, our results clearly indicate that anode overpotential is the dominant factor in the power loss of the cells. Better anode materials and anode processing methods need to be found to fully utilize the high ionic conductivity of the doped lanthanum gallate and achieve higher power density at 800 C from solid oxide fuel cells. (orig.)

  16. High-temperature corrosion of lanthanum in equimole mixture of sodium and potassium chlorides

    International Nuclear Information System (INIS)

    Kochergin, V.P.; Obozhina, R.N.; Dragoshanskaya, T.I.; Startsev, B.P.

    1984-01-01

    Results of investigation into the process of lanthanum corrosion in the molted equimole NaCl-KCl mixture after the change of test time, temperature and lanthanum trichloride were summarized. It was shown that polarization of lanthanum anode in equimole NaCl-KCl melt is controlled by La 3+ diffusion from near-electrode layer to electrolyte depth, which results in decrease of corrosion rate in time. The established electrochemical properties of metallic lanthanum in equimole NaCl-KCl mixture must be considered when improving the technology of electrochemical production of lanthanum or its alloys of molten chlorides of lanthanum and alkaline metals

  17. Separation of lanthanum from nuclear fuel solutions by high performance liquid chromatography

    International Nuclear Information System (INIS)

    Lazar, G. C.; Petre, M.; Androne, G.; Benga, A.

    2016-01-01

    This paper presents the separation of uranium, praseodymium and lanthanum from nuclear fuel solutions by high performance liquid chromatography (HPLC). The aim of this study is to establish a minimum concentration of lanthanum which can be analyzed by high performance liquid chromatography, and also to study the effect of uranium concentration on the separation of praseodymium and lanthanum. Optimum gradient mode was established for mixture standard stoc solutions with uranium in a concentration of 1 mg/ml, praseodymium and lanthanum in a concentration range of 1-5 μg/ml from each element. These conditions were applied for the separation of lanthanum from a nuclear fuel solution in which praseodymium and lanthanum were added in a concentration of 3 μg/ml from each element. The elution behavior of lanthanum as a function of the pH and the concentration of the mobile phase, using a mixture of 1-octanesulfonic acid sodium salt with a-hidroxyisobutiric acid is presented. (authors)

  18. The effect of lanthanum applications on drought tolerance in barley

    International Nuclear Information System (INIS)

    Buckingham, S.; Maheswaran, J.; Peverill, K.; Meehan, B.; Stokes, J.

    1998-01-01

    Full text: Glasshouse investigations carried out by the authors on both perlite and soil, have repeatedly shown that several plant species, when treated with lanthanum, retain greater amounts of moisture under water stressed conditions. Dry matter increases under water stress have been observed in some cases. Barley plants watered to 50% field capacity, and show-ing signs of water stress, yielded 18% more dry matter when treated with 5 kg/ha and 10 kg/ha of lanthanum than control plants (P<0.05). The results of these experiments suggest that increased dry matter production in crops under periods of water stress, is likely when previously treated with lanthanum. Consequently, it is conceivable that lanthanum may have potential as an agent that induces drought tolerance in grain crops, grown in low rainfall areas. Subsequent field trials using barley as a test crop at Walpeup, in the Mallee region of Victoria have shown that in a below average rainfall year, combined soil and foliar applications of lanthanum can significantly increase grain yield. This effect was not evident when barley grown on the same soil type was treated with lanthanum under above average rainfall conditions

  19. Lanthanum trilactate: Vibrational spectroscopic study - infrared/Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Švecová, M.; Novák, Vít; Bartůněk, V.; Člupek, M.

    2016-01-01

    Roč. 87, Nov (2016), s. 123-128 ISSN 0924-2031 Institutional support: RVO:61388963 Keywords : lanthanum trilactate * tris(2-hydroxypropanoato-O1,O2) * lanthanum tris[2-(hydroxy-kappa O)propanoato-kappa O] * Raman spectra * infrared spectra * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.740, year: 2016

  20. Hydrophilic block copolymer-directed growth of lanthanum hydroxide nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Bouyer, F.; Sanson, N.; Gerardin, C. [Laboratoire de Materiaux Catalytiques et Catalyse en Chimie Organique, UMR 5618 CNRS-ENSCM-UM1, FR 1878, Institut Gerhardt, 34 - Montpellier (France); Destarac, M. [Centre de Recherches Rhodia Aubervilliers, 93 - Aubervilliers (France)

    2006-03-15

    Stable hairy lanthanum hydroxide nano-particles were synthesized in water by performing hydrolysis and condensation reactions of lanthanum cations in the presence of double hydrophilic poly-acrylic acid-b-polyacrylamide block copolymers (PAA-b-PAM). In the first step, the addition of asymmetric PAA-b-PAM copolymers (M{sub w,PAA} {<=} M{sub w,PAM}) to lanthanum salt solutions, both at pH = 5.5, induces the formation of monodispersed micellar aggregates, which are predominantly isotropic. The core of the hybrid aggregates is constituted of a lanthanum polyacrylate complex whose formation is due to bidentate coordination bonding between La{sup 3+} and acrylate groups, as shown by ATR-FTIR experiments and pH measurements. The size of the micellar aggregates depends on the molecular weight of the copolymer but is independent of the copolymer to metal ratio in solution. In the second step, the hydrolysis of lanthanum ions is induced by addition of a strong base such as sodium hydroxide. Either flocculated suspensions or stable anisotropic or spherical nano-particles of lanthanum hydrolysis products were obtained depending on the metal complexation ratio [acrylate]/[La]. The variation of that parameter also enables the control of the size of the core-corona nano-particles obtained by lanthanum hydroxylation. The asymmetry degree of the copolymer was shown to influence both the size and the shape of the particles. Elongated particles with a high aspect ratio, up to 10, were obtained with very asymmetric copolymers (M{sub w,PAM}/M{sub w,PAA}{>=}10) while shorter rice grain-like particles were obtained with a less asymmetric copolymer. The asymmetry degree also influences the value of the critical metal complexation degree required to obtain stable colloidal suspensions of polymer-stabilized lanthanum hydroxide. (authors)

  1. Lanthanum titanium perovskite compound: Thin film deposition and high frequency dielectric characterization

    International Nuclear Information System (INIS)

    Le Paven, C.; Lu, Y.; Nguyen, H.V.; Benzerga, R.; Le Gendre, L.; Rioual, S.; Benzegoutta, D.; Tessier, F.; Cheviré, F.

    2014-01-01

    Perovskite lanthanum titanium oxide thin films were deposited on (001) MgO, (001) LaAlO 3 and Pt(111)/TiO 2 /SiO 2 /(001)Si substrates by RF magnetron sputtering, using a La 2 Ti 2 O 7 homemade target sputtered under oxygen reactive plasma. The films deposited at 800 °C display a crystalline growth different than those reported on monoclinic ferroelectric La 2 Ti 2 O 7 films. X-ray photoelectron spectroscopy analysis shows the presence of titanium as Ti 4+ ions, with no trace of Ti 3+ , and provides a La/Ti ratio of 1.02. The depositions being performed from a La 2 Ti 2 O 7 target under oxygen rich plasma, the same composition (La 2 Ti 2 O 7 ) is proposed for the deposited films, with an unusual orthorhombic cell and Cmc2 1 space group. The films have a textured growth on MgO and Pt/Si substrates, and are epitaxially grown on LaAlO 3 substrate. The dielectric characterization displays stable values of the dielectric constant and of the losses in the frequency range [0.1–20] GHz. No variation of the dielectric constant has been observed when a DC electric field up to 250 kV/cm was applied, which does not match a classical ferroelectric behavior at high frequencies and room temperature for the proposed La 2 Ti 2 O 7 orthorhombic phase. At 10 GHz and room temperature, the dielectric constant of the obtained La 2 Ti 2 O 7 films is ε ∼ 60 and the losses are low (tanδ < 0.02). - Highlights: • Lanthanum titanium oxide films were deposited by reactive magnetron sputtering. • A La 2 Ti 2 O 7 chemical composition is proposed, with an unusual orthorhombic cell. • At 10 GHz, the dielectric losses are lower than 0.02. • No variation of the dielectric constant is observed under DC electric biasing

  2. Cytocompatibility of a free machining titanium alloy containing lanthanum.

    Science.gov (United States)

    Feyerabend, Frank; Siemers, Carsten; Willumeit, Regine; Rösler, Joachim

    2009-09-01

    Titanium alloys like Ti6Al4V are widely used in medical engineering. However, the mechanical and chemical properties of titanium alloys lead to poor machinability, resulting in high production costs of medical products. To improve the machinability of Ti6Al4V, 0.9% of the rare earth element lanthanum (La) was added. The microstructure, the mechanical, and the corrosion properties were determined. Lanthanum containing alloys exhibited discrete particles of cubic lanthanum. The mechanical properties and corrosion resistance were slightly decreased but are still sufficient for many applications in the field of medical engineering. In vitro experiments with mouse macrophages (RAW 264.7) and human bone-derived cells (MG-63, HBDC) were performed and revealed that macrophages showed a dose response below and above a LaCl3 concentration of 200 microM, while MG-63 and HBDC tolerated three times higher concentrations without reduction of viability. The viability of cells cultured on disks of the materials showed no differences between the reference and the lanthanum containing alloy. We therefore propose that lanthanum containing alloy appears to be a good alternative for biomedical applications, where machining of parts is necessary.

  3. Investigation of lanthanum- and neodymium ion interaction with potassium polyphosphate in aqueous solution

    International Nuclear Information System (INIS)

    Ezhova, Zh.A.; Tananaev, I.V.; Koval', E.M.

    1983-01-01

    A study was made on the interaction in the LaCl 3 -KPO 3 -H 2 O and NdCl 3 -KPO 3 -H 2 O systems at 0 deg C by methods of solubility of residual concentrations and measurement of the pH value. The formation of binary KLa 2 (PO 3 ) 7 x10H 2 O and KLa(PO 3 ) 4 X5H 2 O lanthanum- and potassium polyphosphates, as well as KNd 2 (PO 3 ) 7 X10H 2 O and KNd(PO 3 ) 4 X5H 2 O neodymium- apd potassiUm polyphasphates was established. Chemical, paper-chromatographic, infrared spectroscopic, X-ray diffraction and differential thermal analyses of the prepared compoUnds were conducted. Anhydrous binary lanthanum- and neodymium polyphosphates with potassium-=Kla(PO 3 ) 4 , KNd(PO 3 ) 4 , KLa 2 (PO 3 ) 7 and KNd 2 x(PO 3 ) 7 - eere prepared

  4. Synthesis and Stability of Lanthanum Superhydrides

    Energy Technology Data Exchange (ETDEWEB)

    Geballe, Zachary M. [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Liu, Hanyu [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Mishra, Ajay K. [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Permanent address: HP& SRPD, Bhabha Atomic Research Center, Mumbai-85 India; Ahart, Muhtar [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Somayazulu, Maddury [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Meng, Yue [HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne IL 60439 USA; Baldini, Maria [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Hemley, Russell J. [Institute of Materials Science and Department of Civil and Environmental Engineering, The George Washington University, Washington DC 20052 USA

    2017-12-15

    Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH10 having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1 Å, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized.

  5. Lanthanum titanium perovskite compound: Thin film deposition and high frequency dielectric characterization

    Energy Technology Data Exchange (ETDEWEB)

    Le Paven, C., E-mail: claire.lepaven@univ-rennes1.fr [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Lu, Y. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Nguyen, H.V. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); CEA LETI, Minatec Campus, 38054 Grenoble (France); Benzerga, R.; Le Gendre, L. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Rioual, S. [Laboratoire de Magnétisme de Brest (EA CNRS 4522), Université de Bretagne Occidentale, 29000 Brest (France); Benzegoutta, D. [Institut des Nanosciences de Paris (INSP, UMR CNRS 7588), Université Pierre et Marie Curie, 75005 Paris (France); Tessier, F.; Cheviré, F. [Institut des Sciences Chimiques de Rennes (ISCR, UMR-CNRS 6226), Equipe Verres et Céramiques, Université de Rennes 1, 35000 Rennes (France); and others

    2014-02-28

    Perovskite lanthanum titanium oxide thin films were deposited on (001) MgO, (001) LaAlO{sub 3} and Pt(111)/TiO{sub 2}/SiO{sub 2}/(001)Si substrates by RF magnetron sputtering, using a La{sub 2}Ti{sub 2}O{sub 7} homemade target sputtered under oxygen reactive plasma. The films deposited at 800 °C display a crystalline growth different than those reported on monoclinic ferroelectric La{sub 2}Ti{sub 2}O{sub 7} films. X-ray photoelectron spectroscopy analysis shows the presence of titanium as Ti{sup 4+} ions, with no trace of Ti{sup 3+}, and provides a La/Ti ratio of 1.02. The depositions being performed from a La{sub 2}Ti{sub 2}O{sub 7} target under oxygen rich plasma, the same composition (La{sub 2}Ti{sub 2}O{sub 7}) is proposed for the deposited films, with an unusual orthorhombic cell and Cmc2{sub 1} space group. The films have a textured growth on MgO and Pt/Si substrates, and are epitaxially grown on LaAlO{sub 3} substrate. The dielectric characterization displays stable values of the dielectric constant and of the losses in the frequency range [0.1–20] GHz. No variation of the dielectric constant has been observed when a DC electric field up to 250 kV/cm was applied, which does not match a classical ferroelectric behavior at high frequencies and room temperature for the proposed La{sub 2}Ti{sub 2}O{sub 7} orthorhombic phase. At 10 GHz and room temperature, the dielectric constant of the obtained La{sub 2}Ti{sub 2}O{sub 7} films is ε ∼ 60 and the losses are low (tanδ < 0.02). - Highlights: • Lanthanum titanium oxide films were deposited by reactive magnetron sputtering. • A La{sub 2}Ti{sub 2}O{sub 7} chemical composition is proposed, with an unusual orthorhombic cell. • At 10 GHz, the dielectric losses are lower than 0.02. • No variation of the dielectric constant is observed under DC electric biasing.

  6. Bio-accumulation of lanthanum from lanthanum modified bentonite treatments in lake restoration

    NARCIS (Netherlands)

    Waajen, G.; Van Oosterhout, F.; Lürling, M.

    2017-01-01

    Abstract Lanthanum (La) modified bentonite (LMB) is one of the available mitigating agents used for the reduction of the phosphorus (P) recycling in eutrophic lakes. The potential toxicity of the La from LMB to aquatic organisms is a matter of concern. In this study the accumulation of La was

  7. Electrochemical reduction of lanthanum trichloride in a molten equimolar mixture of sodium and potassium chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Glagolevskaya, A.L.; Kuznetsov, S.A.; Polyakov, E.G.; Stangrit, P.T.

    1987-09-20

    The authors used linear voltamperometry for the investigation of the mechanism for the cathodic reduction of lanthanum. The mechanism for the cathodic reduction of lanthanum chloride in molten equimolar NaCl-KCl may be seen as consisting of a slow irreversible electrode reaction with a subsequent rapid irreversible chemical reaction. Lanthanum ions in a lower oxidation state were not found upon the prolonged maintenance of metallic lanthanum in molten NaCl-KCl-LaCl/sub 3/. Only an increase in the concentration of lanthanum(III) chloride in the melt was noted. The appearance of oxygen anions in the melt does not lead to a change in the mechanism of the cathodic reduction of lanthanum chloride but reduces the concentration of this chloride due to the formation of lanthanum oxochloride which is insoluble in the melt.

  8. Silica doped with lanthanum sol–gel thin films for corrosion protection

    International Nuclear Information System (INIS)

    Abuín, M.; Serrano, A.; Llopis, J.; García, M.A.; Carmona, N.

    2012-01-01

    We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol–gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: ► Silica sol–gel films doped with lanthanum ions were synthesized. ► Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. ► La-acetate is an affordable chemical reactive preferred for the industry. ► Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. ► An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  9. LANTHANUM STAINING OF THE SURFACE COAT OF CELLS

    Science.gov (United States)

    Shea, Stephen M.

    1971-01-01

    Among the techniques which have been reported to stain the surface coat of cells, for electron microscopy, is lanthanum staining en bloc. Similarly, the presence of the cationic dye, Alcian blue 8GX, in a primary glutaraldehyde fixative has been reported to improve the preservation of the surface coat of cells of many types; however, the preserved coat is not very electron opaque unless thin sections are counterstained. The present paper shows that for several rat tissues lanthanum staining en bloc is an effective electron stain for the cell surface, giving excellent contrast, if combined sequentially with prefixation in an aldehyde fixative containing Alcian blue. The cationic substance cetylpyridinium chloride was found to have a similar effect to that of Alcian blue in enhancing the lanthanum staining of the surface coat material of the brush border of intestinal epithelial cells. The patterns of lanthanum staining obtained for the tissues studied strikingly resemble those reported in the literature where tissues are stained by several standard methods for demonstrating mucosubstances at the ultrastructural level. This fact and the reproduction of the effect of Alcian blue by cetylpyridinium chloride constitute a persuasive empirical argument that the material visualized is a mucopolysaccharide or mucopolysaccharide-protein complex. PMID:4108476

  10. Determination of main components in lanthanum titanates blend

    International Nuclear Information System (INIS)

    Sizonenko, T.N.; Timchenko, A.K.

    1981-01-01

    Conditions for complexonometric determination of lanthanum in the presence of titanium using the disguising of the latter are studied. A method is suggested for lanthanum and titanium determination in a blend of lanthanum titanate which is used to grow monocrystals. Sulfosalicylic acid is chosen as a disguising agent. La has been determined by complexonometric titration using EDTA with xylenol orange in urotropin. The total contents of La and Ti have been determined by titration of EDTA excess with standard solution of zinc sulfate. Ti content has been calculated from the difference between the first two determinations. Reproducibility of Ti and La determination in the blend (n=21) is characterized by the following: at 19.73% La and 57.21% Ti there are (19.72+-0.16)% La and (57.10+-0.22)% Ti, Sr equals 0.0071 and 0.0034, respectively

  11. Synthesis and stability of lanthanum superhydrides

    Energy Technology Data Exchange (ETDEWEB)

    Geballe, Zachary M.; Liu, Hanyu; Mishra, Ajay K.; Ahart, Muhtar; Somayazulu, Maddury; Baldini, Maria [Geophysical Laboratory, Carnegie Institution, Washington, DC (United States); Meng, Yue [HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, IL (United States); Hemley, Russell J. [Institute of Materials Science and Department of Civil and Environmental Engineering, The George Washington University, Washington, DC (United States)

    2018-01-15

    Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH{sub 10} having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1 Aa, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Evolution of the local environment of lanthanum during simplified SON68 glass leaching

    International Nuclear Information System (INIS)

    Jollivet, P.; Delaye, J.M.; Den Auwer, C.; Simoni, E.

    2007-01-01

    The evolution of the short- and medium-range local environment of lanthanum was determined by L-III-edge X-ray absorption spectroscopy (XAS) during leaching of simplified SON68-type glasses. In glass without phosphorus, lanthanum is found in a silicate environment, and its first coordination sphere comprises eight oxygen atoms at a mean distance of 2.51 angstrom. When this glass was leached at a high renewal rate, the lanthanum local environment was significantly modified: it was present at hydroxy-carbonate and silicate sites with a mean La-O distance of 2.56 angstrom, and the second neighbors consisted of La atoms instead of Si for the glass. Conversely, in the gel formed at low renewal rates, lanthanum was found in a silicate environment similar to that of the glass. In phosphorus-doped glass, lanthanum is found in a phosphate environment, although the Si/P atomic ratio is 20:1. Lanthanum is surrounded by seven oxygen atoms at a mean distance of 2.37 angstrom. When phosphorus-doped glass is leached, regardless of the leaching solution flow rate, the short- and medium-range lanthanum local environment remains almost constant; the most significant change is a 0.05 angstrom increase in the La-O distance. (authors)

  13. Lanthanum triflate triggered synthesis of tetrahydroquinazolinone derivatives of N-allyl quinolone and their biological assessment

    Directory of Open Access Journals (Sweden)

    Jardosh Hardik H.

    2012-01-01

    Full Text Available A series of 24 derivatives of tetrahydroquinazolinone has been synthesized by one-pot cyclocondensation reaction of N-allyl quinolones, cyclic β-diketones and (thiourea/N-phenylthiourea in presence of lanthanum triflate catalyst. This methodology allowed us to achieve the products in excellent yield by stirring at room temperature. All the synthesized compounds were investigated against a representative panel of pathogenic strains using broth microdilution MIC (minimum inhibitory concentration method for their in vitro antimicrobial activity. Amongst these sets of heterocyclic compounds 5h, 6b, 6h, 5f, 5l, 5n and 6g found to have admirable activity.

  14. Silica doped with lanthanum sol-gel thin films for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Abuin, M. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Serrano, A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); Llopis, J. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Garcia, M.A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); IMDEA Nanoscience, Fco. Tomas y Valiente 7, 28049 Madrid (Spain); Carmona, N., E-mail: n.carmona@fis.ucm.es [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain)

    2012-06-01

    We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol-gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: Black-Right-Pointing-Pointer Silica sol-gel films doped with lanthanum ions were synthesized. Black-Right-Pointing-Pointer Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. Black-Right-Pointing-Pointer La-acetate is an affordable chemical reactive preferred for the industry. Black-Right-Pointing-Pointer Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. Black-Right-Pointing-Pointer An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  15. The evolution mechanism of the dislocation loops in irradiated lanthanum doped cerium oxide

    International Nuclear Information System (INIS)

    Miao, Yinbin; Aidhy, Dilpuneet; Chen, Wei-Ying; Mo, Kun; Oaks, Aaron; Wolf, Dieter; Stubbins, James F.

    2014-01-01

    Cerium dioxide, a non-radioactive surrogate of uranium dioxide, is useful for simulating the radiation responses of uranium dioxide and mixed oxide fuel (MOX). Controlled additions of lanthanum can also be used to form various levels of lattice oxide or anion vacancies. In previous transmission electron microscopy (TEM) experimental studies, the growth rate of dislocation loops in irradiated lanthanum doped ceria was reported to vary with lanthanum concentration. This work reports findings of the evolution mechanisms of the dislocation loops in cerium oxide with and without lanthanum dopants based on a combination of molecular statics and molecular dynamics simulations. These dislocation loops are found to be b=1/3〈111〉 interstitial type Frank loops. Calculations of the defect energy profiles of the dislocation loops with different structural configurations and radii reveal the basis for preference of nucleation as well as the driving force of growth. Frenkel pair evolution simulations and displacement cascade overlaps simulations were conducted for a variety of lanthanum doping conditions. The nucleation and growth processes of the Frank loop were found to be controlled by the mobility of cation interstitials, which is significantly influenced by the lanthanum doping concentration. Competition mechanisms coupled with the mobility of cation point defects were discovered, and can be used to explain the lanthanum effects observed in experiments

  16. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    Science.gov (United States)

    Fries, B.A.

    1959-11-10

    A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

  17. Adsorption of lithium-lanthanum films on W (112) face

    International Nuclear Information System (INIS)

    Gupalo, M.S.; Smereka, T.P.; Palyukh, B.M.; Babkin, G.V.

    1986-01-01

    The method of contact potential difference is employed to study the electron adsorption properties (the work function phi and adsorption heat q) lithium films on a lanthanized W(112) surface. It is found that the work function of mixed lithium-lanthanum films is intermediate between phi of the summands. The presence of lanthanum on a W(112) face reduces the adsorption heat of lithium

  18. Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, Emerson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: camargo@ufscar.br; Barrado, Cristiano M. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil); Ribeiro, Caue [EMBRAPA Instrumentacao Agropecuaria, Rua XV de Novembro 1452, Sao Carlos SP 13560-970 (Brazil)], E-mail: caue@cnpdia.embrapa.br; Longo, Elson [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP-Sao Paulo State University, Rua Francisco Degni, CP 355, Araraquara SP 14801-907 (Brazil)], E-mail: elson@iq.unesp.br; Leite, Edson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: derl@power.ufscar.br

    2009-05-05

    For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm{sup -1} and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

  19. Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Camargo, Emerson R.; Barrado, Cristiano M.; Ribeiro, Caue; Longo, Elson; Leite, Edson R.

    2009-01-01

    For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm -1 and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

  20. Distribution of lanthanum and neodymium in Di(2-ethlhexyl) phosphoric acid and tributylphosphate

    International Nuclear Information System (INIS)

    Kraikaew, J.; Suparith, N.; Pruantonsai, P.

    1994-01-01

    Lanthanum and neodymium are among the high quantity elements in mixed rare earth from monazite processing. The popular rare earth separation process is liquid-liquid extraction. This research was carried out to study lanthanum and neodymium distribution in two extractants, di(2-ethylhexyl) phosphoric acid and tributylphosphate. The experimental results show that neodymium distributes in both extractants better than lanthanum. The distribution of both elements are higher at low acidity than at high acidity. Quick and rough investigation by calculating the ratio of distribution coefficient of neodymium to lanthanum in each extractant indicated that La-nd separation efficiency of Di(2-ethylhexyl) phosphoric acid is higher than that of tributylphosphate

  1. Pressure behaviour of the superconducting transition temperature of lanthanum

    International Nuclear Information System (INIS)

    Glocker, R.

    1977-01-01

    The dissertation has the following chapters: 1) Introduction, 2) Fundamentals of the microscopic theory of superconductivity, 3) Calculation of the first momentum of the Eliashberg function, 4) Determination of the average values of frequency, 5) The relativistic cellular method and its application to lanthanum, 6) Results of the calculation of the electron-phonon coupling cosntants for f.c.c. lanthanum, 7) Phonon dispersion and phonon state density. (orig.) [de

  2. Functionalization of lanthanum hydroxide nanowires by atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Zhou Mi; Yuan Jinying; Yuan Weizhong; Yin Yingwu; Hong Xiaoyin

    2007-01-01

    Atom transfer radical polymerization (ATRP) has been used to prepare a core-shell hybrid nanostructure successfully: a hard core of single-crystalline lanthanum hydroxide nanowires and a soft shell of polystyrene (PS) brushes. Transmission electron microscopy (TEM) images indicated that the resulting products presented special structures and different thicknesses of polymer layers. The chemical components and grafted PS quantities of the samples were measured by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The polymers showed narrow polydispersity, which proved that the lanthanum hydroxide nanowires initiated the 'living'/controlled polymerization of styrene. With the modifiability of lanthanum hydroxide nanowires, the solubility increased, which affords a new way to functionalize nanowires

  3. Spectrophotometric study of the complexation equilibria of lanthanum(III) with 1,4-bis(4'-methylanilino)anthraquinone and the determination of lanthanum(III)

    International Nuclear Information System (INIS)

    Idriss, K.A.-R; El-Shahawy, A.S.; Sedaira, H.; Harfoush, A.A.

    1985-01-01

    The complexation equilibria of lanthanum(III) with 1,4-bis(4'-methylanilino)anthraquinone (Quinizarin Green) were studied spectrophotometrically in 40% V/V dimethylformamide using graphical analysis of the absorbance curves. The reaction mechanism of lanthanum with the bisarylaminoanthraquinone dye within the pH range 6 to 9.25 was demonstrated. The thermodynamic stabilities and the molar absorptivities of the complexes formed were determined. The optimum conditions for the spectrophotometric determination of La(III) with this reagent were found. (author)

  4. Fabrication of mesoporous and high specific surface area lanthanum carbide-carbon nanotube composites

    International Nuclear Information System (INIS)

    Biasetto, L.; Carturan, S.; Maggioni, G.; Zanonato, P.; Bernardo, P. Di; Colombo, P.; Andrighetto, A.; Prete, G.

    2009-01-01

    Mesoporous lanthanum carbide-carbon nanotube composites were produced by means of carbothermal reaction of lanthanum oxide, graphite and multi-walled carbon nanotube mixtures under high vacuum. Residual gas analysis revealed the higher reactivity of lanthanum oxide towards carbon nanotubes compared to graphite. After sintering, the composites revealed a specific surface area increasing with the amount of carbon nanotubes introduced. The meso-porosity of carbon nanotubes was maintained after thermal treatment.

  5. Effects of the wet air on the properties of the lanthanum oxide and lanthanum aluminate thin films

    International Nuclear Information System (INIS)

    Jun, Jin Hyung; Choi, Doo Jin

    2006-01-01

    Lanthanum oxide and lanthanum aluminate thin films were deposited on Si substrates. The as-grown films were stored in wet ambient and dry ambient for days and annealed after storage and also the structural and the electrical properties of the films were investigated. As the storage time increased, the La 2 O 3 films stored in wet ambient showed rapid reaction with moisture and the properties degraded. In case of the LAO films, although the thickness of the film also increased during hydration, the properties of the film did not so much changed due to the role of the incorporated aluminum. The LAO films showed better hydration resistance characteristics and so more suitable for conventional wet cleaning process in semiconductor fabrication

  6. Improvement of acid and base resistance of nickel phosphate pigment by the addition of lanthanum cation

    International Nuclear Information System (INIS)

    Onoda, Hiroaki; Matsui, Hironori; Tanaka, Isao

    2007-01-01

    Transition metal phosphates are used as inorganic pigments, however these materials had a weak point for acid and base resistance. Because lanthanum phosphate is insoluble in acidic and basic solution, the addition of lanthanum cation was tried for the improvement of the acid and base resistance of nickel phosphate pigment. The lanthanum-doped nickel phosphates were prepared from phosphoric acid, nickel nitrate, and lanthanum nitrate solution. The additional effects of lanthanum cation were studied on the chemical composition, particle shape and size distribution, specific surface area, color, acid and base resistance of the precipitations and their thermal products

  7. Analyzing relation between the radioactivity in lanthanum products and the origins of RE chlorides

    International Nuclear Information System (INIS)

    Wan Rongsheng

    2004-01-01

    Objective: To analyze the relation between the radioactivity in Lanthanum products and the origins of RE Chlorides. Methods: Using JY-38 plus sequential ICP spectrometer to examine the content of the uranium in the RE Chlorides. Using FJ-2603 low background alpha, beta measurement apparatus to measure total alpha and total beta activities of Lanthanum products. Results: The content of the uranium in the RE Chlorides is much lower in Baotou's than Hunan's. The radioactivity in Lanthanum products are made from the RE Chlorides of Baotou is much lower than that in Hunan's too. The radioactivity in Lanthanum products depends on the origins of RE Chlorides. Conclusion: The basic data were provided for radioactivity in Lanthanum products which are made from RE Chlorides of different places of China. The mathematical model was founded for the reasonable use of resource RE Chlorides

  8. Electrical conductivity studies of nanocrystalline lanthanum silicate synthesized by sol-gel route

    International Nuclear Information System (INIS)

    Nallamuthu, N.; Prakash, I.; Satyanarayana, N.; Venkateswarlu, M.

    2011-01-01

    Research highlights: → Nanocrystalline La 10 Si 6 O 27 material was synthesized by sol-gel method. → TG/DTA curves predicted the thermal behavior of the material. → FTIR spectra confirmed the formation of SiO 4 and La-O network in the La 10 Si 6 O 27 . → XRD patterns confirmed the formation of pure crystalline La 10 Si 6 O 27 phase. → The grain interior and the grain boundary conductivities are evaluated. - Abstract: Nanocrystalline apatite type structured lanthanum silicate (La 10 Si 6 O 27 ) sample was synthesized by sol-gel process. Thermal behavior of the dried gel of lanthanum silicate sample was studied using TG/DTA. The structural coordination of the dried gel of lanthanum silicate, calcined at various temperatures, was identified from the observed FTIR spectral results. The observed XRD patterns of the calcined dried gel were compared with the ICDD data and confirmed the formation of crystalline lanthanum silicate phase. The average crystalline size of La 10 Si 6 O 27 was calculated using the Scherrer formula and it is found to be ∼80 nm. The observed SEM images of the lanthanum silicate indicate the formation of the spherical particles and the existence of O, Si and La in the lanthanum silicate are confirmed from the SEM-EDX spectrum. The grain and grain boundary conductivities are evaluated by analyzing the measured impedance data, using winfit software, obtained at different temperatures, of La 10 Si 6 O 27 sample. Also, the observed grain and grain boundary conductivity behaviors of the La 10 Si 6 O 27 sample are analysed using brick layer model. The electrical permittivity and electrical modulus were calculated from the measured impedance data and were analyzed by fitting through the Havriliak and Negami function to describe the dielectric relaxation behavior of the nanocrystalline lanthanum silicate.

  9. Study of behaviour of lanthanum- and yttrium electrodes in chloride melts

    International Nuclear Information System (INIS)

    Shkol'nikov, S.I.; Tolypin, E.S.; Yur'ev, B.P.

    1984-01-01

    A study was made on the lanthanum- and yttrium behaviour in a mixture of molten potassium- and sodium chlorides at various temperatures. It is shown that the lanthanum- and yttrium behaviour in KCl-NaCl melt is similar to the behaviour of other metals. Their corrosion rate is much higher as compared to other metals and it grows rapidly with increasing melt temperature. The temperature growth by 200 deg C results in an increase in the corrosion rate almost by an order. The potentials of lanthanum- and yttrium electrodes at the instant they are immersed in the melt have more negative values than the potentials of alkali metals under similar conditions

  10. Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

    Science.gov (United States)

    Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

    2013-03-01

    Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis.

  11. Properties of gallium lanthanum sulphide glass

    OpenAIRE

    Bastock, P.; Craig, C.; Khan, K.; Weatherby, E.; Yao, J.; Hewak, D.W.

    2015-01-01

    A series of gallium lanthanum sulphide (GLS) glasses has been studied in order to ascertain properties across the entire glass forming region. This is the first comprehensive study of GLS glass over a wide compositional range.

  12. DFT Studies on Interaction between Lanthanum and Hydroxyamide

    Science.gov (United States)

    Pati, Anindita; Kundu, T. K.; Pal, Snehanshu

    2018-03-01

    Extraction and separation of individual rare earth elements has been a challenge as they are chemically very similar. Solvent extraction is the most suitable way for extraction of rare earth elements. Acidic, basic, neutral, chelating are the major classes of extractants for solvent extraction of rare earth elements. The coordination complex of chelating extractants is very selective with positively charged metal ion. Hence they are widely used. Hydroxyamide is capable of forming chelates with metal cations. In this present study interactions of hydroxyamide ligand with lanthanum have been investigated using density functional theory (DFT). Two different functional such as raB97XD and B3LYP are applied along with 6-31+G(d,p) basis set for carbon, nitrogen, hydrogen and SDD basis set for lanthanum. Stability of formed complexes has been evaluated based on calculated interaction energies and solvation energies. Frontier orbital (highest occupied molecular orbital or HOMO and lowest unoccupied molecular orbital or LUMO) energies of the molecule have also been calculated. Electronegativity, chemical hardness, chemical softness and chemical potential are also determined for these complexes to get an idea about the reactivity. From the partial charge distribution it is seen that oxygen atoms in hydroxyamide have higher negative charge. The double bonded oxygen atom present in the hydroxyamide structure has higher electron density and so it forms bond with lanthanum but the singly bonded oxygen atom in the hydroxyamide structure is weaker donor atom and so it is less available for interaction with lanthanum.

  13. PMR investigation into complexes of lanthanum and lutetium with ethylenediaminediacetic acid

    International Nuclear Information System (INIS)

    Kostromina, N.A.; Novikova, L.B.

    1975-01-01

    Proton resonance spectra of ethylendiaminediacetic acid (EDDA) and EDDA mixtures with La and Lu as function of pH of solution was studied. Sequence of EDDA (A 2- ) protonation was established; cations H 3 A + and H 4 A 2+ were found; dissociation constants of above mentioned cations were determined. Formation of H 2 LnA 3+ , HLnA 2+ and LnA + complexes in EDDA-Ln (1:1) system was found. Difference in the bonds mobility of lanthanum and lutetium complexes was determined: lanthanum forms complexes with labile, lutetium with non-labile bonds. Information on complexes structure is collected. Acid dissociation constants of protonated complexes of lanthanum with EDDA were determined

  14. Studies on the promotion of nickel—alumina coprecipitated catalysts: II. Lanthanum oxide

    NARCIS (Netherlands)

    Lansink Rotgerink, H.G.J.; Paalman, R.P.A.M.; van Ommen, J.G.; Ross, J.R.H.

    1988-01-01

    Two series of lanthanum promoted nickel—alumina catalysts have been prepared by coprecipitation of the metal nitrates, using potassium carbonate. The molar ratio between nickel and the sum of aluminium and lanthanum was kept constant at 2.5 or 9.0 within each series. The calcination and reduction of

  15. Cytotoxicity and genotoxicity of a monazite component: lanthanum effects on the viability and induction of breaks in the DNA of human lymphocytes

    International Nuclear Information System (INIS)

    Paiva, Amanda Valle de Almeida

    2007-01-01

    The Monazite is a mineral extracted from open mines. It is constituted by lanthanum element aggregated with cerium, yttrium and thorium [(Ce, La, Y, Th)PO 4 ]. Lanthanum (La) is a rare-earth metal with applications in agriculture, industry and medicine. Since lanthanides and their compounds show a broad spectrum of applications there is an increased risk of incorporation in human. Inhalation of aerosols containing La is the main route of incorporation in workers exposed to several chemical forms of La. Herein, we examined the effect of lanthanum nitrate - La(NO 3 ) 3 in human lymphocytes. JURKAT cells and human peripheral lymphocytes (HPL) were used to evaluate the effect of La(NO 3 ) 3 on viability (apoptosis or necrosis) and DNA strand breaks induction or/and alkali-labile sites (ALS). We demonstrate that La has a cytotoxic and genotoxic effect on both cell lines. The results indicate that necrosis is the pathway by which La(NO 3 ) 3 induces cytotoxicity. The vitamin E is able to diminish DNA strand breaks induced by La(NO 3 ) 3 suggesting that reactive oxygen species (ROS) may be involved in the genotoxic process. (author)

  16. Removal of Lanthanum (III) From Aqueous Solution Using Non-Living Water Hyacinth Roots

    International Nuclear Information System (INIS)

    Aly, A.; Amer, H.A.; Shawky, S.; Shawky, S.; Kandil, A.T.

    2013-01-01

    Removal of lanthanum (III) from aqueous solution using dried roots of water hyacinth (Eichhornia crassipes) has been investigated. The roots have been characterized by determining the ash percentage, the ph of the slurry, the elemental composition, the thermal gravimetric analysis, the surface area, the pore size, the zeta potential and ph of zero point charge. A surface area of 128 m 2 /g has been found and the micropore structure of the roots has been confirmed. Zeta potential and ph of zero point charge of the roots surfaces showed that they are positively charged within the ph range from 2 to 7.5. Sorption is rapid and depends on ph, weight of roots, concentration of lanthanum (III) and ionic strength. The sorption of lanthanum (III) was confirmed by scanning electron microscope, energy dispersive spectroscopy and the release of Ca +2 , Mg +2 and K +1 after sorption of lanthanum (III) have been indicated an ion exchange mechanism. Fourier transform infrared spectra indicated surface complexation mechanism, and sorption isotherms and kinetics were discussed. The roots were tested for removal of radioactive lanthanum ( 140 La) from simulated radioactive waste. Accepted June 2013.

  17. Strengthening and elongation mechanism of Lanthanum-doped Titanium-Zirconium-Molybdenum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Ping, E-mail: huping1985@126.com [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Jinduicheng Molybdenum Co., Ltd., Xi’an 710068 (China); Hu, Bo-liang; Wang, Kuai-she; Song, Rui; Yang, Fan [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Yu, Zhi-tao [Ruifulai Tungsten & Molybdenum Co., Ltd., Xi’an 721914 (China); Tan, Jiang-fei [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Cao, Wei-cheng; Liu, Dong-xin; An, Geng [Jinduicheng Molybdenum Co., Ltd., Xi’an 710068 (China); Guo, Lei [Ruifulai Tungsten & Molybdenum Co., Ltd., Xi’an 721914 (China); Yu, Hai-liang [School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, NSW 2522 (Australia)

    2016-12-15

    The microstructural contributes to understand the strengthening and elongation mechanism in Lanthanum-doped Titanium-Zirconium-Molybdenum alloy. Lanthanum oxide particles not only act as heterogeneous nucleation core, but also act as the second phase to hinder the grain growth during sintering crystallization. The molybdenum substrate formed sub-grain under the effect of second phase when the alloy rolled to plate.

  18. Improved adaptation of test with lanthanum nitrate for the colorimetric estimation of acetate

    Energy Technology Data Exchange (ETDEWEB)

    Szumilo, T [Akademia Medyczna, Lublin (Poland)

    1976-01-01

    A colorimetric method for the determination of acetate based on the production of the blue complex between iodine and lanthanum alkaline acetate has been developed. Optimum concentrations of reagents (acetate, lanthanum nitrate, iodine and ammonia) as well as the volume of acetate were selected to achieve best colour intensity. Coloured complex was stabilized by dilution of reagent mixture with water to the final volume convenient for determinaton. Absorbance of the complex can be measured immediately after dilution and any changes can be observed during at least 15 minutes. Elevation of temperature over 60/sup 0/decreases absorbance. The method fulfills the Beer's law in the range 1,5-3,5 ..mu..moles of acetate, precision of the method 2/sup +/ = 3,7%. Apart from acetate - propionate and fluoroacetate complex is 620 nm, propionate complex - at 590 nm. Propionate complex displayed any relationship between concentration and absorbance. Potassium, sodium, lithium and barium acetates give the identical results as acetic acid, whereas zinc and cupric acetates failed to react. Other derivatives tested, e.g. chloroacetate, trichloroacetate, iodoacetate, chloroporpionate and butyrate are unable to form the coloured complexes. Many compounds interfere with the formation of acetate complex, therefore, in material containing impurities acetate can be determined after purificaton by means of described in literature methods.

  19. Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Alexandre H. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Souza, Flavio L., E-mail: flavio.souza@ufabc.edu.br [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adelia 166, Bangu, Santo Andre, SP 09210-170 (Brazil); Chiquito, Adenilson J., E-mail: chiquito@df.ufscar.br [Departamento de Fisica, UFSCar-Federal University of Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Longo, Elson, E-mail: elson@iq.unesp.br [Instituto de Quimica de Araraquara, UNESP-Universidade Estadual Paulista, Rua Francisco Degni, CP 355 Araraquara, SP 14801-907 (Brazil); Leite, Edson R., E-mail: derl@power.ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Camargo, Emerson R., E-mail: camargo@ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil)

    2010-12-01

    Nanosized powders of lead lanthanum titanate (Pb{sub 1-x}La{sub x}TiO{sub 3}) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

  20. Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Pinto, Alexandre H.; Souza, Flavio L.; Chiquito, Adenilson J.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.

    2010-01-01

    Nanosized powders of lead lanthanum titanate (Pb 1-x La x TiO 3 ) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

  1. Signal amplification of dopamine using lanthanum hexacyanoferrate ...

    Indian Academy of Sciences (India)

    rare earth metal hexacyanoferrates, for e.g., lanthanum ... to facilitate the electrochemical reactions of biological molecules.9,10 In general ... bic acid and potassium hexacyanoferrate (Merck) were ... were prepared using doubly distilled water.

  2. Specific heat studies of lanthanum and yttrium sesquicarbides

    International Nuclear Information System (INIS)

    Cort, B.; Stewart, G.R.; Giorgi, A.L.

    1984-01-01

    The specific heats of the sesquicarbides LaC/sub 1.35/ and La/sub 0.9/Th/sub 0.1/C/sub 1.6/ (prepared by arc melting) and YC/sub 1.35/ (prepared by a high-pressure technique) have been measured for the first time. No bulk specific heat anomaly appears in either lanthanum compounds, even though (1) inductively measured superconducting transition temperatures are respectively high (11.0 K for LaC/sub 1.35/ and 12.7 K for La/sub 0.9/Th/sub 0.1/C/sub 1.6/) and (2) YC/sub 1.35/ is a bulk superconductor with a T/sub c/ = 10.5 K and Y/sub 0.7/Th/sub 0.3/C/sub 1.58/ (also prepared by high pressure) was previously reported to be a bulk superconductor with a T/sub c/ = 17.1 K. The apparent correlation with preparation technique is discussed

  3. Leaching behavior of lanthanum, nickel and iron from spent catalyst using inorganic acids

    Science.gov (United States)

    Astuti, W.; Prilitasari, N. M.; Iskandar, Y.; Bratakusuma, D.; Petrus, H. T. B. M.

    2018-01-01

    Highly technological applications of rare earth metals (REs) and scarcity of supply have become an incentive torecover the REs from various resources, which include high grade and low grade ores, as well as recycledwaste materials. Spent hydrocracking catalyst contain lanthanum and a variety of valuable metals such as nickel and iron. This study investigated the recovery of lanthanum, nickel and iron from spent hydrocracking catalyst by leaching using various inorganic acid (sulfuric acid, hydrochloric acid, and nitric acid). The effect of acid concentration, type of acid and leaching temperature was conducted to study the leaching behavior of each valuable metal from spent-catalyst. It has been shown that it is possible to recover more than 90% of lanthanum, however the leaching efficiency of nickel and iron in this process was very low. It can be concluded that the leaching process is selective for lanthanum recovery from hydrocracking spent-catalyst.

  4. Eutrophication management in surface waters using lanthanum modified bentonite

    DEFF Research Database (Denmark)

    Copetti, Diego; Finsterle, Karin; Marziali, Laura

    2016-01-01

    This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The availa......This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales....... The available data underline a high efficiency for phosphorus binding. This efficiency can be limited by the presence of humic substances and competing oxyanions. Lanthanum concentrations detected during a LMB application are generally below acute toxicological threshold of different organisms, except in low...... alkalinity waters. To date there are no indications for long-term negative effects on LMB treated ecosystems, but issues related to La accumulation, increase of suspended solids and drastic resources depletion still need to be explored, in particular for sediment dwelling organisms. Application of LMB...

  5. High-temperature, Knudsen cell-mass spectroscopic studies on lanthanum oxide/uranium dioxide solid solutions

    International Nuclear Information System (INIS)

    Sunder, S.; McEachern, R.; LeBlanc, J.C.

    2001-01-01

    Knudsen cell-mass spectroscopic experiments were carried out with lanthanum oxide/uranium oxide solid solutions (1%, 2% and 5% (metal at.% basis)) to assess the volatilization characteristics of rare earths present in irradiated nuclear fuel. The oxidation state of each sample used was conditioned to the 'uranium dioxide stage' by heating in the Knudsen cell under an atmosphere of 10% CO 2 in CO. The mass spectra were analyzed to obtain the vapour pressures of the lanthanum and uranium species. It was found that the vapour pressure of lanthanum oxide follows Henry's law, i.e., its value is directly proportional to its concentration in the solid phase. Also, the vapour pressure of lanthanum oxide over the solid solution, after correction for its concentration in the solid phase, is similar to that of uranium dioxide. (authors)

  6. Synthesis characterization and sintering of cobalt-doped lanthanum chromite powders for use in SOFCs

    International Nuclear Information System (INIS)

    Yamagata, Chieko; Mello-Castanho, Sonia R.H.

    2009-01-01

    Doped lanthanum chromite is a promising as interconnect material because of its good conductivity at high temperatures and its stability in oxidizing and reducing atmospheres. Perovskite oxide powders of Co-doped lanthanum chromite were synthesized by dispersing precursor metal salt solutions in a polymer matrix followed by a thermal treatment. XRD patterns showed that a highly crystalline cobalt-doped lanthanum chromite was obtained. Fine perovskite powder with a surface area of 6.15 m 2 g -1 calcined at 700 deg C for 1 h, were obtained. After the sample sintered at 1450 deg C for 3h, the powder reached high densities exceeding 97% of the theoretical density. The proposed here has proved to be a very promising technique for the synthesis of lanthanum chromite powders. (author)

  7. Scanning Auger microscopy study of lanthanum partitioning in sphene-based glass-ceramics

    International Nuclear Information System (INIS)

    Hocking, W.H.; Hayward, P.J.; Watson, D.G.; Allen, G.C.

    1984-01-01

    Glass-ceramics are being investigated as possible hosts for the radioactive wastes that would result from recycling irradiated nuclear fuels. The partitioning of lanthanum in sphene-based glass-ceramics has been studied by scanning Auger electron microscopy for lanthanum concentrations from 0.2 to 2.0 mol.%. Sphene crystals (CaTiSiO 5 ) were located in the silica-rich glass matrix by recording digital Auger images of the calcium and titanium distributions. The sphene crystals were typically 0.5 to 5 μm in size and occupied approximately 40% of the total specimen volume. Auger spot analyses revealed that lanthanum was strongly partitioned into the sphene phase of phosphorus-free glass-ceramics; however, when a small amount of phosphorus was included in the glass-ceramic composition as a crystal nucleating agent, the lanthanum was concentrated in a third minor phase which also contained calcium, phosphorus and oxygen. Chemical shift effects in the Auger spectra of silicon, titanium and phosphorus showed evidence for electron-stimulated desorption of oxygen. (author)

  8. Bifunctional lanthanum phosphate substrates as novel adsorbents and biocatalyst supports for perchlorate removal

    International Nuclear Information System (INIS)

    Sankar, Sasidharan; Prajeesh, Gangadharan Puthiya Veetil; Anupama, Vijaya Nadaraja; Krishnakumar, Bhaskaran; Hareesh, Padinhattayil; Nair, Balagopal N.; Warrier, Krishna Gopakumar; Hareesh, Unnikrishnan Nair Saraswathy

    2014-01-01

    Graphical abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign thermal gelation process, performed the role of dual functional sorbent facilitating perchlorate adsorption and bioremediation through the growth of perchlorate reducing microbial colonies. - Highlights: • Lanthanum phosphate monoliths as efficient perchlorate adsorbents. • And also as substrates for biofilm (perchlorate reducing bacteria) growth. • Environmentally benign thermal gelation process for substrate fabrication. • 98% adsorption efficiency for perchlorate concentrations up to 100 μg/L. • The regenerated monoliths show nearly 100% reusability. - Abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign colloidal forming process employing methyl cellulose, are reported here as excellent adsorbents of perchlorate with >98% efficiency and with 100% reusability. Additionally, the effectiveness of such substrates as biocatalyst supports that facilitate biofilm formation of perchlorate reducing microbes (Serratia marcescens NIIST 5) is also demonstrated for the first time. The adsorption of perchlorate ions is attributed to the pore structure of lanthanum phosphate substrate and the microbial attachment is primarily ascribed to its intrinsic hydrophobic property. Lanthanum phosphate thus emerges as a dual functional material that possesses an integrated adsorption/bioremediation property for the effective removal of ClO 4 − which is an increasingly important environmental contaminant

  9. Bifunctional lanthanum phosphate substrates as novel adsorbents and biocatalyst supports for perchlorate removal

    Energy Technology Data Exchange (ETDEWEB)

    Sankar, Sasidharan [Materials Science and Technology Division (India); Prajeesh, Gangadharan Puthiya Veetil; Anupama, Vijaya Nadaraja [Process Engineering and Environmental Technology Division, CSIR – National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019 (India); Krishnakumar, Bhaskaran [Process Engineering and Environmental Technology Division, CSIR – National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019 (India); Academy of Scientific and Industrial Research (AcSIR) (India); Hareesh, Padinhattayil [Materials Science and Technology Division (India); Nair, Balagopal N. [R and D Centre, Noritake Co. Ltd., Aichi (Japan); Warrier, Krishna Gopakumar [Materials Science and Technology Division (India); Academy of Scientific and Industrial Research (AcSIR) (India); Hareesh, Unnikrishnan Nair Saraswathy, E-mail: hareesh@niist.res.in [Materials Science and Technology Division (India); Academy of Scientific and Industrial Research (AcSIR) (India)

    2014-06-30

    Graphical abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign thermal gelation process, performed the role of dual functional sorbent facilitating perchlorate adsorption and bioremediation through the growth of perchlorate reducing microbial colonies. - Highlights: • Lanthanum phosphate monoliths as efficient perchlorate adsorbents. • And also as substrates for biofilm (perchlorate reducing bacteria) growth. • Environmentally benign thermal gelation process for substrate fabrication. • 98% adsorption efficiency for perchlorate concentrations up to 100 μg/L. • The regenerated monoliths show nearly 100% reusability. - Abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign colloidal forming process employing methyl cellulose, are reported here as excellent adsorbents of perchlorate with >98% efficiency and with 100% reusability. Additionally, the effectiveness of such substrates as biocatalyst supports that facilitate biofilm formation of perchlorate reducing microbes (Serratia marcescens NIIST 5) is also demonstrated for the first time. The adsorption of perchlorate ions is attributed to the pore structure of lanthanum phosphate substrate and the microbial attachment is primarily ascribed to its intrinsic hydrophobic property. Lanthanum phosphate thus emerges as a dual functional material that possesses an integrated adsorption/bioremediation property for the effective removal of ClO{sub 4}{sup −} which is an increasingly important environmental contaminant.

  10. Synthesis of Ni nanoparticles in lanthanum chromite ceramic matrix

    International Nuclear Information System (INIS)

    Tinti, Victor Buratto; Florio, Daniel Zanetti de; Fonseca, Fabio Coral

    2016-01-01

    Full text: Lanthanum chromite is a well-known interconnector for solid oxide fuel cells. It presents electronic conductivity at high temperatures. Moreover it is very stable in oxidizing and reducing atmospheres. Due to its high stability this material is a promising matrix to produce and stabilize nanoparticles by exothermal reaction. The objective of the present work is to synthesize and stabilize nickel nanoparticles in a stable ceramic matrix. Compounds of (La 1-x Sr x ) a (Cr 1-y Ni y )O 3 (x and y = 0, 0.1, and 0.2; a = 1, and 0.8) were synthesized by Pechini method. The powders were heat treated in air at 1300 °C and 1600°C in attempt to solubilise NiO in the matrix. Then the samples were exposed to a reducing treatment in H 2(g) flux at 900°C per 8 hours. XRD measurements were made using a D8 Focus, Bruker AXS. The data was acquired in a range of 2θ from 20° to 90°, with a step of 0,02° per second. Magnetic properties were investigated utilizing a SQUIDVSM from Quantum Design. Magnetic moment at constant magnetic field (100 Oe and 1000 Oe) was measured in a range of 2K to 300K. Analyses with variable magnetic field were performed at 2K, 196K and 390K in a rage from -5 up to 5 T. Samples were observed using TEM technique. The XRD results showed that the stoichiometric samples achieved desiderate phase. Compounds without Sr and non-stoichiometric lanthanum site showed an incomplete nickel solid solution. The addition of 10% of Sr decreases the Neel temperature from 289 K to 285K. Ni doping created a stronger effect, lowering the temperature down to 267 K , in the sample with 10% of dopant. After reduction is possible to observe peaks of Ni in the XRD, indicating that nickel was exoluted form the matrix. Images of TEM confirm the presence of nanoparticles with an approximate diameter of 3 nm. The reducing treatment increased the magnetic response. (author)

  11. Evaluating of electronic structure of Lanthanum chromite under doping of divalent ion using density functional theory

    International Nuclear Information System (INIS)

    Saievar, E.; Gharleghi, A.

    2006-01-01

    Doping Calcium in Lanthanum site of LaCrO 3 compound increasing the density of states in valance band and decreasing the band gap width because of increases of S electrons in valance band and variety of interaction energies from Cr +3 -Cr +4 couple in valance band. We have used Wien2k software for evaluating this mechanisms. Using of 0.25 percent of dopant and a kind of the space group of cell, let us to use one cell in calculations. We have used GGA approximation in this calculations.

  12. Separation of lanthanum (3) and samarium (3) extraction with tributylphosphate in the solvent presence of solid phase

    International Nuclear Information System (INIS)

    Korotkevich, I.B.; Kolesnikov, A.A.; Bomshtejn, V.E.

    1990-01-01

    Lanthanum (3) and samarium (3) extraction from nitric acid solutions by tributylphosphate in the presence of solid phase has been investigated. An increase in samarium α-nitrate distribution factor in the presence of solid phase with a decrease in its concentration in the initial solution and with lanthanum nitrate concentration increase is detected. The greatest effect of separation is observed in samarium nitrate microregion. The method of quantitative extraction of samarium from lanthanum nitrate solutions with samarium-lanthanum separation factor exceeding 50 has been suggested

  13. Lanthanum benzoyl acetonates: an IR and mass spectrometric study of the composition and structure

    International Nuclear Information System (INIS)

    Kostyuk, N.N.; Dik, T.A.; Tereshko, N.V.

    2005-01-01

    IR spectroscopy and mass spectrometry were used to study the structure of lanthanum chelates of benzoyl acetone (1-phenyl-1,3-butadione, HBA) of the following compositions: La(BA) 3 · EtOH, La(BA) 2 , La(BA) 2 · CH 3 CN, and La(BA) 2 · HDA, where EtOH = ethanol, HDA = nonadecanoic acid. It is demonstrated that a quasi-aromatic metalloring is formed in lanthanum chelates studied. Stable metal-containing fragments of the molecular ions of lanthanum bis- and tris-benzoylacetonate were identified [ru

  14. Synthesis and characterization of lanthanum incorporated mesoporous molecular sieves

    International Nuclear Information System (INIS)

    Pesquera, C.; Gonzalez, F.; Blanco, C.; Sanchez, L.

    2004-01-01

    A series of mesoporous materials under reflux conditions have been synthesized with two silicon sources (fumed silica and sodium silicate) and lanthanum added. The following Si/La molar ratio was used in the samples: 100; 75; 50 and 25. The calcined products were characterized by means of X-ray diffraction, nitrogen adsorption isotherms and energy dispersive X-ray spectrometry (EDS). The BET surface area gradually decreases with an increase in the lanthanum content of the LaxMCM-41 samples. Moreover, the average pore size tends to decrease along with the increase in the La content in the samples

  15. Physiological responses in barley to applications of lanthanum

    International Nuclear Information System (INIS)

    Reddy, N.; Maheswaran, J.; Peverill, K.; Meehan, B.

    1998-01-01

    Full text: Chinese research and glasshouse investigations carried out in Victoria by the authors have shown that several plant species, when treated with Rare Earth Elements (REEs), retain greater amounts of moisture under water stressed conditions. The physiological adaptation of the plant to retain moisture in response to REE treatment however, has not been investigated. A glasshouse trial is currently in progress to study the physiological and agronomic responses of barley (cv. Schooner) grown in pots to application of lanthanum (0, 5 and 10 kg/ha), at a concentration of 0.05%, under well-watered (field capacity) and water-deficit (25 - 30% field capacity) conditions. Lanthanum was applied both directly to the soil and as a foliar spray. The physiological measurements include, photosynthetic rate, leaf water potential, osmotic potential, relative water content, stomatal conductance and water use efficiency. Measured agronomic parameters include plant height, tiller production, leaf area development, total grain weight, total biomass, root and shoot ratio and harvest index. Analysis of plant tissue for N, P, K, Ca, Mg, Zn and La to study the relationship between application of REE and nutrient uptake is also being carried out. The paper discusses physiological and agronomic changes in barley plants in response to treatment with lanthanum, under conditions of water stress

  16. Formulation and Assessment of a Wash-Primer Containing Lanthanum "Tannate" for Steel Temporary Protection

    Science.gov (United States)

    D'Alessandro, Oriana; Selmi, Gonzalo J.; Deyá, Cecilia; Di Sarli, Alejandro; Romagnoli, Roberto

    2018-02-01

    Tannins are polyphenols synthesized by plants and useful for the coating industry as corrosion inhibitors. In addition, lanthanum salts have a great inhibitory effect on steel corrosion. The aim of this study was to obtain lanthanum "tannate" with adequate solubility to be incorporated as the corrosion inhibitor in a wash-primer. The "tannate" was obtained from commercial "Quebracho" tannin and 0.1 M La(NO3)3. The soluble tannin was determined by the Folin-Denis reagent, while the concentration of Lanthanum was obtained by a gravimetric procedure. The protective action of "tannate" on SAE 1010 steel was evaluated by linear polarization curves and corrosion potential measurements. Lanthanum "tannate" was incorporated in a wash-primer formulation and tested by corrosion potential and ionic resistance measurements. The corrosion rate was also determined by the polarization resistance technique. Besides, the primer was incorporated in an alkyd paint system and its anticorrosion performance assessed in the salt spray cabinet and by electrochemical impedance spectroscopy. Results showed that lanthanum "tannate" primer inhibits the development of deleterious iron oxyhydroxides on the steel substrate and incorporated into a paint system had a similar behavior to the primer formulated with zinc tetroxychromate.

  17. Separation of lanthanum (3) and neodymium (3) by tributyl phosphate extraction in the presence of solid phase

    International Nuclear Information System (INIS)

    Korotkevich, I.B.; Kolesnikov, A.A.; Bomshtejn, V.E.; Shikhaleeva, N.N.

    1987-01-01

    Lanthanum (3) and neodymium (3) extraction from nitric acid solutions by tributyl phosphate in the presence of solid phase of the element nitrates is investigated. An increase in distribution of neodymium nitrate in the presence of solid phase with the decrease in its concentration in the initial solution and with the increase in lanthanum nitrate concentration is detected. The highest effect of extractive-crystallizational separation is observed in the range of neodymium nitrate microconcentrations. A method of neodymium quantitative extraction from lanthanum nitrate solutions with neodymium - lanthanum separation coefficient exceeding 25 is suggested

  18. Conductivity and hydration trends in disordered fluorite and pyrochlore oxides: A study on lanthanum cerate–zirconate based compounds

    DEFF Research Database (Denmark)

    Besikiotis, Vasileios; Ricote, Sandrine; Jensen, Molly Hjorth

    2012-01-01

    In the present contribution we discuss the influence of order/disorder on the concentration and mobility of ionic charge carriers in undoped and acceptor (calcium) doped fluorite and pyrochlore structured lanthanum cerate–zirconate solid solutions: (La1−yCay)2(Ce1−xZrx)2O7−δ (y=0, 0.02, 0.10; x=0...... enthalpy becomes more exothermic with higher cerium content, i.e. with more disordered materials. The proton conductivity decreases upon acceptor substitution of La3+ with Ca2+ which is attributed to trapping of the charge carriers by the effectively negative acceptor....

  19. Interfacial layers in tape cast anode-supported doped lanthanum gallate SOFC elements

    Energy Technology Data Exchange (ETDEWEB)

    Maffei, N.; De Silveira, G. [Materials Technology Laboratory, Natural Resources Canada, CANMET, 405 Rochester Street, Ottawa, Ontario (Canada) K1A OG3

    2003-04-01

    Lanthanum gallate doped with strontium and magnesium (LSGM) is a promising electrolyte system for intermediate temperature solid oxide fuel cells (SOFCs). The reported formation of interfacial layers in monolithic type SOFCs based on lanthanum gallate is of concern because of its impact on the performance of the fuel cell. Planar anode-supported SOFC elements (without the cathode) were prepared by the tape casting technique in order to determine the nature of the anode/electrolyte interface after sintering. Two anode systems were studied, one a NiO-CeO{sub 2} cermet, and the other, a modified lanthanum gallate anode containing manganese. Sintering studies were conducted at 1250, 1300, 1350, 1400 and 1450 C to determine the effect of temperature on the interfacial characteristics. Scanning electron microscopy (SEM) revealed a significant diffusion of Ni from the NiO-CeO{sub 2} anode resulting in the formation of an interfacial layer regardless of sintering temperature. Significant La diffusion from the electrolyte into the anode was also observed. In the case of the modified lanthanum gallate anode containing manganese, there was no interfacial layer formation, but a significant diffusion of Mn into the electrolyte was observed.

  20. Trimethylphosphide isomerization in lanthanum ions presence

    International Nuclear Information System (INIS)

    Zacharias, M.A.; Massabni, A.M.G.

    1984-01-01

    The integration between the trimethilphosphide and the lanthanum ions carry to the formation of solid complexes in a relation of 6:1 where the ligand is the phosphonate what is resultant of the isomerization of trimetylphosphite. By the RMN -1 H and infra-red spectra the products were characterized. (L.M.J.) [pt

  1. The air oxidation behavior of lanthanum ion implanted zirconium at 500 deg. C

    CERN Document Server

    Peng, D Q; Chen, X W; Zhou, Q G

    2003-01-01

    The beneficial effect of lanthanum ion implantation on the oxidation behavior of zirconium at 500 deg. C has been studied. Zirconium specimens were implanted by lanthanum ions using a MEVVA source at energy of 40 keV with a fluence range from 1x10 sup 1 sup 6 to 1x10 sup 1 sup 7 ions/cm sup 2 at maximum temperature of 130 deg. C, The weight gain curves were measured after being oxidized in air at 500 deg. C for 100 min, which showed that a significant improvement was achieved in the oxidation behavior of zirconium ion implanted with lanthanum compared with that of the as-received zirconium. The valence of the oxides in the scale was analyzed by X-ray photoemission spectroscopy; and then the depth distributions of the elements in the surface of the samples were obtained by Auger electron spectroscopy. Glancing angle X-ray diffraction at 0.3 deg. incident angles was employed to examine the modification of its phase transformation because of the lanthanum ion implantation in the oxide films. It was obviously fou...

  2. Electron paramagnetic resonance of V4+ in the lanthanum and cerium orthophosphates

    International Nuclear Information System (INIS)

    Lima, J.C. de.

    1983-11-01

    The Electron Paramagnetic Resonance (EPR) spectrum of V 4+ was investigated in polycrystalline samples of lanthanum orthophosphate (LaPO 4 ) and cerium orthophosphate (CePO 4 ) doped with 0.2 wt % vanadium pentoxide (V 2 O 5 ). Measurements were performed at room temperature and 9.5 GHz. In LaPO 4 , two non-equivalent axial sites were inferred from the EPR spectra. The most stable of these two sites is probably substitutional. In CePO 4 , a single axial spectrum was observed. It was attributed to V 4+ in substitutional sites. A central, wide line was also seen; it was attributed to ferromagnetic clusters of vanadium ions. Photoacoustic absorption spectra were also recorded for the two compounds. The EPR and photoacoustic absorption data, when analyzed using the molecular orbital theory, show that for both lanthanum orthophosphate and cerium orthophosphate the ground orbital (d sub(x) 2 sub(-y) 2) of the unpainred electron is purely ionic, while the excited orbitals d sub(xy) and d sub(xz,yz) are partly covalent. The degree of covalency is higher for the d sub(xy) orbital. Finally, it should be pointed out that part of the theory used for the interpretation of the EPR and photoacoustic absorption spectra (study of the ligand field splitting of a d orbital in a site of distorted capped antiprism structure) was developed by the author in the present work and is therefore an original contribution. (Author) [pt

  3. Effect of noble metal doping on the structural properties of lanthanum cobaltite

    International Nuclear Information System (INIS)

    Dharmadhikari, Dipti V.; Athawal, Anjali A.

    2016-01-01

    Pristine and Noble metal (Ag and Pd) doped lanthanum cobaltite samples have been synthesised by Hydrothermal method. Lanthanum in the A-Site and Co at B-site of Lanthanum cobaltite (LaCoO 3 ) perovskites were partially doped by silver and palladium (4%). Crystal structure analysis revealed that the hydrothermal synthesis led to the formation of pure nanocrystalline perovskite structure. Morphological analysis of the samples shows that the noble metal doping affects the morphology of the samples. Pristine sample shows spherical to oval shaped particles while the doping results in the formation of irregular shaped, spherical and rod shaped particles. Silver doping results in the agglomeration of particles. The particles were observed to be fused with each other to form rod shaped structures in case of palladium doped samples. (author)

  4. Types of defect ordering in undoped and lanthanum-doped Bi2201 single crystals

    International Nuclear Information System (INIS)

    Martovitsky, V. P.

    2006-01-01

    Undoped and lanthanum-doped Bi2201 single crystals having a perfect average structure have been comparatively studied by x-ray diffraction. The undoped Bi2201 single crystals exhibit very narrow satellite reflections; their half-width is five to six times smaller than that of Bi2212 single crystals grown by the same technique. This narrowness indicates three-dimensional defect ordering in the former crystals. The lanthanumdoped Bi2201 single crystals with x = 0.7 and T c = 8-10 K exhibit very broad satellite reflections consisting of two systems (modulations) misoriented with respect to each other. The modulation-vector components of these two modulations are found to be q 1 = 0.237b* + 0.277c* and q 2 = 0.238b* + 0.037c*. The single crystals having a perfect average structure and a homogeneous average distribution of doping lanthanum consist of 70-to 80-A-thick layers that alternate along the c axis and have two different types of modulated superlattice. The crystals having a less perfect average structure also consist of alternating layers, but they have different lanthanum concentrations. The low value of T c in the undoped Bi2201 single crystals (9.5 K) correlates with three-dimensional defect ordering in them, and an increase in T c to 33 K upon lanthanum doping can be related to a thin-layer structure of these crystals and to partial substitution of lanthanum for the bismuth positions

  5. AB initio energetics of lanthanum substitution in ferroelectric bismuth titanate

    International Nuclear Information System (INIS)

    Shah, S.H.

    2012-01-01

    Density functional theory based electronic structure calculations play a vital role in understanding, controlling and optimizing physical properties of materials at microscopic level. In present study system of interest is bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/)/(BIT) which has wide range of applications such as a high temperature piezoelectric and one of the best material for memory devices. However, it also suffers from serious issues such as oxygen vacancies which degrade its performance as a memory element and piezoelectric material. In this context, the bulk and defect properties of orthorhombic bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/) and bismuth lanthanum titanate (Bi/sub 3.25/La/sub 0.75/Ti/sub 3/O/sub 12/)/(BLT, x=0.75) were investigated by using first principles calculations and atomistic thermodynamics. Heats of formation, valid chemical conditions for synthesis, lanthanum substitution energies and oxygen and bismuth vacancy formation energies were computed. The study improves understanding of how native point defects and substitutional impurities influence the ferroelectric properties of these layered perovskite materials. It was found that lanthanum incorporation could occur on either of the two distinct bismuth sites in the structure and that the effect of substitution is to increase the formation energy of nearby native oxygen vacancies. The results provide direct atomistic evidence over a range of chemical conditions for the suggestion that lanthanum incorporation reduces the oxygen vacancy concentration. Oxygen vacancies contribute to ferroelectric fatigue by interacting strongly with domain walls and therefore a decrease in their concentration is beneficial. (orig./A.B.)

  6. Phase segregation in cerium-lanthanum solid solutions

    NARCIS (Netherlands)

    Belliere, V.; Joorst, G; Stephan, O; de Groot, FMF; Weckhuysen, BM

    2006-01-01

    Electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy ( STEM) reveals that the La enrichment at the surface of cerium-lanthanum solid solutions is an averaged effect and that segregation occurs in a mixed oxide phase. This separation occurs within a

  7. Effect of substituting cerium-rich mischmetal with lanthanum on high temperature properties of die-cast Mg-Zn-Al-Ca-RE alloys

    International Nuclear Information System (INIS)

    Anyanwu, Ifeanyi A.; Gokan, Yasuhiro; Suzuki, Atsuya; Kamado, Shigeharu; Kojima, Yo; Takeda, Suguru; Ishida, Taketoshi

    2004-01-01

    Mg-Zn-Al-Ca-RE alloys have been found to be promising materials for substituting aluminum alloys used for automatic transmission case applications in the automobile industry. Particularly, Mg-0.5%Zn-6%Al-1%Ca-3%RE (ZAXE05613) alloy exhibits comparable creep resistance as ADC12 die-casting aluminum alloy that is currently used for automatic transmission case applications. Changing the rare earth (RE) content of the alloy from mischmetal to lanthanum gives a further improvement in the creep properties of the alloy. Lanthanum addition results in the crystallization of a large amount of acicular Al 11 RE 3 (Al 11 La 3 ) compound along the grain boundaries as well as across the grain boundaries and this effectively controls grain boundary sliding and dislocation motion in the vicinity of the grain boundaries. As a result, die-cast ZAXLa05613 alloy exhibits a higher creep resistance than that of ZAXE05613 alloy

  8. Structural characterization and properties of lanthanum film as chromate replacement for tinplate

    International Nuclear Information System (INIS)

    Huang Xingqiao; Li Ning

    2007-01-01

    Sulfide-stain resistance of La-passivated, unpassivated and Cr-passivated tinplate was measured using a cysteine tarnish test. Corrosion behavior of these tinplates was investigated using electrochemical impedance spectroscopy (EIS) measurement. The morphology, composition and thickness of lanthanum film were studied by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence spectrometry (XRF), respectively. La-passivation treatment remarkably enhances sulfide-stain resistance of tinplate, and sulfide-stain resistance of La-passivated tinplate is slightly higher than that of Cr-passivated tinplate. La-passivation treatment also significantly improves corrosion protection property of tinplate. In contact with 3.5% NaCl solution, corrosion resistance of La-passivated tinplate is close to that of Cr-passivated tinplate, and in contact with 0.1 M citric-citrate buffer solution, corrosion resistance of La-passivated tinplate is higher than that of Cr-passivated tinplate. Lanthanum film is composed of spherical particles about 50-1000 nm in diameter, while most part of tinplate's surface is covered with the small particles about 50-200 nm. The film mainly consists of lanthanum and oxygen, which mainly exist as La 2 O 3 and its hydrates such as La(OH) 3 and LaOOH. The amount of lanthanum in the film is about 0.0409 g/m 2

  9. Effect of lanthanum doping on electrical and electromechanical ...

    Indian Academy of Sciences (India)

    Unknown

    temperature, Tc increased with the increase of lanthanum content. ... By adding oxide group softeners, hardeners and stabi- ... pressed with 2% polyvinyl alcohol as binder under a ... study are dependent on temperature and are shown in.

  10. Lanthanum Nitrate As Electrolyte Additive To Stabilize the Surface Morphology of Lithium Anode for Lithium-Sulfur Battery.

    Science.gov (United States)

    Liu, Sheng; Li, Guo-Ran; Gao, Xue-Ping

    2016-03-01

    Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries. However, the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li-S battery. In this work, lanthanum nitrate, as electrolyte additive, is introduced into Li-S battery to stabilize the surface of lithium anode. By introducing lanthanum nitrate into electrolyte, a composite passivation film of lanthanum/lithium sulfides can be formed on metallic lithium anode, which is beneficial to decrease the reducibility of metallic lithium and slow down the electrochemical dissolution/deposition reaction on lithium anode for stabilizing the surface morphology of metallic Li anode in lithium-sulfur battery. Meanwhile, the cycle stability of the fabricated Li-S cell is improved by introducing lanthanum nitrate into electrolyte. Apparently, lanthanum nitrate is an effective additive for the protection of lithium anode and the cycling stability of Li-S battery.

  11. Synthesis and characterization of lanthanum complex (5-choloro-8-hydroxy quinoline) bis (2-2'bipyridine) lanthanum La(Bpy)2(5-Clq)

    Science.gov (United States)

    Kumar, Rahul; Soam, Ankur; Bhargava, Parag

    2017-05-01

    Lanthanum complex, (5-choloro 8-hydroxy quinoline) bis (2-2'bipyridine) has been synthesized and characterized by different techniques. Lanthanum complex, La(Bpy)2(5-Clq) was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) and material shows the thermal stability up to 400°C. Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy)2(5-Clq) in ethanol showed absorption peak at 332 nm, which may be attributed due to (π - π*) transitions. The photoluminescence spectra of La(Bpy)2(5-Clq) in ethanol solution showed intense peak at 505 nm.

  12. Plasma spheroidization and high temperature stability of lanthanum phosphate and its compatibility with molten uranium

    International Nuclear Information System (INIS)

    Ananthapadmanabhan, P.V.; Sreekumar, K.P.; Thiyagarajan, T.K.; Satpute, R.U.; Krishnan, K.; Kulkarni, N.K.; Kutty, T.R.G.

    2009-01-01

    Lanthanum phosphate has excellent thermal stability and corrosion resistance against many molten metals and other chemically corrosive environments. Lanthanum phosphate (LaPO 4 ) was synthesized from lanthanum oxalate by thermal dissociation of the oxalate to the oxide, followed by conversion to hydrated lanthanum phosphate (LaPO 4 .0.5H 2 O). Thermal treatment of LaPO 4 .0.5H 2 O above 773 K resulted in the irreversible transformation of the hydrated phase to the stable monazite phase. Thermal and chemical stability of monazite was studied by plasma spheroidization experiments using a DC thermal plasma reactor set up. Compatibility of monazite with molten uranium was studied by thermal analysis. Results showed that monazite is thermally stable up to its melting point and also is resistant towards attack by molten uranium. Adherent coatings of LaPO 4 could be deposited onto various substrates by atmospheric plasma spray technique

  13. Nanoscale photoelectron ionisation detector based on lanthanum hexaboride

    International Nuclear Information System (INIS)

    Zimmer, C.M.; Kunze, U.; Schubert, J.; Hamann, S.; Doll, T.

    2011-01-01

    A nanoscale ioniser is presented exceeding the limitation of conventional photoionisation detectors. It employs accelerated photoelectrons that allow obtaining molecule specificity by the tuning of ionisation energies. The material lanthanum hexaboride (LaB 6 ) is used as air stable photo cathode. Thin films of that material deposited by pulsed laser deposition (PLD) show quantum efficiency (QE) in the range of 10 -5 which is comparable to laser photo stimulation results. A careful treatment of the material yields reasonable low work functions even after surface reoxidation which opens up the possibility of using ultraviolet light emitting diodes (UV LEDs) in replacement of discharge lamps. Schematic diagram of a photoelectron ionisation detector (PeID) operating by an electron emitter based on the photoelectric effect of lanthanum hexaboride. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. The study of interaction of lanthanum-, cerium- and neodymium chlorides with sodium borohydride in pyridine- and tetrahydrofuran medium

    International Nuclear Information System (INIS)

    Mirsaidov, U.; Rotenberg, T.G.; Dymova, T.N.

    1976-01-01

    Bis-tetrahydrofurans of lanthanum and neodymium borohydrides and bis-pyridinates of lanthanum, cerium and neodymium borohydrides were obtained by interacting sodium borohydride with lanthanum-, cerium and neodymium chlorides in pyridine and tetrahydrofuran media. All operations involving reagent combination, sampling and phase separation are performed in inert atmosphere using argonvacuum equipment. The reaction in pyridine was virtually instantaneous and accompanied by flocculanet precipitation. The interaction of lanthanum chloride and neodymium chloride with sodium borohydride in tetrahydrofuran (THF) was a slow (23-30 hr) heterophase process. The interaction rate was affected by size reduction of the intial substances, temperature, reagent proportion and mixing rate. The reaction time was twice reduced with boiling tetrahydrofuran

  15. Addition compounds between lanthanide trifluoromethane sulphonates and N,N,N',N' - tetrametilmalonamida (TMMA)

    International Nuclear Information System (INIS)

    Bellis, V.M. de.

    1984-01-01

    The preparation and characterization of the addiction compounds between lanthanide trifluoromethanesulphonates with the N,N,N',N' - tetramethylmodomamide (TMMA) are reported. The characterization of the compounds obtained by microanalytical procedures, infrared spectra, conductance measurements, X-ray powder patterns, absorption spectra of the praseodymium, neodymium, holmium and erbium and the emission spectra of the europium and the europium-doped lanthanum and lutetium adducts were made. (M.J.C.) [pt

  16. Plasma spheroidization and high temperature stability of lanthanum phosphate and its compatibility with molten uranium

    Energy Technology Data Exchange (ETDEWEB)

    Ananthapadmanabhan, P.V. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)], E-mail: pvananth@barc.gov.in; Sreekumar, K.P.; Thiyagarajan, T.K.; Satpute, R.U. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Krishnan, K.; Kulkarni, N.K. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kutty, T.R.G. [Radiometallurgy Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2009-01-15

    Lanthanum phosphate has excellent thermal stability and corrosion resistance against many molten metals and other chemically corrosive environments. Lanthanum phosphate (LaPO{sub 4}) was synthesized from lanthanum oxalate by thermal dissociation of the oxalate to the oxide, followed by conversion to hydrated lanthanum phosphate (LaPO{sub 4}.0.5H{sub 2}O). Thermal treatment of LaPO{sub 4}.0.5H{sub 2}O above 773 K resulted in the irreversible transformation of the hydrated phase to the stable monazite phase. Thermal and chemical stability of monazite was studied by plasma spheroidization experiments using a DC thermal plasma reactor set up. Compatibility of monazite with molten uranium was studied by thermal analysis. Results showed that monazite is thermally stable up to its melting point and also is resistant towards attack by molten uranium. Adherent coatings of LaPO{sub 4} could be deposited onto various substrates by atmospheric plasma spray technique.

  17. Magnetocaloric effect in potassium doped lanthanum manganite perovskites prepared by a pyrophoric method

    Science.gov (United States)

    Das, Soma; Dey, T. K.

    2006-08-01

    The magnetocaloric effect (MCE) in fine grained perovskite manganites of the type La1-xKxMnO3 (0value of 3.00 J kg-1 K-1 at 310 K amongst the compounds investigated. Moreover, the maximum magnetic entropy change exhibits a linear dependence with applied magnetic field. The estimated adiabatic temperature change at TC and at 1 T field also increases with K doping, being a maximum of 2.1 K for the La0.85K0.15MnO3 compound. The relative cooling power (RCP) of La1-xKxMnO3 compounds is estimated to be about one-third of that of the prototype magnetic refrigerant material (pure Gd). However, La1-xKxMnO3 compounds possess an MCE around room temperature, which is comparable to that of Gd. Further, tailoring of their TC, higher chemical stability, lower eddy current heating and lower cost of synthesis are some of the attractive features of K doped lanthanum manganites that are advantageous for a magnetic refrigerant. The temperature dependence of the magnetic entropy change (ΔSM) measured under various magnetic fields is explained fairly well using the Landau theory of phase transitions. Contributions of magnetoelastic and electron interaction are found to have a strong influence in the magnetocaloric effect of manganites.

  18. Lanthanum chromite colloidal processing

    International Nuclear Information System (INIS)

    Setz, Luiz Fernando Grespan

    2009-01-01

    Lanthanum chromite (LaCrO 3 ) is currently the most studied material for applications such as solid oxide fuel cell inter connector (HTSOFC). The complexity of microstructures and geometries of HTSOFC devices, require a precise control of processing parameters to get the desired combination of properties and this, the use of techniques involving concentrated ceramic slips conformation are appropriate, therefore, is well controlled, assist in obtaining homogeneous parts, reproductive and complex geometries. Thus, studies involving the surface chemistry, the stability conditions and slips flow behaviour in the forming conditions, provide important elements for processes control in the inter connectors manufacture, where more applied settings have slots and channels for the gases passage. Thus, surface chemistry, stability and rheological behaviour of strontium and cobalt doped LaCrO 3 (La) 0.80 Sr 0. 2 0 Cr 0.92 Co 0.08 O 3 ) slips prepared with ethanol and water, were studied. The doped lanthanum chromite was produced by combustion synthesis in the IPEN/SP labs. The influence of parameters: pH (water), dispersant concentration, homogenization times and conditions, solid concentration, different ratios binder:plasticizer in the stability and the flow behavior of ceramic suspensions prepared were evaluated. The La) 0.80 Sr 0. 2 0 Cr 0.92 Co 0.08 O 3 products obtained by casting aqueous slips in a plaster mould, using alkaline pH and anionic polyelectrolyte and tapes obtained by using ethanol as a dispersant medium, after sintering at 1600 degree C/4 hours presented theoretical density > 94%, suitable for use as HTSOFC inter connector. (author)

  19. Exchange, x-ray and IR spectral behaviour of lanthanum and praseodymium exchanged zeolite X

    International Nuclear Information System (INIS)

    Das, D.; Upreti, M.C.

    1995-01-01

    Exchange behaviour of lanthanum and praseodymium ions in zeolite X involves three steps: preferential exchange, intrazeolitic exchange and irreversible exchange. At room temperature , higher exchange has been observed with La(III) than with Pr(III) which is attributed to the smaller hydrosphere of lanthanum than praseodymium. IR spectra of these zeolites in KBr pellets show a shift in the major Si-O stretching vibration of 972 cm -1 to higher frequencies. Their x-ray diffraction patterns remain unchanged except a large decrease of the line intensities caused by the absorption of x-rays by heavy La(III) and Pr(III) ions. The present study reports the preparation and physicochemical properties of lanthanum and praseodymium exchanged zeolite X. (author). 12 refs., 3 figs., 3 tabs

  20. Growth and characterization of magnesium chloride and lanthanum chloride doped strontium tartrate crystals - gel method

    International Nuclear Information System (INIS)

    Kalaiarasi, S.; Jaikumar, D.

    2014-01-01

    Growth of single crystals of doped strontium tartrate by controlled diffusion of strontium chloride into the silica gel charged with tartaric acid at room temperature is narrated. In this study, we synthesized magnesium chloride (5% and 10%) doped strontium tartrate crystals and Lanthanum chloride (5%, 10% and 15%) doped strontium tartrate crystals are grown. The crystal structure of the compound crystals was confirmed by single crystal X-ray diffraction. The Fourier transform infrared spectrum of pure and doped crystals are recorded and analyzed. The UV-Vis-NIR spectrum analysis reveals that the optical study of the grown crystals. The second harmonic generation efficiency was measured by using Kurtz powder technique with Nd:YAG laser of wavelength 1064 nm. (author)

  1. Lake responses following lanthanum-modified bentonite clay (Phoslock) application: an analysis of water column lanthanum data from 16 case study lakes

    NARCIS (Netherlands)

    Spears, B.M.; Lürling, M.F.L.L.W.; Yasseri, S.; Castro-Castellon, A.T.; Gibbs, M.; Meis, S.; McDonald, C.; McIntosh, J.; Sleep, D.; Oosterhout, van F.

    2013-01-01

    Phoslock is a lanthanum (La) modified bentonite clay that is being increasingly used as a geo-engineering tool for the control of legacy phosphorus (P) release from lake bed sediments to overlying waters. This study investigates the potential for negative ecological impacts from elevated La

  2. On dependence of stability of lanthanum complexes with aminopolycarboxylic acids on the complex structure

    International Nuclear Information System (INIS)

    Poluehktov, N.S.; Meshkova, S.B.; Danilkovich, M.M.; Topilova, Z.M.

    1985-01-01

    Regularities in changes of stability constants of lanthanum complexes with aminopolycarboxylic acids (APA) versus their structure are studied, The stability of lathanum-APA complexes depends mainly on the number of carboxyl groups in a ligand molecule. At that, the highest stability constant is characteristic of a complex with a ligand, containing 3 nitrogen atoms and 5 carboxyl groups, in the presenoe of which the lanthanum ion coordination sphere gets satupated. The oxyethy group introduction into a ligand molecule also improves the lanthanum complex stability but to a lesser degree than during the introduction of a carboxyl group. The number of nitrogen atoms in a ligand polecule affects insignificantly the complex stability constant value, and the elongation of a chain of CH 2 groups, separating nitrogen atoms, reduces the constant to a -0.6 power

  3. Order parameters in lanthanum gallate lightly doped with manganese and paramagnetic resonance

    Science.gov (United States)

    Vazhenin, V. A.; Potapov, A. P.; Artyomov, M. Yu.; Guseva, V. B.

    2010-09-01

    The Cr3+ centers have been revealed, transitions at room temperature have been identified, and spin Hamiltonian parameters have been determined for the Cr3+ and Fe3+ triclinic centers in lanthanum gallate lightly doped with manganese. The principal axes of the fourth-rank fine-structure tensor for the Fe3+ triclinic centers have been established and used to determine the order parameters, i.e., the angles of rotation of oxygen octahedra of lanthanum gallate with respect to the perovskite structure. The order parameter in the rhombohedral phase has been estimated.

  4. Textile Dye Removal from Aqueous Solution using Modified Graphite Waste/Lanthanum/Chitosan Composite

    Science.gov (United States)

    Kusrini, E.; Wicaksono, B.; Yulizar, Y.; Prasetyanto, EA; Gunawan, C.

    2018-03-01

    We investigated various pre-treatment processes of graphite waste using thermal, mechanical and chemical methods. The aim of this work is to study the performance of modified graphite waste/lanthanum/chitosan composite (MG) as adsorbent for textile dye removal from aqueous solution. Effect of graphite waste resources, adsorbent size and lanthanum concentration on the dye removal were studied in batch experiments. Selectivity of MG was also investigated. Pre-heated graphite waste (NMG) was conducted at 80°C for 1 h, followed by mechanical crushing of the resultant graphite to 75 μm particle size, giving adsorption performance of ˜58%, ˜67%, ˜93% and ˜98% of the model dye rhodamine B (concentration determined by UV-vis spectroscopy at 554 nm), methyl orange (464 nm), methylene blue (664 nm) and methyl violet (580 nm), respectively from aqueous solution. For this process, the system required less than ˜5 min for adsorbent material to be completely saturated with the adsorbate. Further chemical modification of the pre-treated graphite waste (MG) with lanthanum (0.01 – V 0.03 M) and chitosan (0.5% w/w) did not improve the performance of dye adsorption. Under comparable experimental conditions, as those of the ‘thermal-mechanical-pre-treated-only’ (NMG), modification of graphite waste (MG) with 0.03 M lanthanum and 0.5% w/w chitosan resulted in ˜14%, ˜47%, ˜72% and ˜85% adsorption of rhodamine B, methyl orange, methylene blue and methyl violet, respectively. Selective adsorption of methylene blue at most to ˜79%, followed by methyl orange, methyl violet and rhodamine B with adsorption efficiency ˜67, ˜38, and ˜9% sequentially using MG with 0.03 M lanthanum and 0.5% w/w chitosan.

  5. Electrochemical corrosion of lanthanum chromite and yttrium chromite in coal slag

    Energy Technology Data Exchange (ETDEWEB)

    Marchant, D.D.; Bates, J.L.

    1981-01-01

    Lanthanum chromites have long been considered as electrodes for magnetohydrodynamic (MHD) generator channels. These chromites, when doped with divalent ions such as Ca, Mg or Sr, have adequate electronic and electrical conductivity (2), and melting points greater than 2500/sup 0/K. However, above approx. 1850/sup 0/K, selective vapor loss of chromium results in the formation of a La/sub 2/O/sub 3/ phase. The La/sub 2/O/sub 3/ is hydroscopic at room temperature, resulting in a large volume change and loss of mechanical integrity when exposed to H/sub 2/O. The analogous yttrium chromites have thermal and electrical properties similar to that for the lanthanum chromites. Although vapor loss of Cr results in the formation of Y/sub 2/O/sub 3/, this oxide does not hydrate. Corrosion studies of yttrium chromite compositions show that doped YCrO/sub 3/ may be a viable MHD electrode. An electrochemical corrosion study of both magnesium-doped lanthanum and yttrium chromites in synthetic coal slag electrolytes is described. Possible chemical and electrochemical degradation phenomena, as well as the relative rates of corrosion are emphasized.

  6. Phase transformations in lead zirconate-titanate doped with lanthanum

    Energy Technology Data Exchange (ETDEWEB)

    Ishchuk, V M; Morozov, E M

    1979-07-01

    Presented are the results of studies on the character of phase transitions of the lead-lanthanum zirconate-titanate (LLZT) system. The replacement of lead by lanthanum leads to the expansion of the region of antisegnetoelectric (ASE) states of solid solutions of lead zirconate-titanate (LZT) in the direction of PbTiO/sub 3/ concentration growth. An intermediate region is revealed between segnetoelectric (SE) and ASE states, material properties in which depend on their prehistory: annealed samples are in the ASE state, whereas the application of electric field exceeding some critical value induces the SE state. A family of phase diagrams obtained at consequent replacement of lead by lanthanum permits to identify phase states in any series of LLZT with a constant ratio of Zr:Ti, in the x/65/35 series in particular. Thermally depolarized state of materials of this series at x<6.5 is shown to be antisegnetoelectric at all the temperatures below the Curie point Tsub(c), and heating causes phase transition of ASE..-->..PE (paraelectric state) at Tsub(c). Polarized samples being heated, a successiveness of phase transitions of SE..-->..ASE takes place at T/sub 0/, and that of ASE reversible PE at Tsub(C) (Tsub(0)..ASE phase transition in the LZT system.

  7. Lanthanum-silicon-substituted hydroxyapatite: Mechanochemical synthesis and prospects for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Chaikina, M. V., E-mail: chaikinam@solid.nsc.ru; Bulina, N. V., E-mail: bulina@solid.nsc.ru; Prosanov, I. Yu., E-mail: prosanov@mail.ru [Institute of Solid State Chemistry and Mechanochemistry SB RAS, Kutateladze Street 18, Novosibirsk, 630128 (Russian Federation); Komarova, E. G., E-mail: katerina@ispms.tsc.ru; Sharkeev, Yu. P., E-mail: sharkeev@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Academicheskii Pr. 2/4, Tomsk, 634055 (Russian Federation)

    2016-08-02

    The paper presents the results of mechanochemical synthesis of hydroxyapatite (HAP) with simultaneous substitutions of lanthanum (La{sup 3+}) for calcium ions and silicate ((SiO{sub 4}){sup 4−}-group) for the phosphate group with the substituent concentrations in the range 0.2–2.0 mol per HAP mol. The use of Si-substituted HAP as a coating material promotes accelerated osteosynthesis and osteointegration of implants into the bone tissue. The replacement of calcium ions by La{sup 3+} in the HAP structure plays an antimicrobial role preventing inflammatory processes. Annealing-induced variations in the lattice parameters of synthesized samples indicate the substituent incorporation into the HAP structure. It is known that complex compounds with lanthanides are used for cancer chemotherapy. In particular, La plays a key role in the course of treatment of injured defects of bone tissue. In addition, La-substituted HAP can be used for filling bone defects and coating implants in postoperational areas affected by bone cancer.

  8. Lanthanum Deposition in the Stomach in the Absence of Helicobacter pylori Infection.

    Science.gov (United States)

    Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Kawano, Seiji; Kawahara, Yoshiro; Kimoto, Katsuhiko; Okada, Hiroyuki

    2018-03-15

    In this case report, we describe two patients who showed a diffusely whitish mucosa in the posterior wall and the lesser curvature of the gastric body. The patients were serologically- and histopathologically-negative for Helicobacter pylori. Random biopsy specimens from the stomach revealed no regenerative changes, intestinal metaplasia, and/or foveolar hyperplasia in either of the patients. Although lanthanum deposition in the gastric mucosa has been reported to occur in close association with H. pylori-associated gastritis, our patients tested negative for H. pylori. These cases suggest that lanthanum deposition presents as whitish lesions in the gastric body in H. pylori-negative patients.

  9. Properties of lanthanum hexaboride a compilation

    CERN Document Server

    Fisher, D J

    2013-01-01

    Lanthanum hexaboride is useful because it possesses a high melting point (2210C), a low work function, one of the highest known electron emissivities, and is stable in vacuum. This volume summarises the extant data on the properties of this material, including the: bulk modulus, conductivity, crystal structure, Debye temperature, defect structure, elastic constants, electronic structure, emissivity, Fermi surface, hardness, heat capacity, magnetoresistance, reflectivity, resistivity, specific heat, surface structure, thermal conductivity, thermoelectric power, toughness and work function. The

  10. Lake responses following lanthanum-modified bentonite clay (Phoslock®) application: an analysis of water column lanthanum data from 16 case study lakes.

    Science.gov (United States)

    Spears, Bryan M; Lürling, Miquel; Yasseri, Said; Castro-Castellon, Ana T; Gibbs, Max; Meis, Sebastian; McDonald, Claire; McIntosh, John; Sleep, Darren; Van Oosterhout, Frank

    2013-10-01

    Phoslock(®) is a lanthanum (La) modified bentonite clay that is being increasingly used as a geo-engineering tool for the control of legacy phosphorus (P) release from lake bed sediments to overlying waters. This study investigates the potential for negative ecological impacts from elevated La concentrations associated with the use of Phoslock(®) across 16 case study lakes. Impact-recovery trajectories associated with total lanthanum (TLa) and filterable La (FLa) concentrations in surface and bottom waters were quantified over a period of up to 60 months following Phoslock(®) application. Both surface and bottom water TLa and FLa concentrations were 0.8 mEq L(-1)), but higher (up to 0.12 mg L(-1)) in lakes characterised by very low alkalinity. The effects of elevated La(3+) concentrations following Phoslock(®) applications in lakes of very low alkalinity requires further evaluation. The implications for the use of Phoslock(®) in eutrophication management are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Conductometric study of lanthanum chloride interaction with potash soaps of higher fatty acids

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Sazonova, V.F.; Kornelli, M.Eh.; Shumilina, N.A.

    1978-01-01

    Interaction of lanthanum chloride with potassium salts of higher aliphatic acids, containing from 10 to 16 carbon atoms, at room temperature in weakly acid media (pH=5.5) gives rise to neutral soaps of the La[CHsub(3)(CHsub(2))sub(n)COO]sub(3) composition, while in alkaline media (pH=8.0) base soaps of the LaOH[CHsub(3)(CHsub(2))sub(n)COO]sub(2) composition are formed. In acid solutions (pH=2.0) no interaction of lanthanum chloride with potassium soaps of the above carboxylic acids is observed

  12. Room temperature synthesis of high temperature stable lanthanum phosphate–yttria nano composite

    International Nuclear Information System (INIS)

    Sankar, Sasidharan; Raj, Athira N.; Jyothi, C.K.; Warrier, K.G.K.; Padmanabhan, P.V.A.

    2012-01-01

    Graphical abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Highlights: ► A novel lanthanum phosphate–Y 2 O 3 nano composite is synthesized for the first time using a modified facile sol gel process. ► The composite becomes crystalline at 600 °C and X-ray diffraction pattern is indexed for monoclinic LaPO 4 and cubic yttria. ► The composite synthesized was tested up to 1300 °C and no reaction between the phases of the constituents is observed with the morphologies of the phases being retained. -- Abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Lanthanum phosphate (80 wt%)–yttria (20 wt%) nano composite (LaPO 4 –20%Y 2 O 3 ), has an average particle size of ∼70 nm after heat treatment of precursor at 600 °C. TG–DTA analysis reveals that stable phase of the composite is formed on heating the precursor at 600 °C. The TEM images of the composite show rod shape morphology of LaPO 4 in which yttria is acquiring near spherical shape. Phase identification of the composite as well as the phase stability up to 1300 °C was carried out using X-ray diffraction technique. With the phases being stable at higher temperatures, the composite synthesized should be a potential material for high temperature applications like thermal barrier coatings and metal melting applications.

  13. Structural consideration with respect to the thermal stability of a new platinum supported lanthanum-alumina catalyst

    International Nuclear Information System (INIS)

    Oudet, F.; Bordes, E.; Courtine, P.; Maxant, G.; Lambert, C.; Guerlet, J.P.

    1987-01-01

    The influence of lanthanum aluminate, LaAlO 3 , on the thermal stability of both alumina and platinum supported alumina catalysts is investigated. In the case of alumina, the stabilization is interpreted in terms of structural coherence between δ-Al 2 O 3 and a three-fold superstructure of LaAlO 3 . The addition of LaAlO 3 , is shown to increase both the dispersion and the resistance to sintering of the platinum supported alumina catalyst. Moreover, lanthanum hexa-aluminate (La-β-Al 2 O 3 ) is present in the platinum catalyst fired at 1150 0 C. These observations are assumed to result for the epitaxial relations between platinum and the lanthanum-alumina support. 23 refs.; 8 figs.; 2 tabs

  14. Investigation of paramagnetic saturation in lanthanum manganese nitrate

    NARCIS (Netherlands)

    Flokstra, Jakob; Meijer, H.C.; Bots, G.J.C.; Verheij, W.A.; van der Marel, L.C.

    1973-01-01

    Paramagnetic saturation of lanthanum manganese nitrate, La2Mn3(NO3)12·24H2O, has been investigated at liquid He temperatures in a static as well as a dynamical way. With the aid of the molecular-field theory the Casimir and Du Pré dispersion and absorption curves are adapted explicitly to the

  15. Deposition barium titanate (BaTiO3) doped lanthanum with chemical solution deposition

    International Nuclear Information System (INIS)

    Iriani, Y.; Nurhadi, N.; Jamaludin, A.

    2016-01-01

    Deposition of Barium Titanate (BaTiO 3 ) thin films used Chemical Solution Deposition (CSD) method and prepared with spin coater. BaTiO 3 is doped with lanthanum, 1%, 2%, and 3%. The thermal process use annealing temperature 900°C and holding time for 3 hours. The result of characterization with x-ray diffraction (XRD) equipment show that the addition of La 3+ doped on Barium Titanate caused the change of angle diffraction.The result of refine with GSAS software shows that lanthanum have been included in the structure of BaTiO 3 . Increasing mol dopant La 3+ cause lattice parameter and crystal volume become smaller. Characterization result using Scanning Electron Microscopy (SEM) equipment show that grain size (grain size) become smaller with increasing mole dopant (x) La 3+ . The result of characterization using Sawyer Tower methods show that all the samples (Barium Titanante and Barium Titanate doped lanthanum) are ferroelectric material. Increasing of mole dopant La 3+ cause smaller coercive field and remanent polarization increases. (paper)

  16. Fabrication of Polycrystalline Lanthanum Manganite (La0.99 Mn0.01 O3) Powder and Fibres by Electrospinning Method

    International Nuclear Information System (INIS)

    Yin Yin Win; That Htar Lwin; Than Than Win; Yin Maung Maung; Ko Ko Kyaw Soe

    2011-12-01

    Lanthanum manganite (La0.99 Mn0.01 O3) powder have been prepared by using pyrolysis methods. Lanthanum manganite fibres were successfully fabricated by electro-spinning utilizing precursors. Polycrystalline perovskite structure lanthanum manganite powder and fibres showed that the grain size and crystal grain increased significantly with the increase in calcination temperature. A variety of techniques (SEM, FT-IR and TG-DTA) were employed to study the morphology and fibre quality, crystal structure, and thermal analysis of La0.99 Mn0.01 O3 specimen respectively.

  17. The Catalytic Activity of Modified Zeolite Lanthanum on the Catalytic Cracking of Al-Duara Atmospheric Distillation Residue

    Directory of Open Access Journals (Sweden)

    Karim Khalifa Esgair

    2016-03-01

    Full Text Available Atmospheric residue fluid catalytic cracking was selected as a probe reaction to test the catalytic performance of modified NaY zeolites and prepared NaY zeolites. Modified NaY zeolites have been synthesized by simple ion exchange methods. Three samples of modified zeolite Y have been obtained by replacing the sodium ions in the original sample with lanthanum and the weight percent added are 0.28, 0.53, and 1.02 respectively. The effects of addition of lanthanum to zeolite Y in different weight percent on the cracking catalysts were investigated using an experimental laboratory plant scale of fluidized bed reactor. The experiments have been performed with weight hourly space velocity (WHSV range of 6 to 24 h-1, and the range of temperature from 450 to 510 oC. The activity of the catalyst with 1.02 wt% lanthanum has been shown to be much greater than that of the sample parent NaY. Also it was observed that the addition of the lanthanum causes an increase in the thermal stability of the zeolite.

  18. Stability constant of the lanthanum complex with humic acid

    International Nuclear Information System (INIS)

    Jimenez R, M.; Solache R, M. J.

    2008-01-01

    The work described here is a study on the formation of trivalent lanthanum complex with humic acid. Commercial humic acid was purified and then characterized by various analytical techniques. The stability constant determined by a radiochemical method has a worth of log β La , AHA = 13.6. (Author)

  19. Revised energy levels of singly ionized lanthanum

    Science.gov (United States)

    Güzelçimen, Feyza; Tonka, Mehdi; Uddin, Zaheer; Bhatti, Naveed Anjum; Windholz, Laurentius; Kröger, Sophie; Başar, Gönül

    2018-05-01

    Based on the experimental wavenumbers of 344 spectral lines from calibrated Fourier transform (FT) spectra as well as wavenumbers of 81 lines from the wavelength tables from literature, the energy of 115 fine structure levels of singly ionized lanthanum has been revised by weighted global fits. The classifications of the lines are provided by numerous previous investigations of lanthanum by different spectroscopic methods and authors. For the high accurate determination of the center of gravity wavenumbers from the experimental spectrum, the hyperfine constants of the involved levels have been taken into account, if possible. For the 94 levels with known hyperfine constants the accuracy of energy values is better than 0.01 cm-1. For 34 levels the magnetic dipole hyperfine constants A have been determined from FT spectra as part of this work. For four of these 34 levels even electric quadrupole hyperfine constants B could be estimated. For levels, which have experimentally unknown hyperfine constants and which are connected only by lines not found in the FT spectra but taken from literature, the uncertainties of energy values are about a factor of 10 higher. A list of all revised level energies together with a compilation of hyperfine structure data is given as well as a list of all lines used.

  20. Effects of intravenously injected lanthanum chloride on the femur of rats

    International Nuclear Information System (INIS)

    Miyagawa, Makoto; Daimon, Tateo

    2010-01-01

    Lanthanum (La) is widely used in industry and medicine. Because of lanthanum's physicochemical resemblance to calcium, the possible effects of it on bone have to be considered. The aim of this study was to examine the effects of La on bone toxicity. Rats were intravenously administrated with lanthanum chloride at 5 mg La/kg per week for five weeks. Histomorphometric analysis of femurs were performed using micro-CT scan. Compared with normal controls, the total bone area of the femur did not show any change in La-administrated rats, whereas the trabecular area slightly decreased. The trabecular bone mineral density in the experimented rats was higher than that in the normal controls, although the mineral density of the cortical bone and cancerou one was unchanged after the administration of La. La did not alter mechanical barometers of the femur such as mean cross-sectional moment of inertia, minimum cross-sectional moment of inertia and polar moment of inertia. Additionally, light microscopic analysis of the femurs revealed that histological features of osteoid, calcification front and bone matrix were normal after the administration of La. La was detected in the macrophages in the bone marrow, but not in the bone matrix by histological stain for La and X-ray fluorescence microanalysis. Thus, these micro-CT imaging and microscopy of the femurs did not reveal toxic changes due to La. (author)

  1. Microstructured fibers with high lanthanum oxide glass core for nonlinear applications

    Science.gov (United States)

    Kobelke, J.; Schuster, K.; Litzkendorf, D.; Schwuchow, A.; Kirchhof, J.; Bartelt, H.; Tombelaine, V.; Leproux, P.; Couderc, V.; Labruyere, A.

    2009-05-01

    We demonstrate a low loss microstructured fiber (MOF) with a high nonlinear glass core and silica holey cladding. The substitution of mostly used silica as core material of microstructured fibers by lanthanum oxide glass promises a high nonlinear conversion efficiency for supercontinuum (SC) generation. The glass composition is optimized in terms of thermochemical and optical requirements. The glass for the MOF core has a high lanthanum oxide concentration (10 mol% La2O3) and a good compatibility with the silica cladding. This is performed by adding a suitable alumina concentration up to 20 mol%. The lanthanum oxide glass preform rods were manufactured by melting technique. Besides purity issues the material homogeneity plays an important role to achieve low optical loss. The addition of fluorides allows the better homogenization of the glass composition in the preform volume by refining. The minimum attenuation of an unstructured fiber drawn from this glass is about 0.6 dB/m. It is mostly caused by decreasing of scattering effects. The microstructured silica cladding allows the considerable shifting of dispersive behavior of the MOF for an optimal pump light conversion. The MOF shows zero dispersion wavelengths (ZDW) of 1140 nm (LP01 mode) and 970 nm (LP11 mode). The supercontinuum generation was investigated with a 1064 nm pump laser (650 ps). It shows a broad band emission between 500 nm and 2200 nm.

  2. Preparation, characterization and optical properties of Lanthanum-(nanometer MCM-41) composite materials

    International Nuclear Information System (INIS)

    Zhai, Q. Z.; Wang, P.

    2008-01-01

    Nanometer MCM-41 molecular sieve was prepared under a base condition by using cetyltrimethylammonium bromide as template and tetraethyl orthosilicate as silica source by means of hydrothermal method. Lanthanum(III) was incorporated into the nanometer MCM-41 by a liquid phase grafting method. The prepared nano composite materials were characterized by means of powder X-ray diffraction, spectrophotometric analysis, Fourier transform infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid diffuse reflectance absorption spectra and luminescence. The powder X-ray diffraction studies show that the nanometer MCM-41 molecular sieve is successfully prepared. The highly ordered meso porous two-dimensional hexagonal channel structure and framework of the support MCM-41 is retained intact in the prepared composite material La-(nanometer MCM-41). The spectrophotometric analysis indicates that lanthanum exists in the prepared nano composite materials. The Fourier transform infrared spectra indicate that the framework of the MCM-41 molecular sieve still remains in the prepared nano composite materials and some framework vibration peaks show blue shifts relative to those of the MCM-41 molecular sieve. The low temperature nitrogen adsorption-desorption indicates that the guest locales in the channel of the molecular sieve. Compared with bulk lanthanum oxide, the guest in the channel of the molecular sieve has smaller particle size and shows a significant blue shift of optical absorption band in solid diffuse reflectance absorption spectra. The observed blue shift in the solid state diffuse reflectance absorption spectra of the lanthanum-(nanometer MCM-41) sample show the obvious stereoscopic confinement effect of the channel of the host on the guest, which further indicates the successful encapsulation of the guest in the host. The La-(nanometer MCM-41) sample shows luminescence

  3. Energetically benign synthesis of lanthanum silicate through “silica garden” route and its characterization

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, Kavita [Central University of Jharkhand, Ranchi (India); Bhattacharjee, Santanu, E-mail: santanu@nmlindia.org [CSIR-National Metallurgical Laboratory, Jamshedpur (India)

    2017-06-15

    Lanthanum silicate synthesis through “silica garden” route has been reported as an alternative to energy intensive milling procedure. Under optimum conditions lanthanum chloride crystals react with water glass (sodium silicate) to produce self generating hollow lanthanum silicate precipitation tube(s) (LaSPT). The micro tubes are irregular, thick, white coloured and amorphous but are hierarchically built from smaller tubules of 10–20 nm diameters. They retain their amorphous nature on being heated up to 600 °C beyond which crystallization starts. The major phase in the LaSPT heated at 900 °C is La{sub 2}Si{sub 2}O{sub 7}. “As synthesized” LaSPT is heterogeneous and comprises non stoichiometric phases. The exterior and interior surfaces of these tubes are remarkably different in their morphology and chemical composition. LaSPT sintered at 1200 and 1300 °C show fair amount of ionic conductivity. - Graphical abstract: Lanthanum silicate precipitation tube (LaSPT) produced through ‘silica garden’ route offers a green alternative to energy intensive milling procedure. - Highlights: • La-silicate precipitation tube (LaSPT) synthesized via silica garden route. • The microtubes are irregular, thick, white coloured and amorphous. • They are hierarchically built from smaller tubules of 10–20 nm diameters. • The major phase in the LaSPT heated at 900 °C is La{sub 2}Si{sub 2}O{sub 7}. • LaSPT sintered at 1200 °C is fairly conducting.

  4. Energetically benign synthesis of lanthanum silicate through “silica garden” route and its characterization

    International Nuclear Information System (INIS)

    Parmar, Kavita; Bhattacharjee, Santanu

    2017-01-01

    Lanthanum silicate synthesis through “silica garden” route has been reported as an alternative to energy intensive milling procedure. Under optimum conditions lanthanum chloride crystals react with water glass (sodium silicate) to produce self generating hollow lanthanum silicate precipitation tube(s) (LaSPT). The micro tubes are irregular, thick, white coloured and amorphous but are hierarchically built from smaller tubules of 10–20 nm diameters. They retain their amorphous nature on being heated up to 600 °C beyond which crystallization starts. The major phase in the LaSPT heated at 900 °C is La_2Si_2O_7. “As synthesized” LaSPT is heterogeneous and comprises non stoichiometric phases. The exterior and interior surfaces of these tubes are remarkably different in their morphology and chemical composition. LaSPT sintered at 1200 and 1300 °C show fair amount of ionic conductivity. - Graphical abstract: Lanthanum silicate precipitation tube (LaSPT) produced through ‘silica garden’ route offers a green alternative to energy intensive milling procedure. - Highlights: • La-silicate precipitation tube (LaSPT) synthesized via silica garden route. • The microtubes are irregular, thick, white coloured and amorphous. • They are hierarchically built from smaller tubules of 10–20 nm diameters. • The major phase in the LaSPT heated at 900 °C is La_2Si_2O_7. • LaSPT sintered at 1200 °C is fairly conducting.

  5. Effects of lanthanum exposure on elemental distribution in rat brains measured by synchrotron radiation XRF

    International Nuclear Information System (INIS)

    Feng Liuxing; Xiao Haiqing; He Xiao; Liu Nianqing; Zhao Yuliang; Chai Zhifang; Zhang Zhiyong

    2005-01-01

    Rare earth elements (REEs) comprise a coherent series of 15 elements from lanthanum to lutetium and possessing very similar chemical properties. In recent decades, with the rapid increase of the exploitation of REE resources and their applications to modern industry and daily life, particularly to agriculture as fertilizer additives in China, more and more REEs are coming into environmental system as well as food chain through various ways. It has become increasingly important to obtain more information on the physiological function of REEs and their long-term biological effects on body of living beings. Epidemiological investigations found that the intelligence quotients (IQ) of children from the REE-high background regions are obviously different from that of the normal region. This indicated that REEs probably affect the function of brain. However, the mechanism is totally unknown. The contents and distributions of major and trace elements are sometimes good indicators of the physiological and pathological conditions of human and animal brains In this study, the effects of subchronic lanthanum exposure on the elemental distribution in the rat brains were studied. Wistar rats were exposed to lanthanum chloride through oral administration at O, 0.1, 2, and 40-mg/kg doses for 6 months. The elements such as Cl, K, Ca, Fe, Cu, and Zn in brain slices were identified by synchrotron radiation X-ray fluorescence analysis. Differences in two-dimensional maps of elemental distribution were noticed. Cl, Ca, and Zn were primarily concentrated in hippocampus of the controls. With the increase of the lanthanum dosage, the Ca and Zn levels were significantly decreased, while the Cu levels were significantly elevated in cortex, hippocampus and thalamus. Our results suggest that subchronic lanthanum exposure in rats appears to change elemental distribution in brain. The impact of lanthanides on brain function is not negligible.

  6. The rare earth element (REE) lanthanum (La) induces hormesis in plants.

    Science.gov (United States)

    Agathokleous, Evgenios; Kitao, Mitsutoshi; Calabrese, Edward J

    2018-07-01

    Lanthanum is a rare earth element (REE) which has been extensively studied due to its wide application in numerous fields with a potential accumulation in the environment. It has long been known for its potential to stimulate plant growth within a hormetic-biphasic dose response framework. This article provides evidence from a series of high resolution studies published within the last two decades demonstrating a substantial and significant occurrence of lanthanum-induced hormesis in plants. These findings suggest that hormetic responses should be built into the study design of hazard assessment study protocols and included in the risk assessment process. Hormesis also offers the opportunity to substantially improve cost benefit estimates for environmental contaminants, which have the potential to induce beneficial/desirable effects at low doses. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Responses in sediment phosphorus and lanthanum concentrations and composition across 10 lakes following applications of lanthanum modified bentonite

    DEFF Research Database (Denmark)

    Dithmer, Line; Nielsen, Ulla Gro; Lürling, Miquel

    2016-01-01

    and binding forms, P adsorption capacity of discrete sediment layers, and pore water P concentrations. Lanthanum phosphate mineral phases were confirmed by solid state (31)P MAS NMR and LIII EXAFS spectroscopy. Rhabdophane (LaPO4 · nH2O) was the major phase although indications of monazite (LaPO4) formation...... conditions of P retention (with the exception of two lakes) by sediments, indicating effective control of sediment P release, i.e. between two and nine years after treatment....

  8. Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate

    International Nuclear Information System (INIS)

    Vasconcelos, Mari Estela de

    2006-01-01

    In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

  9. Electrical behaviour of strontium-doped lanthanum manganite interfaces

    DEFF Research Database (Denmark)

    Koch, Søren; Hendriksen, P.V.; Jacobsen, Torben

    2005-01-01

    The contact resistance of strontium-doped lanthanum manganite (LSM) contact pairs is investigated by polarisation analysis at different temperatures and atmospheres. The ceramic contacts have a high contact resistance, and strongly nonlinear current–voltage behaviour is observed at low temperatur....... The nonlinear behaviour is ascribed to the presence of energy barriers at the contact interface. Generally, point contacts showed a more linear behaviour than plane contact interfaces....

  10. Selective isotope determination of lanthanum by diode-laser-initiated resonance-ionization mass spectrometry

    International Nuclear Information System (INIS)

    Young, J.P.; Shaw, R.W.

    1995-01-01

    A diode-laser step has been incorporated into a resonance-ionization mass spectrometry optical excitation process to enhance the isotopic selectivity of the technique. Lanthanum isotope ratio enhancements as high as 10 3 were achieved by use of a single-frequency cw diode laser tuned to excite the first step of a three-step excitation--ionization optical process; the subsequent steps were excited by use of a pulsed dye laser. Applying the same optical technique, we measured atomic hyperfine constants for the high-lying even-parity 4 D 5/2 state of lanthanum at 30 354 cm --1 . The general utility of this spectral approach is discussed

  11. Thermoelectric power and electrical conductivity of strontium-doped lanthanum manganite

    DEFF Research Database (Denmark)

    Ahlgren, E.O.; Poulsen, F.W.

    1996-01-01

    Thermoelectric power and electrical conductivity of pure and 5, 10 and 20% strontium-doped lanthanum manganite are determined as function of temperature in air and of P-O2 at 1000 degrees C. At high temperatures the thermoelectric power is negative. Both thermoelectric power and conductivity...

  12. A case of lanthanum carbonate ingestion thought to be phlebosclerotic colitis on CT imaging and abdominal radiograph

    International Nuclear Information System (INIS)

    Harris, K.; Balcam, S.

    2017-01-01

    A male admitted in the early hours of the morning, complained of a four week, right sided, non-radiating, dull and intermittent abdominal pain. Imaging suggested a diagnosis of phlebosclerotic colitis which was later discounted when the patients' history of lanthanum carbonate ingestion was examined. Phlebosclerotic colitis mostly affects the Asian population, and its cause is still not known, but can be associated with specific radiographic features. Collections of lanthanum may confuse a diagnosis of phlebosclerotic colitis as well as other factors such as voxel errors, photon starvation and movement. - Highlights: • PC can be non-specific, its cause unknown, diagnosis is often delayed. • PC depends on specific radiographic features. • Lanthanum Carbonate can collect within the lumen and confuses diagnosis. • Voxel errors, photon starvation and patient movement can displace densities.

  13. Modification of radiation sensitivity by salts of the metals beryllium and indium and the rare earths cerium, lanthanum and scandium

    International Nuclear Information System (INIS)

    Floersheim, G.L.

    1995-01-01

    The LD 50 of 46 salts of metals and rare earths (lanthanoids) was determined in mice. Half the LD 50 of the compounds was then combined with lethal radiation (10.5 Gy) and the modification of survival time was scored. Only the metals beryllium and indium and the rare earths cerium, lanthanum and scandium displayed activity in our assay. There were then tested at a wider range of lower doses and reduced survival time in a dose-dependent fashion. This appears to be compatible with enhancement of radiation sensitivity. The interaction of these metals and rare earths with radiation adds a new facet to their toxicological spectrum and, by enhancing radiation effects, may influence estimates of risk. On the other hand, radiosensitizing properties of the metals may be useful for further development of compounds to be used as adjuncts in specific situations of cancer radiotherapy. 31 refs., 1 fig., 1 tab

  14. On magnetic ordering in heavily sodium substituted hole doped lanthanum manganites

    Energy Technology Data Exchange (ETDEWEB)

    Sethulakshmi, N. [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Unnimaya, A.N. [Centre for Materials for Electronic Technology (CMET), Thrissur 680581, Kerala (India); Al-Omari, I.A.; Al-Harthi, Salim [Department of Physics, Sultan Qaboos University, PC 123 Muscat (Oman); Sagar, S. [Government College for Women, Thiruvananthapuram 695014, Kerala (India); Thomas, Senoy [Materials Science and Technology Division, National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram 695019, Kerala (India); Srinivasan, G. [Department of Physics, Oakland University, Rochester (United States); Anantharaman, M.R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India)

    2015-10-01

    Mixed valence manganite system with monovalent sodium substituted lanthanum manganites form the basis of the present work. Lanthanum manganites belonging to the series La{sub 1−x}Na{sub x}MnO{sub 3} with x=0.5–0.9 were synthesized using modified citrate gel method. Variation of lattice parameters and unit cell volume with Na concentration were analyzed and the magnetization measurements indicated ferromagnetic ordering in all samples at room temperature. Low temperature magnetization behavior indicated that all samples exhibit antiferromagnetism along with ferromagnetism and it has also been observed that antiferromagnetic ordering dominates ferromagnetic ordering as concentration is increased. Evidence for such a magnetic inhomogeneity in these samples has been confirmed from the variation in Mn{sup 3+}/Mn{sup 4+} ion ratio from X-ray Photoelectron Spectroscopy and from the absorption peak studies using Ferromagnetic Resonance Spectroscopy. - Highlights: • Higher substitution of more than 50 percent of monovalent ion, sodium for La sites in lanthanum manganites scarce in literature. • Structural studies using XRD and further structure refinement by Rietveld refinement confirmed orthorhombic pbnm spacegroup. • Ferromagnetic behavior at room temperature with saturation magnetization decreasing with increase in sodium concentration. • M vs T measurements using FC ZFC proved coexisting FM/AFM behavior arising from exchange interactions between different valence states of Mn ions. • Disparity in ratio of Mn valence ions indicated presence of vacancies providing the role of vacancies and oxygen stoichiometry in deciding magnetic inhomogeneity.

  15. Self-assembly in lanthanum(III) and calcium(II) complexes of salicylaldimines derived from putrescine

    International Nuclear Information System (INIS)

    Pospieszna-Markiewicz, Izabela; Kaczmarek, Malgorzata T.; Kubicki, Maciej; Radecka-Paryzek, Wanda

    2008-01-01

    The one-step template reaction of salicylaldehyde with putrescine, a biogenic diamine, in the presence of lanthanum(III) or calcium(II) ions produces salicylaldimine complexes containing the N,N'-bis(salicylidene)-1,4-butanediamine ligand L as a result of the [2 + 1] Schiff base condensation. The X-ray diffraction studies of the lanthanum complex reveals an infinite [La 2 L 4 (NO 3 ) 6 ] ∞ polymeric structure based on networks of 10-coordinated La(III) nodes linked by bridging unionized ligands that use exclusively the oxygens as donor atoms with the nitrogen atoms not being involved in coordination

  16. Application of the Rietveld method in powders of strontium-doped lanthanum manganite calcined in different temperatures

    International Nuclear Information System (INIS)

    Chiba, R.; Vargas, R.A.; Martinez, L.G.; Andreoli, M.; Seo, E.S.M.

    2010-01-01

    The strontium-doped lanthanum manganite (LSM) is a ceramic material used as cathode in device called High Temperature Solid Oxide Fuel Cell. In this work, the LSM was synthesized by the citrate technique with the objective to get powders without the formation of secondary phases, such as lanthanum oxide and the lanthanum hydroxide, harmful for the functional performance of the device. The definitive calcination temperatures had been 700, 900 and 1100 deg C, due the decomposition of the polymeric precursors to present stabilization from 480 deg C. The analysis by X-ray diffraction of the calcined powders in different temperatures shows the formation only of phase LSM of hexagonal crystalline structure, type pseudo-perovskite. Using the refinement of Rietveld was determined the parameters and volumes of unity cells, atomic positions and occupations. These results confirm that the chemical compositions obtained are similar to the nominal. (author)

  17. Effect of voltage on the characteristics of magnesium-lanthanum deposits synthesized by an electrodeposition process

    Energy Technology Data Exchange (ETDEWEB)

    Sahli, M. [Laboratoire de Physique Energétique, Université de Constantine 1 (Algeria); Chetehouna, K.; Gascoin, N. [INSA-CVL, Univ. Orléans, PRISME, EA 4229, F-18020, Bourges (France); Bellel, N. [Laboratoire de Physique Energétique, Université de Constantine 1 (Algeria); Tadini, P., E-mail: tadini.pietro@gmail.com [INSA-CVL, Univ. Orléans, PRISME, EA 4229, F-18020, Bourges (France)

    2017-04-15

    This work deals with the characterization of magnesium-lanthanum powders deposits produced with an electrodeposition technique using an aqueous solution based on magnesium chloride and lanthanum(III) nitrate. In recent years, the interest for magnesium-based alloys is growing due to their potential use as solid state systems for hydrogen storage. This work is a preliminary study on the synthesis of magnesium-lanthanum powders oriented to their later evaluation in systems for hydrogen storage. Magnesium and Lanthanum are deposited on a copper plate used as a cathode. Chemical composition, structure and morphology are investigated by EDS, XRD, FTIR and SEM. The effect of voltage on powders characteristics is studied considering three values (3, 3.5 and 4 V). EDS analysis shows the presence of three major elements (Mg, La and O) with a little amount of Cl. The weight percentages of Mg and O increase whereas the one of La decreases with the growth of voltage. Morphological characterization reveals that heterogeneous chemical structures are formed on the surface of the electrode and the size of aggregates decreases with the increase of voltage. From the results of X-ray analysis the deposits reveal the significant presence of two phases: Mg(OH){sub 2} and La(OH){sub 3}. The peaks originating from the Mg(OH){sub 2} phase has a non-monotonic behavior and those of La(OH){sub 3} phase increase with the increase of voltage. FTIR analysis confirms the presence of the two phases identified in XRD diffractograms and exhibits that their corresponding transmittance values increase for higher voltage values. - Highlights: • Synthesis of magnesium-lanthanum deposits by an electrodeposition process. • Voltage effect is investigated using different physicochemical analysis techniques (EDS, XRD, FTIR and SEM). • The EDS analysis shows the presence of three major elements (Mg, La and O) and a little amount of Cl. • Two phases, namely Mg(OH){sub 2} and La(OH){sub 3} are

  18. ELECTRICAL RESISTIVITY AND SEEBECK COEFFICIENT IN Ca(LaMnO COMPOUNDS PREPARED BY SOLID STATE REACTION METHOD

    Directory of Open Access Journals (Sweden)

    Jorge I. Villa

    2017-01-01

    Full Text Available By using the solid state reaction method samples of  Ca1-xLaxMnO3 (0 ≤ x ≥ 0.15 were prepared. Their transport properties were studied by electrical resistivity rho(T and Seebeck coefficient S(T measurements as a function of temperature and lanthanum content, in the temperature range between 100 and 290K. The structural and morphological properties were studied by X-ray diffraction analysis (XRD and scanning electron microscopy (SEM, respectively. The Seebeck coefficient is negative throughout the studied temperature range indicating a conduction given by negative charge carriers, its magnitude decreases with the lanthanum content from |-261| mV/K to |-120| mV/K. The electrical resistivity shows a semiconducting behavior, it was interpreted in terms of small polaron hopping model. Thermoelectric properties of the obtained compounds were studied by the thermoelectric power factor PF, which reaches maximum values around 2mW/K2cm, these values become this kind of ceramics promising thermoelectric compound, to be used in technological applications.

  19. Modification of TiO2 nanoparticles through lanthanum doping and PEG templating

    Directory of Open Access Journals (Sweden)

    Marija Milanovic

    2014-12-01

    Full Text Available Pure and lanthanum doped titania nanopowders were synthesized through a room temperature sol-gel method using a template of polyethylene glycol (PEG. The progress of the synthesis in terms of phase formation and size of nanoparticles was monitored by X-ray diffraction, FTIR spectroscopy and SEM analysis. After calcination at 450 °C in air, the results have shown the presence of small particles crystallized predominantly in the form of anatase phase, with significant agglomeration. Nitrogen adsorption-desorption measurements confirmed that all prepared powders are mesoporous with an average pore diameter in range 3.1–3.8 nm. The addition of lanthanum ions leads to the nanopowders with the highest specific surface (BET area (203 m2/g. The obtained powders were compared to TiO2 prepared without a template.

  20. Molecular absorption spectra of beryllium, cerium, lanthanum, iron, and platinum salts

    International Nuclear Information System (INIS)

    Daidoji, Hidehiro

    1980-01-01

    The absorption spectra of some salts of beryllium, cerium, lanthanum, iron and platinum in air-acetylene flame were measured in the wavelength range from 200 to 400 nm. A Hitachi 207 type atomic absorption spectrophotometer was used. A deuterium lamp, a home-made continuous radiation lamp and some hollow cathode lamps were used as light sources. The new molecular absorption spectra of cerium, lanthanum and platinum and the absorption spectra due to Be(OH) 2 , LaO, PtH, FeO and FeCl in 200-400 nm region were obtained. Emission spectra of CeO, LaO and FeOH were also obtained. These molecular absorption bands were estimated as absorption errors of maximum 15 times to the sensitivity of each elements in atomic absorption spectrometry. In addition, spectral line interferences of iron were observed in atomic absorption spectrometry of Zn, Cd, Ni, Cu and Cr. (author)

  1. The combination of lanthanum chloride and the calcimimetic calindol delays the progression of vascular smooth muscle cells calcification

    Energy Technology Data Exchange (ETDEWEB)

    Ciceri, Paola; Volpi, Elisa; Brenna, Irene; Elli, Francesca [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy); Borghi, Elisa [Dipartimento di Salute Pubblica, Microbiologia e Virologia, Universita di Milano, Milan (Italy); Brancaccio, Diego [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy); Cozzolino, Mario, E-mail: mario.cozzolino@unimi.it [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy)

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer Lanthanum reduces the progression of high phosphate-induced calcium deposition. Black-Right-Pointing-Pointer Calcium receptor agonists and the calcimimetic calindol reduce calcium deposition. Black-Right-Pointing-Pointer Lanthanum and calindol cooperate on reducing calcium deposition. Black-Right-Pointing-Pointer Lanthanum and calindol may interact with the same receptor. -- Abstract: Phosphate (Pi)-binders are commonly used in dialysis patients to control high Pi levels, that associated with vascular calcification (VC). The aim of this study was to investigate the effects of lanthanum chloride (LaCl{sub 3}) on the progression of high Pi-induced VC, in rat vascular smooth muscle cells (VSMCs). Pi-induced Ca deposition was inhibited by LaCl{sub 3}, with a maximal effect at 100 {mu}M (59.0 {+-} 2.5% inhibition). Furthermore, we studied the effects on VC of calcium sensing receptor (CaSR) agonists. Gadolinium chloride, neomycin, spermine, and the calcimimetic calindol significantly inhibited Pi-induced VC (55.9 {+-} 2.2%, 37.3 {+-} 4.7%, 30.2 {+-} 5.7%, and 63.8 {+-} 5.7%, respectively). To investigate the hypothesis that LaCl{sub 3} reduces the progression of VC by interacting with the CaSR, we performed a concentration-response curve of LaCl{sub 3} in presence of a sub-effective concentration of calindol (10 nM). Interestingly, this curve was shifted to the left (IC{sub 50} 9.6 {+-} 2.6 {mu}M), compared to the curve in the presence of LaCl{sub 3} alone (IC{sub 50} 19.0 {+-} 4.8 {mu}M). In conclusion, we demonstrated that lanthanum chloride effectively reduces the progression of high phosphate-induced vascular calcification. In addition, LaCl{sub 3} cooperates with the calcimimetic calindol in decreasing Ca deposition in this in vitro model. These results suggest the potential role of lanthanum in the treatment of VC induced by high Pi.

  2. The effect of samarium doping on structure and enhanced thermionic emission properties of lanthanum hexaboride fabricated by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shenlin; Hu, Qianglin [College of Mathematics and Physics, Jinggangshan University, Jian (China); Zhang, Jiuxing; Liu, Danmin [Key Laboratory of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing (China); Huang, Qingzhen [NIST Center for Neutron Research, National Institute of Standards and Technology, MD (United States)

    2014-03-15

    Single-phase polycrystalline solid solutions (La{sub 1-x}Sm{sub x})B{sub 6} (x = 0, 0.2, 0.4, 0.8, 1) are fabricated by spark plasma sintering (SPS). This study demonstrates a systematic investigation of structure-property relationships in Sm-doped LaB{sub 6} ternary rare-earth hexaborides. The microstructure, crystallographic orientation, electrical resistivity, and thermionic emission performance of these compounds are investigated. Analysis of the results indicates that samarium (Sm) doping has a noticeable effect on the structure and performance of lanthanum hexaboride (LaB{sub 6}). The analytical investigation of the electron backscatter diffraction confirms that (La{sub 0.6}Sm{sub 0.4})B{sub 6} exhibits a clear (001) texture that results in a low work function. Work functions are determined by pulsed thermionic diode measurements at 1500-1873 K. The (La{sub 0.6}Sm{sub 0.4})B{sub 6} possesses improved thermionic emission properties compared to LaB{sub 6}. The current density of (La{sub 0.6}Sm{sub 0.4})B{sub 6} is 42.4 A cm{sup -2} at 1873 K, which is 17.5% larger than that of LaB{sub 6}. The values of Φ{sub R} for (La{sub 0.6}Sm{sub 0.4})B{sub 6} and LaB{sub 6} are 1.98 ± 0.03 and 1.67 ± 0.03 eV, respectively. Furthermore, the Sm substitution of lanthanum (La) effectively increases the electrical resistivity. These results reveal that Sm doping lead to significantly enhanced thermionic emission properties of LaB{sub 6}. The compound (La{sub 0.6}Sm{sub 0.4})B{sub 6} appears most promising as a future emitter material. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Effects of adding lanthanum to Ni/ZrO2 catalysts on ethanol steam reforming

    International Nuclear Information System (INIS)

    Profeti, Luciene Paula Roberto; Habitzheuter, Filipe; Assaf, Elisabete Moreira

    2012-01-01

    The catalytic performance of Ni/ZrO 2 catalysts loaded with different lanthanum content for steam reforming of ethanol was investigated. Catalysts were characterized by BET surface area, X-ray diffraction, UV-vis spectroscopy, temperature programmed reduction, and X-ray absorption fine structure techniques. Results showed that lanthanum addition led to an increase in the degree of reduction of both NiO and nickel surface species interacting with the support, due to the higher dispersion effect. The best catalytic performance at 450 deg C was found for the Ni/12LZ catalyst, which exhibited an effluent gaseous mixture with the highest H 2 yield. (author)

  4. Growth and physico chemical characterization of lanthanum neodymium oxalate single crystals

    International Nuclear Information System (INIS)

    Raju, K.S.; John, Varughese; Ittyachen, M.A.

    1998-01-01

    Single crystals of lanthanum neodymium oxalate (LNO) are grown in sodium meta silicate gels, by the diffusion of a mixture of aqueous solutions of lanthanum nitrate and neodymium nitrate into the test tube having the set gel containing oxalic acid. The bluish pink coloured tabular crystals of LNO having well defined hexagonal basal planes appear either as foggy or clear, the latter at the greater depths inside the gel. The coloration of LNO visually observed is evidenced in UV-visible spectrum, by the revelation of well pronounced characteristic peaks in the visible region (500-900 nm). X-ray diffraction (XRD) of powdered LNO is ordered, meaning crystalline in nature, besides its isostructurality with similarly grown lanthanum samarium oxalate crystals. The single crystallinity of LNO is established by its oscillation XRD pattern. Thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) support that LNO loses water of crystallization around 120 degC and CO and CO 2 around 350-450 degC, while the infrared absorption (IR) spectrum of LNO establishes the presence of oxalate (C 2 O 4 ) 2- ions. Energy dispersive x-ray analysis (EDAX) confirms the presence of La and Nd in the sample. X-ray photoelectron spectroscopic (XPS) studies of LNO establish the presence of La and Nd in their respective oxide states. An empirical structure for LNO has been proposed on the basis of these findings. The smokiness in the foggy LNO crystal has been attributed due to the gel inclusion during the growth process. (author)

  5. Synthesis and Characterization of Lanthanum Complexes with Amino Acid Schiff Base

    Institute of Scientific and Technical Information of China (English)

    张秀英; 张有娟; 杨林

    2001-01-01

    Six new complexes of lanthanum with amino acid Schiff base ligands, A-F, were prepared in methanol-aqueous solution. The composition and properties of the title complexes were characterized by elemental analysis, molar conductance, infrared, electronic spectra, 1H NMR, thermogravimetric and differential thermal analysis.

  6. Effect of long-term intake of lanthanum chloride on the concentrations of some macro- and trace elements in rat brains using NAA

    International Nuclear Information System (INIS)

    Yu Tong; Li Yaming; Ren Yan; Wang Enbo; Xu Hongying; Wang Wenzhong

    2005-01-01

    Effects of long-term intake of lanthanum in drinking water on the concentrations of twelve kinds of macro- and trace elements in rat brains were primarily studied by neutron activation analysis. The results show that, along with the elevation of the dose of lanthanum, more and more elements were affected in the rat brain tissues. Compared with control group, the concentrations of five elements were changed in the 1000 mg/L group. These elements have close relations with brain function. Accordingly, intake of lanthanum may have negative effects on brain function. (authors)

  7. Studies on the lanthanum arsenate ion-exchanger: preparation, physicochemical properties and applications

    International Nuclear Information System (INIS)

    Mukherjee, A.K.; Mandal, S.K.

    1984-01-01

    The cation-exchange behaviour of lanthanum arsenate has been studied. This paper reports the preparation and physicochemical properties of the exchanger. Its analytical utility is compared with that of other arsenate exchangers. Some practical analytical applications are described. (author)

  8. Development of a 1 kW Class SOFC Stack using Doped Lanthanum Gallate

    Energy Technology Data Exchange (ETDEWEB)

    Akikusa, J.; Adachi, K.; Yamada, T.; Akbay, T.; Murakami, N.; Chitose, N.; Hoshino, K.; Hosoi, K.; Yoshida, H.; Sasaki, T.; Inagaki, T.; Ishihara, T.; Takita, Y.

    2002-06-01

    The performance of lanthanum gallate based SOFC has been investigated as a high-energy conversion device. A planar type SOFC which could operate at temperatures below 800 {sup o}C has been jointly developed. As an electrolyte material, lanthanum gallate (LaGaO{sub 3}) with substitutions of Sr for the La site and Mg and Co for the Ga site (LSGMC) was used. The synthesis technique for large-sized cell production has been established, and the performance of a self- supported diameter 154 mm cell with 200 {mu}m electrolyte thickness is investigated. The output power of 50 W has been obtained with a conversion efficiency [LHV] of 45 % for a single cell. In addition, a metallic separator made of stainless steel was chosen and tested successfully for a seal-less stack. The output power of 1 kW by means of the stack of 18 cells has been achieved for the first time utilizing lanthanum gallate. Moreover, NiO-SDC composite powders were prepared by the spray pyrolysis method and used for the anode on 100 {mu}m thickness LSGMC electrolyte with a combination of samarium cobaltite for the cathode. The power density of as high as 1.8 W/cm{sup 2} at 0.7 V terminal voltage was achieved at 800{sup o}C. (author)

  9. Materials system for intermediate temperature solid oxide fuel cells based on doped lanthanum-gallate electrolyte

    Science.gov (United States)

    Gong, Wenquan

    2005-07-01

    The objective of this work was to identify a materials system for intermediate temperature solid oxide fuel cells (IT-SOFCs). Towards this goal, alternating current complex impedance spectroscopy was employed as a tool to study electrode polarization effects in symmetrical cells employing strontium and magnesium doped lanthanum gallate (LSGM) electrolyte. Several cathode materials were investigated including strontium doped lanthanum manganite (LSM), Strontium and iron doped lanthanum cobaltate (LSCF), LSM-LSGM, and LSCF-LSGM composites. Investigated Anode materials included nickel-gadolinium or lanthanum doped cerium oxide (Ni-GDC, or Ni-LDC) composites. The ohmic and the polarization resistances of the symmetrical cells were obtained as a function of temperature, time, thickness, and the composition of the electrodes. Based on these studies, the single phase LSM electrode had the highest polarization resistance among the cathode materials. The mixed-conducting LSCF electrode had polarization resistance orders of magnitude lower than that of the LSM-LSGM composite electrodes. Although incorporating LSGM in the LSCF electrode did not reduce the cell polarization resistance significantly, it could reduce the thermal expansion coefficient mismatch between the LSCF electrodes and LSGM electrolyte. Moreover, the polarization resistance of the LSCF electrode decreased asymptotically as the electrode thickness was increased thus suggesting that the electrode thickness needed not be thicker than this asymptotic limit. On the anode side of the IT-SOFC, Ni reacted with LSGM electrolyte, and lanthanum diffusion occurred from the LSGM electrolyte to the GDC barrier layer, which was between the LSGM electrolyte and the Ni-composite anode. However, LDC served as an effective barrier layer. Ni-LDC (70 v% Ni) anode had the largest polarization resistance, while all other anode materials, i.e. Ni-LDC (50 v% Ni), Ni-GDC (70 v% NO, and Ni-GDC (50 v% Ni), had similar polarization

  10. Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation and Detection

    International Nuclear Information System (INIS)

    Guss, Paul; Mukhopadhyay, Sanjoy; Guise, Ron; Yuan, Ding

    2010-01-01

    Scintillator materials are used to detect, and in some cases identify, gamma rays. Higher performance scintillators are expensive, hard to manufacture, fragile, and sometimes require liquid nitrogen or cooling engines. But whereas lower-quality scintillators are cheap, easy to manufacture, and more rugged, their performance is lower. At issue: can the desirable qualities of high-and low-performance scintillators be combined to achieve better performance at lower cost? Preliminary experiments show that a LaF 3 :Ce oleic acid-based nanocomposite exhibits a photopeak when exposed to 137 Cs source gamma-radiation. The chemical synthesis of the cerium-doped lanthanum halide nanoparticles are scalable and large quantities of material can be produced at a time, unlike typical crystal growth processes such as the Bridgeman process. Using a polymer composite (Figure 1), produced by LANL, initial measurements of the unloaded and 8% LaF 3 :Ce-loaded sample have been made using 137 Cs sources. Figure 2 shows an energy spectrum acquired for CeF 3 . The lighter plot is the measured polymer-only spectrum and the black plot is the spectrum from the nanocomposite scintillator. As the development of this material continues, the energy resolution is expected to improve and the photopeak-to-Compton ratio will become greater at higher loadings. These measurements show the expected Compton edge in the polymer-only sample, and the Compton edge and photo-peak expected in the nanophosphor composites that LANL has produced. Using a porous VYCORR with CdSe/ZnS core shell quantum dots, Letant has demonstrated that he has obtained signatures of the 241Am photopeak with energy resolution as good at NaI (Figure 3). We begin with the fact that CeBr 3 crystals do not have a self-activity component as strong as the lanthanum halides. The radioactive 0.090% 138 La component of lanthanum leads to significant self-activity, which will be a problem for very large detector volumes. Yet a significant

  11. The effect of physiologic aqueous solutions on the perovskite material lead-lanthanum-zirconium titanate (PLZT)

    Science.gov (United States)

    Foster, William J.; Meen, James K.; Fox, Donald A.

    2016-01-01

    Context Perovskite compounds, including Lead-Lanthanum-Zirconium Titanate (PLZT), have wide technological application because of their unique physical properties. The use of PLZT in neuro-prosthetic systems, such as retinal implants, have been discussed in a number of publications. Since inorganic lead is a retinotoxic compound that produces retinal degeneration, the long-term stability of PLZT in aqueous biological solutions must be determined. Objective We evaluated the stability and effects of prolonged immersion of a PLZT-coated crystal in a buffered balanced salt solution. Materials and Methods Scanning Electron Microscopy and Electron Dispersive Spectroscopy (EDS) using a JEOL JSM 5410 microscope equipped with EDS were utilized to evaluate the samples before and after prolonged immersion. Results We found that lead and other constituents of PLZT leached into the surrounding aqueous medium. Discussion By comparing the unit cell of PLZT with that of CaTiO3, which has been found to react with aqueous fluids, Lead is in the same site in PLZT as Ca is in CaTiO3. It is thus reasonable that PLZT will react with aqueous solutions. Conclusion The results suggest that PLZT must either be coated with a protective layer or is not appropriate for long-term in vivo or in vitro biological applications. PMID:22697294

  12. Apparent molar volumes and compressibilities of lanthanum, gadolinium and lutetium trifluoromethanesulfonates in dimethylsulfoxide

    International Nuclear Information System (INIS)

    Warmińska, Dorota; Wawer, Jarosław

    2012-01-01

    Highlights: ► Sequence of volumes and compressibilities of Ln 3+ ions in DMSO is: La 3+ > Gd 3+ 3+ . ► Sequence of the partial molar volumes do not change with temperature. ► These results are the consequence of nature of the ion–solvent bonding. - Abstract: Temperature dependencies of the densities of dimethylsulfoxide solutions of lanthanum, gadolinium and lutetium trifluoromethanesulfonates have been determined over a wide range of concentrations. The apparent molar volumes and partial molar volumes of the salts at infinite dilution, as well as the expansibilities of the salts, have been calculated from density data. Additionally, the apparent molar isentropic compressibilities of lanthanum, gadolinium and lutetium trifluoromethanesulfonates have been calculated from sound velocity data at 298.15 K. The data obtained have been interpreted in terms of ion−solvent interactions.

  13. Effect of various lanthanum sol-gel coatings on the 330Cb (Fe-35Ni-18Cr-1Nb-2Si) oxidation at 900 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Buscail, H., E-mail: buscail@iut.u-clermont1.fr [Clermont Universite- LVEEM, 8 rue J.B. Fabre, BP 219, 43006 Le Puy en Velay (France); Issartel, C.; Riffard, F.; Rolland, R.; Perrier, S. [Clermont Universite- LVEEM, 8 rue J.B. Fabre, BP 219, 43006 Le Puy en Velay (France); Fleurentin, A. [CETIM, 52 av Felix Louat, BP 80067, 60304 Senlis (France); Josse, C. [L' ICB UMR5209 CNRS, BP 47870, 21078 Dijon (France)

    2011-11-01

    The influence of a lanthanum sol-gel coating on the oxide scale adherence has been studied during the 330Cb (Fe-35Ni-18Cr-1Nb-2Si) oxidation at 900 deg. C, in air. The alloy oxidation is performed in order to generate a protective chromia scale acting as a good barrier against carburization. Argon annealing of lanthanum sol-gel coatings have been performed at various temperatures in order to find the best conditions to insure the scale adherence. Kinetic results show that lanthanum sol-gel coatings lead to a lower oxidation rate compared to blank specimens. Thermal cycling tests on lanthanum the sol-gel coated specimen show that the oxide scale formed at 900 deg. C, in air, is adherent.

  14. Hydrocarbon conversion with cracking catalyst having co-combustion promoters lanthanum and iron

    International Nuclear Information System (INIS)

    Csicsery, S.M.

    1979-01-01

    A composition useful in hydrocarbon conversion processes such as catalytic cracking comprises 0.05 to 10 weight percent lanthanum associated with a refractory support. The composition may also include 0.02 to 10 weight percent iron. The refractory support is a zeolitic crystalline aluminosilicate

  15. Paramagnetic resonance of Mn4+ and Mn2+ centers in lanthanum gallate single crystals

    Science.gov (United States)

    Vazhenin, V. A.; Potapov, A. P.; Guseva, V. B.; Artyomov, M. Yu.

    2010-03-01

    An increase in the manganese concentration in lanthanum gallate in the range 0.5-5.0% has been found to result in a complete replacement of individual Mn4+ ions by Mn2+ ions. The relative concentrations and binding energies of individual Mn4+, Mn3+, and Mn2+ ions have been determined. The spin Hamiltonians of the Mn2+ and Mn4+ centers in the rhombohedral and orthorhombic phases, respectively, have been constructed and the orientation of the principal axes of the fine-structure tensor of Mn4+ at room temperature has been found. The possibility of using electron paramagnetic resonance for determining the rotation angles of oxygen octahedra of lanthanum gallate with respect to the perovskite structure has been discussed.

  16. Adsorbtion of oxygen and cesium on lanthanum hexaboride

    International Nuclear Information System (INIS)

    Gorodetskij, D.A.; Tskhakaya, V.K.; Shchudlo, Yu.G.; Yarygin, V.I.; Yas'ko, A.A.

    1982-01-01

    Oxygen and cesium adsorption on lanthanum hexaboride was investigated. Especial attention was paid to structural investigations of the LaB 6 (100)-O system. Diffraction pictures and curves of changes in work function in the process of oxygen disorption have been obtained. At oxygen adsorption on a crystal heated up to different temperatures in the range of 900-1400 K the same diffraction pictures as at corresponding annealing temperatures observed were. It is noted that adsorption heat changes slightly in the LaB 6 -O-Cs system

  17. Synthesis and characterization of nanoporous strontium-doped lanthanum cobaltite thin film using metal organic chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun-Sik [Department of Mechanical Convergence Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Young-Beom, E-mail: ybkim@hanyang.ac.kr [Department of Mechanical Convergence Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2016-01-29

    By employing strontium as a dopant of lanthanum cobaltite (LaCoO{sub 3}), strontium-doped lanthanum cobaltite (La{sub 1−x}Sr{sub x}CoO{sub 3−δ}, LSC) thin film was fabricated using a metal organic chemical solution deposition (MOCSD) method. Lanthanum nitrate hexahydrate [La(NO{sub 3}){sub 3}6H{sub 2}O], strontium acetate [Sr(CH{sub 3}COO){sub 2}], and cobalt acetate tetrahydrate [Co(CH{sub 3}COO){sub 2}4H{sub 2}O] were used as precursors. The coating process was performed through a spin coating method on a substrate, which were then heat treated under various temperature conditions. Electrical properties, microstructures, and crystalline structures with respect to sintering temperature were analyzed. According to these analyses, the change in surface morphology, phase shift, and conductive properties were closely related, which could explain their respective behaviors. Furthermore, sintered strontium-doped lanthanum perovskite oxides showed various conductivities according to the amount of dopant. With the molar ratio of strontium that is stoichiometrically equivalent to lanthanum (La{sub 0.5}Sr{sub 0.5}CoO{sub 3−δ}) thin film showed the best conductivity in the sintering temperature range of 650–700 °C, with perovskite phases formed at this temperature condition. As the electrically conductive properties of the thin film are a function of thickness, the films were coated several times to a thickness of approximately 300 nm, with the lowest resistivity (approximately 9.06 × 10{sup −4} Ω cm) observed at the optimized sintering temperature and solution composition. - Highlights: • LSC thin film was fabricated by metal organic chemical solution deposition (MOCSD). • The film shows good agreement on the electrical conductivity of LSC by conventional methods. • The properties of LSC film are influenced by the surface morphology and crystalline phase. • Optimal molar ratio of strontium for the highest conductivity was investigated.

  18. Lanthanum carbonate versus placebo for management of hyperphosphatemia in patients undergoing peritoneal dialysis: a subgroup analysis of a phase 2 randomized controlled study of dialysis patients

    Directory of Open Access Journals (Sweden)

    Hutchison Alastair J

    2013-02-01

    Full Text Available Abstract Background This short-term study assessed the efficacy and safety of lanthanum carbonate in the treatment of hyperphosphatemia in dialysis patients; here, we report a prespecified subgroup analysis of patients undergoing peritoneal dialysis. Methods Men and women (n = 39 who had received continuous ambulatory peritoneal dialysis for chronic kidney disease for 6 months or more were enrolled in eight renal medicine departments in the United Kingdom. A 2-week washout period was followed by a 4-week dose-titration phase during which patients received lanthanum carbonate titrated up to 2250 mg/day. This was followed by a 4-week, randomized, placebo-controlled, parallel-group phase during which patients continued to receive either lanthanum carbonate at the titrated dose, or a matched dose of placebo. The main outcome measure was control of serum phosphate levels (1.3-1.8 mmol/l at the end of the parallel-group phase. Results Serum phosphate was controlled in 3/39 (8% patients at the beginning of the dose-titration phase (after washout and in 18/31 (58% patients treated with lanthanum carbonate at its end. After the parallel-group phase, 60% of lanthanum carbonate-treated patients and 10% of those receiving placebo had controlled serum phosphate. There was no difference in mean (95% confidence interval serum phosphate levels between groups at randomization: lanthanum carbonate, 1.57 (1.34-1.81 mmol/l; placebo, 1.58 (1.40-1.76 mmol/l (p = 0.96. However, a difference was seen at the end of the parallel-group phase: lanthanum carbonate, 1.56 (1.33-1.79 mmol/l; placebo, 2.25 (1.81-2.68 mmol/l (p = 0.0015. There were no clinically important changes in nutritional parameters and no serious treatment-related adverse events were recorded. Conclusions At doses up to 2250 mg/day, lanthanum carbonate is well tolerated and controls hyperphosphatemia effectively. Treatment with higher doses of lanthanum carbonate may allow patients undergoing

  19. Photoluminescence properties of cerium oxide nanoparticles as a function of lanthanum content

    International Nuclear Information System (INIS)

    Deus, R.C.; Cortés, J.A.; Ramirez, M.A.; Ponce, M.A.; Andres, J.; Rocha, L.S.R.

    2015-01-01

    Highlights: • CeO 2 nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO 2 and La-doped CeO 2 particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in the cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission

  20. Structures, stabilities, and electronic properties for rare-earth lanthanum doped gold clusters

    International Nuclear Information System (INIS)

    Zhao, Ya-Ru

    2015-01-01

    The structures, stabilities, and electronic properties of rare-earth lanthanum doped gold La 2 Au n (n = 1-9) and pure gold Au n (n ≤ 11) clusters have been investigated by using density functional theory. The optimized geometries show that the lowest energy structures of La 2 Au n clusters favour the 3D structure at n ≥ 3. The lanthanum atoms can strongly enhance the stabilities of gold clusters and tend to occupy the most highly coordinated position. By analysing the gap, vertical ionization potential, and chemical hardness, it is found that the La 2 Au 6 isomer possesses higher stability for small-sized La 2 Au n clusters (n = 1-9). The charges in the La 2 Au n clusters transfer from La atoms to the Au n host. In addition, Wiberg bond indices analysis reveals that the intensity of different bonds of La 2 Au n clusters exhibits a sequence of La-La bond > La-Au bond > Au-Au bond.

  1. Induced assembly and photoluminescence of lanthanum (Tb, Eu, Dy) complexes/ZnO/polyethylene glycol hybrid phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Yan Bing [Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092 (China)]. E-mail: byan@tongji.edu.cn; Chen Xi [Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092 (China); Wu Jianhua [Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092 (China)

    2007-08-31

    Some novel kinds of hybrid phosphors were assembled with lanthanum (Tb, Eu, Dy) complexes (with four kinds of terbium complexes is 2,4-dihydroxybenzonic acid (DHBA), 1,10-phenanthroline (phen), acetylacetone (AA) and nicotinic acid (Nic), respectively) doped ZnO/PEG particles by co-precipitation approach derived from Zn(CH{sub 3}COO){sub 2} (Zn(AC){sub 2}), NaOH, PEG as precursors at room temperature. The characteristic luminescence spectra for f-f transitions of Tb{sup 3+}, Eu{sup 3+}, Dy{sup 3+} were observed. It is worthy to point out that ZnO is the excellent host for lanthanum ions by the assembly of PEG matrices.

  2. Cytotoxicity and genotoxicity of a monazite component: lanthanum effects on the viability and induction of breaks in the DNA of human lymphocytes; Citotoxicidade e genotoxicidade de um componente da monazita: efeitos do lantanio na viabilidade e inducao de quebras no DNA de linfocitos humanos

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Amanda Valle de Almeida

    2007-07-01

    The Monazite is a mineral extracted from open mines. It is constituted by lanthanum element aggregated with cerium, yttrium and thorium [(Ce, La, Y, Th)PO{sub 4}]. Lanthanum (La) is a rare-earth metal with applications in agriculture, industry and medicine. Since lanthanides and their compounds show a broad spectrum of applications there is an increased risk of incorporation in human. Inhalation of aerosols containing La is the main route of incorporation in workers exposed to several chemical forms of La. Herein, we examined the effect of lanthanum nitrate - La(NO{sub 3}){sub 3} in human lymphocytes. JURKAT cells and human peripheral lymphocytes (HPL) were used to evaluate the effect of La(NO{sub 3}){sub 3} on viability (apoptosis or necrosis) and DNA strand breaks induction or/and alkali-labile sites (ALS). We demonstrate that La has a cytotoxic and genotoxic effect on both cell lines. The results indicate that necrosis is the pathway by which La(NO{sub 3}){sub 3} induces cytotoxicity. The vitamin E is able to diminish DNA strand breaks induced by La(NO{sub 3}){sub 3} suggesting that reactive oxygen species (ROS) may be involved in the genotoxic process. (author)

  3. Effects of combined flocculant – Lanthanum modified bentonite treatment on aquatic macroinvertebrate fauna

    NARCIS (Netherlands)

    Waajen, G.; Pauwels, M.; Lürling, M.

    2017-01-01

    A low dose flocculant (FeCl3), combined with lanthanum modified bentonite (LMB) as phosphate-binding agent, has been applied for eutrophication management in Lake De Kuil (The Netherlands). After the treatment, the state of the lake shifted from hypertrophic to mesotrophic. Although

  4. Removing Phosphorus from Aqueous Solutions Using Lanthanum Modified Pine Needles.

    Directory of Open Access Journals (Sweden)

    Xianze Wang

    Full Text Available The renewable pine needles was used as an adsorbent to remove phosphorus from aqueous solutions. Using batch experiments, pine needles pretreated with alkali-isopropanol (AI failed to effectively remove phosphorus, while pine needles modified with lanthanum hydroxide (LH showed relatively high removal efficiency. LH pine needles were effective at a wide pH ranges, with the highest removal efficiency reaching approximately 85% at a pH of 3. The removal efficiency was kept above 65% using 10 mg/L phosphorus solutions at desired pH values. There was no apparent significant competitive behavior between co-existing anions of sulfate, nitrate, and chloride (SO4(2-, NO3(- and Cl(-; however, CO3(2- exhibited increased interfering behavior as concentrations increased. An intraparticle diffusion model showed that the adsorption process occurred in three phases, suggesting that a boundary layer adsorption phenomena slightly affected the adsorption process, and that intraparticle diffusion was dominant. The adsorption process was thermodynamically unfavorable and non-spontaneous; temperature increases improved phosphorus removal. Total organic carbon (TOC assays indicated that chemical modification reduced the release of soluble organic compounds from 135.6 mg/L to 7.76 mg/L. This new information about adsorption performances provides valuable information, and can inform future technological applications designed to remove phosphorus from aqueous solutions.

  5. Effect of pressure on the magnetic properties of lanthanum manganite

    International Nuclear Information System (INIS)

    Gonchar', L. E.; Leskova, Yu. V.; Nikiforov, A. E.; Kozlenko, D. P.

    2010-01-01

    The crystalline structure of pure lanthanum manganite under external hydrostatic pressure has been studied. The behavior of magnetic properties and nuclear magnetic resonance (NMR) spectra under these conditions is theoretically predicted. It is shown that an increase in the Neel temperature with pressure is not only caused by the general contraction of the crystal, but is also related to certain peculiarities in the baric behavior of the orbital structure.

  6. Uranyl(VI) and lanthanum(III) complexes with functionalized macrocyclic and macroacyclic Schiff bases

    International Nuclear Information System (INIS)

    Aguiari, A.; Brianese, N.; Tamburini, S.; Vigato, P.A.

    1995-01-01

    Acyclic Schiff bases have been prepared by [2 + 1] condensation of 2,6-diformyl-4-chlorophenol and H 2 NCH 2 [CH 2 XCH 2 ] n CH 2 NH 2 (n =3D 0 H 2 -I; X =3D NH, S, O n =3D 1 H 2 -II...H 2 -IV; X =3D 0 n =3D 2 H 2 -V; X =3D 0 n =3D 3 H 2 -VI). The related uranlyl(VI) and lanthanum (III) complexes have bee synthesized by reaction by reaction of the preformed ligands with the appropriate salt or by the template procedure, in the presence of base. No base was employed in the preparation of lanthanum (III) complexes, La(H 2 -II)(NO 3 ) 3 , La(H 2 -IV)(NO 3 ) 3 where the Schiff bases coordinate as neutral chelate ligands. These acyclic complexes have been used for further condensation, and symmetric and asymmetric cyclic complexes have been obtained by their reaction with the polyamines H 2 NCH 2 [CH 2 XCH 2 ]nCH 2 NH 2 or with 4,4'-diaminodibenzo -18-crown-6. By reaction with 4-aminobenzo-15-crown-5 or 2-amino-methyl-15-crown-5, the same acyclic complexes give rise to functionalized complexes bearing crown-ether moieties. Analogously, the acyclic ligand H 3 -IXX, prepared by condensation of 2,6 diformyl-4-chlorophenol and tris(aminoethyl)amine, forms mono and homodinuclear lanthanum (III) complexes, which may undergo further condensation when reacted with primary functionalized amines. (authors). 42 refs., 2 figs., 2 schemes, 1 tab

  7. Method of producing a solution of radioactive lanthanum-140 from radioactive barium-140 in an isotope generator and installation to carry out the method

    International Nuclear Information System (INIS)

    Akerman, K.; Jacobs, G.; Sauerwein, K.

    1979-01-01

    A method of separating radioactive lanthanum-140 from radioactive Ba-140 is proposed. The lanthanum-140 will be washed out of a sulphate precipitate and separated from Ba-140-sulphate by a granular filter mass of CaSO 4 and BaSO 4 . Details of the process are given. (UWI) [de

  8. The effect of physiologic aqueous solutions on the perovskite material lead-lanthanum-zirconium titanate (PLZT): potential retinotoxicity.

    Science.gov (United States)

    Foster, William J; Meen, James K; Fox, Donald A

    2013-03-01

    Perovskite compounds, including lead-lanthanum-zirconium titanate (PLZT), have wide technological application because of their unique physical properties. The use of PLZT in neuro-prosthetic systems, such as retinal implants, has been discussed in a number of publications. Since inorganic lead is a retinotoxic compound that produces retinal degeneration, the long-term stability of PLZT in aqueous biological solutions must be determined. We evaluated the stability and effects of prolonged immersion of a PLZT-coated crystal in a buffered balanced salt solution. Scanning Electron Microscopy and Electron Dispersive Spectroscopy (EDS) using a JEOL JSM 5410 microscope equipped with EDS were utilized to evaluate the samples before and after prolonged immersion. We found that lead and other constituents of PLZT leached into the surrounding aqueous medium. By comparing the unit cell of PLZT with that of CaTiO(3), which has been found to react with aqueous fluids, Lead is in the same site in PLZT as Ca is in CaTiO(3). It is thus reasonable that PLZT will react with aqueous solutions. The results suggest that PLZT must either be coated with a protective layer or is not appropriate for long-term in vivo or in vitro biological applications.

  9. Photoluminescence properties of cerium oxide nanoparticles as a function of lanthanum content

    Energy Technology Data Exchange (ETDEWEB)

    Deus, R.C. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Cortés, J.A., E-mail: leandrosrr89@gmail.com [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ramirez, M.A. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ponce, M.A. [Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA) (CONICET-Universidad Nacional de Mar del Plata), Juan B. Justo 4302, 7600 Mar del Plata (Argentina); Andres, J. [Laboratório Interdisciplinar em Cerâmica, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, São Paulo (Brazil); Rocha, L.S.R. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); and others

    2015-10-15

    Highlights: • CeO{sub 2} nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO{sub 2} and La-doped CeO{sub 2} particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in the cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission.

  10. Lanthanum-modified bentonite: potential for efficient removal of phosphates from fishpond effluents.

    Science.gov (United States)

    Kurzbaum, Eyal; Raizner, Yasmin; Cohen, Oded; Rubinstein, Guy; Bar Shalom, Oded

    2017-06-01

    Adsorption has been suggested as an effective method for removing phosphates from agricultural wastewater effluents that contain relatively high phosphate concentrations. The present study focused on the use of a bentonite-lanthanum clay (Phoslock ® ) for reducing the dissolved phosphate concentration in fishpond effluents. Batch experiments with synthetic phosphate-spiked solutions and with fishpond effluents were performed in order to determine adsorption equilibrium isotherms and kinetics as well as to determine the efficiency of Phoslock ® in removing phosphate from these solutions. In the synthetic phosphate-spiked solution, the mean maximum phosphate adsorption capacity was 92 mg Phoslock ® /mg phosphate removal. A ratio of 50, 100, and 200 mg Phoslock ® /mg phosphate removal was found for complete phosphate removal from the fishpond effluents, where higher doses of Phoslock ® led to a faster removal rate (94% removal within the first 150 min). These results show that bentonite-lanthanum clay can be employed for designing a treatment process for efficient phosphate removal from fishpond effluents.

  11. Chemically produced nanostructured ODS-lanthanum oxide-tungsten composites sintered by spark plasma

    International Nuclear Information System (INIS)

    Yar, Mazher Ahmed; Wahlberg, Sverker; Bergqvist, Hans; Salem, Hanadi G.; Johnsson, Mats; Muhammed, Mamoun

    2011-01-01

    High purity W and W-0.9La 2 O 3 (wt.%) nanopowders were produced by a wet chemical route. The precursor was prepared by the reaction of ammonium paratungstate (APT) with lanthanum salt in aqueous solutions. High resolution electron microscopy investigations revealed that the tungstate particles were coated with oxide precipitates. The precursor powder was reduced to tungsten metal with dispersed lanthanum oxide. Powders were consolidated by spark plasma sintering (SPS) at 1300 and 1400 o C to suppress grain growth during sintering. The final grain size relates to the SPS conditions, i.e. temperature and heating rate, regardless of the starting powder particle size. Scanning electron microscopy revealed that oxide phases were mainly accumulated at grain boundaries while the tungsten matrix constituted of nanosized sub-grains. The transmission electron microscopy revealed that the tungsten grains consist of micron-scale grains and finer sub-grains. EDX analysis confirmed the presence of W in dispersed oxide phases with varying chemical composition, which evidenced the presence of complex oxide phases (W-O-La) in the sintered metals.

  12. Simultaneous determination of dopamine, uric acid and nitrite using carboxylated graphene oxide/lanthanum modified electrode

    International Nuclear Information System (INIS)

    Ye, Fengying; Feng, Chenqi; Jiang, Jibo; Han, Sheng

    2015-01-01

    Highlights: • The carboxylated graphene oxide/lanthanum-modified glassy carbon electrode (GO-COOLa/GCE) was successfully utilized for the simultaneous detection and quantification of DA, UA and NO 2 − . • Combining the benefits of carboxylated graphene oxide and lanthanum, the modified sensor displayed large peak separations, long linear ranges and low detection limits for simultaneously detecting DA, UA and NO 2 − . • The GO-COOLa/GCE electrode showed well stability, good repeatability, rapid response, and high catalytic performance toward the oxidations of DA, UA and NO 2 − . - Abstract: A bare glassy carbon electrode (GCE) was reformed by carboxylated graphene oxide/lanthanum, and the modified electrode, called GO-COOLa/GCE, was fabricated for simultaneously detecting dopamine (DA), uric acid (UA) and nitrite (NO 2 − ) by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. Several factors which affected the electrocatalytic activity of the GO-COOLa/GCE electrode, such as the effect of pH, scan rate and concentration were studied. Due to the combination of carboxylated graphene oxide and lanthanum ions, the GO-COOLa/GCE sensor showed rapid response, excellent selectivity and high catalytic performance toward the electrooxidation of DA, UA and NO 2 − . In optimized conditions, two linear response ranges for determining DA were obtained over ranges of 0.01-1.96×10 2 μM and 1.96×10 2 -1.23×10 3 μM with detection limit of 0.018 μM (S/N = 3). And the responses of the GO-COOLa/GCE electrode for UA and NO 2 − were linear in the region of 1-1.53×10 3 μM and 1-2.75×10 3 μM with detection limits of 0.058 μM and 0.070 μM, respectively. Furthermore, this reformed electrode was successfully used to the detection of DA, UA and NO 2 − in real urine and serum samples, showing its promising application in the electroanalysis of real samples.

  13. Determination of Aluminum in Dialysis Concentrates by Atomic Absorption Spectrometry after Coprecipitation with Lanthanum Phosphate.

    Science.gov (United States)

    Selvi, Emine Kılıçkaya; Şahin, Uğur; Şahan, Serkan

    2017-01-01

    This method was developed for the determination of trace amounts of aluminum(III) in dialysis concentrates using atomic absorption spectrometry after coprecipitation with lanthanum phosphate. The analytical parameters that influenced the quantitative coprecipitation of analyte including amount of lanthanum, amount of phosfate, pH and duration time were optimized. The % recoveries of the analyte ion were in the range of 95-105 % with limit of detection (3s) of 0.5 µg l -1 . Preconcentration factor was found as 1000 and Relative Standard Deviation (RSD) % value obtained from model solutions was 2.5% for 0.02 mg L -1 . The accuracy of the method was evaluated with standard reference material (CWW-TMD Waste Water). The method was also applied to most concentrated acidic and basic dialysis concentrates with satisfactory results.

  14. PROCESS USING POTASSIUM LANTHANUM SULFATE FOR FORMING A CARRIER PRECIPITATE FOR PLUTONIUM VALUES

    Science.gov (United States)

    Angerman, A.A.

    1958-10-21

    A process is presented for recovering plutonium values in an oxidation state not greater than +4 from fluoride-soluble fission products. The process consists of adding to an aqueous acidic solution of such plutonium values a crystalline potassium lanthanum sulfate precipitate which carries the plutonium values from the solution.

  15. Hydrothermal synthesis and crystal structure of a new lanthanum(III coordination polymer with fumaric acid

    Directory of Open Access Journals (Sweden)

    Hayet Anana

    2015-05-01

    Full Text Available The title compound, poly[diaquatris(μ4-but-2-enedioato(μ2-but-2-enedioic aciddilanthanum(III], [La2(C4H2O43(C4H4O4(H2O2]n, was synthesized by the reaction of lanthanum chloride pentahydrate with fumaric acid under hydrothermal conditions. The asymmetric unit comprises an LaIII cation, one and a half fumarate dianions (L2−, one a half-molecule of fumaric acid (H2L and one coordinated water molecule. Each LaIII cation has the same nine-coordinate environment and is surrounded by eight O atoms from seven distinct fumarate moieties, including one protonated fumarate unit and one water molecule in a distorted tricapped trigonal–prismatic environment. The LaO8(H2O polyhedra centres are edge-shared through three carboxylate bridges of the fumarate ligand, forming chains in three dimensions to construct the MOF. The crystal structure is stabilized by O—H...O hydrogen-bond interactions between the coordinated water molecule and the carboxylate O atoms, and also between oxygen atoms of fumaric acid

  16. 海藻酸镧颗粒除氟研究:吸附剂物性和吸附机理%Fluoride Removal by Lanthanum Alginate Bead:Adsorbent Characterization and Adsorption Mechanism

    Institute of Scientific and Technical Information of China (English)

    霍亚坤; 丁文明; 黄霞; 徐静年; 赵梦华

    2011-01-01

    Lanthanum alginate bead is a new, highly active adsorbent. In the present study, we investigated its adsorption performance and its adsorption mechanism. The adsorption isotherm for fluoride onto lanthanum alginate bead fits the Langmuir model well, and the maximum adsorption capacity is 197.2 mg·g-1. X-ray diffraction shows the amorphous nature of lanthanum alginate bead, which allows for better accessibility to fluoride and thus better activity. Infrared spectra of lanthanum alginate bead before and after adsorption confirm its stable skeletal structure.Scanning electron microscopy shows that the dense surface structure of the adsorbent appear cracks after adsorption.The adsorption mechanism of lanthanum alginate bead is considered as an ion exchange between F- and Cl- or OH-,as verified from the adsorbent and the solution by pH effect, energy dispersive X-ray, and ion chromatography.

  17. Inductively coupled plasma optical emission spectrometry analysis of lanthanum, samarium and gadolinium oxides for rare earths impurities

    International Nuclear Information System (INIS)

    Reino, L.C.P.; Lordello, A.R.

    1990-09-01

    An inductively coupled plasma optical emission spectrometry method is described for the determination of Sm, Eu, La, Gd, Dy, Pr, Ho, Nd, Tb and Y in purified oxides of lanthanum, samarium and gadolinium. The method enables a simple, precise and readily available determination. Dissolution of the samples is achieved with diluted hydrochloric acid (1:1). The solutions are diluted to volume for a concentration of 1mg/ml. The lowest determination limit is 0,01% for most elements and 0,05 or 0,1% for a few rare earths in samarium and gadolinium matrices. Lanthanum, Samarium and Gadolinium concentrates with purity grade of 99,9%, 99,6% and 99,8%, respectively, can be analysed by this procedure. (author)

  18. The oxidation of carbon monoxide over transition metal doped lanthanum manganates nanoparticles

    International Nuclear Information System (INIS)

    Fal Desai, M.S.; Salker, A.V.

    2012-01-01

    Lanthanum manganates perovskites (ABO 3 ) has been widely studied and applied. Many perovskites with A and B sites doped with different metals show good catalytic activity in many oxidation reactions than the individual perovskite. In present study, an attempt has been made to show comparative account of CO oxidation by doping the B site with different cations using sol-gel method

  19. Thermal stability and microstructure of catalytic alumina composite support with lanthanum species

    Science.gov (United States)

    Ozawa, Masakuni; Nishio, Yoshitoyo

    2016-09-01

    Lanthanum (La) modified γ-alumina composite was examined for application toward thermostable catalytic support at elevated temperature. La added alumina was prepared through an aqueous process using lanthanum (III) nitrate and then characterized by surface area measurement, X-ray powder diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoemission spectroscopy (XPS) and surface desorption of CO2. It was found that the properties depended on the La content and heat treatment temperatures. The characterization of the surface, structural and chemical properties of La-Al2O3 showed the existence of a strong interaction between the La species and alumina via formation of new phase and modified surface in Al2O3 samples. LaAlO3 nanoparticle formed among alumina particles by the solid phase reaction of Al2O3 and La2O3. The increase of the surface basicity of La modified alumina was demonstrated using CO2 temperature programmed desorption experiments. The controlled surface interaction between La oxide and alumina provide the unique surface and structural properties of the resulting mixed oxides as catalysts and catalytic supports.

  20. Cost-Effectiveness of First-Line Sevelamer and Lanthanum versus Calcium-Based Binders for Hyperphosphatemia of Chronic Kidney Disease.

    Science.gov (United States)

    Habbous, Steven; Przech, Sebastian; Martin, Janet; Garg, Amit X; Sarma, Sisira

    2018-03-01

    Phosphate binders are used to treat hyperphosphatemia among patients with chronic kidney disease (CKD). To conduct an economic evaluation comparing calcium-free binders sevelamer and lanthanum with calcium-based binders for patients with CKD. Effectiveness data were obtained from a recent meta-analysis of randomized trials. Effectiveness was measured as life-years gained and translated to quality-adjusted life-years (QALYs) using utility weights from the literature. A Markov model consisting of non-dialysis-dependent (NDD)-CKD, dialysis-dependent (DD)-CKD, and death was developed to estimate the incremental costs and effects of sevelamer and lanthanum versus those of calcium-based binders. A lifetime horizon was used and both costs and effects were discounted at 1.5%. All costs are presented in 2015 Canadian dollars from the Canadian public payer perspective. Results of probabilistic sensitivity analysis were presented using cost-effectiveness acceptability curves. Sensitivity analyses were conducted for risk pooling methods, omission of dialysis costs, and persistence of drug effects on mortality. Sevelamer resulted in an incremental cost-effectiveness ratio of $106,522/QALY for NDD-CKD and $133,847/QALY for DD-CKD cohorts. Excluding dialysis costs, sevelamer was cost-effective in the NDD-CKD cohort ($5,847/QALY) and the DD-CKD cohort ($11,178/QALY). Lanthanum was dominated regardless of whether dialysis costs were included. Existing evidence does not clearly support the cost-effectiveness of non-calcium-containing phosphate binders (sevelamer and lanthanum) relative to calcium-containing phosphate binders in DD-CKD patients. Our study suggests that sevelamer may be cost-effective before dialysis onset. Because of the remaining uncertainty in several clinically relevant outcomes over time in DD-CKD and NDD-CKD patients, further research is encouraged. Copyright © 2018 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier

  1. Cerium-activated lanthanum beryllate as a gamma detector material

    International Nuclear Information System (INIS)

    Czirr, J.B.; Berrondo, M.

    1994-01-01

    The authors have tested a single crystal of Ce-activated lanthanum beryllate BEL(Ce) as a potential gamma detector material. The density (6.1 g.cm -3 ) and decay time (50 ns) are competitive with other recently developed materials. The scintillation efficiency is 57 to 95% that of BGO. For an excitation wavelength of 340 nm, the emission spectra is a broad peak centered at 450 mn. The H 2 annealed sample is transparent for wavelengths greater than 400 mn. They are continuing a program to improve the scintillation efficiency by varying the crystal growth conditions

  2. Solid state interaction studies on binary nitrate mixtures of uranyl nitrate hexahydrate and lanthanum nitrate hexahydrate at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kalekar, Bhupesh; Raje, Naina, E-mail: nraje@barc.gov.in; Reddy, A.V.R.

    2017-02-15

    Interaction behavior of uranyl nitrate hexahydrate (UNH) and lanthanum nitrate hexahydrate (LaNH) have been investigated on the mixtures in different molar ratios of the two precursors and monitoring the reactions at elevated temperatures with thermoanalytical and X-ray diffraction measurement techniques. During the decomposition of equimolar mixture of LaNH and UNH, formation of lanthanum uranate (U{sub 0.5}La{sub 0.5})O{sub 2}, was seen by the temperature of 500 °C along with lanthanum oxide (La{sub 2}O{sub 3}) and uranium trioxide (UO{sub 3}). By the temperature of 700 °C, the formation of uranium sesquioxide (U{sub 3}O{sub 8}) was observed along with (U{sub 0.5}La{sub 0.5})O{sub 2} as end products in uranium rich mixtures. Lanthanum rich compositions decomposed by the temperature of 700 °C to give (U{sub 0.5}La{sub 0.5})O{sub 2} and La{sub 2}O{sub 3} as end products. - Highlights: • UO{sub 2}(NO{sub 3}){sub 2}.6H{sub 2}O and La(NO{sub 3}){sub 3}.6H{sub 2}O interact through their intermediates. • Formation of (U{sub 0.5}La{sub 0.5})O{sub 2} by 500 °C. • La deficient mixtures decompose to give U{sub 3}O{sub 8} and (U{sub 0.5}La{sub 0.5})O{sub 2} as end products. • La rich mixtures decompose to give La{sub 2}O{sub 3} and (U{sub 0.5}La{sub 0.5})O{sub 2} as end product.

  3. Paramagnetic centers in two phases of manganese-doped lanthanum gallate

    Science.gov (United States)

    Vazhenin, V. A.; Potapov, A. P.; Guseva, V. B.; Artyomov, M. Yu.

    2009-05-01

    An EPR study of two phases of manganese-doped lanthanum gallate (with a first-order structural transition occurring at 430 K) has revealed Gd3+, Fe3+, and Mn4+ centers at room temperature and 438 K. The parameters of spin Hamiltonians are determined for the Gd3+, Fe3+, and Mn4+ rhombohedral centers in the high-temperature phase (with no other centers found here) and for the monoclinic center Gd3+ in the low-temperature phase. Both in the orthorhombic and in the rhombohedral phase, crystallographic twins (or ferroelastic domains) are observed.

  4. Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

    Science.gov (United States)

    Sandstrom, R. L.; Giess, E. A.; Gallagher, W. J.; Segmuller, A.; Cooper, E. I.

    1988-11-01

    It is demonstrated that lanthanum gallate (LaGaO3) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa2Cu3O(7-x), can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant and low dielectric losses. Epitaxial YBa2Cu3O(7-x) films grown on LaGaO3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K.

  5. Controlling the reaction between boron-containing sealing glass and a lanthanum-containing cathode by adding Nb2O5

    Science.gov (United States)

    Zhao, Dandan; Fang, Lihua; Tang, Dian; Zhang, Teng

    2016-09-01

    In solid oxide fuel cell (SOFC) stacks, the volatile boron species present in the sealing glass often react with the lanthanum-containing cathode, degrading the activity of the cathode (this phenomenon is known as boron poisoning). In this work, we report that this detrimental reaction can be effectively reduced by doping bismuth-containing borosilicate sealing glass-ceramic with a niobium dopant. The addition of Nb2O5 not only condenses the [SiO4] structural units in the glass network, but also promotes the conversion of [BO3] to [BO4]. Moreover, the Nb2O5 dopant enhances the formation of boron-containing phases (Ca3B2O6 and CaB2Si2O8), which significantly reduces the volatility of boron compounds in the sealing glass, suppressing the formation of LaBO3 in the reaction couple between the glass and the cathode. The reported results provide a new approach to solve the problem of boron poisoning.

  6. Bordoni relaxation and magnetic transformation in cerium and cerium-lanthanum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Postnikov, V S; Polner, G L; Sharshakov, I M

    1975-11-01

    The internal friction in pure cerium and cerium-base alloys with 2.5 and 12 weight percent of lanthanum added at temperature ranging from 4.2 deg up to 77/sup 0/K is described. Amplitude-independent internal friction has been measured with an inverse torsion pendulum with a specimen oscillation frequency of 1-30 hz in vacuum not less than 1.10/sup -5/ torr. A temperature of the specimen has been determined with a capacitance-type sensor and a gas gage. A curve showing the dependence of internal friction upon a temperature of pure cerium has two distinct peaks; the first at 12.5/sup 0/K, the second at 45/sup 0/K. The 12.5/sup 0/K peak is accounted for by a transition of antiferromagnetic ..beta..-Ce into a paramagnetic state. The 45/sup 0/K peak is a Bordoni maximum. The paper describes an influence of additions, specimen oscillation frequency variations, deformation and annealing upon the peak behavor. Added lanthanum reduces not only a peak temperature but a height as well. Studies of the 45/sup 0/K peak have shown that its temperature location depends upon the specimen oscillation frequency. As the frequency increases the peak tends to a range of high temperatures which confirms its relaxation nature.

  7. Phases in lanthanum-nickel-aluminum alloys

    International Nuclear Information System (INIS)

    Mosley, W.C.

    1992-01-01

    Lanthanum-nickel-aluminum (LANA) alloys will be used to pump, store and separate hydrogen isotopes in the Replacement Tritium Facility (RTF). The aluminum content (y) of the primary LaNi 5 -phase is controlled to produce the desired pressure-temperature behavior for adsorption and desorption of hydrogen. However, secondary phases cause decreased capacity and some may cause undesirable retention of tritium. Twenty-three alloys purchased from Ergenics, Inc. for development of RTF processes have been characterized by scanning electron microscopy (SEM) and by electron microprobe analysis (EMPA) to determine the distributions and compositions of constituent phases. This memorandum reports the results of these characterization studies. Knowledge of the structural characteristics of these alloys is a useful first step in selecting materials for specific process development tests and in interpreting results of those tests. Once this information is coupled with data on hydrogen plateau pressures, retention and capacity, secondary phase limits for RTF alloys can be specified

  8. Preferable adsorption of phosphate using lanthanum-incorporated porous zeolite: Characteristics and mechanism

    Science.gov (United States)

    He, Yinhai; Lin, Hai; Dong, Yingbo; Wang, Liang

    2017-12-01

    The adsorbent, where lanthanum oxide was incorporated onto porous zeolite (La-Z), of preferable adsorption towards phosphate was prepared by hydrothermal synthesis. Based on pH effect results, La-Z would effectively sequestrate phosphate over wider pH range of 3.0-7.0, alkaline conditions were unfavorable for phosphate. The adsorption of phosphate was not significantly influenced by ionic strength and by coexisting anions of chloride, nitrate and sulfate but bicarbonate showed slightly greater negative effects, indicating La-Z possessed highly selectivity to phosphate. Adsorption of phosphate could be well fitted by pseudo-second-order model and the process was mainly controlled by intra-particle diffusion. Equilibrium adsorption demonstrated that Langmuir model was more suitable than Freundlich model for description phosphate adsorption and the adsorption capacity was 17.2 mg P g-1, which exhibited 95% utilization of incorporated La. Over 95% phosphate was eliminated in real effluent treatment when the dose was 2 g L-1. The underlying mechanism for phosphate capture was probed with Zeta potential and X-ray photoelectron spectroscope analysis, and the formation of La-P inner-sphere complexation was testified to be the dominant pathway. All the results suggested that the porous zeolite-supported lanthanum oxide can serve as a promising adsorbent for phosphate removal in realistic application.

  9. Atom states and interatomic interactions in complex perovskite-like oxides. Communication XX. Origin of electron-ionic conductivity in lanthanum gallates doped with strontium and chromium

    International Nuclear Information System (INIS)

    Chezhina, N.V.; Zolotukhina, N.V.; Pijr, I.V.

    2006-01-01

    Magnetic susceptibilities and electric conductivities of solid solutions based on lanthanum gallate containing chromium and strontium atoms in the ratio of 10 : 2 were studied. It was shown that no partial oxidation of chromium to Cr(IV) occurs when lanthanum gallate is doped with chromium and strontium simultaneously, whereas the ionic conductivity is associated with the appearance of vacancies stabilized by chromium atoms in the oxygen sublattice [ru

  10. Internal-standard method for the determination of uranium, thorium, lanthanum and europium in carbonaceous shale and monazite by epithermal neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shuenn-Gang; Tsai, Hui-Tuh; Wu, Shaw-Chii [Institute of Nuclear Energy Research, Lung-Tan (Taiwan, Republic of China)

    1981-10-03

    An internal-standard method was applied for the determination of uranium, thorium, lanthanum and europium is carbonaceous shale samples and monazite sand by epithermal neutron activation analysis using gold as an internal standard element. The samples were irradiated in a zero-power reactor at the Institute of Nuclear Energy Research and measured with a high-resolution Ge(Li) detector. The detection limit is 0.1 ppm for uranium and europium, 1 ppm for thorium, 5 ppm for lanthanum, and the realative error of all elements is within +-2.6%.

  11. Evolution of the corrosion process of AA 2024-T3 in an alkaline NaCl solution with sodium dodecylbenzenesulfonate and lanthanum chloride inhibitors

    International Nuclear Information System (INIS)

    Zhou, Biner; Wang, Yishan; Zuo, Yu

    2015-01-01

    Highlights: • Inhibition effect of LaCl 3 and SDBS for AA 2024 in NaCl solution (pH 10) was studied. • At the beginning the active polarization behavior of the alloy changed to passivation. • The passive behavior gradually disappeared with time and pitting happened at S-phases. • The compounded inhibitors showed good inhibition but cannot totally inhibit pitting. • The adsorption of SDBS played the key role for inhibition to the corrosion process. - Abstract: The evolution of the corrosion process of AA 2024-T3 in 0.58 g L −1 NaCl solution (pH 10) with sodium dodecylbenzenesulfonate (SDBS) and lanthanum chloride inhibitors was studied with electrochemical and surface analysis methods. With the addition of the compounded LaCl 3 and SDBS inhibitors, in the early stage the polarization behavior of AA 2024-T3 changed from active corrosion to passivation, and both the general corrosion and pitting corrosion were inhibited. However, with the immersion time extended, the passive behavior gradually disappeared and pitting happened at the Cu-rich phases. After 24 h immersion, the compounded inhibitors still showed good inhibition for general corrosion, but the polarization curve again presented the characteristic similar to active polarization. The compounded inhibitors also inhibited the pitting corrosion to some extent. The acting mechanism of the inhibitors SDBS and La 3 Cl on the corrosion process of AA 2024-T3 in the test solution was discussed.

  12. Investigation of the complex structure, comparative DNA-binding and DNA cleavage of two water-soluble mono-nuclear lanthanum(III) complexes and cytotoxic activity of chitosan-coated magnetic nanoparticles as drug delivery for the complexes

    Science.gov (United States)

    Asadi, Zahra; Nasrollahi, Neda; Karbalaei-Heidari, Hamidreza; Eigner, Vaclav; Dusek, Michal; Mobaraki, Nabiallah; Pournejati, Roya

    2017-05-01

    Two water-soluble mono-nuclear macrocyclic lanthanum(III) complexes of 2,6-diformyl-4-methylphenol with 1,3-diamino-2-propanol (C1) or 1,3-propylenediamine (C2) were synthesized and characterized by UV-Vis, FT-IR, 13C and 1H NMR spectroscopy and elemental analysis. C1 complex was structurally characterized by single-crystal X-ray diffraction, which revealed that the complex was mononuclear and ten-coordinated. The coordination sites around lanthanum(III) were occupied with a five-dentate ligand, two bidentate nitrates, and one water molecule. The interaction of complexes with DNA was studied in buffered aqueous solution at pH 7.4. UV-Vis absorption spectroscopy, emission spectroscopy, circular dichroism (CD) and viscometric measurements provided clear evidence of the intercalation mechanism of binding. The obtained intrinsic binding constants (Kb) 9.3 × 103 and 1.2 × 103 M- 1 for C1 and C2, respectively confirmed that C1 is better intercalator than C2. The DNA docking studies suggested that the complexes bind with DNA in a groove binding mode with the binding affinity of C1 > C2. Moreover, agarose gel electrophoresis study of the DNA-complex for both compounds revealed that the C1 intercalation cause ethidium bromide replacement in a competitive manner which confirms the suggested mechanism of binding. Finally, the anticancer experiments for the treated cancerous cell lines with both synthesized compounds show that these hydrophilic molecules need a suitable carrier to pass through the hydrophobic nature of cell membrane efficiently.

  13. Relaxation effects in oxygen-conducting oxides on base of lanthanum gallate (La, Sr)(Ga, Me)O3, Me = Mg, Fe

    International Nuclear Information System (INIS)

    Glavatskikh, T.Yu.; Venskovskij, N.U.; Kaleva, G.M.; Mosunov, A.V.; Politova, E.D.; Stefanovich, S.Yu.

    2003-01-01

    The dielectric and electric conducting properties of the heterosubstituted perovskite-like solid solutions (La, Sr)(Ga, Me)O 3 , Me Mg, Fe are studied. The increase in the ceramics electric conductivity, conditioned by increase in the ion constituent at strengthening the nonstoichiometry by oxygen and electron constituent by the additional introduction of iron is observed by replacing the part of the lanthanum and gallium cations by strontium, magnesium and iron in the solid solutions on the basis of the lanthanum gallate. The ceramics relaxation behavior is identified; the applicability of the model of the vacational electron transfer for the dipole relaxation is established [ru

  14. Ionic conductivity and fuel cell properties of apatite-type lanthanum silicates doped with Mg and containing excess oxide ions

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Hideki [Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira-cho, Suma-ku, Kobe 654-0037 (Japan); Nojiri, Yoshihiro [Kyushu University, Department of Mechanical Engineering Science, Faculty of Engineering, Motooka 744, Nishi-ku, Fukuoka 819-0935 (Japan); Tanase, Shigeo [National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

    2008-11-30

    Enhancement of the ionic conductivity of lanthanum silicate-based apatites is examined with emphasis on optimizing the La composition and the Mg doping level at the same time. La{sub 10}Si{sub 5.8}Mg{sub 0.2}O{sub 26.8} and La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} show the highest level of the ionic conductivities among apatite silicates, 8.8 and 7.4 x 10{sup -} {sup 2} S cm{sup -} {sup 1} at 800 C, respectively, with a very low level of activation energy (0.42-0.43 eV). Their conductivities are higher than yttria stabilized zirconia (YSZ) below 900 C and even comparable to Sr and Mg doped lanthanum gallate (LSGM) below 550 C. A solid oxide fuel cell using La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} as an electrolyte with Ni-ceria cermet anode and Sr doped lanthanum cobaltite cathode exhibits a remarkable improvement in power generation compared to previous data using Pt electrodes. Structural investigation by the Rietveld analysis on the powder X-ray diffraction pattern shows significant enlargement of the bottleneck triangle sizes of the conduction channel with the Mg doping. (author)

  15. Sinterability and conductivity of barium doped aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} electrolyte of solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Cao Xiaoguo [Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Jiang Sanping, E-mail: s.jiang@curtin.edu.au [Fuels and Energy Technology Institute and Department of Chemical Engineering, Curtin University, Perth, WA 6102 (Australia)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Ba doping enhances the sintering and densification properties of aluminium lanthanum apatite. Black-Right-Pointing-Pointer Ba doping improves the oxide conductivity of aluminium lanthanum apatite. Black-Right-Pointing-Pointer The enhancement of Ba doping is mainly due to the significantly reduced grain boundary resistance of the aluminium lanthanum apatite. - Abstract: Apatite ceramics are interesting alternative solid oxide fuel cells (SOFCs) electrolytes because of their open structure for the transportation of oxide ions and their good chemical stability. This study reports the influence of barium doping on the microstructure, sinterability and oxide conductivity properties of the aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5}. SEM results show that lanthanum substitution with barium improves the sinterability of apatite ceramics. The barium doping also enhances the conductivity of the aluminium lanthanum silicates. The oxygen ion conductivity of La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} sintered at 1600 Degree-Sign C is 2.21 Multiplication-Sign 10{sup -2} S cm{sup -1} at 800 Degree-Sign C, higher than 9.81 Multiplication-Sign 10{sup -3} S cm{sup -1} of La{sub 10}Si{sub 5}AlO{sub 26.5} sample prepared under the same conditions. The results in the present study demonstrate that doping Ba on the La site for aluminium lanthanum oxyapatite reduces the sintering temperature and improves the ion conductivity. The enhancement of Ba dopant is mainly on the improvement of the densification and thus substantially reduced grain boundary resistance of aluminium lanthanum oxyapatite particularly at low temperatures.

  16. In situ XANES cell used for the study of lanthanum strontium cuprate deNOx catalysts

    DEFF Research Database (Denmark)

    Hagen, Anke

    2011-01-01

    , maintaining charge neutrality, with the concentration of oxygen vacancies likely increasing at substitution ratios larger than Sr/La>0.08. During heating in air, the valence of copper ions in the structure increased. Upon exposure to NO at 500 °C the valence of copper ions in a lanthanum strontium cuprate...

  17. Spectrographic determination of lanthanides in high-purity uranium compounds, after chromatographic separation by alumina-hydrofluoric acid

    International Nuclear Information System (INIS)

    Lordello, A.R.; Abrao, A.

    1979-01-01

    A method is presented for the determination of fourteen rare earth elements in high-purity uranium compounds by emission spectrography. The rare earths are chromatographically separated from uranium by using alumina-hydrofluoric acid. Lanthanum is used both as collector and internal standard. The technique of excitation involves a total consumption of the sample in a 17 ampere direct current arc. The range of determination is about 0.005 to 0.5 μg/g uranium. The coefficient of variation for Pr, Ho, Dy, Er, Tm, Lu, Gd and Tb amounts to 10%. (Author) [pt

  18. Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

    International Nuclear Information System (INIS)

    Sandstrom, R.L.; Giess, E.A.; Gallagher, W.J.; Segmueller, A.; Cooper, E.I.; Chisholm, M.F.; Gupta, A.; Shinde, S.; Laibowitz, R.B.

    1988-01-01

    We demonstrate that lanthanum gallate (LaGaO 3 ) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa 2 Cu 3 O/sub 7-//sub x/, can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant (ε≅25) and low dielectric losses. Epitaxial YBa 2 Cu 3 O/sub 7-//sub x/ films grown on LaGaO 3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K

  19. Catalytic activity of lanthanum oxide for the reduction of cyclohexanone

    International Nuclear Information System (INIS)

    Sugunan, S.; Sherly, K.B.

    1994-01-01

    Lanthanum oxides, La 2 O 3 has been found to be an effective catalyst for the liquid phase reduction of cyclohexanone. The catalytic activities of La 2 O 3 activated at 300, 500 and 800 degC and its mixed oxides with alumina for the reduction of cylcohexanone with 2-propanol have been determined and the data parallel that of the electron donating properties of the catalysts. The electron donating properties of the catalysts have been determined from the adsorption of electron acceptors of different electron affinities on the surface of these oxides. (author). 15 refs., 2 figs., 1 tab

  20. Effects of polyaluminum chloride and lanthanum-modified bentonite on the growth rates of three Cylindrospermopsis raciborskii strains

    NARCIS (Netherlands)

    Araújo, Fabiana; van Oosterhout, Frank; Becker, Vanessa; Attayde, José Luiz; Lürling, Miquel

    2018-01-01

    In tropical and subtropical lakes, eutrophication often leads to nuisance blooms of Cylindrospermopsis raciborskii. In laboratory experiments, we tested the combined effects of flocculant polyaluminum chloride (PAC) and lanthanum-modified bentonite (LMB) on the sinking and growth rates of three C.

  1. catena-Poly[[tetrakis(hexamethylphosphoramide-κObis(nitrato-κ2O,O′lanthanum(III] [silver(I-di-μ2-sulfido-tungstate(VI-di-μ2-sulfido

    Directory of Open Access Journals (Sweden)

    Lude Lu

    2008-02-01

    Full Text Available Hexamethylphosphoramide (hmp, tetrathiotungstate(VI, silver sulfide and lanthanum(III nitrate are self-assembled to form discrete cations one-dimensional poylmeric anionic chains [AgWS4]nn− in the title compound, {[La(NO32(C6H18N3OP4][AgWS4]}n. The central La atom in the cation is coordinated by eight O atoms from two nitrate and four hmp ligands. Together with the two nitrate ligands, the cation is monovalent, which leads to the anionic chain having a monovalent repeat unit. The polymeric anionic chain with W...Ag...W and Ag...W...Ag angles of 165.94 (3 and 155.894 (14° presents a distorted linear configuration. Five N atoms, 18 C atoms and their attached H atoms are disordered equally over two positions.

  2. effect of post-precipitation treatment on the pore-structure stability of sol-gel derived lanthanum zirconate

    NARCIS (Netherlands)

    Nair, Jalajakumari; Kumar, K.N.P.; Nair, P.; van Ommen, J.G.; Ross, J.R.H.; Ross, Julian R.H.; Burggraaf, Anthonie J.; Burggraaf, Anthonie

    1998-01-01

    The importance of post-precipitation treatments (pore-fluid exchange and its removal) on the evolution of the texture of coprecipitated lanthanum zirconate has been investigated. The nature of the pore fluid and the type of fluid-removal (drying) process have shown a profound effect on the aggregate

  3. Synthesis, thermal properties and growing of strontium and lanthanum aluminates and gallates and the phases on their basis

    International Nuclear Information System (INIS)

    Zimina, G.V.; Novoselov, A.V.; Filaretov, A.A.; Payachkovskaya, A.; Drobot, D.V.

    2000-01-01

    With the aim of manufacturing single crystal substrates for HTSC films a study is made into various ways of synthesis of strontium-lanthanum aluminate and gallate, as well as phases on their base. It is shown that the codeposition of difficulty soluble compounds with their subsequent heat treatment is an optimal method of synthesis for SrLaAlO 4 . For preparation of SrLaGaO 4 and SrLaAl x Ga 1-x O 4 a cryochemical method is shown to be best suited. High quality SrLaGaO 4 and SrLaAlO 4 single crystals are grown in [100] direction at oxygen pressure of 5 Pa. The formation of continuous series of solid solutions is revealed in the system of SrLaAlO 4 -SrLaGaO 4 . The compositions of SrLaAl 0.2 Ga 0.8 O 4 and SrLaAl 0.4 Ga 0.6 O 4 in the crystallochemical properties are marked to meet the requirements to the substrates [ru

  4. Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, S., E-mail: suhaimihas@uthm.edu.my; Yusof, M. S., E-mail: mdsalleh@uthm.edu.my; Maksud, M. I., E-mail: midris1973@gmail.com [Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia); Embong, Z., E-mail: zaidi@uthm.edu.my [Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia)

    2016-01-22

    Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La{sub 2}O{sub 3}) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La{sub 2}O{sub 3} deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La{sub 2}O{sub 3} and La(OH){sub 3}. The information of oxygen species, O{sup 2-} component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O{sup 2−}), two chemisorb component (La{sub 2}O{sub 3}) and La(OH){sub 3} and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.

  5. Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

    Science.gov (United States)

    Hassan, S.; Yusof, M. S.; Embong, Z.; Maksud, M. I.

    2016-01-01

    Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La2O3) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La2O3 deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La2O3 and La(OH)3. The information of oxygen species, O2- component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O2-), two chemisorb component (La2O3) and La(OH)3 and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.

  6. Thermoluminescent kinetic parameters of the perovskite, KMgF3, activated with lanthanum

    International Nuclear Information System (INIS)

    Sepulveda M, F.; Azorin N, J.; Rivera M, T.; Furetta, C.; Sanipoli, C.

    2004-01-01

    The thermoluminescent curves induced by the beta radiation in the perovskite KMgF 3 were investigated activated with lanthanum. The classic methods were used to determine the kinetic parameters (the kinetic order b, the activation energy E and the frequency of escape intent s) associated with the peaks of the thermoluminescent curve (Tl) in the KMgF 3 activated with lanthanum after the irradiation with beta rays. The method is based on the position of the thermoluminescent peaks, obtained of the temperature change of the peak in the maximum emission caused by the change in the heating rapidity to which the samples were measured. In this work, the samples in form of pellets were re cooked previously at 400 C during one hour before irradiating them with beta particles. The Tl measures were made with a Tl reader system using three different heating rapidities and storing the glow curves. To calculate the depth of the E traps and the frequency factor s, the parameters of the glow curve were determined experimentally of the shame of the glow curve by means of the mensuration of the shame of the maximum temperature of the peak, T M like a function of the heating rapidity. The results indicate that the values of the kinetic parameters are very near among if when they are obtained indistinctly of anyone of the different methods. (Author)

  7. The origin of current blocking in interfacial conduction in Sr-doped lanthanum gallates

    Science.gov (United States)

    Park, Hee Jung

    2018-02-01

    The grain boundary transport of lanthanum gallate has been studied with various doping concentrations, and the origins of blocking on the grain boundary are compared. La1-xSrxGaO3 samples (x = 0.005, 0.01, 0.05 and 0.1) have been prepared and their bulk (grain) and grain boundary resistances been experimentally measured as a function of temperature (T: 200-550 °C) and oxygen partial pressure (Po2) using ac-impedance measurements. In addition, Hebb-Wagner polarization measurements have been conducted to investigate the electrical conductivity of minor charge carriers in the lanthanum gallates. The grain boundary resistance in the low-doped materials (x = 0.005 and 0.01) increases with increasing Po2 while in the highly-doped materials (x = 0.05, 0.1) it hardly depended on Po2. At lower concentrations conduction is mixed and at higher concentrations is found to be predominantly ionic conductivity. The space charge model successfully describes the mixed conduction at the grain boundary at low-doping, but does not explain the predominant ionic conductivity at high-doping. The origin of blocking at high-doping is explained by the crystallographic asymmetry of the grain boundary with respect to the bulk and/or Sr-segregation.

  8. On the stability of the ternary phases in the La-Co-O system and the nonstoichiometry of lanthanum cobaltate

    International Nuclear Information System (INIS)

    Seppaenen, Matti

    1979-01-01

    The crystal structure of La 4 Co 3 O 10 , which is a new ternary phase identified in the present study, was determined by means of X-ray diffraction. It has an orthorhombic symmetry and its space group is most likely Fsub(mmm) (face-centered). On the basis of the thermodynamical studies of the La-Co-O system, the stable ternary phases are LaCoO 3 , La 4 Co 3 O 10 and La 2 CoO 4 . The stability limits of these phases were determined as a function of oxygen activity and temperature, and their molar Gibbs standard formation functions were calculated. Electrons, e', and electron holes, hsup(.), are majority defects in lanthanum cobaltate and their concentrations are exceptionally high and nearly constant in the temperature range 1178 - 1295 K. Under thermodynamically well defined conditions the nonstoichiometry of lanthanum cobaltate was determined as a function of oxygen activity and temperature by coulometric titration. In the oxygen partial pressure and temperature range of the present study the oxygen vacancies were ionic minority defects dependent on the activity of oxygen. Due to the high concentration of electronic defects the oxygen vancancy concentration increases high at low oxygen pressures. Oxygen vacancies behave ideally in lanthanum cobaltate i.e. obey Henry's law when their concentrations are <=0.01. (author)

  9. Effect of Lanthanum as a Promoter on Fe-Co/SiO2 Catalyst for Fischer-Tropsch Synthesis

    Directory of Open Access Journals (Sweden)

    Ali Abbasi

    2014-03-01

    Full Text Available Iron-Cobalt catalyst is well known from both operational and economical aspects for Fischer-Tropsch synthesis. Effort to increase the efficiency of this kind of catalyst is an important research topic. In this work, the effect of lanthanum on characteristic behavior, conversion and selectivity of a Fe-Co/SiO2 Fischer-Tropsch catalyst was studied. The Fe-Co-La/SiO2 Catalysts were prepared using an incipient wetness impregnation method. These catalysts were then characterized by XRF-EDAX, BET and TPR techniques, and their performance were evaluated in a lab-scale reactor at 250ºC, H2/CO = 1.8 of molar ratio, 16 barg pressure and GHSV=600 h-1. TPR analysis showed that the addition of La lowered the reduction temperature of Fe-Co catalyst, and due to a lower temperature, the sintering of the catalyst can be mitigated. Furthermore, from the micro reactor tests (about 4 days, it was found that lanthanum promoted catalyst had higher selectivity toward hydrocarbons, and lower selectivity toward CO2.Received: 8th July 2013; Revised: 18th November 2013; Accepted: 1st December 2013[How to Cite: Abbasi, A., Ghasemi, M., Sadighi, S. (2014. Effect of Lanthanum as a Promoter on Fe-Co/SiO2 Catalyst for Fischer-Tropsch Synthesis. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (1: 23-27. (doi:10.9767/bcrec.9.1.5142.23-27][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.1.5142.23-27

  10. Lanthanum chromite colloidal processing; Processamento coloidal de cromito de lantanio

    Energy Technology Data Exchange (ETDEWEB)

    Setz, Luiz Fernando Grespan

    2009-07-01

    Lanthanum chromite (LaCrO{sub 3}) is currently the most studied material for applications such as solid oxide fuel cell inter connector (HTSOFC). The complexity of microstructures and geometries of HTSOFC devices, require a precise control of processing parameters to get the desired combination of properties and this, the use of techniques involving concentrated ceramic slips conformation are appropriate, therefore, is well controlled, assist in obtaining homogeneous parts, reproductive and complex geometries. Thus, studies involving the surface chemistry, the stability conditions and slips flow behaviour in the forming conditions, provide important elements for processes control in the inter connectors manufacture, where more applied settings have slots and channels for the gases passage. Thus, surface chemistry, stability and rheological behaviour of strontium and cobalt doped LaCrO{sub 3} (La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3}) slips prepared with ethanol and water, were studied. The doped lanthanum chromite was produced by combustion synthesis in the IPEN/SP labs. The influence of parameters: p H (water), dispersant concentration, homogenization times and conditions, solid concentration, different ratios binder:plasticizer in the stability and the flow behavior of ceramic suspensions prepared were evaluated. The La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} products obtained by casting aqueous slips in a plaster mould, using alkaline p H and anionic polyelectrolyte and tapes obtained by using ethanol as a dispersant medium, after sintering at 1600 deg C/4h presented theoretical density > 94%, suitable for use as HTSOFC inter connector. (author)

  11. Promising Ni-Fe-LSGMC anode compatible with lanthanum gallate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Wang Shizhong [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)], E-mail: shizwang@sohu.com; He, Qiong [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu Meilin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)], E-mail: meilin.liu@mse.gatech.edu

    2009-06-01

    A number of composite materials in the Ni-Fe-LSGMC family have been studied as potential anodes for solid oxide fuel cells (SOFCs) based on strontium, magnesium, and cobalt doped lanthanum gallate electrolyte (LSGMC). The results show that Ni reacts with LSGMC especially under reducing conditions at high temperatures, resulting in high contact resistance, large electrode polarization, and poor performance. The reaction between Ni and LSGMC depends strongly on the composition and pre-sintering temperature of LSGMC, the concentration of iron in the electrode, and the processing and operating temperatures. Under proper conditions, Ni-Fe-LSGMC5 could be a promising high-performance anode with good compatibility with LSGMC5 electrolyte.

  12. Promising Ni-Fe-LSGMC anode compatible with lanthanum gallate electrolyte

    International Nuclear Information System (INIS)

    Wang Shizhong; He, Qiong; Liu Meilin

    2009-01-01

    A number of composite materials in the Ni-Fe-LSGMC family have been studied as potential anodes for solid oxide fuel cells (SOFCs) based on strontium, magnesium, and cobalt doped lanthanum gallate electrolyte (LSGMC). The results show that Ni reacts with LSGMC especially under reducing conditions at high temperatures, resulting in high contact resistance, large electrode polarization, and poor performance. The reaction between Ni and LSGMC depends strongly on the composition and pre-sintering temperature of LSGMC, the concentration of iron in the electrode, and the processing and operating temperatures. Under proper conditions, Ni-Fe-LSGMC5 could be a promising high-performance anode with good compatibility with LSGMC5 electrolyte.

  13. Gamma-induced radiation polymerization of kaolin composite for sorption of lanthanum, europium and uranium ions from low-grade monazite leachate

    International Nuclear Information System (INIS)

    Metwally, S.S.; Hassan, R.S.; El-Masry, E.H.; Borai, E.H.

    2018-01-01

    Gamma radiation polymerization method was used for the modification of kaolin to produce (poly acrylamide-acrylic acid)-Kaolin (PAM-AA-K). Monazite ore is one of the main resources of uranium and lanthanide elements, therefore, this work focused on sorption of uranium, lanthanum and europium ions from low grade monazite leachate. The removal percent for Eu 3+ , La 3+ and UO 2 2+ are 94.6, 91.6 and 73.4%, respectively. Monolayer capacity of Eu 3+ , La 3+ and UO 2 2+ were found to be 54.64, 45.87 and 37.59 mg/g, respectively. The sorption mechanism of lanthanum and europium ions on PAM-AA-K composite mainly takes place as Ln(OH) 2+ , and for uranium as uranyl ion, UO 2 2+ . (author)

  14. Analysis of the elements sputtered during the lanthanum implantation in stainless steels

    International Nuclear Information System (INIS)

    Ager, F.J.; Respaldiza, M.A.; Silva, M.F. da; Redondo, L.M.; Soares, J.C.

    1998-01-01

    The evidence of the modification of the surface structure of the AISI-304 stainless steel during the implantation of lanthanum makes the analysis of the sputtered elements very interesting. Those sputtered elements are deposited on a carbon sheet placed in front of the steel being implanted, and studied by means of RBS and PIXE, together with the implanted specimens. Besides, the protective effect of the implanted ions during the high temperature oxidation is also studied by those techniques together with XRD and thermogravimetric methods. (orig.)

  15. Vaporization and diffusion studies on the stability of doped lanthanum gallates

    Energy Technology Data Exchange (ETDEWEB)

    Stanislowski, M.; Singheiser, L.; Hilpert, K. [Research Center Juelich, Institute for Materials and Processes in Energy Systems, IWV-2, 52425 Juelich (Germany); Peck, D.H.; Woo, S.K. [Korea Institute of Energy Research, 71-2 Jang-Dong, Yuseong, 305-343 Daejeon (Korea); Schulz, O.; Martin, M. [RWTH Aachen University, Institute of Physical Chemistry, Landoltweg 2, 52056 Aachen (Germany)

    2006-07-15

    Vaporization and diffusion determine the stability of doped lanthanum gallates under SOFC operating conditions. Systematic vaporization studies of Ga and other elements were carried out using the vapor transpiration method. It was shown that the Ga vaporization is controlled by diffusion from the bulk to the surface. Diffusion coefficients D{sub Ga} and vaporization coefficients {alpha}{sub Ga} were determined by fitting the measured vaporization data to a vaporization model. Secondary phases formed as a result of the vaporization were detected. The influence of different doping levels of Sr, Mg and Fe on the Ga vaporization was elucidated. Moreover, cation self-diffusion of {sup 139}La, {sup 84}Sr and {sup 25}Mg as well as cation impurity diffusion of {sup 144}Nd, {sup 89}Y and {sup 56}Fe in polycrystalline samples of doped lanthanum gallate were directly determined for the composition La{sub 0.9}Sr{sub 0.1}Ga{sub 0.9}Mg{sub 0.1}O{sub 2.9} as an example, from diffusion profiles determined by SIMS. It was found that diffusion occurs by means of bulk and grain boundaries. The bulk diffusion coefficients are similar for all cations with activation energies which are strongly dependent on temperature. The results are explained by a frozen-in defect structure at low temperatures in the ABO{sub 3} perovskite lattice and by proposing a defect cluster containing cation vacancies in the A and B sublattices, as well as oxygen vacancies. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  16. Study of lanthanum aluminate for cost effective electrolyte material for SOFC

    Science.gov (United States)

    Verma, O. N.; Shahi, A. K.; Singh, P.

    2018-05-01

    The perovskite type electrolyte material LaAlO3 (abbreviated LAO) has been prepared by easy processing of auto-combustion synthesis using lanthanum nitrate and aluminium nitrate salts as precursors and citric acid as the fuel. The XRD analysis reveals that as synthesized material exhibits only single phase having rhombohedral structure. The measured density and theoretical density have been deliberated. The temperature dependent electrical conductivity of LAO increases with increasing the temperature which leads to increased mobility of oxide ion. The major contribution of such a significant value of ionic conductivity of LAO can be inferred to grain boundary resistance.

  17. Relaxation features of the Young's modulus and internal friction of lanthanum

    International Nuclear Information System (INIS)

    Bodryakov, V.Yu.

    1993-01-01

    E Young module and Q -1 inner friction of polycrystalline lanthanum specimens are studied comprehensively within 4.2-420 K temperature range using bend autovibrations of a specimen represented by a thin rod within ∼ 1-2 kHz frequency range. Three maximums of relaxation nature innner friction are detected under ∼ 380-410, 250-270 and 90-120 K temperatures with 0.29, 0.21 and 0.02 eV activation energies, respectively, on Q -1 (T) curves. Maximums of inner friction are accompanied by peculiarities of E(T) Young module behaviour. 21 refs., 3 figs., 2 tabs

  18. Study of binding properties of lanthanum to wheat roots by INAA

    International Nuclear Information System (INIS)

    Zhang, Z.Y.; Li, F.L.; Xiao, H.Q.; Chai, Z.F.; Xu, L.; Liu, N.

    2004-01-01

    Chemical behavior of lanthanum in root tips excized from wheat seedlings growing at both promotional and inhibitory levels of LaCl 3 in culture solutions was investigated by a sequential leaching procedure combined with instrumental neutron activation analysis. The results indicate that most of La exists in non-exchangeable species and the binding of La 3+ to the root tips is extremely stable. The root tips during growing at the inhibitory level of LaCl 3 absorb much more La than those at the promotional level. However, the La proportion in each fraction is similar for both groups. (author)

  19. Effects of Dredging and Lanthanum-Modified Clay on Water Quality Variables in an Enclosure Study in a Hypertrophic Pond

    Directory of Open Access Journals (Sweden)

    Miquel Lürling Guido Waajen

    2017-05-01

    Full Text Available An enclosure experiment was conducted between July and September 2009 to compare the effectiveness of a phosphate fixative, the lanthanum-modified bentonite clay Phoslock® (LMB, dredging, and their combination in controlling eutrophication in a hypertrophic urban pond in Heesch, The Netherlands. In total, 25 water quality variables were monitored. Multivariate analysis revealed that the combination LMB-treated and dredged enclosures deviated most from the pond (reference and the controls, and showed the strongest eutrophication reduction. Overall, dredging significantly increased transparency, lowered turbidity, and improved the oxygen conditions in the enclosures compared to non-dredged ones. Nonetheless, one dredged enclosure deviated dramatically from the others, which might reflect methodological issues with dredging. The LMB treatment appeared to be less effective at mitigating eutrophication than dredging, and phosphate concentrations even increased during the experiment in the LMB-treated enclosures. Chemical equilibrium modeling suggested that humic substances could have formed complexes with lanthanum (La from the LMB, rendering it unavailable for intercepting P over the course of the enclosure experiment. Residual lanthanum concentrations in combination dredging and LMB treatments exceeded the Dutch standard 10-fold. Total zooplankton abundance, and particularly Cladocera, increased in all enclosures over the course of the experiment. The limited effect of LMB in the enclosure experiment and the violation of the Dutch La standard when combined with dredging disqualify LMB as an intervention agent in the restoration of the pond.

  20. Phosphate binding therapy in dialysis patients: focus on lanthanum carbonate

    Directory of Open Access Journals (Sweden)

    Ismail A Mohammed

    2008-11-01

    Full Text Available Ismail A Mohammed, Alastair J HutchisonManchester Institute of Nephrology and Transplantation, Manchester Royal Infirmary, Oxford Road, Manchester, UKAbstract: Hyperphosphatemia is an inevitable consequence of end stage chronic kidney disease and is present in the majority of dialysis patients. Recent observational data has associated hyperphosphatemia with increased cardiovascular mortality among dialysis patients. Dietary restriction of phosphate and current dialysis prescription practices are not enough to maintain serum phosphate levels within the recommended range so that the majority of dialysis patients require oral phosphate binders. Unfortunately, conventional phosphate binders are not reliably effective and are associated with a range of limitations and side effects. Aluminium-containing agents are highly efficient but no longer widely used because of well established and proven toxicity. Calcium based salts are inexpensive, effective and most widely used but there is now concern about their association with hypercalcemia and vascular calcification. Sevelamer hydrochloride is associated with fewer adverse effects, but a large pill burden and high cost are limiting factors to its wider use. In addition, the efficacy of sevelamer as a monotherapy in lowering phosphate to target levels in severe hyperphosphatemia remains debatable. Lanthanum carbonate is a promising new non-aluminium, calcium-free phosphate binder. Preclinical and clinical studies have demonstrated a good safety profile, and it appears well tolerated and effective in reducing phosphate levels in dialysis patients. Its identified adverse events are apparently mild to moderate in severity and mostly GI related. It appears to be effective as a monotherapy, with a reduced pill burden, but like sevelamer, it is significantly more expensive than calcium-based binders. Data on its safety profile over 6 years of treatment are now available.Keywords: hyperphosphatemia, lanthanum

  1. STRUCTURE AND THERMAL STABILITY OF THE BENZO-15-CROWN-5 WITH LANTHANUM (III BROMIDE COMPLEX

    Directory of Open Access Journals (Sweden)

    Muhammad Idiris Saleh

    2010-06-01

    Full Text Available The reaction of benzo-15-crown-5 (C14H20O5 ligand with La(NO33.7H2O in the presence of HBr has resulted in the production of an exotic sandwich complex, [LaC28H36Br4O10][3Br]. The crystal system is triclinic with space group P1, a = 12.5834(14 Å, b = 13.5816(16 Å, c = 13.8403(16 Å, a = 70.751(2°, b = 66.773(2° and g = 67.631(2°. The cation comprises of the lanthanum atom coordinated to two crowns via three oxygen atoms from each crown in a η3-sandwich fashion. The two phenyl groups of the crown are brominated. The La-OLigand bond lengths are between 2.857(7 and 2.949(7 Å. The trianion [3Br]3- is linear with Br-Br bond lengths of 2.518(2 and 2.560(2 Å respectively. The molecule is stabilized by intermolecular interactions of the type C-H...Br to form dimers and are arranged parallel to bc face.  Keywords: lanthanum, benzo-15-crown-5, hydrogen bonding, bromination, x-ray structure

  2. On isomorphous substitution of calcium by sodium and lanthanum in synthetic hydroxyapatite

    International Nuclear Information System (INIS)

    Get'man, E.I.; Kanyuka, Yu.V.; Loboda, S.N.

    1998-01-01

    Isomorphous substitution of calcium by sodium and lanthanum in synthetic hydroxyapatite Ca 5-2x La x (PO 4 ) 3 OH by x=0-2.5 within the temperature range 1100-800 deg C is studied through the roentgenophase analysis and IR-spectroscopy methods. It is established that singlephase solid solutions are formed in the area of x≥0.4 by a≤0.4 there exist phases with LaPO 4 , LaNa 6 (PO 4 ) 3 structures and unknown phase along with solid solution of the apatite structure

  3. Characterization of phosphate sequestration by a lanthanum modified bentonite clay: A solid-state NMR, EXAFS and PXRD study

    DEFF Research Database (Denmark)

    Dithmer, Line; Lipton, Andrew S; Reitzel, Kasper

    2015-01-01

    Phosphate (Pi) sequestration by a lanthanum (La) exchanged clay mineral (La-Bentonite), which is extensively used in chemical lake restoration, was investigated on the molecular level using a combination of 31P and 139La solid state NMR spectroscopy (SSNMR), extended X-ray absorption spectroscopy...

  4. Equidensitometry: a method for characterising the structure of plasmas. Qualitative characterisation of the lanthanum d.c. arc by equidensitometry of monochromatic arc photographs

    International Nuclear Information System (INIS)

    Dittrich, K.; Niebergall, K.; Roessler, H.

    1976-01-01

    A new method has been developed for the experimental characterization of d.c. arc plasmas. The method consists of the combination of the spectral photography of d.c. arc plasmas with a slitless, stigmatic plane-grating spectrograph and the characterization of the photographs with the aid of photographic equidensitometry. The principles of the method are described. The method is used for the investigation of a lanthanum d.c. arc plasma. The qualitative results of the measurements of the axial distributions of the light emission and lanthanum and calcium particle concentrations in the arc are discussed. The limitations and shortcomings of the method are pointed out. (author)

  5. Potentiometric measurement of polymer-membrane electrodes based on lanthanum

    Energy Technology Data Exchange (ETDEWEB)

    Saefurohman, Asep, E-mail: saefurohman.asep78@Gmail.com; Buchari,, E-mail: saefurohman.asep78@Gmail.com; Noviandri, Indra, E-mail: saefurohman.asep78@Gmail.com [Department of Chemistry, Bandung Institute of Technology (Indonesia); Syoni [Department of Metallurgy Engineering, Bandung Institute of Technology (Indonesia)

    2014-03-24

    Quantitative analysis of rare earth elements which are considered as the standard method that has a high accuracy, and detection limits achieved by the order of ppm is inductively coupled plasma atomic emission spectroscopy (ICPAES). But these tools are expensive and valuable analysis of the high cost of implementation. In this study be made and characterized selective electrode for the determination of rare earth ions is potentiometric. Membrane manufacturing techniques studied is based on immersion (liquid impregnated membrane) in PTFE 0.5 pore size. As ionophores to be used tri butyl phosphate (TBP) and bis(2-etylhexyl) hydrogen phosphate. There is no report previously that TBP used as ionophore in polymeric membrane based lanthanum. Some parameters that affect the performance of membrane electrode such as membrane composition, membrane thickness, and types of membrane materials studied in this research. Manufacturing of Ion Selective Electrodes (ISE) Lanthanum (La) by means of impregnation La membrane in TBP in kerosene solution has been done and showed performance for ISE-La. FTIR spectrum results for PTFE 0.5 pore size which impregnated in TBP and PTFE blank showed difference of spectra in the top 1257 cm{sup −1}, 1031 cm{sup −1} and 794.7 cm{sup −1} for P=O stretching and stretching POC from group −OP =O. The result showed shift wave number for P =O stretching of the cluster (−OP=O) in PTFE-TBP mixture that is at the peak of 1230 cm{sup −1} indicated that no interaction bond between hydroxyl group of molecules with molecular clusters fosforil of TBP or R{sub 3}P = O. The membrane had stable responses in pH range between 1 and 9. Good responses were obtained using 10{sup −3} M La(III) internal solution, which produced relatively high potential. ISE-La showed relatively good performances. The electrode had a response time of 29±4.5 second and could be use for 50 days. The linear range was between 10{sup −5} and 10{sup −1} M.

  6. Temperature dependence of magnetoresistance in lanthanum manganite ceramics

    International Nuclear Information System (INIS)

    Gubkin, M.K.; Zalesskii, A.V.; Perekalina, T.M.

    1996-01-01

    Magnetoresistivity in the La0.9Na0.1Mn0.9(V,Co)0.1O3 and LaMnO3+δ ceramics was studied. The temperature dependence of magnetoresistance in these specimens was found to differ qualitatively from that in the La0.9Na0.1MnO3 single crystal (the magnetoresistance value remains rather high throughout the measurement range below the Curie temperature), with the maximum values being about the same (20-40% in the field of 20 kOe). Previously published data on magnetization, high frequency magnetic susceptibility, and local fields at the 139La nuclei of the specimens with similar properties attest to their magnetic inhomogeneity. The computation of the conductivity of the nonuniformly ordered lanthanum manganite was performed according to the mean field theory. The calculation results allow one to interpret qualitatively various types of experimental temperature dependences of magnetoresistance

  7. Photocatalytic degradation of the Paracetamol drug using Lanthanum doped ZnO nanoparticles and their in-vitro cytotoxicity assay

    International Nuclear Information System (INIS)

    Shakir, Mohammad; Faraz, Mohd; Sherwani, Mohd Asif; Al-Resayes, Saud I.

    2016-01-01

    The doping of semiconductor by rare earth metals nanoparticles is an effective way for increasing photocatalytic activity. Zinc oxide and Lanthanum doped Zinc oxide nanoparticles were synthesized by modifying the gel-combustion method. It was found that La can greatly enhance the cytotoxicity and photocatalytic activity of ZnO nanoparticles towards various cell lines and Paracetamol drug. These nanoparticles were characterized by various spectroscopic and other techniques which clearly revealed the presence of lanthanum ions. The absorption edge shifts towards the visible region after doping with La ions. This shift shows that the doping of La ions is favorable for absorbing the visible light. The comparative photocatalytic and cytotoxicity activity revealed that La doped ZnO nanoparticles remarkably enhanced activities as compared to the ZnO nanoparticles. The outcome of these studies offers valuable for planning La doped ZnO nanoparticles having cytotoxicity and photocatalytic activities helpful for the formulation of anticancer product and waste water remediation.

  8. Photocatalytic degradation of the Paracetamol drug using Lanthanum doped ZnO nanoparticles and their in-vitro cytotoxicity assay

    Energy Technology Data Exchange (ETDEWEB)

    Shakir, Mohammad, E-mail: shakir078@yahoo.com [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Faraz, Mohd [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Sherwani, Mohd Asif [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India); Al-Resayes, Saud I. [Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)

    2016-08-15

    The doping of semiconductor by rare earth metals nanoparticles is an effective way for increasing photocatalytic activity. Zinc oxide and Lanthanum doped Zinc oxide nanoparticles were synthesized by modifying the gel-combustion method. It was found that La can greatly enhance the cytotoxicity and photocatalytic activity of ZnO nanoparticles towards various cell lines and Paracetamol drug. These nanoparticles were characterized by various spectroscopic and other techniques which clearly revealed the presence of lanthanum ions. The absorption edge shifts towards the visible region after doping with La ions. This shift shows that the doping of La ions is favorable for absorbing the visible light. The comparative photocatalytic and cytotoxicity activity revealed that La doped ZnO nanoparticles remarkably enhanced activities as compared to the ZnO nanoparticles. The outcome of these studies offers valuable for planning La doped ZnO nanoparticles having cytotoxicity and photocatalytic activities helpful for the formulation of anticancer product and waste water remediation.

  9. The influence of lake water alkalinity and humic substances on particle dispersion and lanthanum desorption from a lanthanum modified bentonite

    DEFF Research Database (Denmark)

    Reitzel, Kasper; Balslev, Kristiane Astrid; Jensen, Henning S

    2017-01-01

    A 12 days laboratory study on potential desorption of Lanthanum (La) from a commercial La modified clay (Phoslock) was conducted using lake water from 17 Danish lakes with alkalinities between 0.02 and 3.7 meq L-1and varying concentrations of DOC and humic acids (HA's). A similar study...... was conducted in artificial lake water with alkalinities from 0 to 2.5 meq L-1in order to exclude interference from dissolved HA's. To test if La in solution (FLa) was associated with fine particles, the water samples were filtered sequentially through three filter sizes (1.2 μm, 0.45 μm and 0.2 μm...... at low alkalinities. In addition, this study showed that HA's seem to increase the FLa concentrations in soft water lakes, most likely through complexation of La retained in the Phoslock matrix. In summary, we conclude that elevated La concentrations in lake water after a Phoslock treatment should only...

  10. Solid-phase extraction (SPE) of Iron using Lanthanum Silicate ion exchange

    International Nuclear Information System (INIS)

    Kiarostami, V.; Husain, W.

    2002-01-01

    Solid-phase extraction (SPE) is gaining wide use as an effective and speedy technique which reduces solvent usage, disposal costs and extraction time. The analyte is adsorbed from solution onto a solid adsorbent, which is followed by elution of the analyte with a solvent appropriate for instrumental analysis. However, there is an increasing need for new selective adsorbents to expand the area of this technique. Lanthanum silicate ion exchanger, which shows unusual selectivity elements and in this study, it was employed to develop a SPE method for iron ion. Special experiments such as determination of distribution coefficient for iron ion in different solvent systems have been determined

  11. Cerium-modified Aurivillius-type sodium lanthanum bismuth titanate with enhanced piezoactivities

    International Nuclear Information System (INIS)

    Wang Chunming; Zhao Liang; Wang Jinfeng; Zheng Limei; Du Juan; Zhao Minglei; Wang Chunlei

    2009-01-01

    The electrical, piezoelectric and dielectric properties of cerium-modified Aurivillius-type sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) ceramics were investigated. It was found the piezoelectric activities of NLBT ceramics were significantly improved by cerium modification. The piezoelectric coefficient d 33 and Curie temperature T c for the 0.50 wt.% cerium-modified NLBT were found to be 29 pC/N and 573 deg. C, respectively. The reasons for piezoelectric activities improvement by cerium modification were given. A small dielectric abnormity was observed in NLBT ceramics, which can be suppressed by cerium modification.

  12. Enhanced electrocaloric analysis and energy-storage performance of lanthanum modified lead titanate ceramics for potential solid-state refrigeration applications.

    Science.gov (United States)

    Zhang, Tian-Fu; Huang, Xian-Xiong; Tang, Xin-Gui; Jiang, Yan-Ping; Liu, Qiu-Xiang; Lu, Biao; Lu, Sheng-Guo

    2018-01-10

    The unique properties and great variety of relaxer ferroelectrics make them highly attractive in energy-storage and solid-state refrigeration technologies. In this work, lanthanum modified lead titanate ceramics are prepared and studied. The giant electrocaloric effect in lanthanum modified lead titanate ceramics is revealed for the first time. Large refrigeration efficiency (27.4) and high adiabatic temperature change (1.67 K) are achieved by indirect analysis. Direct measurements of electrocaloric effect show that reversible adiabatic temperature change is also about 1.67 K, which exceeds many electrocaloric effect values in current direct measured electrocaloric studies. Both theoretical calculated and direct measured electrocaloric effects are in good agreements in high temperatures. Temperature and electric field related energy storage properties are also analyzed, maximum energy-storage density and energy-storage efficiency are about 0.31 J/cm 3 and 91.2%, respectively.

  13. Effect of lead dioxide on the radiation decomposition of hydrated lanthanum nitrate (Preprint No. RES-05)

    International Nuclear Information System (INIS)

    Patil, S.F.; Bedekar, A.G.; Chiplunkar, N.R.

    1988-02-01

    The rate of radiation induced decomposition of lanthanum nitrate is found to increase in the presence of lead dioxide as a heterophase impurity. Further, the rate also increases with increasing mole percent of the oxide. The results are explained on the basis of energy transfer processes taking place at the interface between nitrate and oxide crystals. (aut hor). 9 refs

  14. Ouabain enhancement of compound 48/80 induced histamine secretion from rat peritoneal mast cells: dependence on extracellular sodium

    DEFF Research Database (Denmark)

    Knudsen, T; Bertelsen, Niels Haldor; Johansen, Torben

    1992-01-01

    Purified populations of rat peritoneal mast cells were used to study the effect of ouabain on compound 48/80-induced histamine secretion and on 86Rb+ uptake. 86Rb+ was used as a tracer for extracellular K+. The calculated value of the ouabain-sensitive uptake of K+ and 86Rb+ was considered...... on the secretion occurs in the presence of sodium but not when sodium was replaced by lithium. Preservation by ouabain of a high intracellular sodium content in sodium-loaded cells was associated with preservation of the secretory response in a calcium-free medium. In the presence of lanthanum in a calcium...

  15. Electronic Conductivity of Doped-Lanthanum Gallate Electrolytes

    Science.gov (United States)

    Yamaji, Katsuhiko; Xiong, Yue Ping; Kishimoto, Haruo; Horita, Teruhisa; Sakai, Natsuko; Brito, Manuel E.; Yokokawa, Harumi

    Electronic conductivity of doped lanthanum gallate electrolytes were determined by using a Hebb-Wagner type polarization cell. Electronic conductivity of cobalt-doped, La0.8Sr0.2Ga0.8Mg0.15Co0.5O3-δ (LSGMC), and non cobalt-doped, La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM8282), were measured as a function of oxygen partial pressures. The electronic conductivity of LSGM8282 showed a linear dependence on p(O2)1/4 in the higher p(O2) region, which is attributed to the electronic hole conductivity. The electronic conductivity of LSGMC showed a linear dependence on p(O2)1/6 in the higher p(O2) region. LSGMC has higher electronic conductivity than LSGM, and the conductivity was not clearly changed with temperatures between 600 and 800 °C. In lower p(O2) region, the electronic conductivity data have poor reproducibility and did not show any dependence on p(O2) because of the degradation of the electrolytes in severe reducing atmospheres.

  16. Mechanical properties of lanthanum and yttrium chromites

    Energy Technology Data Exchange (ETDEWEB)

    Paulik, S.W.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    In an operating high-temperature (1000{degrees}C) solid oxide fuel cell (SOFC), the interconnect separates the fuel (P(O{sub 2}){approx}10{sup -16} atm) and the oxidant (P(O2){approx}10{sup 0.2} atm), while being electrically conductive and connecting the cells in series. Such severe atmospheric and thermal demands greatly reduce the number of viable candidate materials. Only two materials, acceptor substituted lanthanum chromite and yttrium chromite, meet these severe requirements. In acceptor substituted chromites (Sr{sup 2+} or Ca{sup 2+} for La{sup 3+}), charge compensation is primarily electronic in oxidizing conditions (through the formation of Cr{sup 4+}). Under reducing conditions, ionic charge compensation becomes significant as the lattice becomes oxygen deficient. The formation of oxygen vacancies is accompanied by the reduction of Cr{sup 4+} ions to Cr{sup 3+} and a resultant lattice expansion. The lattice expansion observed in large chemical potential gradients is not desirable and has been found to result in greatly reduced mechanical strength.

  17. Thermal stability and microstructure of catalytic alumina composite support with lanthanum species

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Masakuni, E-mail: ozawa@numse.nagoya-u.ac.jp; Nishio, Yoshitoyo

    2016-09-01

    Highlights: • Thermal stability of La-modified γ-Al{sub 2}O{sub 3} with nanometer-scaled structure. • LaAlO{sub 3} particles are dispersed in the aggregated particles of alumina. • Increase of the surface basicity of La modified alumina using CO{sub 2}-TPD. - Abstract: Lanthanum (La) modified γ-alumina composite was examined for application toward thermostable catalytic support at elevated temperature. La added alumina was prepared through an aqueous process using lanthanum (III) nitrate and then characterized by surface area measurement, X-ray powder diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoemission spectroscopy (XPS) and surface desorption of CO{sub 2}. It was found that the properties depended on the La content and heat treatment temperatures. The characterization of the surface, structural and chemical properties of La-Al{sub 2}O{sub 3} showed the existence of a strong interaction between the La species and alumina via formation of new phase and modified surface in Al{sub 2}O{sub 3} samples. LaAlO{sub 3} nanoparticle formed among alumina particles by the solid phase reaction of Al{sub 2}O{sub 3} and La{sub 2}O{sub 3}. The increase of the surface basicity of La modified alumina was demonstrated using CO{sub 2} temperature programmed desorption experiments. The controlled surface interaction between La oxide and alumina provide the unique surface and structural properties of the resulting mixed oxides as catalysts and catalytic supports.

  18. Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

    Science.gov (United States)

    Madhu, A.; Eraiah, B.

    2018-04-01

    Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

  19. Performance of planar single cell lanthanum gallate based solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Maffei, N.; Kuriakose, A.K. [Materials Technology Labs., CANMET, Natural Resources Canada, Ottawa, ON (Canada)

    1998-09-01

    A novel synthesis of high purity, single phase strontium-magnesium doped lanthanum gallate through a nitrate route is described. The prepared powder is formed into planar monolithic elements by uniaxial pressing followed by isostatic pressing and sintering. XRD analysis of the sintered elements reveal no detectable secondary phases. The performance of the electrolyte in solid oxide fuel cells (SOFC) with three different anode/cathode combinations tested at 700 C with respect to the J-V and power density is reported. The data show that the characteristics of this SOFC are strongly dependent on the particular anode/cathode system chosen. (orig.)

  20. Performance of planar single cell lanthanum gallate based solid oxide fuel cells

    Science.gov (United States)

    Maffei, N.; Kuriakose, A. K.

    A novel synthesis of high purity, single phase strontium-magnesium doped lanthanum gallate through a nitrate route is described. The prepared powder is formed into planar monolithic elements by uniaxial pressing followed by isostatic pressing and sintering. XRD analysis of the sintered elements reveal no detectable secondary phases. The performance of the electrolyte in solid oxide fuel cells (SOFC) with three different anode/cathode combinations tested at 700°C with respect to the J- V and power density is reported. The data show that the characteristics of this SOFC are strongly dependent on the particular anode/cathode system chosen.

  1. Lanthanum chloride impairs spatial memory through ERK/MSK1 signaling pathway of hippocampus in rats.

    Science.gov (United States)

    Liu, Huiying; Yang, Jinghua; Liu, Qiufang; Jin, Cuihong; Wu, Shengwen; Lu, Xiaobo; Zheng, Linlin; Xi, Qi; Cai, Yuan

    2014-12-01

    Rare earth elements (REEs) are used in many fields for their diverse physical and chemical properties. Surveys have shown that REEs can impair learning and memory in children and cause neurobehavioral defects in animals. However, the mechanism underlying these impairments has not yet been completely elucidated. Lanthanum (La) is often selected to study the effects of REEs. The aim of this study was to investigate the spatial memory impairments induced by lanthanum chloride (LaCl3) and the probable underlying mechanism. Wistar rats were exposed to LaCl3 in drinking water at 0 % (control, 0 mM), 0.25 % (18 mM), 0.50 % (36 mM), and 1.00 % (72 mM) from birth to 2 months after weaning. LaCl3 considerably impaired the spatial learning and memory of rats in the Morris water maze test, damaged the synaptic ultrastructure and downregulated the expression of p-MEK1/2, p-ERK1/2, p-MSK1, p-CREB, c-FOS and BDNF in the hippocampus. These results indicate that LaCl3 exposure impairs the spatial learning and memory of rats, which may be attributed to disruption of the synaptic ultrastructure and inhibition of the ERK/MSK1 signaling pathway in the hippocampus.

  2. Cationic copolymerization of cycloaliphatic epoxy resin with an spirobislactone with lanthanum triflate as initiator

    International Nuclear Information System (INIS)

    Fernandez, Xavier; Ramis, Xavier; Salla, Josep M.

    2005-01-01

    3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (ECH) was cured with different proportions of 1,6-dioxaspiro[4,4]nonane-2,7-dione (s(γ-BL)) using lanthanum triflate as a catalyst. DSC was used to obtain kinetic data associated to the curing process by means of series of non-isothermal experiments. Fourier transform infrared spectroscopy in attenuated total reflection mode (FT-IR/ATR) was used to study the evolution of the epoxide group in order to compare experimental isothermal data with simulated isothermal data. The complexity of the process itself enabled us to compare different procedures for obtaining isoconversional data and to determine the kinetic model that best describes the curing process. An increase in the proportion of s(γ-BL) increases the speed of the curing process. By means of applying isoconversional methods to dynamic experimental data, we observed that an increase in the proportion of s(γ-BL) leads to an overall decrease in the activation energy for the different formulations. Kinetic parameters that were determined using both differential and integral isoconversional procedures were compared. This allowed us to analyze and to discuss the usefulness of different methods in order to obtain a suitable kinetic triplet at each step of the curing of the ECH/s(γ-BL) system using lanthanum triflate as a catalyst

  3. Fabrication of Sr- and Co-doped lanthanum chromite interconnectors for SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Setz, L.F.G. [Departamento de Engenharia de Materiais, Universidade Federal de Sao Carlos - DEMa/UFSCar (Brazil); Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil); Santacruz, I. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Colomer, M.T., E-mail: tcolomer@icv.csic.es [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain); Mello-Castanho, S.R.H. [Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil); Moreno, R. [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain)

    2011-07-15

    Graphical abstract: FESEM micrographs of the fresh fracture surfaces for the La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} sintered specimens cast from optimised suspensions with 13.5, 15 and 17.5 vol.% solids loading. Aqueous suspensions were prepared using ammonium polyacrylate (PAA) as dispersant and tetramethylammonium hydroxide (TMAH) to assure a basic pH and providing stabilization. Sintering of the green discs was performed in air at 1600 {sup o}C for 4 h. Highlights: {yields} Optimum casting slips were achieved with 3 wt.% of ammonium polyacrylate and 1 wt.% of tetramethylammonium hydroxide. -- Abstract: Many studies have been performed dealing with the processing conditions of electrodes and electrolytes in solid oxide fuel cells (SOFCs). However, the processing of the interconnector material has received less attention. Lanthanum chromite (LaCrO{sub 3}) is probably the most studied material as SOFCs interconnector. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA) as dispersant and tetramethylammonium hydroxide (TMAH) to assure a basic pH and providing stabilization. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.% of PAA and TMAH, respectively, yielded the best conditions for successful slip casting. Sintering of the green discs was performed in air at 1600 {sup o}C for 4 h leading to relatively dense materials.

  4. Apparent molar volumes and compressibilities of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in N,N-dimethylformamide and N,N-dimethylacetamide

    International Nuclear Information System (INIS)

    Warmińska, Dorota; Fuchs, Anna; Lundberg, Daniel

    2013-01-01

    Highlights: ► In DMF the sequence values of both volumes and compressibilities of Ln 3+ ions are: La 3+ ≈ Gd 3+ > Lu 3+ . ► In DMA the ionic volumes of lanthanoid(III) metal ions are, within error limits, identical. ► Obtained results are the consequence of an ion–solvent bonding nature. -- Abstract: The concentration and temperature dependencies of density of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) have been determined. From density data the apparent molar volumes and partial molar volumes of the salts at infinite dilution as well as the expansibilities have been evaluated. The apparent molar isentropic compressibilities of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in DMF and DMA have been calculated from sound velocity data obtained at 298.15 K. The results have been discussed in terms of ion–solvent interactions

  5. Doping and temperature dependence of incommensurate antiferromagnetism in underdoped lanthanum cuprates

    International Nuclear Information System (INIS)

    Yuan Feng; Feng Shiping; Su Zhaobin; Yu Lu

    2001-08-01

    The doping, temperature and energy dependence of the dynamical spin structure factors of the underdoped lanthanum cuprates in the normal state is studied within the t-J model using the fermion-spin transformation technique. Incommensurate peaks are found at [(1±δ)π, π], [π, (1±δ)π] at relatively low temperatures with δ linearly increasing with doping at the beginning and then saturating at higher dopings. These peaks broaden and weaken in amplitude with temperature and energy, in good agreement with experiments. The theory also predicts a rotation of these peaks by π/4 at even higher temperatures, being shifted to [(1±δ/√2)π, (1±δ/√2)π]. (author)

  6. A meta-analysis of water quality and aquatic macrophyte responses in 18 lakes treated with lanthanum modified bentonite (PHOSLOCK®)

    NARCIS (Netherlands)

    Spears, B.M.; Mackay, E.; Yasseri, S.; Gunn, I.D.M.; Waters, K.E.; Andrews, C.; Cole, S.; Ville, de M.; Kelly, M.; Meis, S.; Moore, A.L.; Nurnberg, G.K.; Oosterhout, van Frank; Lurling, M.F.L.L.W.

    2016-01-01

    Lanthanum (La) modified bentonite is being increasingly used as a geo-engineering tool for the control of phosphorus (P) release from lake bed sediments to overlying waters. However, little is known about its effectiveness in controlling P across a wide range of lake conditions or of its potential

  7. Variation in band gap of lanthanum chromate by transition metals doping LaCr0.9A0.1O3 (A:Fe/Co/Ni)

    International Nuclear Information System (INIS)

    Naseem, Swaleha; Khan, Wasi; Saad, A. A.; Shoeb, M.; Ahmed, Hilal; Naqvi, A. H.; Husain, Shahid

    2014-01-01

    Transition metal (Fe, Co, Ni) doped lanthanum chromate (LaCrO 3 ) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 800°C. Microstructural studies were carried by XRD and SEM/EDS techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible and photoluminescence techniques. The energy band gap was calculated and the variation was observed with the doping of transition metal ions. Photoluminescence spectra show the emission peak maxima for the pure LaCrO 3 at about 315 nm. Influence of Fe, Co, Ni doping was studied and compared with pure lanthanum chromate nanoparticles

  8. Study of the Effect on Ionic Conductivity and Structral Morphology of the SR Doped Lanthanum Gallate Solid Electrolyte

    Science.gov (United States)

    Sood, Kapil; Singh, K.; Pandey, O. P.

    2013-07-01

    In the present study, lanthanum gallate and Sr-doped lanthanum gallate samples were prepared by conventional solid state reaction method. The phase conformation has been performed by using X-ray diffraction (XRD) study. The elemental composition has been confirmed using energy dispersive spectroscopy (EDS) analysis. Ac conductivity of the samples has been measured in the frequency range 0.1-106 Hz and from 50-800 °C. The impedance plots among real and complex impedances at particular temperature have been discussed. The behavior shows the effect of bulk and grain boundary effects of the doped sample. The impedance plots with frequency have been analyzed. The plots have been well fitted to equivalent circuit model. The conductivity shows the Arrhenius type of behavior. The activation energy has been calculated from the plots and represents that the conductivity through the material is mainly ionic. The structural morphology of the samples has been investigated using scanning electron microscope (SEM). The micrograph shows that the porosity and grain size both decreases with Sr-doping.

  9. High concentrations of cadmium, cerium and lanthanum in indoor air due to environmental tobacco smoke

    International Nuclear Information System (INIS)

    Böhlandt, Antje; Schierl, Rudolf; Diemer, Juergen; Koch, Christoph; Bolte, Gabriele; Kiranoglu, Mandy; Fromme, Hermann; Nowak, Dennis

    2012-01-01

    Background: Environmental tobacco smoke (ETS) is one of the most important sources for indoor air pollution and a substantial threat to human health, but data on the concentrations of the trace metals cerium (Ce) and lanthanum (La) in context with ETS exposure are scarce. Therefore the aim of our study was to quantify Ce and La concentrations in indoor air with high ETS load. Methods: In two subsequent investigations Ce, La and cadmium (Cd) in 3 smokers' (11 samples) and 7 non-smokers' (28 samples) households as well as in 28 hospitality venues in Southern Germany were analysed. Active sampling of indoor air was conducted continuously for seven days in every season in the smokers' and non-smokers' residences, and for 4 h during the main visiting hours in the hospitality venues (restaurants, pubs, and discotheques). Results: In terms of residences median levels of Cd were 0.1 ng/m 3 for non-smokers' and 0.8 ng/m 3 for smokers' households. Median concentrations of Ce were 0.4 ng/m 3 and 9.6 ng/m 3 , and median concentrations of La were 0.2 ng/m 3 and 5.9 ng/m 3 for non-smokers' and for smokers' households, respectively. In the different types of hospitality venues median levels ranged from 2.6 to 9.7 ng/m 3 for Cd, from 18.5 to 50.0 ng/m 3 for Ce and from 10.6 to 23.0 ng/m 3 for La with highest median levels in discotheques. Conclusions: The high concentrations of Ce and La found in ETS enriched indoor air of smokers' households and hospitality venues are an important finding as Ce and La are associated with adverse health effects and data on this issue are scarce. Further research on their toxicological, human and public health consequences is urgently required. - Highlights: ► We quantified cer, lanthanum and cadmium concentrations in indoor air. ► Cer and lanthanum concentrations were high in tobacco smoke enriched locations. ► Both elements can be considered as good markers for indoor air quality.

  10. Accomplishment of highly porous-lithium lanthanum titanate through microwave treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmi, D.; Nalini, B., E-mail: jyothsnalalin99@gmail.com [Department of Physics, Avinashilingam University for Women, Coimbatore, Tamilnadu (India); Abhilash, K. P.; Selvin, P. Christopher [Department of Physics, NGM college for arts and science, Pollachi, Tamilnadu (India)

    2016-05-23

    Perovskite structured (ABO{sub 3}) lithium lanthanum titanate (LLTO) is a successful electrolyte reported by several scientists in the recent past. It is believed that intercalation and de-intercalation of Li ions inside solid electrolyte can be improved by increasing the porosity of the material. Hence in this research work, an attempt is made to increase the porosity of the LLTO electrolyte by rapid-microwave synthesis route. The microwave prepared LLTO is compared with the sol-gel synthesized LLTO. The prepared samples are analyzed with XRD, SEM, PL and cyclic Voltammetry studies. Morphological analysis proves that microwave synthesized LLTO contains much pores compared to the Sol-gel LLTO. A remarkable difference in its electrochemical property is also demonstrated and analysed with cyclic voltammetric studies and the results are presented.

  11. Vaporization study on lanthanum-neodymium alloys by mass-spectrometry

    International Nuclear Information System (INIS)

    Shoji, Y.; Matsui, T.

    1999-01-01

    Partial vapor pressure of Nd(g) over La x Nd 1-x alloys (x = 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 and 0.90) was measured with a time-of-flight mass-spectrometer equipped with a tungsten Knudsen cell over the temperature range of 1474-1767 K. Thermodynamic activity of neodymium in the liquid alloys was determined by comparing the partial vapor pressure of Nd(g) over the alloys with that over the pure metal. The thermodynamic activity of lanthanum in the alloys was calculated from that of neodymium obtained experimentally in this study by graphic integration using the Gibbs-Duhem equation. Both activities for each element, thus obtained, showed positive deviations from Raoult's law over the entire compositional range. Thermodynamic quantities such as Gibbs free energy of formation, excess enthalpy etc. were also calculated from the thermodynamic activities. (orig.)

  12. Ethanol Electrooxidation on Pt with Lanthanum Oxide as Cocatalyst in a DAFC

    Directory of Open Access Journals (Sweden)

    T. A. B. Santoro

    2012-01-01

    Full Text Available Electrocatalytic activity toward ethanol electrooxidation of Pt particles in PtLa/C catalysts with different Pt : La ratios has been studied with different electrochemical and spectroscopic techniques, and the results were compared to those of Pt/C catalyst. Significant enhancement in the electrocatalytic activity has been achieved by depositing the Pt particles with lanthanum oxides/hydroxides using an alcohol reduction method. Compared to Pt/C catalyst, PtLa/C materials exhibit a lower onset potential and a higher electron-transfer rate constant for the investigated reaction. These studies illustrate the possibility of utilizing Pt/C with La oxides/hidroxides as electrocatalyst for direct alcohol fuel cells (DAFCs.

  13. Optical and photoemission studies of lanthanum hydrides

    International Nuclear Information System (INIS)

    Peterman, D.J.; Peterson, D.T.; Weaver, J.H.

    1980-01-01

    The results of optical absorptivity and photoemission measurements on lanthanum hydrides, LaH/sub x/ (1.98 less than or equal to x less than or equal to 2.89) are reported. The low energy (hν less than or equal to 0.5 eV) optical features in LaH/sub x/ are attributed to the filling of octahedral sites. Higher energy interband absorption involves states within the d-band complex, analogous to other dihydrides. As x increases above 2.0, the optical features change rapidly due to the increase in the number of occupied octahedral sites. Various band structure studies suggest that LaH 3 might be a semiconductor. Photoemission results show that as x increases, the d-derived states at E/sub F/ are drawn down and that for LaH 2 89 only very weak valence band emission is observed. The hydrogen-derived bonding bands are shown centered approx. 5 eV below E/sub F/. Observed chemical shifts in the La 5p/sub 1/2 3/2/ cores are discussed for 1.98 less than or equal to x less than or equal to 2.89

  14. Size effects of polycrystalline lanthanum modified Bi4Ti3O12 thin films

    International Nuclear Information System (INIS)

    Simoes, A.Z.; Riccardi, C.S.; Cavalcante, L.S.; Gonzalez, A.H.M.; Longo, E.; Varela, J.A.

    2008-01-01

    The film thickness dependence on the ferroelectric properties of lanthanum modified bismuth titanate Bi 3.25 La 0.75 Ti 3 O 12 was investigated. Films with thicknesses ranging from 230 to 404 nm were grown on platinum-coated silicon substrates by the polymeric precursor method. The internal strain is strongly influenced by the film thickness. The morphology of the film changes as the number of layers increases indicating a thickness dependent grain size. The leakage current, remanent polarization and drive voltage were also affected by the film thickness

  15. The lanthanum(III molybdate(VI La4Mo7O27

    Directory of Open Access Journals (Sweden)

    Petra Becker

    2009-08-01

    Full Text Available Crystals of the orthorhombic phase La4Mo7O27 (lanthanum molybdenum oxide were obtained from a non-stoichiometric melt in the pseudo-ternary system La2O3–MoO3–B2O3. In the crystal structure, distorted square-antiprismatic [LaO8] and monocapped square-antiprismatic [LaO9] polyhedra are connected via common edges and faces into chains along [010]. These chains are arranged in layers that alternate with layers of [MoO4] and [MoO5] polyhedra parallel to (001. In the molybdate layers, a distorted [MoO5] trigonal bipyramid is axially connected to two [MoO4] tetrahedra, forming a [Mo3O11] unit.

  16. Evaluation and comparison of two complexometric titration methods for determining of lanthanum in cloridric solutions

    International Nuclear Information System (INIS)

    Menezes, M.F.; Santos, R.L.C. dos; Goes, M.A.C. de

    1994-01-01

    The fast determination of total rare earth concentration in aqueous solutions is based on titrimetric methods using EDTA as complexing agent. This paper evaluates two among several others titrimetric methods used in the determination of lanthanum in hydrochloric acid solutions, using xylenol orange and a mixture of methyl orange and xylenol orange as indicators. The applied statistical evaluation allowed the determination of the stability, accuracy and adequacy of these methods on a given technical specification. (author). 12 refs., 03 tabs., 01 fig

  17. Sintering and electrical properties of strontium-doped lanthanum manganite

    Energy Technology Data Exchange (ETDEWEB)

    Tarrago, Diego Pereira; Sousa, Vania Caldas de [Universidade Federal do Rio Grande do Sul (LABIOMAT/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Biomateriais], Email: dptarrago@gmail.com; Moreno Buriel, Berta; Chinarro Martini, Eva; Jurado Egea, Jose Ramon [Consejo Superior de Investigaciones Cientificas (ICV/CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio; Malfatti, Celia de Fraga [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Pesquisa em Corrosao

    2010-07-01

    Lanthanum strontium manganites (LSM) are potential materials for cathode applications in solid oxide fuel cells (SOFC) due to their good catalytic activity, chemical stability and compatibility with electrolyte materials in high temperatures. The sinterability of single phase La{sub 1-x}Sr{sub x}Mn{sub O3} (x=0.18) perovskite powders and the electrical properties of the resulting samples are analyzed in this study. Using a heating microscope, the powders were pressed and sintered at different pressures and temperatures, resulting in an open porosity of 33.36% when compacted at 125 MPa and sintered at 1200 degree C. Top and cross-section s canning electron microscopy (SEM) micrographs revealed interconnected pores in the sintered body and, hence, a suitable microstructure for the application. The activation energy for conductance was 0.04 eV and the tested LSM bulk started to exhibit adequate electrical properties at about 500 degree C. (author)

  18. Thermoluminescent dosimetric characterization of the perovskite, KMgF3, activated with lanthanum

    International Nuclear Information System (INIS)

    Sepulveda M, F.

    2003-01-01

    The new ICRP regulation about the Radiological Protection allows to the different groups to study new thermoluminescent materials highly sensitive for dosimetric applications (personal and environmental). This work reports the relative experimental results to the thermoluminescent characteristic of a new preparation of the fluorine perovskite activated with lanthanum absorbed in polytetrafluoroethylene (KMgF 3 : LaF 3 + Ptfe). The main thermoluminescent properties investigated were: the TL response like a function of the absorbed dose, the attainable accuracy in the dose measurement, the reproducibility of the TL readings and the threshold dose. The obtained results were compared with the requirements of the ANSI protocol for the environmental dosimetry, resulting in a very good agreement with the required yields. (Author)

  19. Study of the Durability of Doped Lanthanum Manganite and Cobaltite Cathode Materials under ''Real World'' Air Exposure Atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Prabhakar [Univ. of Connecticut, Storrs, CT (United States); Mahapatra, Manoj [Univ. of Connecticut, Storrs, CT (United States); Ramprasad, Rampi [Univ. of Connecticut, Storrs, CT (United States); Minh, Nguyen [Univ. of California, San Diego, CA (United States); Misture, Scott [Alfred Univ., NY (United States)

    2014-11-30

    The overall objective of the program is to develop and validate mechanisms responsible for the overall structural and chemical degradation of lanthanum manganite as well as lanthanum ferrite cobaltite based cathode when exposed to “real world” air atmosphere exposure conditions during SOFC systems operation. Of particular interest are the evaluation and analysis of degradation phenomena related to and responsible for (a) products formation and interactions with air contaminants, (b) dopant segregation and oxide exolution at free surfaces, (c) cation interdiffusion and reaction products formation at the buried interfaces, (d) interface morphology changes, lattice transformation and the development of interfacial porosity and (e) micro-cracking and delamination from the stack repeat units. Reaction processes have been studied using electrochemical and high temperature materials compatibility tests followed by structural and chemical characterization. Degradation hypothesis has been proposed and validated through further experimentation and computational simulation.

  20. Formation of Lanthanum Hydroxide nano structures: Effect of NaOH and KOH solvents

    International Nuclear Information System (INIS)

    Mazloumi, M.; Zanganeh, S.; Kajbafvala, A.; Shayegh, M. R.; Sadrnezhaad, S. K.

    2008-01-01

    Lanthanum hydroxide (La(OH) 3 ) nano structures, including elliptical nanoparticles, octahedral rods and irregular nanoparticles were prepared chemically in NaOH and KOH solutions with 10 M concentration. The obtained powders were characterized with x-ray diffraction, scanning electron microscopy, transmission electron microscopy and differential thermal analysis. Crystallinities, morphologies and thermal behavior of the obtained nano structure powders were investigated under the influence of above mentioned solvents. The effect of chemical's temperature was also determined in one of the solvents (i.e. NaOH). The formation of growth in nano structure mechanism under the influence of alkali solutions (i.e., KOH and NaOH) have been discussed considerably in this paper

  1. Production of the Lax Ca1-x Cry Al1-y O3 compound through hydroxide precipitation

    International Nuclear Information System (INIS)

    Martins, L.C.; Machado, A.J.S.

    1996-01-01

    Purposing to reduce the cost of preparation of the lanthanum chromite doped with calcium and aluminum, it was made a study of the condition of hydroxide precipitation, using calcium, chromium and aluminum nitrates and lanthanum oxide, as precursors and as precipitate agent was used potassium hydroxide. In this study are showed results about the reaction kinetic, x-ray diffraction and yield as function of the pH. These results suggest a high yield for also elements studied. The phase of stoichiometry, La 0.8 Ca 0.2 Cr 0.75 Al 0.25 O 3 was obtained in low temperature. In fact, this process is viable to produce of lanthanum chromite doped with calcium and aluminum. (author)

  2. A meta-analysis of water quality and aquatic macrophyte responses in 18 lakes treated with lanthanum modified bentonite (Phoslock®)

    NARCIS (Netherlands)

    Spears, Bryan M.; Mackay, Eleanor B.; Yasseri, Said; Gunn, Iain D.M.; Waters, Kate E.; Andrews, Christopher; Cole, Stephanie; De Ville, Mitzi; Kelly, Andrea; Meis, Sebastian; Moore, Alanna L.; Nürnberg, Gertrud K.; van Oosterhout, Frank; Pitt, Jo-Anne; Madgwick, Genevieve; Woods, Helen J.; Lürling, Miquel

    2016-01-01

    Abstract Lanthanum (La) modified bentonite is being increasingly used as a geo-engineering tool for the control of phosphorus (P) release from lake bed sediments to overlying waters. However, little is known about its effectiveness in controlling P across a wide range of lake conditions or of its

  3. Lanthanum and cerium co-modified Ni/SiO2 catalyst for CO methanation from syngas

    Science.gov (United States)

    Gong, Dandan; Li, Shuangshuang; Guo, Shaoxia; Tang, Honggui; Wang, Hong; Liu, Yuan

    2018-03-01

    Sintering of active metal nanoparticles (NPs) and carbon deposition is critical problems for many metal catalysts, such as nickel based catalysts for generating methane from syngas. To improve the resistance to the sintering and carbon deposition, a new scheme was proposed in this work. Lanthanum and cerium co-modified Ni/SiO2 catalysts were synthesized by using perovskite type oxide of La1-xCexNiO3 loaded on SiO2 as the precursor. In a nanocrystallite of La1-xCexNiO3, ions of nickel, lanthanum and cerium are evenly mixed at atomic level and confined in the nanocrystallite, therefore, Ni NPs and the two promoters of La2O3 and CeO2 should be in close contact and highly dispersed on SiO2 after reduction. The catalysts were characterized by using XRD, TEM, BET, H2-TPD, XPS, TG and Raman techniques. Compared with the mono-promoted catalysts, the bi-promoted La0.75Ce0.25NiO3/SiO2 showed much better resistance to carbon deposition, higher resistance to sintering and higher activity for CO methanation, which are attributed to co-eliminating effect of the two promoters for the deposited carbon, confinement of the interacted two promoters for Ni NPs and the higher dispersion of Ni NPs derived from the smaller size of La0.75Ce0.25NiO3.

  4. Carbon doped lanthanum aluminate (LaAlO3:C) synthesized by solid state reaction for application in UV thermoluminescent dosimetry

    International Nuclear Information System (INIS)

    Alves, N.

    2015-01-01

    In this work we discuss the TL output for LaAlO 3 :C crystals grown by using three different combinations of Al 2 O 3 , La 2 O 3 and carbon atoms during the synthesis process. Recently, LaAlO 3 single crystals, co-doped with Ce 3+ and Dy 3+ rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO 3 synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce 3+ and Dy 3+ . It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO 3 by this solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO 3 crystallographic phase, however a small percentage (15%) of Al 2 O 3 has been also identified. The UV-Vis absorbance spectra were obtained and F and F + - center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

  5. Variation in band gap of lanthanum chromate by transition metals doping LaCr{sub 0.9}A{sub 0.1}O{sub 3} (A:Fe/Co/Ni)

    Energy Technology Data Exchange (ETDEWEB)

    Naseem, Swaleha, E-mail: wasiamu@gmail.com; Khan, Wasi, E-mail: wasiamu@gmail.com; Saad, A. A., E-mail: wasiamu@gmail.com; Shoeb, M., E-mail: wasiamu@gmail.com; Ahmed, Hilal, E-mail: wasiamu@gmail.com; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Technology, Aligarh Muslim University, Aligarh-202002 (India); Husain, Shahid [Department of Physics, Aligarh Muslim University, Aligarh-202002 (India)

    2014-04-24

    Transition metal (Fe, Co, Ni) doped lanthanum chromate (LaCrO{sub 3}) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 800°C. Microstructural studies were carried by XRD and SEM/EDS techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible and photoluminescence techniques. The energy band gap was calculated and the variation was observed with the doping of transition metal ions. Photoluminescence spectra show the emission peak maxima for the pure LaCrO{sub 3} at about 315 nm. Influence of Fe, Co, Ni doping was studied and compared with pure lanthanum chromate nanoparticles.

  6. Polarization of lanthanum nucleus by dynamic polarization method

    International Nuclear Information System (INIS)

    Adachi, Toshikazu; Ishimoto, Shigeru; Masuda, Yasuhiro; Morimoto, Kimio

    1989-01-01

    Preliminary studies have been carried out concerning the application of a dynamic polarization method to polarizing lanthanum fluoride single crystal to be employed as target in experiments with time reversal invariance. The present report briefly outlines the dynamic polarization method and describes some preliminary studies carried out so far. Dynamic polarization is of particular importance because no techniques are currently available that can produce highly polarized static nucleus. Spin interaction between electrons and protons (nuclei) plays a major role in the dynamic polarization method. In a thermal equilibrium state, electrons are polarized almost completely while most protons are not polarized. Positively polarized proton spin is produced by applying microwave to this system. The most hopeful candidate target material is single crystal of LaF 3 containing neodymium because the crystal is chemically stable and easy to handle. The spin direction is of great importance in experiments with time reversal invariance. The spin of neutrons in the target can be cancelled by adjusting the external magnetic field applied to a frozen polarized target. In a frozen spin state, the polarity decreases slowly with a relaxation time that depends on the external magnetic field and temperature. (N.K.)

  7. Production and processing of spinel semi-porous sintered blocks to CAD-CAM with lanthanum-glass infiltration for dental applications

    International Nuclear Information System (INIS)

    Lourenco, A.A.C.; Ogasawara, T.; Costa Neto, C.A.; Santos, F.V.C.

    2009-01-01

    The objective of this research was to obtain direct synthesis and sintering spinel by using powder mixing method for CAD-CAM ceramics manufacturing. Powders of alumina and magnesia (71.8 wt% Al2O3 and 28.2 wt% MgO) were mixed with 5 wt% of PVA and PEG binders and homogenized using ball mill (12h), then deagglomerated and submitted to uniaxial pressing into discs and plates (54 to 221.96 MPa), followed by isostatic pressing (186.03 MPa) and sintering at 1500 deg C(GrI) , 1600 C(GrII) and 1700 deg C(GrIII). Characterizations: XRD, density and four-point flexural strength and (for GrIII) elasticity modulus and Vickers microhardness. Lanthanum-glass was infiltrated into samples from all three Groups. Conclusions: (1) Plenty success for the pediatrician method; (2) Maximum density achieved for GrIII, best mechanical strength for GrII (compared to that of commercial product ), this last one being the most indicated for In-Ceram manufacturing via CAD-CAM route; (3) The flexural strength of GrI might be improved a lot after Lanthanum-glass infiltration. (author)

  8. Development of proton conducting materials and membranes based on lanthanum tungstate for hydrogen separation from gas mixtures

    International Nuclear Information System (INIS)

    Seeger, Janka

    2013-01-01

    Lanthanum tungstate La 6-x WO 12-δ (named LWO) is a ceramic material with mixed protonic electronic conductivity. Thereby it is a good candidate membrane material for hydrogen separation from synthesis gas in a fossil pre-combustion power plant. This work shows a material optimization by substitution targeted to clearly enhance the mixed conductivity and thereby the hydrogen flow through the LWO membrane. The first part of the work shows the synthesis and characterization of unsubstituted LWO. It points out that monophase LWO powder can be reproducibly synthesized. The La/W-ratio has to be considerably smaller than the nominal ratio of La/W = 6.0. It also depends on the used sintering conditions. Different relevant properties of LWO like stability in conditions close to application, thermal expansion, sintering behavior or microstructure were determined. Furthermore, the electrical conductivity of the material was investigated. LWO exhibits a prevailing protonic conductivity up to 750 C in wet atmospheres. Under dry atmospheres n-type conductivity was dominating. Oxygen ion and n-type conductivity dominated in wet and dry atmospheres above 750 C. The main part of the work is concerned with the development of new LWO based materials by substitutions. The aim is to achieve an improved mixed protonic electronic conductivity. Substitution elements for lanthanum side were Mg, Ca, Sr, Ba, Ce, Nd, Tb, Y and Al, while for the tungsten side Mo, Re and Ir were used. The total conductivity of the developed materials was investigated and compared to that of the unsubstituted LWO. The substitution of lanthanum led to no appreciable enhancement of the conductivity whereas the substitution of tungsten with 20 mol% molybdenum or 20 mol% rhenium clearly improved it. This caused a hydrogen flow about seven times higher for 20 mol% molybdenum- and about ten times higher for 20 mol% rhenium-substituted LWO in comparison with the unsubstituted LWO at 700 C. In the last part of the

  9. Polarization study on doped lanthanum gallate electrolyte using impedance spectroscopy

    Science.gov (United States)

    Gong, Wenquan; Gopalan, Srikanth; Pal, Uday B.

    2004-06-01

    Alternating current complex impedance spectroscopy studies were conducted on symmetrical cells of the type [gas, electrode/La1-x Sr x Ga1-y Mg y O3 (LSGM) electrolyte/electrode, gas]. The electrode materials were slurry-coated on both sides of the LSGM electrolyte support. The electrodes selected for this investigation are candidate materials for solid oxide fuel cell (SOFC) electrodes. Cathode materials include La1-x Sr x MnO3 (LSM), La1-x Sr x Co y Fe1-y O3 (LSCF), a two-phase particulate composite consisting of LSM and doped-lanthanum gallate (LSGM), and LSCF + LSGM. Pt metal electrodes were also used for the purpose of comparison. Anode material investigated was the Ni + Ce0.85Gd0.15O2 composite. The study revealed important details pertaining to the charge-transfer reactions that occur in such electrodes. The information obtained can be used to design electrodes for intermediate temperature SOFCs based on LSGM electrolytes.

  10. Molten salt synthesis of lead lanthanum zirconate titanate ceramic powders

    International Nuclear Information System (INIS)

    Cai Zongying; Xing Xianran; Li Lu; Xu Yeming

    2008-01-01

    Lead lanthanum zirconate titanate (Pb 0.95 La 0.03 )(Zr 0.52 Ti 0.48 )O 3 (PLZT) was synthesized by one step molten salt method with the starting materials of PbC 2 O 4 , La 2 O 3 , ZrO(NO 3 ) 2 .2H 2 O and TiO 2 in the NaCl-KCl eutectic mixtures in the temperature range of 700-1000 deg. C. The single phase of (Pb 0.95 La 0.03 )(Zr 0.52 Ti 0.48 )O 3 powders was prepared at a temperature as low as 850 deg. C for 5 h. The effects of process parameters, such as soaking temperature and time, salt species, and the amount of flux with respect to the starting materials were investigated. The growth process of the PLZT particles in the molten salt undergoes a transition from a diffusion controlled mechanism to an interfacial reaction controlled mechanism at 900 deg. C

  11. Microstructural development and characterization of lanthanum chromite-based ceramics to application in solid oxide fuel cells; Desenvolvimento microestrutural e caracterizacao de ceramicas a base de cromita de lantanio para aplicacao em celulas a combustivel de oxido solido

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, R.N.; Furtado, J.G. de M.; Soares, C.M.; Serra, E.T. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)], e-mail: rnunes@cepel.br

    2006-07-01

    This work has for objective to investigate and to characterize the microstructural development of lanthanum chromite-based ceramics (LaCrO{sub 3}) doped with earth alkaline metals, correlating the microstructural parameters (mainly the densification level) and processing parameters with the electrothermal properties reached. Lanthanum chromite-based ceramic systems doped with earth-alkaline metals (Ca, Mg and Sr) had been produced from respective metallic nitrates by solid state reactions process. The phase compositions were evaluated by X-ray diffraction and the densification level by Archimedes method. The microstructural characterization was effected by scanning electron microscopy, energy dispersive X-ray spectroscopy and thermal analysis techniques. Electrical tests were used to evaluate the electrical conductivity of the studied ceramics. The obtained results corroborate the literature comments concerning the difficulty of lanthanum chromite-based ceramics with high densification level and evidence the great influence of the nature of the dopants on the sintering mechanism and the microstructural and electric characteristics of the produced ceramics. The best ones results, in terms of densification and electrical conductivity, had been gotten through multiple doping with calcium and strontium, and in sintering temperature conditions lower that the normally considered to pure or monodoped lanthanum chromite-based ceramics. (author)

  12. Linear Optical Properties of Zinc Borotellurite Glass Doped with Lanthanum Oxide Nanoparticles for Optoelectronic and Photonic Application

    Directory of Open Access Journals (Sweden)

    Faznny Mohd Fudzi

    2017-01-01

    Full Text Available Enhancing the optical properties of glasses for the sake of optical application in various fields is an ongoing challenge in materials science and technology. Thus, the optical properties of zinc borotellurite glass doped with lanthanum oxide nanoparticles (La2O3 NPs with the chemical composition of {[(TeO20.7(B2O30.3]0.7(ZnO0.3}1−x (La2O3 NPsx, where x = 0.01, 0.02, 0.03, 0.04, and 0.05 molar fraction, have been investigated. Characterization techniques such as x-ray diffraction, Fourier Transform Infrared Spectroscopy, and Ultraviolet-Visible Spectroscopy are employed to yield the structural properties and optical parameter of the glass. The amorphous nature of the fabricated glasses is confirmed with the presence of a broad hump via XRD diffraction pattern. The decreasing amount of high polarizable nonbridging oxygen as the concentration of La2O3 NPs increases has contributed to the increasing trend of energy band gap in the range of 2.70 to 3.52 eV and decreasing value of refractive index between 2.34 and 2.48. The fabricated glasses that have a higher refractive index than the widely used fiber material, pure silica glass, indicate that zinc borotellurite glass doped with lanthanum nanoparticles is a promising material to be applied as optical fibers.

  13. Bio-accumulation of lanthanum from lanthanum modified bentonite treatments in lake restoration.

    Science.gov (United States)

    Waajen, G; van Oosterhout, F; Lürling, M

    2017-11-01

    Lanthanum (La) modified bentonite (LMB) is one of the available mitigating agents used for the reduction of the phosphorus (P) recycling in eutrophic lakes. The potential toxicity of the La from LMB to aquatic organisms is a matter of concern. In this study the accumulation of La was investigated in the macrophyte Elodea nuttallii, in chironomid larvae and in several fish species during periods up to five years following in situ LMB applications. The application of LMB increased the La concentration of exposed plants and animals. During the first growing season following LMB applications, the La content of E. nuttallii increased 78 fold (3.98-310.68 μg La g -1 DW) to 127 fold (2.46-311.44 μg La g -1 ). During the second growing season following application, the La content decreased but was still raised compared to plants that had not been exposed. The La content of chironomids was doubled in the two years following LMB application, although the increase was not significant. Raised La concentrations in fish liver, bone, muscle and skin were observed two and five years following to LMB application. Liver tissues showed the highest La increase, ranging from 6 fold (0.046-0.285 μg La g -1 DW) to ∼20 fold (0.080-1.886 μg La g -1 , and 0.122-2.109 μg La g -1 ) two years following application and from 6 fold (0.046-0.262 μg La g -1 ) to 13 fold (0.013-0.167 μg La g -1 ) after five years in pelagic and littoral fish. The La content of the liver from Anguilla anguilla (eel) had increased 94 fold (0.034-3.176 μg La g -1 ) two years and 133 fold (0.034-4.538 μg La g -1 ) five years following LMB application. No acute and chronic effects of La accumulation were observed and human health risks are considered negligible. We advocate the long-term study of effects of La accumulation following future LMB applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Rare earths: preparation of spectro chemically pure standards, study of their carbonates and synthesis of a new compound series - the peroxy carbonates

    International Nuclear Information System (INIS)

    Queiroz, Carlos Alberto da Silva

    1996-05-01

    In this work the following studies are concerned: I) preparation of lanthanum, cerium, praseodymium, neodymium and samarium oxides for use as spectro chemically pure standards; II) behavior of the rare earth (La, Ce, Pr, Nd, Sm) carbonates soluble in ammonium carbonate and mixture of ammonium carbonate/ammonium hydroxide, and III) synthesis and characterization of rare earth peroxy carbonates - a new series of compounds. Data for the synthesis and characterization of the rare earths peroxy carbonates described for the first time in this work are presented and discussed. With the aid of thermal analysis (TG-DTG) the thermal stability and the stoichiometric composition for new compounds were established and a mechanism of thermal decomposition was proposed. The peroxy carbonate was prepared by the addition of hydrogen peroxyde to the complexed soluble rare earths carbonates. These studies included also the determinations of active oxygen, the total rare earth oxide by gravimetry and complexometry and the C, H and N contents by microanalysis. The new compounds were also investigated by infrared spectroscopy. (author)

  15. Lanthanum(III) and praseodymium(III) complexes with bidentate and tetradentate Schiff base ligands containing indole ring

    International Nuclear Information System (INIS)

    Rai, Anita; Sengupta, Soumitra Kumar; Pandey, Om Prakash

    2000-01-01

    Complexes of lanthanum(III) and praseodymium(III) with Schiff bases, prepared from isatin with aniline, 4-chloroaniline, 2- bromoaniline, 2-nitroaniline (Hl), ethylenediamine, o- phenylenediamine and 4-methyl-o-phenylenediamine (H 2 L') have been synthesised and their physico-chemical properties investigated using elemental analysis, molar conductivities, magnetic susceptibility measurements and spectral (visible, infrared and 1 H NMR) data. The Schiff bases HL bind in a bidentate manner while schiff bases H 2 L' bind in a tetradentate manner. The probable structures of the complexes are proposed. (author)

  16. Phytotoxic Effects of Lanthanum Oxide Nanoparticles on Maize (Zea mays L.)

    Science.gov (United States)

    Liu, Yinglin; Xu, Lina; Dai, Yanhui

    2018-02-01

    The use of lanthanum oxide nanoparticles (La2O3 NPs) in life products have increased dramatically in the past decades, which are inevitable released into natural environment. In this study, we determined the phytotoxicity of La2O3 NPs to maize (Zea mays L.) grown in one-fourth strength Hoagland solution. After being exposed for two weeks, the biomass, roots length and the relative chlorophyll content were measured. La2O3 NPs had phytotoxicity to maize at 5 mg/L. La2O3 NPs decreased shoot biomass (≥10 mg/L), the root biomass and length (≥5 mg/L). Moreover, La2O3 NPs had adverse effects on the chlorophyll content (≥10 mg/L). The decreased chlorophyll content may reduce net photosynthetic rate. This research offers vital information about the phytotoxicity of La2O3 NPs.

  17. Carbon doped lanthanum aluminate (LaAlO3:C) UV thermoluminescent properties synthesized by solid state reaction with three different mixing methodologies

    International Nuclear Information System (INIS)

    Alves, N.

    2017-01-01

    In this work we discuss the thermoluminescent (TL) response for LaAlO 3 :C crystals grown by using three different combinations of Al 2 O 3 , La 2 O 3 and carbon atoms during the synthesis process. Recently, LaAlO 3 single crystals, co-doped with Ce 3+ and Dy 3+ rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO 3 synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce 3+ and Dy 3+ . It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO 3 by the solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO 3 crystallographic phase, however a small percentage (15%) of Al 2 O 3 has been also identified. The UV-Vis absorbance spectra were obtained and F and F + - center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

  18. Ductility of Mo–12Si–8.5B alloys doped with lanthanum oxide by the liquid–liquid doping method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenhu [School of Materials Science & Engineering, Xi’an University of Technology, Xi’an 710048 (China); School of Materials Science & Engineering, Shaanxi University of Technology, Hanzhong 723000 (China); Zhang, Guojun, E-mail: zhangguojun@xaut.edu.cn [School of Materials Science & Engineering, Xi’an University of Technology, Xi’an 710048 (China); Wang, Shixiong [School of Materials Science & Engineering, Xi’an University of Technology, Xi’an 710048 (China); Li, Bin; Sun, Jun [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China)

    2015-09-05

    Highlights: • Alloys doping lanthanum oxide by L–L doped method were prepared by hot pressing. • The compression strength of alloys are superior. • The fracture toughness of alloys is improved by L–L doped method. - Abstract: Mo–12Si–8.5B (Mo–Si–B) alloys doped with different mass fractions (0.3 wt%, 0.6 wt%, and 0.9 wt%) of lanthanum oxide (La{sub 2}O{sub 3}) were prepared by liquid–liquid (L–L) doping, mechanical alloying and hot pressing sintering techniques. The observation of the microstructures of the Mo–Si–B alloys reveals that the grain sizes of the alloys were refined with the increase in La{sub 2}O{sub 3} doping. The fracture toughness values of the alloys of over 10 MPa m{sup 1/2} reveal that the addition of La{sub 2}O{sub 3} via the L–L doping method can obviously improve the alloy fracture toughness compared to the alloys doped with La{sub 2}O{sub 3} via the solid–solid (S–S) doping method. In addition, compression tests indicate that the compression strength of the alloys was improved compared to Mo–12Si–8.5B alloys.

  19. Molecular dynamics study of the coordination sphere of trivalent lanthanum in a highly concentrated LiCl aqueous solution: A combined classical and ab initio approach

    International Nuclear Information System (INIS)

    Vuilleumier, R.; Petit, L.; Maldivi, P.; Adamo, C.

    2008-01-01

    The first coordination sphere of trivalent lanthanum in a highly concentrated (14 M) lithium chloride solution is studied with a combination of classical molecular dynamics and density functional theory based first principle molecular dynamics. This method enables us to obtain a solvation shell of La 3+ containing 2 chloride ions and 6 water molecules. After refinement using first principle molecular dynamics, the resulting cation-water and cation-anion distances are in very good agreement with experiment. The 2 Cl - and the 6 water molecules arrange in a square anti-prism around La 3+ . Exchange of water molecules was also observed in the first-principle simulation, with an intermediate structure comprising 7 water molecules stable for 2.5 ps. Finally, evaluation of dipole moments using maximally localized Wannier functions shows a substantial polarization of the chloride anions and the water molecules in the first solvation shell of trivalent lanthanum. (authors)

  20. Selective dehydration of bio-ethanol to ethylene catalyzed by lanthanum-phosphorous-modified HZSM-5: influence of the fusel.

    Science.gov (United States)

    Hu, Yaochi; Zhan, Nina; Dou, Chang; Huang, He; Han, Yuwang; Yu, Dinghua; Hu, Yi

    2010-11-01

    Bio-ethanol dehydration to ethylene is an attractive alternative to oil-based ethylene. The influence of fusel, main byproducts in the fermentation process of bio-ethanol production, on the bio-ethanol dehydration should not be ignored. We studied the catalytic dehydration of bio-ethanol to ethylene over parent and modified HZSM-5 at 250°C, with weight hourly space velocity (WHSV) equal to 2.0/h. The influences of a series of fusel, such as isopropanol, isobutanol and isopentanol, on the ethanol dehydration over the catalysts were investigated. The 0.5%La-2%PHZSM-5 catalyst exhibited higher ethanol conversion (100%), ethylene selectivity (99%), and especially enhanced stability (more than 70 h) than the parent and other modified HZSM-5. We demonstrated that the introduction of lanthanum and phosphorous to HZSM-5 could weaken the negative influence of fusel on the formation of ethylene. The physicochemical properties of the catalysts were characterized by ammonia temperature-programmed desorption (NH(3)-TPD), nitrogen adsorption and thermogravimetry (TG)/differential thermogravimetry (DTG)/differential thermal analysis (DTA) (TG/DTG/DTA) techniques. The results indicated that the introduction of lanthanum and phosphorous to HZSM-5 could inhibit the formation of coking during the ethanol dehydration to ethylene in the presence of fusel. The development of an efficient catalyst is one of the key technologies for the industrialization of bio-ethylene.

  1. Estimation of cerium and lanthanum content in core material of high intensity carbon arc electrodes by x-ray fluorescence method

    International Nuclear Information System (INIS)

    Nagpal, K.C.; Bhavalkar, R.H.

    1977-01-01

    The X-ray fluorescence method has been used to determine the weight percentages of cerium and lanthanum in the core material of high intensity carbon arc electrodes from the calibration curves plotted between the weight percentages of these elements and the peak-intensity ratios of CeLsub(α1), and LaLsub(α1) peaks to the neighbouring peak SnLsub(α1) due to an internal standard element. (author)

  2. Influence of crystal phases on electro-optic properties of epitaxially grown lanthanum-modified lead zirconate titanate films

    Science.gov (United States)

    Masuda, Shin; Seki, Atsushi; Masuda, Yoichiro

    2010-02-01

    We describe here how we have improved the crystal qualities and controlled the crystal phase of the lanthanum-modified lead zirconate titanate (PLZT) film without changing the composition ratio using an oxygen-pressure crystallization process. A PLZT film deposited on a SrTiO3 substrate with the largest electro-optic (EO) coefficient of 498 pm/V has been achieved by controlling the crystal phase of the film. Additionally, a fatigue-free lead zirconate titanate (PZT) capacitor with platinum electrodes has been realized by reducing the oxygen vacancies in the films.

  3. Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

    Science.gov (United States)

    Fan, E. S. C.; Kesler, O.

    2015-08-01

    Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

  4. Effects of lanthanum and acid rain stress on the bio-sequestration of lanthanum in phytoliths in germinated rice seeds

    Science.gov (United States)

    Si, Yong; Wang, Lihong; Huang, Xiaohua

    2018-01-01

    REEs in the environment can be absorbed by plants and sequestered by plant phytoliths. Acid rain can directly or indirectly affect plant physiological functions. Currently, the effects of REEs and acid rain on phytolith-REEs complex in plants are not yet fully understood. In this study, a high-silicon accumulation crop, rice (Oryza sativa L.), was selected as a representative of plants, and orthogonal experiments were conducted under various levels of lanthanum [La(III)] and pH. The results showed that various La(III) concentrations could significantly improve the efficiency and sequestration of phytolith La(III) in germinated rice seeds. A pH of 4.5 promoted phytolith La(III) sequestration, while a pH of 3.5 inhibited sequestration. Compared with the single treatment with La(III), the combination of La(III) and acid rain inhibited the efficiency and sequestration of phytolith La(III). Correlation analysis showed that the efficiency of phytolith La(III) sequestration had no correlation with the production of phytolith but was closely correlated with the sequestration of phytolith La(III) and the physiological changes of germinated rice seeds. Phytolith morphology was an important factor affecting phytolith La(III) sequestration in germinated rice seeds, and the effect of tubes on sequestration was more significant than that of dumbbells. This study demonstrated that the formation of the phytolith and La(III) complex could be affected by exogenous La(III) and acid rain in germinated rice seeds. PMID:29763463

  5. Energy transfer driven tunable emission of Tb/Eu co-doped lanthanum molybdate nanophosphors

    Science.gov (United States)

    Thomas, Kukku; Alexander, Dinu; Sisira, S.; Gopi, Subash; Biju, P. R.; Unnikrishnan, N. V.; Joseph, Cyriac

    2018-06-01

    Tb3+/Eu3+ co-doped lanthanum molybdate nanophosphors were synthesized by conventional co-precipitation method. The Powder X-ray diffractogram revealed the formation of highly crystalline tetragonal nanocrystals with space group I41/a and the detailed analysis of the small variation of lattice parameters with Tb/Eu co-doping on the host lattice were carried out based on the ionic radii of the dopants. The FTIR spectra is employed to identify the fundamental vibrational modes in La2-x-y (MoO4)3:xTb, yEu nanocrystals. The formation of nanocrystals by oriented attachment was recognized from the HR TEM images and the d-spacing calculated was in accordance with that corresponding to highest intensity diffraction peak in the XRD patterns. The constituent elements present in the samples were identified with the aid of EDAX and elemental mapping analysis. The broad Mo6+- O2- CTB and the sharp excitation peaks of Tb and Eu identified from the UV-Vis absorption spectra facilitates the suitability of exciting the phosphors effectively over NUV and visible region of the spectra. The possibility of energy transfer from host to Tb3+/Eu3+ ions and from Tb3+ to Eu3+ ions were confirmed from the PL excitation spectra monitoring 5D0→7F2 transition of Eu3+ ions around 615 nm. The correlated analysis of PL emission spectra, life time measurements and CIE diagram, upon different excitation channels elucidate the excellent luminescent properties of La2-x-y (MoO4)3:xTb, yEu nanophosphors with tunable emission colours in a wide range varying from yellow green region to reddish orange region and the efficient energy transfer from Tb3+ to Eu3+ ions in lanthanum molybdate host lattice. The Tb→Eu energy transfer efficiency and probability were calculated from the decay measurements and the values were found to be satisfactory for exploiting the prepared nanophosphors for the development of multifunctional luminescent nanophosphors.

  6. Lanthanum hexaboride as advanced structural refiner/getter in TiAl-based refractory intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Kartavykh, A.V., E-mail: karta@korolev-net.ru [Technological Institute for Superhard and Novel Carbon Materials (TISNCM), 7a Centralnaya str., 142190 Troitsk, Moscow (Russian Federation); National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation); Asnis, E.A.; Piskun, N.V.; Statkevich, I.I. [The E.O. Paton Electric Welding Institute, 11 Bozhenko str., 03680 Kyiv (Ukraine); Gorshenkov, M.V.; Tcherdyntsev, V.V. [National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation)

    2014-03-05

    Highlights: • Fist application of LaB{sub 6} additive in TiAl-based intermetallics casting. • Pilot synthesis/casting and study of selected TiAl(Nb,Cr,Zr)B,La alloys set. • Dual effect observed: phase structure refinement and oxygen impurity removal. • Co-precipitation of TiB and La{sub 2}O{sub 3} in melt: 2LaB{sub 6} + 12Ti + 3O → 12TiB↓ + La{sub 2}O{sub 3}↓. • Features of structure refinement and oxygen gettering mechanisms reported. -- Abstract: The work is aimed at the study of the formation and refinement of microstructure appearing in the solidifying refractory TiAl-based intermetallics being inoculated with precise boron addition. The novelty of research consists in test application of lanthanum hexaboride (LaB{sub 6}) ligature within semi-continuous electron beam casting process of selected alloys. Two ingots with nominal compositions Ti–44Al–5Nb–2Cr–1.5Zr–0.4B–0.07La and Ti–44Al–5Nb–1Cr–1.5Zr–1B–0.17La (at.%) have been synthesized and cast along with the reference alloy Ti–44Al–5Nb–3Cr–1.5Zr. Their comparative examination suggests (i) essential microstructural phase refinement effect coupled with (ii) threefold/fourfold decrease of background content of undesirable residual oxygen impurity in both alloys containing LaB{sub 6}. This advanced dual activity (i–ii) of LaB{sub 6} is explained by its complete dissolution, dissociation and following re-precipitation of effective Ti-based monoboride nucleants of orthorhombic B27 structure, those being accompanied by strong internal gettering of dissolved oxygen from the melt and from boride-inoculated solid α{sub 2}-Ti{sub 3}Al phase with liberated elemental lanthanum. The phase composition and structure of cast alloys; state and characterization of newly precipitated TiB boride; features of La{sub 2}O{sub 3} micro/nano-dimensional precipitation and oxygen gettering mechanism are reported and discussed.

  7. Structural stability of the smectite-doped lanthanum under high pressures and high temperatures

    International Nuclear Information System (INIS)

    Stefani, Vicente Fiorini

    2012-01-01

    Smectites are phyllosilicates that have a tetrahedron: octahedron structure ratio of 2:1, with high cation exchange capacity (CEC) in the interlayers. For these and other features, smectites have been used in many parts of the world as secondary barriers with the goal of containing a possible leak of radioactive elements in final disposal facilities for radioactive waste through cation exchange. Our aim in this work is to reach the cation exchange in calcium montmorillonite (smectite dioctahedral) by lanthanum to simulate trivalent radionuclides and to study the stability of this structure under high pressure and high temperature. To achieve high pressure it was used two different technique: DAC (Diamond Anvil Cell), achieving pressures up to 12GPa at room temperature and hydraulic press with a toroidal chamber profile to achieve pressures up to 7,7GPa and temperatures up to 900 degree C. The heating is achieved simultaneously by an electric system coupled in the hydraulic press. The outcomes show that the smectite structure doped with lanthanum remains stable under 12GPa at room temperature and 2.5GPa at 200 degree C. However, above 300 degree C at 2.5GPa the structure becomes a new phase of muscovite-like, rich of La, where it loses its interlayer water and turns out to be irreversible. Furthermore, it is important to point out that the higher temperature the better ordered is the structure and it is still stable under 7.7GPa and 900 degree C. Moreover, after all experiments the structure continues being dioctahedral. The new phase of muscovite-like, rich of La, in contact with a calcium solution remains partially unchanged, whereas the other part returns to the original structure (montmorillonite-Ca). The following analyses were performed: X-ray diffraction (XRD) for evaluating the spatial structure; Fourier transform infrared spectroscopy (FTIR) for getting information about the vibrational modes; scanning electron microscopy with dispersive Xray spectroscopy

  8. Carbon doped lanthanum aluminate (LaAlO{sub 3}:C) UV thermoluminescent properties synthesized by solid state reaction with three different mixing methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Alves, N., E-mail: neire.radiologia@yahoo.com.br, E-mail: farialo@cdtn.br [Universidade Federal do Estado de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Ferraz, W.B.; Faria, L.O., E-mail: ferrazw@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-07-01

    In this work we discuss the thermoluminescent (TL) response for LaAlO{sub 3}:C crystals grown by using three different combinations of Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and carbon atoms during the synthesis process. Recently, LaAlO{sub 3} single crystals, co-doped with Ce{sup 3+} and Dy{sup 3+} rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO{sub 3} synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce{sup 3+} and Dy{sup 3+}. It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO{sub 3} by the solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO{sub 3} crystallographic phase, however a small percentage (15%) of Al{sub 2}O{sub 3} has been also identified. The UV-Vis absorbance spectra were obtained and F and F{sup +}- center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

  9. The production of grain oriented lanthanum titanate (La2Ti2O7) ceramics by uniaxial hot-forging process for improved fracture toughness

    International Nuclear Information System (INIS)

    Ceylan, Ali

    2008-01-01

    The layered-structural ceramics, such as lanthanum titanate (La 2 Ti 2 O 7 ), have been known for their good electrical and optical properties at high frequencies and temperatures. However, few studies have been conducted on the mechanical properties of these ceramics. The interest in ceramic hot-forging (HF) has been greatly increased recently due to the enhancement in fracture toughness via bridging effect of oriented grains. In this study, grain oriented lanthanum titanate was produced by the hot-forging process. The characterizations of the samples were achieved by density measurement, scanning electron microscopy (SEM), optical microscopy, X-ray diffraction (XRD), Vickers indentation and three-point bending test. According to X-ray diffraction patterns, the orientation factor (f) was found to be 0.73 for certain hot-forging conditions resulting an improved fracture toughness. The improved fracture toughness of La 2 Ti 2 O 7 (3.2 MPa m 1/2 ) reached to the value of monolithic alumina (Al 2 O 3 ) between 3 and 4 MPa m 1/2

  10. Red, green, and blue lanthanum phosphate phosphors obtained via surfactant-controlled hydrothermal synthesis

    International Nuclear Information System (INIS)

    Sousa Filho, Paulo C. de; Serra, Osvaldo A.

    2009-01-01

    A new solution route for the obtainment of highly pure luminescent rare-earth orthophosphates in hydrothermal conditions was developed. By starting from soluble precursors (lanthanide tripolyphosphato complexes, i.e. with P 3 O 10 5- as a complexing agent and as an orthophosphate source) and by applying surfactants in a water/toluene medium, the precipitations are confined to reverse micelle structures, thus yielding nanosized and homogeneous orthophosphates. The method was employed to obtain lanthanide-activated lanthanum phosphates, which can be applied as red (LaPO 4 :Eu 3+ ), green (LaPO 4 :Ce 3+ ,Tb 3+ ) and blue (LaPO 4 :Tm 3+ ) phosphors. The produced materials were analyzed by powder X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and luminescence spectroscopy (emission, excitation, lifetimes and chromaticity coordinates).

  11. Fabrication of large-volume, low-cost ceramic lanthanum halide scintillators for gamma ray detection : final report for DHS/DNDO/TRDD project TA-01-SL01.

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, Timothy J.; Ottley, Leigh Anna M.; Yang, Pin; Chen, Ching-Fong; Sanchez, Margaret R.; Bell, Nelson Simmons

    2008-10-01

    This project uses advanced ceramic processes to fabricate large, optical-quality, polycrystalline lanthanum halide scintillators to replace small single crystals produced by the conventional Bridgman growth method. The new approach not only removes the size constraint imposed by the growth method, but also offers the potential advantages of both reducing manufacturing cost and increasing production rate. The project goal is to fabricate dense lanthanum halide ceramics with a preferred crystal orientation by applying texture engineering and solid-state conversion to reduce the thermal mechanical stress in the ceramic and minimize scintillation light scattering at grain boundaries. Ultimately, this method could deliver the sought-after high sensitivity and <3% energy resolution at 662 keV of lanthanum halide scintillators and unleash their full potential for advanced gamma ray detection, enabling rapid identification of radioactive materials in a variety of practical applications. This report documents processing details from powder synthesis, seed particle growth, to final densification and texture development of cerium doped lanthanum bromide (LaBr{sub 3}:Ce{sup +3}) ceramics. This investigation demonstrated that: (1) A rapid, flexible, cost efficient synthesis method of anhydrous lanthanum halides and their solid solutions was developed. Several batches of ultrafine LaBr{sub 3}:Ce{sup +3} powder, free of oxyhalide, were produced by a rigorously controlled process. (2) Micron size ({approx} 5 {micro}m), platelet shape LaBr{sub 3} seed particles of high purity can be synthesized by a vapor phase transport process. (3) High aspect-ratio seed particles can be effectively aligned in the shear direction in the ceramic matrix, using a rotational shear-forming process. (4) Small size, highly translucent LaBr{sub 3} (0.25-inch diameter, 0.08-inch thick) samples were successfully fabricated by the equal channel angular consolidation process. (5) Large size, high density

  12. Radiation defects in some oxide compounds

    International Nuclear Information System (INIS)

    Kaczmarek, S.M.

    1999-01-01

    Yttrium aluminium garnets, yttrium aluminium perovskite, strontium and barium lanthanum and gadolinium gallates, lithium niobate and tantalate as-grown crystals and doped by diffusion with rare-earth (Nd, Dy, Er, Tm, Ho, Pr, Ce, Eu) and ions of the first transition series (Mn, Cr, Cu, Fe) were investigated optically and using electron spin resonance method before and after gamma, electron and proton irradiation. (author)

  13. Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Li Shuai; Li Zhicheng; Bergman, Bill

    2010-01-01

    The composite of doped lanthanum gallate (La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 , LSGM) and doped ceria (Ce 0.8 Sm 0.2 O 1.9 , CSO) was investigated as an electrolyte for solid oxide fuel cell (SOFC). The LSGM-CSO composite was examined by X-ray diffraction (XRD) and impedance spectroscopy. It was found that the sintered LSGM-CSO composite contains mainly fluorite CeO 2 phase and a minority impurity phase, Sm 3 Ga 5 O 12 . The LSGM-CSO composite electrolyte shows a small grain boundary response in the impedance spectroscopy as compared to LSGM and CSO pellets. The composite electrolyte exhibits the highest conductivity in the temperature range of 250-600 o C, compared to LSGM and CSO. The LSGM-CSO composite can be expected to be an attractive intermediate temperature electrolyte material for solid oxide fuel cells.

  14. Volatile mixed-ligand lanthanum (3) complex with acetylacetone and 1,10-phenanthroline

    International Nuclear Information System (INIS)

    Kuz'mina, N.P.; Chuparov, N.V.; Pisarevskij, A.P.; Martynenko, L.I.

    1997-01-01

    La(Acac) 3 Phen complex is synthetized, its X-tray structure analysis is carried out. Crystals are monoclinic ones, sp.gr. P2 1 /n, a=17.11 (12), b=18.16 (3), c=17.86 (2) A, β=91.32 (2) deg, V=5548 (13) A 3 , Z=8. Structure contains two crystallographically non-equivalent types of molecules differing in interatomic distances and valent angles, as well as, in angles between ligand planes. Behaviour of La(Acac) 3 Phen at heating in vacuum (0.1-0.01 mm Hg) is studied. It is shown that under those conditions processes of Phen splitting, of sublimation and polymerization of La(Acac) 3 lanthanum acetylacetonate formed following Phen splitting and that under 220 deg C during 30 min quantitative transition of La(Acac) 3 Phen into gas phase is reached. 10 refs., 2 figs., 3 tabs

  15. The electrochemical behaviour study of La3+ ion in fused chlorides bath. The LaNi5 formation

    International Nuclear Information System (INIS)

    Dias, Cristiane

    2002-01-01

    The electrochemical behaviour of La 3+ ion was studied in fused chlorides bath, with purpose to obtain LaNi 5 formation parameters. The lanthanum reduction/reoxidation mechanism and intermetallic compound formation were investigated by cyclic voltammetry, chronopotentiommetry and galvanostatic electrodeposition. The electrolyte employed was eutectic mixture NaCl-KCl (1:1) with anhydrous LaCl 3 as solute, since 0,25 mol. L -1 up to 2 mol. L -1 , between 700 deg C and 800 deg C. The anhydrous LaCl 3 was prepared by lanthanum chloride slow dehydration with HCl flow and heating until 300 deg C. Over molybdenum, results depicted that lanthanum electrochemical behaviour was quasi-reversible and electrodeposition occurred in a charge transfer step with three electrons. In nickel, intermetallic compound formation was observed by interdiffusion. The scanning electronic microscopy (SEM-EDS) and X ray diffraction analysis indicated that layers composition depend on temperature and solute concentration in fused bath. Mainly LaNi 5 intermetallic compound was formed with LaCl 3 anhydrous concentration of 2 mol. L -1 at 750 deg C, with cathodic current density until 100 mA.cm -2 . (author)

  16. The electrochemical behaviour study of La{sup 3+} ion in fused chlorides bath. The LaNi{sub 5} formation; Estudo do comportamento eletroquimico do ion La{sup 3+} em meio a cloretos fundidos. A formacao de LaNi{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Cristiane

    2002-07-01

    The electrochemical behaviour of La{sup 3+} ion was studied in fused chlorides bath, with purpose to obtain LaNi{sub 5} formation parameters. The lanthanum reduction/reoxidation mechanism and intermetallic compound formation were investigated by cyclic voltammetry, chronopotentiommetry and galvanostatic electrodeposition. The electrolyte employed was eutectic mixture NaCl-KCl (1:1) with anhydrous LaCl{sub 3} as solute, since 0,25 mol. L{sup -1} up to 2 mol. L{sup -1}, between 700 deg C and 800 deg C. The anhydrous LaCl{sub 3} was prepared by lanthanum chloride slow dehydration with HCl flow and heating until 300 deg C. Over molybdenum, results depicted that lanthanum electrochemical behaviour was quasi-reversible and electrodeposition occurred in a charge transfer step with three electrons. In nickel, intermetallic compound formation was observed by interdiffusion. The scanning electronic microscopy (SEM-EDS) and X ray diffraction analysis indicated that layers composition depend on temperature and solute concentration in fused bath. Mainly LaNi{sub 5} intermetallic compound was formed with LaCl{sub 3} anhydrous concentration of 2 mol. L{sup -1} at 750 deg C, with cathodic current density until 100 mA.cm{sup -2}. (author)

  17. Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio

    International Nuclear Information System (INIS)

    Kojo, Gen; Shono, Yohei; Ushiyama, Hiroshi; Oshima, Yoshito; Otomo, Junichiro

    2017-01-01

    The proton-conducting properties of lanthanum tungstates (LWOs) with high La/W ratios were investigated using electrochemical measurements and quantum chemical calculations. Single phases of LWOs with high La/W ratios (6.3≤La/W≤6.7) were synthesized by high-temperature sintering at around 1700 °C. The electrical conductivity of LWO increased with increasing La/W ratio in the single-phase region. The LWO synthesized at the optimum sintering temperature and time, and with the optimum La/W ratio gave the maximum conductivity, i.e., 2.7×10 −3 S cm −1 with La/W=6.7 at 500 °C. Density functional theory calculations, using the nudged elastic band method, were performed to investigate the proton diffusion barrier. The results suggest that the proton diffusion paths around La sites have the lowest proton diffusion barrier. These findings improve our understanding of LWO synthesis and the proton-conducting mechanism and provide a strategy for improving proton conduction in LWOs. - Graphical abstract: The LWOs with high La/W ratios were synthesized for the first time. The optimum La/W ratio gave the maximum conductivity with La/W=6.7 at 500 °C. The proton diffusion paths were also considered with density functional theory calculations. - Highlights: • The proton-conducting properties of lanthanum tungstates (LWOs) were investigated. • Single phase LWOs with high La/W ratios (6.3≤La/W≤6.7) were synthesized successfully. • LWOs with the high La/W ratios showed high proton conductivity. • The DFT calculation suggested the lowest proton diffusion barrier in the path around La sites.

  18. Structural, microstructural and transport properties study of lanthanum lithium titanium perovskite thin films grown by Pulsed Laser Deposition

    International Nuclear Information System (INIS)

    Maqueda, O.; Sauvage, F.; Laffont, L.; Martinez-Sarrion, M.L.; Mestres, L.; Baudrin, E.

    2008-01-01

    Lanthanum lithium titanate thin films were grown by Pulsed Laser Deposition. La 0.57 Li 0.29 TiO 3 dense films with smooth surfaces were obtained after optimization of the growth parameters. Such films deposited at 700 deg. C under 15 Pa are nano-crystalline with domains corresponding to the cubic and tetragonal modifications of this phase. In relation to the measured conductivities/activation energy and to previous works, we clearly underlined that the films of practical interest, prepared at relatively low temperature, are predominantly formed from the tetragonal ordered phase

  19. An in-vacuum diffractometer for resonant elastic soft x-ray scattering

    Czech Academy of Sciences Publication Activity Database

    Hawthorn, D.G.; He, F.; Venema, L.; Davis, H.; Achkar, A.J.; Zhang, J.; Sutarto, R.; Wadati, H.; Radi, A.; Wilson, T.; Wright, G.; Shen, K.M.; Geck, J.; Zhang, H.; Novák, Vít; Sawatzky, G.A.

    2011-01-01

    Roč. 82, č. 7 (2011), 073104/1-073104/8 ISSN 0034-6748 Institutional research plan: CEZ:AV0Z10100521 Keywords : gallium arsenide * lanthanum compounds * manganese compounds * neodymium * reflectivity * semiconductor thin films * strontium compounds * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.367, year: 2011

  20. Influence of lanthanum distribution on dielectric and ferroelectric properties of BaBi4-xLaxTi4O15 ceramics

    International Nuclear Information System (INIS)

    Khokhar, Anita; Goyal, Parveen K.; Thakur, O.P.; Shukla, A.K.; Sreenivas, K.

    2015-01-01

    Structural and electrical properties of Lanthanum substituted barium bismuth titanate BaBi 4-x La x Ti 4 O 15 (0 ≤ x ≤ 0.50) ceramics prepared by conventional solid-state reaction method have been investigated. Raman spectra reveals the distribution of lanthanum into the perovskite layers and (Bi 2 O 2 ) 2+ layers of BaBi 4 Ti 4 O 15 ceramics. Room temperature dielectric constant (ε′) increases and considerable reduction in the low frequency (10 −2 to 10 Hz) dielectric losses and in dc conductivity (σ dc ) are seen with lanthanum substitution. A critical La content of x ∼0.20 in BaBi 4-x La x Ti 4 O 15 exhibits a well-defined relaxor behavior as seen from the temperature and frequency dependence of the dielectric parameters ε′(T) and ε″(T). The dielectric data fit well to the modified Curie–Weiss law and the Lorentz-type relation and show increasing diffuseness in the phase transition with increasing La content. The temperature dependence of the characteristic relaxation time obtained from the Cole–Cole model shows a good fit to the non-linear Vogel–Fulcher relation. Improvements in the remnant polarization and a stable piezoelectric charge coefficient are seen up to a La content of x ∼0.20. The observed increase in dielectric loss and σ dc in addition to the diminished ferroelectric/piezoelectric properties for higher La content are explained in terms of changing oxygen vacancy concentration and structural relaxation due to the preferential incorporation of La into the (Bi 2 O 2 ) 2+ layers as evidenced through the Raman spectroscopy. - Highlights: • La distribution in BaBi 4-x La x Ti 4 O 15 ceramics is analyzed through Raman spectroscopy. • Low and a nearly constant loss over wide frequency range (10 −2 –10 7  Hz) obtained. • Critical La content x = 0.2 identified for high resistivity and ideal relaxor characteristics. • Improved P-E hysteresis loops and large remnant polarization measured. • Changes in the

  1. The influence of lake water alkalinity and humic substances on particle dispersion and lanthanum desorption from a lanthanum modified bentonite.

    Science.gov (United States)

    Reitzel, Kasper; Balslev, Kristiane Astrid; Jensen, Henning S

    2017-11-15

    A 12 days laboratory study on potential desorption of Lanthanum (La) from a commercial La modified clay (Phoslock) was conducted using lake water from 17 Danish lakes with alkalinities between 0.02 and 3.7 meq L -1 and varying concentrations of DOC and humic acids (HA's). A similar study was conducted in artificial lake water with alkalinities from 0 to 2.5 meq L -1 in order to exclude interference from dissolved HA's. To test if La in solution (FLa) was associated with fine particles, the water samples were filtered sequentially through three filter sizes (1.2 μm, 0.45 μm and 0.2 μm), and finally, ultracentrifugation was used in an attempt to separate colloidal La from dissolved La. The study showed that higher FLa (up to 2.5 mg L -1 or 14% of the total La in the Phoslock) concentrations were found in soft water lakes compared to hard water lakes, probably due to dispersion of the clay at low alkalinities. In addition, this study showed that HA's seem to increase the FLa concentrations in soft water lakes, most likely through complexation of La retained in the Phoslock matrix. In summary, we conclude that elevated La concentrations in lake water after a Phoslock treatment should only be expected in soft water lakes rich in DOC and HA's. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Memory phenomenon in a lanthanum based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ye [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Huang, Wei Min, E-mail: mwmhuang@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Zhao, Yong [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Ding, Zhen [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Li, Yan [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Tor, Shu Beng; Liu, Erjia [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    2016-07-05

    In this paper, we experimentally investigate two memory phenomena in a lanthanum based bulk metallic glass (BMG). While the temperature memory effect (TME) is not found by differential scanning calorimeter (DSC) test, shape recovery is observed in samples indented at both low and high temperatures. In terms of shape memory related characteristics, this BMG shares some features of shape memory alloys (SMAs) due to its metal nature, and some other features of shape memory polymers (SMPs) owing to its glassy–rubbery transition. The formation of protrusion in the polished sample after heating to super-cooled liquid region (SCLR) indicates that surface tension is not a necessarily positive contributor for shape recovery. Release of internal elastic stress is concluded as the major player. Although the amorphous nature of BMGs enables for storing appreciable amount of internal elastic stress upon deformation, without the presence of cross-linker as in typical SMPs, the shape recovery in BMGs is rather limited. - Highlights: • Experimental investigation of shape recovery in BMG. • Surface tension is not the major reason for shape recovery in BMG. • Release of internal stress is the major contributor for shape recovery. • Comparison of shape memory features of BMG with other shape memory materials.

  3. Memory phenomenon in a lanthanum based bulk metallic glass

    International Nuclear Information System (INIS)

    Zhou, Ye; Huang, Wei Min; Zhao, Yong; Ding, Zhen; Li, Yan; Tor, Shu Beng; Liu, Erjia

    2016-01-01

    In this paper, we experimentally investigate two memory phenomena in a lanthanum based bulk metallic glass (BMG). While the temperature memory effect (TME) is not found by differential scanning calorimeter (DSC) test, shape recovery is observed in samples indented at both low and high temperatures. In terms of shape memory related characteristics, this BMG shares some features of shape memory alloys (SMAs) due to its metal nature, and some other features of shape memory polymers (SMPs) owing to its glassy–rubbery transition. The formation of protrusion in the polished sample after heating to super-cooled liquid region (SCLR) indicates that surface tension is not a necessarily positive contributor for shape recovery. Release of internal elastic stress is concluded as the major player. Although the amorphous nature of BMGs enables for storing appreciable amount of internal elastic stress upon deformation, without the presence of cross-linker as in typical SMPs, the shape recovery in BMGs is rather limited. - Highlights: • Experimental investigation of shape recovery in BMG. • Surface tension is not the major reason for shape recovery in BMG. • Release of internal stress is the major contributor for shape recovery. • Comparison of shape memory features of BMG with other shape memory materials.

  4. Europium-Doped Lanthanum Hafnate Nanoparticles: Structure, Photoluminescence, and Radioluminescence

    Science.gov (United States)

    Wahid, Kareem; Pokhrel, Madhab; Mao, Yuanbing

    Due to their novel physical properties, nanostructured phosphors are of interest for radiation-based imaging and therapeutics. Herein, the structural and luminescent properties of europium-doped lanthanum hafnate (La2Hf2O7:xmol%Eu3+, x = 0 - 35) nanoparticles are investigated for use as scintillators. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy confirm samples prepared through a combined co-precipitation and low-temperature molten salt synthetic process homogenously form spherical nanocrystals of 36 nm in the ordered pyrochlore phase. Ultraviolet and X-ray excitation of these samples induce strong red emissions in the 580 - 590 and 612 - 630 nm range corresponding to the 5D0->7 F1 magnetic dipole and 5D0->7 F2 electric dipole transitions of Eu3+. Optical response and quantum yield are optimized at 5% Eu3+; a proposed trade-off between quenching mechanisms (defect-states/cross-relaxation) and dopant concentration is discussed. Owing to their high density, large effective atomic number, and bright luminescence, these La2Hf2O7:xmol%Eu3+ nanoparticles warrant further investigation for scintillator applications. The authors thank the support from the Defense Threat Reduction Agency of the U.S. Department of Defense (award #HDTRA1- 10-1-0114).

  5. Rare Earth Doped Lanthanum Calcium Borate Polycrystalline Red Phosphors

    Directory of Open Access Journals (Sweden)

    H. H. Xiong

    2014-01-01

    Full Text Available Single-phased Sm3+ doped lanthanum calcium borate (SmxLa2−xCaB10O19, SLCB, x=0.06 polycrystalline red phosphor was prepared by solid-state reaction method. The phosphor has two main excitation peaks located at 398.5 nm and 469.0 nm, which are nicely in accordance with the emitting wavelengths of commercial near-UV and blue light emitting diode chips. Under the excitation of 398.0 nm, the dominant red emission of Sm3+ in SLCB phosphor is centered at 598.0 nm corresponding to the transition of 4G5/2 → 6H7/2. The Eu3+ fluorescence in the red spectral region is applied as a spectroscopic probe to reveal the local site symmetry in the host lattice and, hence, Judd-Ofelt parameters Ωt  (t=2, 4 of Eu3+ in the phosphor matrix are derived to be 3.62×10-20 and 1.97×10-20 cm2, indicating a high asymmetrical and strong covalent environment around rare earth luminescence centers. Herein, the red phosphors are promising good candidates employed in white light emitting diodes (LEDs illumination.

  6. Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Li Shuai, E-mail: shuail@kth.s [Department of Materials Science and Engineering, School of Industrial Engineering and Management, Royal Institute of Technology, SE 10044 Stockholm (Sweden); Li Zhicheng [School of Materials Science and Engineering, Central South University, 410083 Changsha, Hunan (China); Bergman, Bill [Department of Materials Science and Engineering, School of Industrial Engineering and Management, Royal Institute of Technology, SE 10044 Stockholm (Sweden)

    2010-03-04

    The composite of doped lanthanum gallate (La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85}, LSGM) and doped ceria (Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9}, CSO) was investigated as an electrolyte for solid oxide fuel cell (SOFC). The LSGM-CSO composite was examined by X-ray diffraction (XRD) and impedance spectroscopy. It was found that the sintered LSGM-CSO composite contains mainly fluorite CeO{sub 2} phase and a minority impurity phase, Sm{sub 3}Ga{sub 5}O{sub 12}. The LSGM-CSO composite electrolyte shows a small grain boundary response in the impedance spectroscopy as compared to LSGM and CSO pellets. The composite electrolyte exhibits the highest conductivity in the temperature range of 250-600 {sup o}C, compared to LSGM and CSO. The LSGM-CSO composite can be expected to be an attractive intermediate temperature electrolyte material for solid oxide fuel cells.

  7. Gelcasting of strontium doped lanthanum manganite for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    Abdul Haleem, B.; Bhuvana, R.; Udayakumar, A.

    2009-01-01

    Solid oxide fuel cells (SOFCs) are devices that offer high efficiency power output with negligible emissions. Cathode supported tubular SOFCs consist of porous cathode tubes made up of strontium doped lanthanum manganite, La 1-x Sr x MnO 3 (LSM) that work as functional component as well as structural support for the rest of the cell components. Gelcasting is one of the most suitable methods for the fabrication of porous ceramics. This paper describes the fabrication of porous LSM cathode by gelcasting process. Gelcasting parameters such as monomer concentration, powder volume fraction, pH of the slurry, etc were optimized. Slow drying of green specimens minimized warpage and cracking. Sintered specimens with controlled porosity were obtained by the use of suitable pore-forming agents. The coefficient of thermal expansion (CTE) of sintered specimens was measured, which was found matching with the CTE values of cell components reported in the literature. These results have shown the suitability of the gelcast generated LSM cathodes for SOFC applications. (author)

  8. Suppression of cavitation in melted tungsten by doping with lanthanum oxide

    International Nuclear Information System (INIS)

    Yuan, Y.; Lu, G.H.; Xu, B.; Fu, B.Q.; Xu, H.Y.; Li, C.; Jia, Y.Z.; Qu, S.L.; Liu, W.; Greuner, H.; Böswirth, B.; Luo, G.-N.

    2014-01-01

    Melting and boiling behaviour of pure tungsten and 1 wt% lanthanum-oxide-doped tungsten (WL10) are investigated, focusing on the material selection with respect to material loss induced by cavitation. Melting experiments under high heat loads are carried out in the high heat flux facility GLADIS. Pulsed hydrogen neutral beams with heat flux of 10 and 23 MW m −2 are applied onto the adiabatically loaded samples for intense surface melting. Melt layer of the two tungsten grades exhibit different microstructure characteristics. Substantive voids owing to cavitation in the liquid phase are observed in pure W and lead to porous resolidified material. However, little cavitation bubbles can be found in the dense resolidified layer of WL10. In order to find out the gaseous sources, vapour collection is performed and the components are subsequently detected. Based on the observations and analyses, the microstructure evolutions corresponding to melting and vapourization behaviour of the two tungsten grades are tentatively described, and furthermore, the underlying mechanisms of cavitation in pure W and its suppression in WL10 are discussed. (paper)

  9. Assignment of 4f-5d absorption bands in Ce-doped RAlO.sub.3./sub. (R=La, Gd, Y, Lu) perovskites

    Czech Academy of Sciences Publication Activity Database

    Mihóková, Eva; Nikl, Martin; Bacci, M.; Dušek, Michal; Petříček, Václav

    2009-01-01

    Roč. 79, č. 19 (2009), 1951309/1-1951309/7 ISSN 1098-0121 R&D Projects: GA MŠk ME 903; GA AV ČR IAA100100810 Institutional research plan: CEZ:AV0Z10100521 Keywords : cerium * EHT calculations * gadolinium compounds * lanthanum compounds * lutetium compounds * ultraviolet spectra * yttrium compounds Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  10. Structural phase transition in lanthanum gallate as studied by Raman and X-ray diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dhak, P.; Pramanik, P. [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Bhattacharya, S.; Roy, Anushree [Department of Physics, Indian Institute of Technology, Kharagpur 721302 (India); Achary, S.N.; Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2011-08-15

    Lanthanum gallate (LaGaO{sub 3}) is known to undergo orthorhombic to rhombohedral first order phase transition at 150 C. In this article we have shown that by introducing 2% La deficiency in the system, coexistence of above two phases can be obtained at lower temperature and a complete phase transition occurs at 200 C. The evolution of structural parameters of the system with temperature is reported from X-ray diffraction measurements and Rietveld analysis of the diffraction patterns. The change in local octahedral distortion due to 2% La deficiency is revealed through the shift in the phonon modes of GaO{sub 6} octahedra, in both orthorhombic and rhombohedral phase. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Thermal decomposition behavior of the co-precipitated carbonate precursor for La0.84Sr0.16MnO3

    International Nuclear Information System (INIS)

    Sankaranarayanan, A.; Kalekar, B.B.; Ramanathan, S.

    2004-01-01

    A carbonate precursor for lanthanum strontium manganite powder (La 0.84 Sr 0.16 MnO 3 - LSM) was obtained by addition of an aqueous solution of nitrates of lanthanum, strontium and manganese into a bath of ammonium carbonate solution. The precipitate was filtered, washed, dried and dry ground for homogenization. The thermal decomposition behavior of the precursor was studied by simultaneous TG-DTA-EGA technique while the precursor and intermediates formed at different temperatures were characterized by FTIR and XRD techniques for decomposition of carbonate and compound formation. It exhibited a loss in weight and endotherms in stages in the temperature ranges of 20 to 260 deg C, 260 deg to 500 deg C, 500 deg to 600 deg C, 600 deg to 900 deg C. The loss of carbon dioxide was exhibited in the EGA data and FTIR spectra while phase formation was confirmed by XRD. A comparative study of all these results showed that the processes occurring at various temperature ranges (20 deg to 260 deg C, 260 deg to 500 deg C, 500 deg to 600 deg C, 600 deg to 900 deg C) are dehydration of adsorbed moisture and water of crystallization, decomposition of manganese hydroxycarbonate to manganese dioxide, lanthanum carbonate to lanthanum oxy-carbonate and interaction between lanthanum oxy-carbonate, manganese dioxide and strontium carbonate to form finally LSM. Even though decomposition of carbonates into oxides was complete at 900 deg C, phase pure compound formation occurred at 1100 deg C, under the conditions used. (author)

  12. Cerium doped lanthanum halides: fast scintillators for medical imaging

    International Nuclear Information System (INIS)

    Selles, O.

    2006-12-01

    This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl 3 :Ce 3+ and LaBr 3 :Ce 3+ ).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce 3+ ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

  13. Spectrophotometric determination of neodymium in mixture with lanthanum by eosin and 2,2'-dipyridyl

    International Nuclear Information System (INIS)

    Ovchar, L.A.; Poluehktov, N.S.

    1980-01-01

    The possibility of using rare earth complexes with eosin (EO) and 2.2-dipyridyl (DP) for spectrophotometric determination of some rare earths in the presence of the others. It has been out that the complexes are not extracted by organic solvents. The PH region of complex existence (approximately 6) and the relation of components in them (rare earths:DP:EO=1:2:3) are determined. The possibility has been shown of determining all the rare earts from praseodymium to lutetium and yttrium in a binary mixture with lanthanum based on different stability of the studied complexes. The method has been tested on the example of determining Nd 2 O 3 in a mixture with La 2 O 3 . The low limit of determined contents is 1-2%. The relative standard deviation is 0.035-0.17 [ru

  14. Data for effects of lanthanum complex on the thermo-oxidative aging of natural rubber

    Directory of Open Access Journals (Sweden)

    Wei Zheng

    2015-12-01

    Full Text Available Novel mixed antioxidants composed of antioxidant IPPD and lanthanum (La complex were added as a filler to form natural rubber (NR composites. By mechanical testing, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR and thermogravimetric analysis (TGA, a string of data, including the mechanical properties, the variation of internal groups and the thermal and thermo-oxidative decompositions of NR, was presented in this data article. The data accompanying its research article [1] studied the thermo-oxidative aging properties of NR in detail. The density function theoretical (DFT calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR. The data revealed that this new rare-earth antioxidant could indeed enhance the thermo-oxidative aging resistance of NR, which is associated with its different function mechanism from that of the pure antioxidant IPPD.

  15. Data for effects of lanthanum complex on the thermo-oxidative aging of natural rubber.

    Science.gov (United States)

    Zheng, Wei; Liu, Li; Zhao, Xiuying; He, Jingwei; Wang, Ao; Chan, Tung W; Wu, Sizhu

    2015-12-01

    Novel mixed antioxidants composed of antioxidant IPPD and lanthanum (La) complex were added as a filler to form natural rubber (NR) composites. By mechanical testing, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and thermogravimetric analysis (TGA), a string of data, including the mechanical properties, the variation of internal groups and the thermal and thermo-oxidative decompositions of NR, was presented in this data article. The data accompanying its research article [1] studied the thermo-oxidative aging properties of NR in detail. The density function theoretical (DFT) calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR. The data revealed that this new rare-earth antioxidant could indeed enhance the thermo-oxidative aging resistance of NR, which is associated with its different function mechanism from that of the pure antioxidant IPPD.

  16. Data for effects of lanthanum complex on the thermo-oxidative aging of natural rubber

    Science.gov (United States)

    Zheng, Wei; Liu, Li; Zhao, Xiuying; He, Jingwei; Wang, Ao; Chan, Tung W.; Wu, Sizhu

    2015-01-01

    Novel mixed antioxidants composed of antioxidant IPPD and lanthanum (La) complex were added as a filler to form natural rubber (NR) composites. By mechanical testing, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and thermogravimetric analysis (TGA), a string of data, including the mechanical properties, the variation of internal groups and the thermal and thermo-oxidative decompositions of NR, was presented in this data article. The data accompanying its research article [1] studied the thermo-oxidative aging properties of NR in detail. The density function theoretical (DFT) calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR. The data revealed that this new rare-earth antioxidant could indeed enhance the thermo-oxidative aging resistance of NR, which is associated with its different function mechanism from that of the pure antioxidant IPPD. PMID:26693513

  17. Enhanced corrosion resistance of A3xx.x/SiCp composites in chloride media by La surface treatments

    International Nuclear Information System (INIS)

    Pardo, A.; Merino, M.C.; Arrabal, R.; Feliu, S.; Viejo, F.; Carboneras, M.

    2006-01-01

    The influence of silicon carbide particles (SiCp) proportion and matrix composition of aluminium metal matrix composites (A3xx.x/SiCp) modified by lanthanum-based conversion or electrolysis coating was evaluated in 3.5 wt% NaCl aerated solution. The intermetallic compounds were preferentially covered by lanthanum-based conversion coatings obtained by immersion in 50 deg. C solution of La(III) salt, and the intermetallic compounds, SiCp and aluminium matrix were covered by lanthanum electrolysis treatment. The corrosion process was studied on the basis of gravimetric tests and electrochemical impedance spectroscopy (EIS) during immersion in 3.5 wt% NaCl aerated solution. The composition of both La coating and corrosion products was analyzed before and after accelerated testing, by scanning electron microscopy (SEM), atomic force microscopy (AFM), low-angle X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to determine the influence of surface microstructural changes on corrosion behaviour during exposure to the corrosive environment. The corrosion process was more influenced by the concentration of alloy elements in the matrix than by the proportion of SiCp reinforcement. Both lanthanum treated surfaces presented better behaviour to chloride solution corrosion than original composite surfaces without treatment; however, electrolysis afforded a higher degree of protection than the conversion treatment because the coating was more extensive

  18. Spectroscopic properties of Sm{sup 3+}-doped lanthanum borogermanate glass

    Energy Technology Data Exchange (ETDEWEB)

    Rajaramakrishna, R. [Department of Physics, Bangalore University, Bangalore 560056 (India); Knorr, Brian; Dierolf, Volkmar [Department of Physics, Lehigh University Bethlehem, PA 18015 (United States); Anavekar, R.V., E-mail: anavekar_271@yahoo.co.in [Department of Physics, Bangalore University, Bangalore 560056 (India); Jain, H. [Department of Materials Science and Engineering, Lehigh University Bethlehem, PA 18015 (United States)

    2014-12-15

    Ultraviolet–visible–near infrared (UV–vis–NIR) absorption and photoluminescence of (25−x) La{sub 2}O{sub 3}–25B{sub 2}O{sub 3}–50GeO{sub 2} glass series have been studied with different concentrations (x=0.1–1.0 wt%) of Sm{sub 2}O{sub 3} as an optically active dopant. The values of Judd–Ofelt (JO) parameters (Ω{sub t}) follow the trend Ω{sub 2}>Ω{sub 4}>Ω{sub 6}. Visible emission and decay times from the {sup 4}G{sub 5/2} level and its relative quantum efficiencies are measured. Intense reddish-orange emission corresponding to {sup 4}G{sub 5/2}→{sup 6}H{sub 7/2} transition has been observed in these glasses under 488 nm excitation. A decrease in the quantum yield is observed with increasing Sm{sup 3+} ion concentration beyond 1% doping level. - Highlights: • Lanthanum boro-germanate glasses doped with samarium ions are good laser host matrix. • These glasses show large emission cross-sections (σ{sub P}) values. • These glasses show large gain bandwidth and optical gain parameters. • These glasses are suitable candidate for reddish-orange laser applications.

  19. A multi-scale study of the adsorption of lanthanum on the (110) surface of tungsten

    International Nuclear Information System (INIS)

    Samin, Adib J.; Zhang, Jinsuo

    2016-01-01

    In this study, we utilize a multi-scale approach to studying lanthanum adsorption on the (110) plane of tungsten. The energy of the system is described from density functional theory calculations within the framework of the cluster expansion method. It is found that including two-body figures up to the sixth nearest neighbor yielded a reasonable agreement with density functional theory calculations as evidenced by the reported cross validation score. The results indicate that the interaction between the adsorbate atoms in the adlayer is important and cannot be ignored. The parameterized cluster expansion expression is used in a lattice gas Monte Carlo simulation in the grand canonical ensemble at 773 K and the adsorption isotherm is recorded. Implications of the obtained results for the pyroprocessing application are discussed.

  20. A multi-scale study of the adsorption of lanthanum on the (110) surface of tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Samin, Adib J.; Zhang, Jinsuo [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201W 19th Avenue, Columbus, Ohio 43210 (United States)

    2016-07-28

    In this study, we utilize a multi-scale approach to studying lanthanum adsorption on the (110) plane of tungsten. The energy of the system is described from density functional theory calculations within the framework of the cluster expansion method. It is found that including two-body figures up to the sixth nearest neighbor yielded a reasonable agreement with density functional theory calculations as evidenced by the reported cross validation score. The results indicate that the interaction between the adsorbate atoms in the adlayer is important and cannot be ignored. The parameterized cluster expansion expression is used in a lattice gas Monte Carlo simulation in the grand canonical ensemble at 773 K and the adsorption isotherm is recorded. Implications of the obtained results for the pyroprocessing application are discussed.

  1. Back bombardment for dispenser and lanthanum hexaboride cathodes

    Directory of Open Access Journals (Sweden)

    Mahmoud Bakr

    2011-06-01

    Full Text Available The back bombardment (BB effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC and lanthanum hexaboride (LaB_{6} thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6  μs duration, the DC cathode experiences a large change in the temperature compared with LaB_{6}, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

  2. Rare earth impurities in high purity lanthanum oxide determined by neutron activation analysis

    International Nuclear Information System (INIS)

    Nguyen Van Suc; Desai, H.B.; Parthasarathy, R.; Gangadharan, S.

    1992-01-01

    Individual rare earth impurities in high purity La 2 O 3 (≥99.9%) have been determined by NAA after pre-separation of the matrix (La). The separation is carried out on an anion exchanger (Dowex 1x8) using different mixtures of methanol/nitric acid as eluants. The rare earth elements from Dy to Lu are eluted quantitatively using a 10% 1M HNO 3 - 90% methanol mixture, while the light rare earths from Ce to Gd are eluted quantitatively using a 10% 0.05M HNO 3 - 90% methanol mixture. La, which is retained on the column, is eluted using 0.1M HNO 3 . The recoveries of the various rare earth elements have been checked using radiotracers and also by spiking the sample with known amount of elements, and the recoveries are found to be quantitative. Results obtained on a typical high purity lanthanum oxide are reported here. (author) 5 refs.; 1 fig

  3. Synthesis and luminescence studies of novel rare earth activated lanthanum pentaborate

    International Nuclear Information System (INIS)

    Nagpure, P.A.; Bajaj, N.S.; Omanwar, S.K.; Sonekar, R.P.

    2011-01-01

    The lanthanum pentaborate (LaB 5 O 9 ) is a novel material which exhibits excellent luminescence when doped with rare earth ions. It was prepared by a novel technique which is a slight variation of solution combustion synthesis. The synthesis is based on the exothermic reaction between the fuel (urea) and oxidizer (ammonium nitrate). The structure of the prepared material was confirmed by powder XRD technique. The photoluminescence of rare earth ions (Ce 3+ , Eu 3+ ) and sensitized luminescence of Gd 3+ (Pr 3+ -Gd 3+ and Bi 3+ -Gd 3+ ) in LaB 5 O 9 have been studied. LaB 5 O 9 :Ce 3+ shows broad band UV emission at 317 nm and LaB 5 O 9 :Eu 3+ shows orange red emission. LaB 5 O 9 : Pr 3+ -Gd 3+ and LaB 5 O 9 : Bi 3+ -Gd 3+ exhibit efficient luminescence of Gd 3+ in narrow UVB region at 310 nm. The material (La 0.5 Pr 0.4 )B 5 O 9 :Gd 0.1 exhibits intense narrow band UVB emission at 310 nm and could be a potential candidate for UVB phosphors used in phototherapy lamps. (author)

  4. RM1 Semiempirical Quantum Chemistry: Parameters for Trivalent Lanthanum, Cerium and Praseodymium.

    Directory of Open Access Journals (Sweden)

    José Diogo L Dutra

    Full Text Available The RM1 model for the lanthanides is parameterized for complexes of the trications of lanthanum, cerium, and praseodymium. The semiempirical quantum chemical model core stands for the [Xe]4fn electronic configuration, with n =0,1,2 for La(III, Ce(III, and Pr(III, respectively. In addition, the valence shell is described by three electrons in a set of 5d, 6s, and 6p orbitals. Results indicate that the present model is more accurate than the previous sparkle models, although these are still very good methods provided the ligands only possess oxygen or nitrogen atoms directly coordinated to the lanthanide ion. For all other different types of coordination, the present RM1 model for the lanthanides is much superior and must definitely be used. Overall, the accuracy of the model is of the order of 0.07Å for La(III and Pr(III, and 0.08Å for Ce(III for lanthanide-ligand atom distances which lie mostly around the 2.3Å to 2.6Å interval, implying an error around 3% only.

  5. Effect of the melting conditions on the properties of radiation color centers in lanthanum phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Karapetyan, G.O.; Rusan, V.V.; Yashchurzhinskaya, O.A.

    1986-01-01

    The authors investigate the spatial effects of ionizing radiation on the radiation processes in phosphate glasses to make a comparative estimate of the radiation yield from the radiation color centers (RCC) of different types. A study is made of their behavior under thermal decoloration. The results of a comparison of the integrated intensities of the ESR signal from trapping centers are given. The ESR spectrum of the glasses are presented--one differs slightly from the others. On the basis of the result of processing the ESR and optical spectra of gamma-irradiated lanthanum phosphate glasses synthesized under various conditions, the radiation yield of the RCC and the behavior of the intensity of their absorption under thermodecoloration are significantly affected by the conditions of synthesis of the glass.

  6. Tm3+ activated lanthanum phosphate: a blue PDP phosphor

    International Nuclear Information System (INIS)

    Rao, R.P.

    2005-01-01

    Plasma display panels (PDPs) are gaining attention due to their high performance and scalability as a medium for large format TVs. The performance and life of a PDP strongly depends upon the nature of phosphors. Currently, Eu 2+ activated barium magnesium aluminate (BAM) is being used as a blue component. Because of its low life, efforts are being made to explore new blue emitting phosphors. One of the alternatives to BAM is Tm 3+ activated lanthanum phosphate (LPTM) phosphor. LPTM phosphor samples are prepared by a solid-state as well as sol-gel process in presence of flux. The phosphor of the present investigation, having uniform and spherical shape particles in the range of 0.1-2 μm, is appropriate for thin phosphor screens required for PDP applications. It exhibits a narrow band emission in the blue region, peaking at 452 nm and also a number of narrow bands in the UV region when excited by 147 and 173 nm radiation from a xenon gas mixture. Various possible transitions responsible for UV and visible emission from Tm 3+ ion are presented. These phosphors also exhibit good color saturation and better stability when excited with VUV radiation. To achieve higher brightness, they are blended with other UV excited blue emitting phosphors such as BAM. Results related to morphology, excitation, after glow decay, emission and degradation of these phosphors in the powder form as well as in plasma display panels are presented and discussed

  7. Kinetics and thermodynamic for sorption of arsenate by Lanthanum-exchanged zeolite

    International Nuclear Information System (INIS)

    Mohd Jelas Haron; Saiful Adli Masdan; Mohd Zobir Hussein; Zulkarnain Zainal; Anuar Kassim

    2007-01-01

    Zeolites are crystalline, hydrated aluminosilicate containing exchangeable alkaline and alkaline earth cations in their structural frameworks. Since zeolites have permanent negative charges on their surfaces, they have no affinity for anions. However recent studies have shown that modification of zeolites with certain surfactants or metal cations yield sorbents with a strong affinity for many anions. In this paper, modification of zeolites (zeolite A, X and ZSM5) were performed by exchange of naturally occurring cations with lanthanum ion that forms low solubility arsenate salt. The exchanged zeolites were used to sorb arsenate from aqueous solution. Among parameters investigated were effect of pH, arsenate initial concentrations, contact time and temperature. The maximum exchanged capacity of La (III) ion was obtained when using solution with initial pH of 4. Zeolite X gives the highest La (III) exchanged capacity compared to other zeolites. The results showed that As (V) sorption by La-zeolites occurred at about pH 6.5 and increased as pH increased and reaching maximum at equilibrium pH about 7.8. On the other hand, almost no arsenate sorption occurred on un exchanged zeolites. This indicates that La (III) ion on the exchanged zeolites is taking part on the As(V) sorption via surface precipitation. The results also showed that the sorption capacities increased with increasing initial As (V) concentrations. The sorption followed Langmuir model with maximum sorption capacities of 0.41, 0.21 and 0.19 mmol/g at 25 degree Celsius for La exchanged zeolite X (La-ZX), La exchanged zeolite ZSM5 (La-ZSM) and La exchanged zeolite A (La-ZA), respectively. The amounts of sorption of As (V) by La exchanged zeolite increased as temperature increased from 25 to 70 degree Celsius indicating that the process is endothermic. The free energy changes ( ΔG degree) for the sorption at 25 degree Celsius were -10.25, -9.65 and -8.49 kJ/ mol for La-ZX, La-ZSM and La-ZA, respectively. The

  8. Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate; Aproveitamento de itrio e lantanio de um carbonato de terras raras de baixo teor em cerio, de um carbonato de itrio e de um oxido de terras itricas

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Mari Estela de

    2006-07-01

    In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

  9. Investigation of thermal transformation of lanthanum and neodymium hydroxides by IK-spectroscopy

    International Nuclear Information System (INIS)

    Filippova, A.A.; Davydov, A.A.; Shchekochikhin, Yu.M.

    1976-01-01

    The spectral polymorphic transformations of lanthanum and neodymium oxides at the thermal decomposition of the hydroxides and carbonates of these elements are studied. The thermal decomposition was observed during 3-5 hours. The i.r. spectra of the decomposition products were measured for temperatures of 100-1000 0 C. The i.r. spectra of C-Nd 2 O 3 , of A-Nd 2 O 3 , of C-La 2 O 3 and of A-La 2 O 3 were obtained in the range of 250-4000cm -1 . The spectral consequences of the C→A-Nd 2 O 3 polymorphic transformation were also studied for the decomposition of the neodymium carbonate. The spectra of the calcination products of the hydroxides (400-700 0 C) are similar to characteristic spectra of cubic rare earth oxides in the spectral range of 250-700cm -1 . An increase of the calcination temperature (800-1000 0 C) leads to changes in the oxide spectrum. New maxima appear at 260, 360 and 450cm -1 . The absorption bands characteristic for cubic oxide lattices disappear. From spectral data it can be concluded that neodymium carbonate begins to decompose at 450 0 C if it is heated in vacuum. The decomposition products are oxycarbonate and oxide. The maximum at 520cm -1 confirms the crystallization of the oxide in the cubic C-form. At 800 0 C the polymorphic transformation C→A-Nd 2 O 3 sets in. In the oxide spectra traces of the carbonate can still be detected up to the polymorphic transformation temperature. From a comparison of X-ray and spectral data it is followed that the i.r. spectra of the decomposition product of the lanthanum hydroxide at 500 0 C are essentially the spectra of C-La 2 O 3 which are characterized by the absorption bands at 320, 340, 380 and 495cm -1 . The absorption band of A-La 2 O 3 , which is present in the sample, is not observed. I.r. spectra of C-La 2 O 3 are very similar to the spectra of the cubic form of rare earth oxides in the range of 250-600cm -1 . Changes in the spectrum at 600 0 C can be explained by the polymorphic transformation

  10. Spark plasma sintering of hydrothermally derived ultrafine Ca doped lanthanum chromite powders

    Directory of Open Access Journals (Sweden)

    Rendón-Angeles, J. C.

    2006-08-01

    Full Text Available Lanthanum chromite nano-particles, with a composition of La0.9Ca0.1CrO3 and La0.8Ca0.2CrO3, were produced by 1 h of hydrothermal reaction at 400 and 425°C respectively. The sintering of the powders was conducted using a spark plasma apparatus over the temperature range 1300-1550ºC for 1 min with a constant loading pressure of 45 MPa. Additional sintering experiments using conventional firing were carried out for comparison. Fully densified (98 % r.d. lanthanum chromite pellets with fine equiaxial grains 2.3 μm in size were obtained using the SPS (spark plasma sintering method. In contrast, a maximum relative density of 97 % was produced using La0.8Ca0.2CrO3 sintered conventionally at 1400ºC for 300 min, and the average grain size of the resulting sintered sample was 6 μm.

    Partículas ultrafinas de cromita de lantano, con una composición de La0.9Ca0.1CrO3 y La0.8Ca0.2CrO3, se obtuvieron después de 1 hora de síntesis hidrotermal a las temperaturas de 400 y 425°C respectivamente. Los compuestos obtenidos, con un tamaño de partícula de ~ 200 nm, se caracterizaron utilizando las técnicas de DRX, MEB y MET. La sinterización de estos polvos se efectuó en un equipo de chispa de plasma en el rango de temperatura de 1300-1500°C durante 1 min, y a una presión de compactación de 45 MPa. Ambos polvos también se sinterizaron siguiendo un tratamiento térmico convencional, en aire, con el propósito de comparar ambos métodos de sinterización. Las muestras de cromita de lantano sinterizadas por plasma presentaban una densidad relativa del 98 % (/t; y una microestructura monofásica con granos equaxiales con un tamaño medio de grano menor de 2.3 μm. En contraste, la composición La0.8Ca0.2CrO3, sinterizada a 1400°C/300 min, por métodos convencionales alcanzó una densidad relativa máxima del 97 % y su microestructura estaba formada por una sola fase con un tamaño medio de grano de 6 μm.

  11. Spectroscopic properties of Er/Nd co-doped yttrium lanthanum oxide transparent ceramics pumped at 980 nm

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yingjie; Yang, Qiuhong, E-mail: yangqiuhong@shu.edu.cn; Gui, Yan; Yuan, Ye; Lu, Qing

    2016-05-15

    (Er{sub 0.01}Nd{sub x}Y{sub 0.89-x}La{sub 0.1}){sub 2}O{sub 3} (x = 0, 0.001, 0.002, 0.005, 0.01) transparent ceramics were prepared by conventional ceramic processing. The Nd{sup 3+} content dependencies of mid-infrared, near infrared and up-conversion emission of Er{sup 3+} pumped at 980 nm were fully presented. Mechanism of energy transfer between Er{sup 3+} and Nd{sup 3+} was also demonstrated. The results showed that co-doping 0.1 at% Nd{sup 3+} into 1 at% Er{sup 3+} doped yttrium lanthanum oxide transparent ceramic enhanced the 2.7 μm emission significantly and meanwhile suppressed the 1.5 μm emission effectively which indicated an improvement in population inversion between Er:{sup 4}I{sub 11/2} and Er:{sup 4}I{sub 13/2}. Moreover, green up-conversion emission of Er{sup 3+} ion also showed a great improvement by co-doping 0.1 at% Nd{sup 3+}. Those great results were attributed to energy recycle from Er:{sup 4}I{sub 13/2} to Er:{sup 4}I{sub 11/2}. The energy recycle was mainly built by the two energy transfer between Er{sup 3+} and Nd{sup 3+} (one is from Er to Nd, another is in opposite way). So, Er/Nd co-doped yttrium lanthanum oxide transparent ceramic with Nd in low concentration can be considered as a promising laser material for ∼3 μm and up-conversion laser application. - Highlights: • (Er{sub 0.01}Nd{sub x}Y{sub 0.89-x}La{sub 0.1}){sub 2}O{sub 3} transparent ceramics were prepared. • The emission of 2.7 μm of Er{sup 3+} ion was significantly enhanced as x was 0.001. • The emission of 1.5 μm of Er{sup 3+} ion was suppressed greatly by co-doping Nd{sup 3+} ion. • Mechanism of Er–Nd energy transfer was discussed by the energy sketch.

  12. Effects of DTPA aerosol on lung contamination by lanthanum; Influence du DTPA en aerosol sur les contaminations pulmonaires au lanthane

    Energy Technology Data Exchange (ETDEWEB)

    Pasquier, C; Voisin, D; Thieblement, P; Perrault, G; Bayard, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    Applying DTPA aerosol for the treatment of lung contamination by lanthanum we were able to determine its effectiveness as a function of time. Provided it was administered early during the two hours after exposure, over 50 per cent could be removed using lower therapeutic doses than those prescribed for other routes of administration. Its association with some enzymes did not enhance the chelator therapeutic effect. We also calculated the constant of passage of lanthanum through the alveolar wall and found a value of 0.016 mn{sup -1}. Finally, as we have discovered a large part cannot be mobilized by DTPA, we shall now study the physico-chemical mechanisms involved in this protection. (authors) [French] L'emploi du DTPA en aerosol dans le traitement des contaminations pulmonaires par le lanthane, nous a permis d'etablir et d'evaluer son efficacite en fonction du temps. A condition d'etre utilise precocement, dans les deux heures qui suivent la contamination, une fraction superieure a 50 pour cent peut etre eliminee et ceci avec des doses therapeutiques inferieures a celles preconisees pour les autres voies d'administration. L'association avec quelques autres enzymes n'a pas permis d'ameliorer l'effet therapeutique de ce chelateur. Nous avons egalement chiffre la constante de passage du lanthane a travers la barriere alveolaire dont la valeur est de l'ordre de 0.016 mn{sup -1} Enfin, la decouverte d'une importante partie non piegeable par le DTPA nous amene maintenant a etudier les mecanismes physico-chimiques de cette protection. (auteurs)

  13. Structural transition in lanthanum gallate and transformation of the fine structure of the EPR spectrum of a Gd3+ impurity center

    Science.gov (United States)

    Vazhenin, V. A.; Guseva, V. B.; Fokin, A. V.; Potapov, A. P.; Artyomov, M. Yu.

    2011-04-01

    Abrupt changes in resonance positions, hysteretic temperature behavior, and coexistence of phases, which indicate a first-order phase transition, have been revealed from measurements of temperature dependences of the EPR spectra of Gd3+ and Mn4+ centers in the vicinity of the structural transition of lanthanum gallate. The transformation of monoclinic Gd3+ centers into trigonal Gd3+ centers upon the phase transition has been used to estimate the adequacy of two approximations of the superposition model for parameters of the zero-field splitting of the ground state.

  14. Mixed ionic-electronic conduction in Ni doped lanthanum gallate perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Long, N.J.; Tuller, H.L.

    1998-07-01

    Lanthanum gallate is a promising material for monolithic fuel cells or oxygen pumps, i.e., one in which the electrolyte and electrodes are formed from a common phase. The authors have investigated La{sub 1{minus}x}Sr{sub x}Ga{sub 1{minus}y}Ni{sub y}O{sub 3} (LSGN{sub x{minus}y}) with x = 0.1 and y = 0.2 and 0.5 as a potential cathode material for such an electrochemical device. The {sigma}(PO{sub 2},T) for LSGN{sub 10--20} points to a p-type electronic conductivity at high PO{sub 2} and predominantly ionic conductivity at low PO{sub 2}. LSGN{sub 10-50} has an electronic conductivity suitable for SOFC applications of approximately 50 S/cm in air at high temperature. AC impedance spectroscopy on an electron blocking cell of the form M/LSG/LSGN/LSG/M was used to isolate the ionic conductivity in the LSGN{sub 10--20} material. The ionic conductivity was found to have a similar magnitude and activation energy to that of undoped LSG material with {sigma}{sub i} = 0.12 S/cm at 800 C and E{sub A} = 1.0 {+-} 0.1 eV. Thermal expansion measurements on the LSGN materials were characterized as a function of temperature and dopant level and were found to match that of the electrolyte under operating conditions.

  15. Impact of a small amount of vacancy in both lanthanum and calcium on the physical properties of nanocrystalline La_0_._7Ca_0_._3MnO_3 manganite

    International Nuclear Information System (INIS)

    Makni-Chakroun, J.; Cheikhrouhou-Koubaa, W.; Koubaa, M.; Cheikhrouhou, A.

    2015-01-01

    In this paper, we report the effect of both lanthanum and calcium (1%) on the structural and magnetic properties of nanocrystalline La_0_._7Ca_0_._3MnO_3 manganite. Our powder specimens were synthesized using the sol–gel method with an annealing temperature of 850 °C. The X-ray diffraction patterns refined using Rietveld method confirms that our compounds are single phase and crystallize in the orthorhombic perovskite structure (Pbnm space group). The morphology of the samples, observed using a scanning electron microscope (SEM), reveals a spherical shape with an average grain size lower than 100 nm. Magnetization measurements versus temperature under low magnetic applied field (0.05T) show a paramagnetic–ferromagnetic transition for all compounds. The Curie temperature T_C is found to increase with lacuna in both cases. In addition, the inverse of the susceptibility (1/χ) as a function of temperature indicates a deviation from the Curie Weiss lawn, signature of Griffiths phase occurrence. Experimental results for the critical β and γ exponents are typical of a behavior governed by the tricritical mean-field theory model. Using magnetization measurements as a function of magnetic applied field at several temperatures, we have deduced the magnetic entropy change, which undergoes an enlargement for both lacuna sites. The obtained results are compared to calculated ones based on the Landau theory and a good concordance is observed. - Graphical abstract: (a) Spontaneous magnetization and inverse of susceptibility versus T for La_0_._7Ca_0_._2_9□_0_._0_1MnO_3 compound. Inset the Ln–Ln plot used to determine the critical exponents β and γ. (b) M vs μ_0H isotherm measured at T_C = 200 K. Inset the Ln–Ln plot for the critical exponent δ calculation as well as the modified Arrott plot for La_0_._7Ca_0_._2_9□_0_._0_1MnO_3 compound. - Highlights: • SEM images reveal a spherical shape with an average grain size lower than 100 nm. • Curie temperature T

  16. Lanthanum cobalt oxides as models for La-promoted Co/{gamma}-Al{sub 2}O{sub 3} catalys

    Energy Technology Data Exchange (ETDEWEB)

    Hansteen, Ole Henrik

    1998-12-31

    Cobalt supported on {gamma}-Al{sub 2}O{sub 3} have for a long time been interesting catalysts for the synthesis of hydrocarbons by hydrogenation of carbonmonoxide, the so-called Fischer-Tropsch synthesis. The reduction and catalytic properties of these catalysts are largely improved by addition of promotors like rhenium and lanthanum. This thesis attempts to provide additional knowledge to the nature of the reduction processes from metal oxides via partially reduced phases into metal and to the large degree of interaction/reaction between the catalyst components. It focuses on detailed studies of model oxides in the La-Co-O and Co-Al-O systems under reducing conditions typically used for the synthesis of the catalysts. 132 refs., 41 figs., 16 tabs.

  17. Develop techniques for ion implantation of PLZT [lead-lanthanum-zirconate-titanate] for adaptive optics

    International Nuclear Information System (INIS)

    Batishko, C.R.; Brimhall, J.L.; Pawlewicz, W.T.; Stahl, K.A.; Toburen, L.H.

    1987-09-01

    Research was conducted at Pacific Northwest Laboratory to develop high photosensitivity adaptive optical elements utilizing ion implanted lanthanum-doped lead-zirconate-titanate (PLZT). One centimeter square samples were prepared by implanting ferroelectric and anti-ferroelectric PLZT with a variety of species or combinations of species. These included Ne, O, Ni, Ne/Cr, Ne/Al, Ne/Ni, Ne/O, and Ni/O, at a variety of energies and fluences. An indium-tin oxide (ITO) electrode coating was designed to give a balance of high conductivity and optical transmission at near uv to near ir wavelengths. Samples were characterized for photosensitivity; implanted layer thickness, index of refraction, and density; electrode (ITO) conductivity; and in some cases, residual stress curvature. Thin film anti-ferroelectric PLZT was deposited in a preliminary experiment. The structure was amorphous with x-ray diffraction showing the beginnings of a structure at substrate temperatures of approximately 550 0 C. This report summarizes the research and provides a sampling of the data taken during the report period

  18. Wave and transport studies utilizing dense plasma filaments generated with a lanthanum hexaboride cathode

    International Nuclear Information System (INIS)

    Van Compernolle, B.; Gekelman, W.; Pribyl, P.; Cooper, C. M.

    2011-01-01

    A portable lanthanum hexaboride (LaB 6 ) cathode has been developed for use in the LArge Plasma Device (LAPD) at UCLA. The LaB 6 cathode can be used as a tool for many different studies in experimental plasma physics. To date, the cathode has been used as a source of a plasma with a hot dense core for transport studies and diagnostics development, as a source of gradient driven modes, as a source of shear Alfven waves, and as a source of interacting current channels in reconnection experiments. The LaB 6 cathode is capable of higher discharge current densities than the main barium oxide coated LAPD cathode and is therefore able to produce plasmas of higher densities and higher electron temperatures. The 8.25 cm diameter cathode can be introduced into the LAPD at different axial locations without the need to break vacuum. The cathode can be scaled up or down for use as a portable secondary plasma source in other machines.

  19. Signal intensity of lanthanum carbonate on magnetic resonance images: phantom study.

    Science.gov (United States)

    Nakamura, Shinichi; Awai, Kazuo; Komi, Masanori; Morita, Kosuke; Namimoto, Tomohiro; Yanaga, Yumi; Utsunomiya, Daisuke; Date, Shuji; Yamashita, Yasuyuki

    2011-06-01

    Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms. LC tablets were thoroughly ground and mixed with distilled water or edible agar (0.05, 0.25, 0.5, and 2.5 mg/ml) in plastic bottles. Four intact tablets were placed in plastic bottles that did or did not contain distilled water or agar. Two radiologists consensually evaluated T1- and T2-weighted images (WIs) obtained with 1.5- and 3.0-T MRI systems for the SI of unground and ground tablets. On T1- and T2WI, the SIs of the LC suspensions and the solvents alone were similar; the SIs of unground tablets alone and of the air were also similar. Unground tablets in phantoms filled with solvent exhibited lower SI than the solvent. Ground tablets in suspension were not visualized on MRI or computed tomography. These results remained unchanged regardless of differences in magnetic field strength or the solvent used. Ground LC had no contrast enhancement effect on T1WI; on T2WI it did not affect the SI of the solvent. Unground LC tablets may be visualized as a "filling defect" on MRI.

  20. Signal intensity of lanthanum carbonate on magnetic resonance images. Phantom study

    International Nuclear Information System (INIS)

    Nakamura, Shinichi; Awai, Kazuo; Namimoto, Tomohiro; Yanaga, Yumi; Utsunomiya, Daisuke; Date, Shuji; Yamashita, Yasuyuki; Komi, Masanori; Morita, Kosuke

    2011-01-01

    Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms. LC tablets were thoroughly ground and mixed with distilled water or edible agar (0.05, 0.25, 0.5, and 2.5 mg/ml) in plastic bottles. Four intact tablets were placed in plastic bottles that did or did not contain distilled water or agar. Two radiologists consensually evaluated T1- and T2-weighted images (WIs) obtained with 1.5- and 3.0-T MRI systems for the SI of unground and ground tablets. On T1- and T2WI, the SIs of the LC suspensions and the solvents alone were similar; the SIs of unground tablets alone and of the air were also similar. Unground tablets in phantoms filled with solvent exhibited lower SI than the solvent. Ground tablets in suspension were not visualized on MRI or computed tomography. These results remained unchanged regardless of differences in magnetic field strength or the solvent used. Ground LC had no contrast enhancement effect on T1WI; on T2WI it did not affect the SI of the solvent. Unground LC tablets may be visualized as a 'filling defect' on MRI. (author)

  1. Inhibition mechanism of lanthanum ion on the activity of horseradish peroxidase in vitro

    Science.gov (United States)

    Guo, Shaofen; Wang, Lihong; Lu, Aihua; Lu, Tianhong; Ding, Xiaolan; Huang, Xiaohua

    2010-02-01

    In order to understand the inhibition mechanism of lanthanum ion (La 3+) on the activity of horseradish peroxidase (HRP), the effects of La 3+ on the activity, electron transfer and conformation of HRP in vitro were investigated by using cyclic voltammetry (CV), atomic force microscopy (AFM), circular dichroism (CD), high performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF/MS) and inductively coupled plasma mass spectrometry (ICP-MS). It was found that La 3+ can combine with the amide groups of the polypeptide chain in HRP molecule, forming the complex of La 3+ and HRP (La-HRP). The formation of the La-HRP complex causes the destruction of the native structure of HRP molecule, leading to the decrease in the non-planarity of the porphyrin ring in the heme group of HRP molecule, and then in the exposure extent of active center, Fe(III) of the porphyrin ring of HRP molecule. Thus, the direct electrochemical and catalytic activities of HRP are decreased. It is a possible inhibition mechanism of La 3+ on the activity of peroxidase.

  2. Electronic structure of lanthanum calcium oxoborate LaCa4O(BO3)3

    International Nuclear Information System (INIS)

    Nelson, A.J.; Buuren, T. van; Willey, Trevor M.; Bostedt, C.; Adams, J.J.; Schaffers, K.I.; Terminello, Lou; Callcott, T.A.

    2004-01-01

    Lanthanum calcium oxoborate (LaCOB) is a nonlinear optical (NLO) material that belongs to the calcium-rare-earth (R) oxoborate family, with general composition Ca 4 RO(BO 3 ) 3 (R 3+ =La, Sm, Gd, Lu, Y). X-ray photoemission, photoabsorption, and resonant fluorescence were applied to study the electronic structure of this material. High resolution photoemission measurements on the valence band (VB) electronic structure and La 3d and 4d, Ca 2p, B 1s, and O 1s core lines were used to evaluate the surface and near surface chemistry. Element specific density of unoccupied electronic states in LaCOB were probed by X-ray absorption spectroscopy (XAS) at the La 3d (M 4,5 -edge), B 1s, and O 1s (K-edges) absorption edges. Soft X-ray fluorescence was used to further examine valence band states associated with spectral differences noted in the absorption measurements. These results provide the first measurements of the electronic structure and surface chemistry of this rare-earth oxoborate

  3. Priprava lantanovega galata iz mešanega sistema reducentov in nitrata:

    OpenAIRE

    Kapun, Barbara; Maček, Jadran; Pejovnik, Stane; Zupan, Klementina

    2004-01-01

    Lanthanum-gallate-based material is a candidate for the electrolyte in a new generation of low-temperature ceramic fuel cells due to its good ionic and negligible electronic conductivity. Lantn!an!um gallate is one of two compounds in the binary system La2O3-Ga2O3 together with La4Ga2O9. Undoped lanthanum gallate was prepared using combustion synthesis from metal nitrates and a reducing agent (urea and/or citric acid). In the mixed-fuel-type system the reaction intensifies and higer temperatu...

  4. Synthesis of Sr- and Mg- doped lanthanum gallate by carbonate co-precipitation

    International Nuclear Information System (INIS)

    Sunitha, Y.; Narasimham, K.V.N.S.V.P.L.; Raju, V.S.; Kumar, Sanjiv

    2010-01-01

    Sr- and Mg- doped lanthanum gallate (LSGM) are promising electrolytes for low temperature solid oxide fuel cells (SOFCs) in view of their high ionic conductivity and stability over a wide range of oxygen partial pressures. LSGM powders are usually prepared by solid-state reactions. However high sintering temperature (∼ 1500 deg C) required for densification and the formation of secondary phases are the major drawbacks of the method. Wet-chemical method is a suitable alternative to solid-state synthesis with the prospect of the realisation of phase pure material with good sinterability at comparatively lower temperatures. In this paper we present the results of our investigation on the synthesis of LaGaO 3 and LSGM by a wet-chemical method through carbonate co-precipitation using ammonium carbonate and ammonium bicarbonate as precipitants. Phase and microstructural evolution of the material have been studied by XRD and SEM respectively, while compositional analysis has been performed by ion beam analysis (IBA) techniques. In addition we have also investigated the incorporation of Sr and Mg in the lattice of LaGaO 3 by (a) solid-state reaction route and (b) wet-chemical approach

  5. Local structure and oxide-ion conduction mechanism in apatite-type lanthanum silicates.

    Science.gov (United States)

    Masson, Olivier; Berghout, Abid; Béchade, Emilie; Jouin, Jenny; Thomas, Philippe; Asaka, Toru; Fukuda, Koichiro

    2017-01-01

    The local structure of apatite-type lanthanum silicates of general formula La 9.33+x (SiO 4 ) 6 O 2+3x/2 has been investigated by combining the atomic pair distribution function (PDF) method, conventional X-ray and neutron powder diffraction (NPD) data and density functional theory (DFT) calculations. DFT was used to build structure models with stable positions of excess oxide ions within the conduction channel. Two stable interstitial positions were obtained in accordance with literature, the first one located at the very periphery of the conduction channel, neighbouring the SiO 4 tetrahedral units, and the second one closer to the channel axis. The corresponding PDFs and average structures were then calculated and tested against experimental PDFs obtained by X-ray total scattering and NPD Rietveld refinements results gathered from literature. It was shown that of the two stable interstitial positions obtained with DFT only the second one located within the channel is consistent with experimental data. This result consolidates one of the two main conduction mechanisms along the c-axis reported in the literature, namely the one involving cooperative movement of O4 and Oi ions.

  6. Synthesis, processing and characterization of the solid oxide half-cells cathode/electrolyte of strontium-doped lanthanum manganite/Yttria-stabilized zirconia

    International Nuclear Information System (INIS)

    Chiba, Rubens

    2010-01-01

    The ceramic films of strontium-doped lanthanum manganite (LSM) and strontium doped lanthanum manganite/Yttria-stabilized zirconia (LSM/YSZ) are used as cathodes of the high temperature solid oxide fuel cells (HTSOFC). These porous ceramic films had been deposited on the YSZ dense ceramic substrate, used as electrolyte, structural component of the module, thus conferring a configuration of half-cell called auto-support. The study of the half-cell it is basic, therefore in the interface cathode/electrolyte occurs the oxygen reduction reaction, consequently influencing in the performance of the HTSOFC. In this direction, the present work contributes for the processing of thin films, using the wet powder spraying technique, adopted for the conformation of the ceramic films for allowing the attainment of porous layers with thicknesses varied in the order of micrometers. The LSM powders were synthesized by the citrate technique and the LSM/YSZ powders synthesized by the solid mixture technique. In the stage of formation were prepared organic suspensions of LSM and LSM/YSZ fed by gravity in a manual aerograph. For the formation of the YSZ substrate was used a hydraulic uniaxial press. The attainment of solid oxide half-cells cathode/electrolyte was possible of crystalline structures hexagonal for phase LSM and cubic for phase YSZ. The half-cells micrographs show that the YSZ substrate is dense, enough to be used as solid electrolyte, and the LSM and LSM/YSZ films are presented porous with approximately 30 μm of thickness and good adherence between the cathodes and the electrolyte. The presence of composite cathode between the LSM cathode and YSZ substrate, presented an increase in the electrochemical performance in the oxygen reduction reaction. (author)

  7. Synthesis of lanthanum tungstate interconnecting nanoparticles by high voltage electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Keereeta, Yanee, E-mail: ynkeereeta@gmail.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Titipun, E-mail: ttpthongtem@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Somchai [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-10-01

    Graphical abstract: - Highlights: • La{sub 2}(WO{sub 4}){sub 3} as one of semiconducting materials. • H.V. electrospinning was used to synthesize La{sub 2}(WO{sub 4}){sub 3} interconnecting nanoparticles. • A promising material for photoemission. - Abstract: Lanthanum tungstate (La{sub 2}(WO{sub 4}){sub 3}) interconnecting nanoparticles in the shape of fibers were successfully synthesized by electrospinning in combination with high temperature calcination. In this research, calcination temperature for the synthesis of the fibers evidently influenced the diameter, morphology and crystalline degree. The crystalline monoclinic La{sub 2}(WO{sub 4}){sub 3} fibers with 200–700 nm in diameter, two main Raman peaks at 945 and 927 cm{sup −1}, FTIR stretching modes at 936 and 847 cm{sup −1}, 2.02 eV energy gap and 415–430 nm blue emission were synthesized by calcination of inorganic/organic hybrid fibers at 750 °C for 5 h, characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–visible spectroscopy and photoluminescence (PL) spectroscopy. The surface of the composite fibers before calcination was very smooth. Upon calcination the composite fibers at 750 °C for 5 h, they were transformed into nanoparticles join together in the shape of fibers with rough surface.

  8. Rare earths: preparation of spectro chemically pure standards, study of their carbonates and synthesis of a new compound series - the peroxy carbonates; Terras-raras: obtencao de padroes espectroquimicos, estudo dos carbonatos e sintese dos peroxicarbonatos. Uma nova serie de compostos

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Carlos Alberto da Silva

    1996-05-01

    In this work the following studies are concerned: I) preparation of lanthanum, cerium, praseodymium, neodymium and samarium oxides for use as spectro chemically pure standards; II) behavior of the rare earth (La, Ce, Pr, Nd, Sm) carbonates soluble in ammonium carbonate and mixture of ammonium carbonate/ammonium hydroxide, and III) synthesis and characterization of rare earth peroxy carbonates - a new series of compounds. Data for the synthesis and characterization of the rare earths peroxy carbonates described for the first time in this work are presented and discussed. With the aid of thermal analysis (TG-DTG) the thermal stability and the stoichiometric composition for new compounds were established and a mechanism of thermal decomposition was proposed. The peroxy carbonate was prepared by the addition of hydrogen peroxyde to the complexed soluble rare earths carbonates. These studies included also the determinations of active oxygen, the total rare earth oxide by gravimetry and complexometry and the C, H and N contents by microanalysis. The new compounds were also investigated by infrared spectroscopy. (author)

  9. Microstructural characterization of composite cobaltite and lanthanum-based ceria for use as fuel cell cathodes

    International Nuclear Information System (INIS)

    Rodrigues, E.R.T.; Nascimento, R.M.; Miranda, A.C. de; Lima, A.M. de; Macedo, D.A.

    2016-01-01

    Fuel cells are devices that convert chemical energy into electricity via redox reactions. In this work, the lanthanum cobaltite doped with strontium and iron (La_0_,_6Sr_0_,_4Co_0_,_2Fe_0_,_8O_3 - LSCF) a traditional cathodes material of the fuel cell was mixed with an electrolyte material (composite) to the base ceria doped with gadolinia and a eutectic mixture of lithium carbonates and sodium (CGO-NLC). The powders of LSCF and CGO-NLC were obtained by the citrate method and mixed to obtain a composite cathode. Samples obtained by uniaxial pressure between 5 and 10 MPa were sintered at 1100°C and investigated by X-ray diffraction, scanning electron microscopy and micro hardness test. A symmetric cell cathode / electrolyte / cathode, obtained by co-pressing and co-sintering was investigated by electron microscopy. The results indicated that the composite is chemically stable up to the sintering temperature used. The hardness ranged between 51 and 227 HV. (author)

  10. Lanthanum manganate based cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Juhl Joergensen, M.

    2001-07-01

    Composite cathodes for solid oxide fuel cells were investigated using electrochemical impedance spectroscopy and scanning electron microscopy. The aim was to study the oxygen reduction process in the electrode in order to minimise the voltage drop in the cathode. The electrodes contained a composite layer made from lanthanum strontium manganate (LSM) and yttria stabilised zirconia (YSZ) and a layer of pure LSM aimed for current collection. The performance of the composite electrodes was sensitive to microstructure and thickness. Further, the interface between the composite and the current collecting layer proved to affect the performance. In a durability study severe deg-radation of the composite electrodes was found when passing current through the electrode for 2000 hours at 1000 deg. C. This was ascribed to pore formation along the composite interfaces and densification of the composite and current collector microstructure. An evaluation of the measurement approach indicated that impedance spectroscopy is a very sensitive method. This affects the reproducibility, as small undesirable variations in for instance the microstructure from electrode to electrode may change the impedance. At least five processes were found to affect the impedance of LSM/YSZ composite electrodes. Two high frequency processes were ascribed to transport of oxide ions/oxygen intermediates across LSM/YSZ interfaces and through YSZ in the composite. Several competitive elementary reaction steps, which appear as one medium frequency process in the impedance spectra, were observed. A low frequency arc related to gas diffusion limitation in a stagnant gas layer above the composite structure was detected. Finally, an inductive process, assumed to be connected to an activation process involving segregates at the triple phase boundary between electrode, electrolyte and gas phase, was found. (au)

  11. A PPy-B15C5 modified lanthanum (III electrode in acetonitrile and its thermodynamic application

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Arbab Zavar

    2017-02-01

    Full Text Available Polypyrrole modified electrode prepared by electropolymerization of pyrrole in the presence of a complexing ligand, benzo-15-crown-5 (B15C5, was prepared and investigated as a La3+-selective electrode in acetonitrile. The potentiometric response of the electrode was linear within the La3+ concentration range 1 × 10−4 to 1 × 10−1 M with a Nernstian slope of 19.5 mV decade−1 in AN. The electrode was applied to study the complexation of the lanthanum (III ion in acetonitrile with other basic solvent molecules (D such as dimethyl sulfoxide, N,N-dimethylformamide, propylene carbonate, N,N,Diethylaniline and methanol. The successive complex formation constant (βi and Gibbs energies of transfer (ΔGtr of La3+ in AN in relation to such D were obtained.

  12. Solvent extraction of anionic chelate complexes of lanthanum(III), europium(III), lutetium(III), scandium(III), and indium(III) with 2-thenoyltrifluoroacetone as ion-pairs with tetrabutylammonium ions

    International Nuclear Information System (INIS)

    Noro, Junji; Sekine, Tatsuya.

    1992-01-01

    The solvent extraction of lanthanum(III), europium(III), lutetium(III), scandium(III), and indium(III) in 0.1 mol dm -3 sodium nitrate solutions with 2-thenoyltrifluoroacetone (Htta) in the absence and presence of tetrabutylammonium ions (tba + ) into carbon tetrachloride was measured. The extraction of lanthanum(III), europium(III), and lutetium(III) was greatly enhanced by the addition of tba + ; this could be explained in terms of the extraction of a ternary complex, M(tta) 4 - tba + . However, the extractions of scandium(III) and indium(III) were nearly the same when tba + was added. The data were treated on the basis of the formation equilibrium of the ternary complex from the neutral chelate, M(tta) 3 , with the extracted ion-pairs of the reagents, tta - tba + , in the organic phase. It was concluded that the degree of association of M(tta) 3 with the ion-pair, tta - tba + , is greater in the order La(tta) 3 ≅ Eu(tta) 3 > Lu(tta) 3 , or that the stability of the ternary complex in the organic phase is higher in the order La(tta) 4 - tba + ≅ Eu(tta) 4 - tba + > Lu(tta) 4 - tba + . This is similar to those of adduct metal chelates of Htta with tributylphosphate (TBP) in synergistic extraction systems. (author)

  13. Preparation and luminescence properties of terbium-doped lanthanum oxide nanofibers by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Song Lixin; Du Pingfan [Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University), Ministry of Education, Hangzhou 310018 (China); Xiong Jie, E-mail: jxiong@zstu.edu.cn [Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University), Ministry of Education, Hangzhou 310018 (China); Fan Xiaona; Jiao Yuxue [Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University), Ministry of Education, Hangzhou 310018 (China)

    2012-01-15

    Terbium-doped lanthanum oxide (La{sub 2}O{sub 3}:Tb{sup 3+}) nanofibers were prepared by electrospinning followed by calcination at high temperature. Thermogravimetric analyzer (TGA), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence (PL) were used to characterize the obtained fibers. The results reveal that the nanofibers have an average diameter of ca. 95{+-}25 nm and are composed of pure La{sub 2}O{sub 3} phase. Under the excitation of 274 nm light, the La{sub 2}O{sub 3}:Tb{sup 3+} nanofibers exhibit the characteristic emission resulting from the {sup 5}D{sub 4}{yields}{sup 7}F{sub J} (J=3, 4, 5, 6) transitions of Tb{sup 3+} ions. And the PL emission intensity is stronger than that of their nanoparticle counterparts. - Highlights: > Tb{sup 3+}-doped La{sub 2}O{sub 3} (La{sub 2}O{sub 3}:Tb{sup 3+}) fluorescent nanofibers were prepared via a simple electrospinning technique. > Luminescent properties and other characteristics of the nanofibers were investigated in details. > Potential applications of La{sub 2}O{sub 3}:Tb{sup 3+} nanofibers and electrospinning technique described in this paper are suggested.

  14. Effect of additions of cerium, lanthanum, and zirconium on the state of plantinum and the activity of aluminoplatinum catalysts for the complete oxidation of hydrocarbons

    International Nuclear Information System (INIS)

    Drozdov, V.A.; Davydov, A.A.; Popovskii, V.V.; Tsyrul'nikov, P.G.

    1986-01-01

    It is shown from an analysis of the diffuse reflectance spectra that additions of cerium, lanthanum or zirconium to aluminoplatinum catalyst stabilize the platinum in an oxidized state. This leads to a change in the specific catalytic activity (SCA) towards the total oxidation of methane and butane. The SCA of modified, reduced samples is greater than the SCA of samples that were calcined in air. This is because of the greater activity of metallic platinum compared to the ionic form

  15. Tunable field emission characteristics of ZnO nanowires coated with varied thickness of lanthanum boride thin films

    International Nuclear Information System (INIS)

    Zhao, C.X.; Li, Y.F.; Chen, Jun; Deng, S.Z.; Xu, N.S.

    2013-01-01

    Lanthanum boride (LaB x ) thin films with various thicknesses were deposited on ZnO nanowire arrays by electron beam evaporation. Field emission characteristics of ZnO nanowires show close dependence on LaB x coating thickness. The turn-on field increases with increasing LaB x coating thickness from 10 nm to 50 nm. The observed phenomena were explained by a model that the tunneling at ZnO/LaB x interface dominates the emission process. - Highlights: ► Coating thickness dependence of field emission characteristics of ZnO nanowires was observed from LaB x coated ZnO nanowires. ► More stable field emission was observed from ZnO nanowires with LaB x coating. ► A model was proposed that the tunneling at ZnO/LaB x interface dominates the emission process

  16. Near-ambient X-ray photoemission spectroscopy and kinetic approach to the mechanism of carbon monoxide oxidation over lanthanum substituted cobaltites

    Energy Technology Data Exchange (ETDEWEB)

    Hueso, J. L.; Martinez-Martinez, D.; Cabalerro, Alfonso; Gonzalez-Elipe, Agustin Rodriguez; Mun, Bongjin Simon; Salmeron, Miquel

    2009-07-31

    We have studied the oxidation of carbon monoxide over a lanthanum substituted perovskite (La0.5Sr0.5CoO3-d) catalyst prepared by spray pyrolysis. Under the assumption of a first-order kinetics mechanism for CO, it has been found that the activation energy barrier of the reaction changes from 80 to 40 kJ mol-1 at a threshold temperature of ca. 320 oC. In situ XPS near-ambient pressure ( 0.2 torr) shows that the gas phase oxygen concentration over the sample decreases sharply at ca. 300 oC. These two observations suggest that the oxidation of CO undergoes a change of mechanism at temperatures higher than 300 oC.

  17. Response surface methodology for the optimization of lanthanum removal from an aqueous solution using a Fe{sub 3}O{sub 4}/chitosan nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Haldorai, Yuvaraj [Department of Energy and Materials Engineering, Dongguk University-Seoul, Seoul (Korea, Republic of); Rengaraj, Arunkumar [Department of Biological Engineering, Biohybrid Systems Research Center (BSRC), Inha University, Incheon 402-751 (Korea, Republic of); Ryu, Taegong; Shin, Junho [Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Huh, Yun Suk, E-mail: yunsuk.huh0311@gmail.com [Department of Biological Engineering, Biohybrid Systems Research Center (BSRC), Inha University, Incheon 402-751 (Korea, Republic of); Han, Young-Kyu, E-mail: ykenergy@dongguk.edu [Department of Energy and Materials Engineering, Dongguk University-Seoul, Seoul (Korea, Republic of)

    2015-05-15

    Highlights: • Magnetite/chitosan composite for lanthanum removal. • Response surface methodology was used for optimization. • A 99.88% removal of La{sup 3+} was observed at 40 °C, pH 11, and 50 min. • Adsorption process was significantly affected by pH and adsorbent dosage. • Biocompatible, eco-friendly and a low-cost adsorbent. - Abstract: In the present work, magnetite nanoparticles/chitosan composites (Fe{sub 3}O{sub 4}/CS) were prepared by a chemical precipitation method. We demonstrated the efficient removal of a rare earth metal, lanthanum (La{sup 3+}), from an aqueous solution using the composite. The removal of La{sup 3+} was optimized by using response surface methodology. Analysis of variance and Fisher's F-test were used to determine the reaction parameters which affect the removal of La{sup 3+}. Optimal conditions, including adsorbent dosage, pH, temperature, and contact time for the removal of La{sup 3+}, were found to be 6.5 mg, pH 11, 40 °C, and 50 min, respectively. The adsorption capacity was 99.88%. The rate of La{sup 3+} adsorption was significantly affected by the solution pH and adsorbent amount. An adsorption isotherm was fitted well by the Freundlich model with a linear regression correlation value of 0.9975. The adsorption of La{sup 3+} using the composite followed pseudo second-order kinetics. Thermodynamic studies have revealed that the negative values of Gibbs free energy confirmed the spontaneous and feasible nature of adsorption.

  18. Small polaron conduction in lead modified lanthanum ferrite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Bhargav, K.K.; Ram, S.; Majumder, S.B., E-mail: subhasish@matsc.iitkgp.ernet.in

    2015-07-25

    Highlights: • La{sub 0.8}Pb{sub 0.2}FeO{sub 3} (ε{sub r} ∼ 30,000) shows higher dielectric constant than LaFeO{sub 3} (∼14,000). • Lower A-site dopant content, the dielectric maxima shift to higher temperature. • The frequency dependence of ε{sub r} and tan δ vs. temperature exhibit CDC like behavior. • R{sub g} and R{sub gb} of Pb modified LaFeO{sub 3} follow small polaron hopping conduction model. - Abstract: In the present work we have illustrated the physics of the electrical characteristics of nanocrystalline La{sub 1−x}Pb{sub x}FeO{sub 3,} (0 ⩽ x ⩽ 0.2) powder prepared using auto-combustion synthesis. The effect of lead doping on the dielectric, impedance and ac conductivity characteristics of lanthanum ferrite has systematically been investigated. The synthesized powders were phase pure and crystallized into centro-symmetric Pnma space group. As compared to pure LaFeO{sub 3} ceramics (dielectric constant ∼ 14,000), the dielectric constant is grossly increased (∼30,000) in Pb doped LaFeO{sub 3}. The temperature dependence of dielectric constant of 10.0 at.% Pb doped LaFeO{sub 3} exhibits dielectric maxima similar to that observed in ferroelectric ceramics with non-centrosymmetric point group. For La{sub 0.8}Pb{sub 0.2}FeO{sub 3} ceramics, the frequency dependence of the dielectric constant and loss tangent at various temperatures (300–450 K) exhibit typical colossal dielectric constant (CDC) like behavior. From the impedance spectroscopy we have estimated the grain and grain boundary resistance and capacitance of Pb doped LaFeO{sub 3} that follow a small polaron hopping conduction model. Long range movement of the charge carriers govern the CDC behavior.

  19. Influence of lanthanum distribution on dielectric and ferroelectric properties of BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Khokhar, Anita [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Goyal, Parveen K., E-mail: goyalphy@gmail.com [Department of Physics, ARSD College, University of Delhi, Dhaula Kuan, New Delhi 110 021 (India); Thakur, O.P. [Electroceramics Group, Solid State Physics Laboratory, Lucknow Road, Delhi 110 054 (India); Shukla, A.K. [Department of Physics, Amity Institute of Applied Sciences, Amity University, Noida 201301 (India); Sreenivas, K., E-mail: kondepudysreenivas@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India)

    2015-02-15

    Structural and electrical properties of Lanthanum substituted barium bismuth titanate BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} (0 ≤ x ≤ 0.50) ceramics prepared by conventional solid-state reaction method have been investigated. Raman spectra reveals the distribution of lanthanum into the perovskite layers and (Bi{sub 2}O{sub 2}){sup 2+} layers of BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics. Room temperature dielectric constant (ε′) increases and considerable reduction in the low frequency (10{sup −2} to 10 Hz) dielectric losses and in dc conductivity (σ{sub dc}) are seen with lanthanum substitution. A critical La content of x ∼0.20 in BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} exhibits a well-defined relaxor behavior as seen from the temperature and frequency dependence of the dielectric parameters ε′(T) and ε″(T). The dielectric data fit well to the modified Curie–Weiss law and the Lorentz-type relation and show increasing diffuseness in the phase transition with increasing La content. The temperature dependence of the characteristic relaxation time obtained from the Cole–Cole model shows a good fit to the non-linear Vogel–Fulcher relation. Improvements in the remnant polarization and a stable piezoelectric charge coefficient are seen up to a La content of x ∼0.20. The observed increase in dielectric loss and σ{sub dc} in addition to the diminished ferroelectric/piezoelectric properties for higher La content are explained in terms of changing oxygen vacancy concentration and structural relaxation due to the preferential incorporation of La into the (Bi{sub 2}O{sub 2}){sup 2+} layers as evidenced through the Raman spectroscopy. - Highlights: • La distribution in BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} ceramics is analyzed through Raman spectroscopy. • Low and a nearly constant loss over wide frequency range (10{sup −2}–10{sup 7} Hz) obtained. • Critical La content x = 0.2 identified for high resistivity and ideal relaxor

  20. Intermediate temperature solid oxide fuel cell based on lanthanum gallate electrolyte

    Science.gov (United States)

    Inagaki, Toru; Nishiwaki, Futoshi; Yamasaki, Satoru; Akbay, Taner; Hosoi, Kei

    The Kansai Electric Power Co. Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been developing intermediate temperature solid oxide fuel cells (IT-SOFCs) which are operable at a temperature range between 600 and 800 °C. There are some significant features in IT-SOFC of KEPCO-MMC: (1) highly conductive lanthanum gallate-based oxide is adopted as an electrolyte to realize high-performance disk-type electrolyte-supported cells; (2) the cell-stacks with seal-less structure using metallic separators allow residual fuel to burn around the stack and the combustion heat is utilized for thermally self-sustainable operation; (3) the separators have flexible arms by which separate compressive forces can be applied for manifold parts and interconnection parts. We are currently participating in the project by New Energy and Industrial Technology Development Organization (NEDO) to develop 10 kW-class combined heat and power (CHP) systems. In FY2006, a 10 kW-class module was developed, with which the electrical efficiency of 50%HHV was obtained based on DC 12.6 kW. In the first quarter of FY2007, the 10 kW-class CHP system using the module gave the electrical efficiency of 41%HHV on AC 10 kW and the overall efficiency of 82%HHV when exhaust heat was recovered as 60 °C hot water. Currently, the operation has been accumulated for about 2500 h to evaluate the long-term stability of the system.

  1. Intermediate temperature solid oxide fuel cell based on lanthanum gallate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, Toru; Nishiwaki, Futoshi; Yamasaki, Satoru [The Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-choume, Amagasaki, Hyogo 661-0974 (Japan); Akbay, Taner; Hosoi, Kei [Mitsubishi Materials Corporation, Corporate Technology and Development Division, 1002-14 Mukohyama, Naka, Ibaraki 311-0102 (Japan)

    2008-07-01

    The Kansai Electric Power Co. Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been developing intermediate temperature solid oxide fuel cells (IT-SOFCs) which are operable at a temperature range between 600 and 800 C. There are some significant features in IT-SOFC of KEPCO-MMC: (1) highly conductive lanthanum gallate-based oxide is adopted as an electrolyte to realize high-performance disk-type electrolyte-supported cells; (2) the cell-stacks with seal-less structure using metallic separators allow residual fuel to burn around the stack and the combustion heat is utilized for thermally self-sustainable operation; (3) the separators have flexible arms by which separate compressive forces can be applied for manifold parts and interconnection parts. We are currently participating in the project by New Energy and Industrial Technology Development Organization (NEDO) to develop 10 kW-class combined heat and power (CHP) systems. In FY2006, a 10 kW-class module was developed, with which the electrical efficiency of 50%HHV was obtained based on DC 12.6 kW. In the first quarter of FY2007, the 10 kW-class CHP system using the module gave the electrical efficiency of 41%HHV on AC 10 kW and the overall efficiency of 82%HHV when exhaust heat was recovered as 60 C hot water. Currently, the operation has been accumulated for about 2500 h to evaluate the long-term stability of the system. (author)

  2. Studies on the thermal decomposition of lanthanum(III) valerate and lanthanum(III) caproate in argon

    Energy Technology Data Exchange (ETDEWEB)

    Grivel, J.-C., E-mail: jean@dtu.dk [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK - 4000 Roskilde (Denmark); Zhao, Y.; Suarez Guevara, M.J. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK - 4000 Roskilde (Denmark); Watenphul, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Institute of Mineralogy and Petrography, University of Hamburg, Grindelallee 48, 20146 Hamburg (Germany)

    2015-07-20

    Highlights: • The thermal decomposition of Lathanum valerate and caproate has been studied in Ar. • The compounds melt prior to decomposition. • Gas release in the molten state results in irregular mass loss. • CO{sub 2} and symmetrical ketones are the main evolving gas species. - Abstract: The decomposition of La-valerate (La(C{sub 4}H{sub 9}CO{sub 2}){sub 3}·xH{sub 2}O (x ≈ 0.45)) and La-caproate (La(C{sub 5}H{sub 11}CO{sub 2}){sub 3}·xH{sub 2}O (x ≈ 0.30)) was studied upon heating at 5 °C/min in a flow of argon. Using a variety of techniques including simultaneous TG-DTA, FTIR, X-ray diffraction with both laboratory Cu Kα and synchrotron sources as well as hot-stage microscopy, it was found that both compounds melt prior to decomposition and that the main decomposition stage from the molten, anhydrous state leads to the formation of La-dioxycarbonate (La{sub 2}O{sub 2}CO{sub 3}) via an unstable intermediate product and release of symmetrical ketones. Final decomposition to La{sub 2}O{sub 3} takes place with release of CO{sub 2}.

  3. PRELIMINARY RESULTS FROM APPLICATION PHOSLOCK® TO REMOVE PHOSPHORUS COMPOUNDS FROM WASTEWATER

    Directory of Open Access Journals (Sweden)

    Magdalena Hanna Gajewska

    2017-07-01

    Full Text Available The aim of the study is to assess the removal effectiveness of phosphorus compounds by using lanthanum-modified bentonite. This material was produced by the Australian company Phoslock® Water Solutions Pty Ltd. According to the company, Phoslock® has substantial capacity to bound phosphate anions. The investigation was carried out in steady conditions in laboratory model with beakers. The results of the study are related to the determination of hydraulic load, time of mixing and time of sedimentation. Research with synthetic wastewater was conducted in 4 beakers which were mixing by 5, 10, 20 and 30 minutes respectively. Samples for analyzing were taken from each beaker after 30 minutes, 1, 2, 3, 4 and 24 hours of sedimentation. Studies were conducted to determine the optimal dose of Phoslock® with a known concentration of phosphate anions PO43- in artificial wastewater, time of mixing and time of sedimentation. All samples were taken before and after the treatment with Phoslock® and they were analyzed with following parameters: pH, total suspended solids, conductivity, turbidity, color and phosphate concentration. The carried out investigations confirmed high efficiency of phosphate anions PO43- removal (over 95%, and the final concentration as average was 0.1 mg/dm3. The application of Phoslock® for phosphate anions PO43- did not change the pH of final effluent

  4. Colossal thermoelectric power in charge ordered lanthanum calcium manganites (La{sub 0.5}Ca{sub 0.5}MnO{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Joy, Lija K.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India); Shanmukharao Samatham, S.; Ganesan, V. [Low temperature division, UGC-DAE Consortium for Scientific Research, Indore (India); Thomas, Senoy [Material Science and Technology Division, National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram–695019 (India); Al-Harthi, Salim [Department of Physics, Sultan Qaboos University, Muscat PC 123, Sultanate of Oman (Oman); Liebig, A.; Albrecht, M. [Institute of Physics, University of Augsburg, Augsburg 86135 (Germany)

    2014-12-07

    Lanthanum calcium manganites (La{sub 0.5}Ca{sub 0.5}MnO{sub 3}) with a composition close to charge ordering, synthesized by high energy ball milling, was found to exhibit colossal thermoelectric power. Thermoelectric power (TEP) data was systematically analyzed by dividing the entire temperature range (5 K–300 K) into three different regimes to explore different scattering mechanisms involved. Mandal's model has been applied to explain TEP data in the region below the Curie temperature (T{sub C}). It has been found that the variation of thermoelectric power with temperature is pronounced when the system enters the charge ordered region at T < 200 K. For temperatures lower than 120 K, due to the co-existence of charge ordered state with a spin-glass state, the variation of thermoelectric power is maximum and exhibited a peak value of −80 mV/K at 58 K. This has been explained by incorporating Kondo properties of the spin-glass along with magnon scattering. FC-ZFC magnetization measurements indicate the existence of a glassy state in the region corresponding to a maximum value of thermoelectric power. Phonon drag contribution instead of spin-glass contribution is taken into account to explain TEP in the region 120 K < T < T{sub C}. Mott's polaronic contribution of charge carriers are considered to interpret TEP in the high temperature region (T > T{sub C}). The optimal Mn{sup 4+}-Mn{sup 3+} concentration in charge ordered La{sub 0.5}Ca{sub 0.5}MnO{sub 3} was examined by X-ray Photoelectron Spectroscopy analysis which confirms the charge ordered nature of this compound.

  5. Grain growth kinetics and electrical properties of lanthanum modified lead zirconate titanate (9/65/35) based ferroelectric ceramics

    International Nuclear Information System (INIS)

    Roca, R. Alvarez; Guerrero, F.; Botero, E. R.; Garcia, D.; Eiras, J. A.; Guerra, J. D. S.

    2009-01-01

    The influence of the microstructural characteristics on the dielectric and electrical properties has been investigated for Nd 3+ doped lanthanum modified lead zirconate titanate ferroelectric ceramics, obtained by the conventional solid-state reaction method, by taking into account different sintering conditions. The grain growth mechanism has been investigated and a cubic-type grain growth law was observed for samples with grain size varying from 1.00 up to 2.35 μm. The porosity and grain size dependences of the phase transition parameters, such as the maximum dielectric permittivity and its corresponding temperature (ε m and T m , respectively) were also investigated. The ac conductivity analyses followed the universal Jonscher law. The behavior of the frequency exponent (s) was analyzed through the correlated barrier hopping model. Both ac and dc conductivity results have been correlated with the observed microstructural features

  6. Study of lanthanum aluminum silicate glasses for passive and active optical fibers

    Science.gov (United States)

    Schuster, K.; Litzkendorf, D.; Grimm, S.; Kobelke, J.; Schwuchow, A.; Ludwig, A.; Leich, M.; Jetschke, S.; Dellith, J.; Auguste, J.-L.; Leparmentier, S.; Humbert, G.; Werner, G.

    2013-03-01

    We report on SiO2-Al2O3-La2O3 glasses - with and without Yb2O3 - suitable for nonlinear and fiber laser applications. We also present successful supercontinuum generation and fiber laser operation around 1060 nm in step-index fibers. We have optimized the glass compositions in terms of thermal and optical requirements for both a high La2O3 (24 mol%) and Yb2O3(6 mol%) concentration. The aluminum concentration was adjusted to about 21 mol% Al2O3 to increase the solubility of lanthanum and ytterbium in the glass beyond possible MCVD based techniques. The glasses have been characterized by dilatometrical methods to find transition temperatures from 860 to 880°C and thermal expansion coefficients between 4.1 and 7.0 × 10-6 K-1. Structured step index fibers with a SiO2-Al2O3-La2O3 core and silica cladding have been realized showing a fiber loss minimum of about 500 dB/km at 1200 nm wavelength. The chromatic dispersion could be adjusted to shift the zero dispersion wavelength (ZDW) close to the pump wavelength of 1550 nm in a supercontinuum generation setup. First fiber laser experiments show an efficiency of about 41 % with a remarkably reduced photodarkening compared to MCVD based fibers.

  7. L-cysteine capped lanthanum hydroxide nanostructures for non-invasive detection of oral cancer biomarker.

    Science.gov (United States)

    Tiwari, Sachchidanand; Gupta, Pramod K; Bagbi, Yana; Sarkar, Tamal; Solanki, Pratima R

    2017-03-15

    In this paper, we present the result of studies related to the in situ synthesis of amino acid (L-Cysteine) capped lanthanum hydroxide nanoparticles [Cys-La(OH) 3 NPs] towards the fabrication of efficient immunosensor for non-invasive detection of oral cancer. The characterization of Cys-La(OH) 3 NPs was carried out by different techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy and electrochemical techniques. These Cys-La(OH) 3 NPs were electrophoretically deposited onto an indium-tin-oxide glass substrate and used for immobilization of anti-cytokeratin fragment-21-1 (anti-Cyfra-21-1) for the electrochemical detection of Cyfra-21-1. This immunosensor shows a broad detection range of 0.001-10.2ngmL -1 , the low detection limit of 0.001ngmL -1 , and high sensitivity of 12.044µA (ng per mL cm -2 ) -1 with a response time of 5min. This immunosensor was found to be more advanced in terms of high sensitivity and low detection limit as compared to previously reported biosensors and commercially available ELISA kit (Kinesis DX). Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Comprehensive Study of Lanthanum Aluminate High-Dielectric-Constant Gate Oxides for Advanced CMOS Devices

    Directory of Open Access Journals (Sweden)

    Masamichi Suzuki

    2012-03-01

    Full Text Available A comprehensive study of the electrical and physical characteristics of Lanthanum Aluminate (LaAlO3 high-dielectric-constant gate oxides for advanced CMOS devices was performed. The most distinctive feature of LaAlO3 as compared with Hf-based high-k materials is the thermal stability at the interface with Si, which suppresses the formation of a low-permittivity Si oxide interfacial layer. Careful selection of the film deposition conditions has enabled successful deposition of an LaAlO3 gate dielectric film with an equivalent oxide thickness (EOT of 0.31 nm. Direct contact with Si has been revealed to cause significant tensile strain to the Si in the interface region. The high stability of the effective work function with respect to the annealing conditions has been demonstrated through comparison with Hf-based dielectrics. It has also been shown that the effective work function can be tuned over a wide range by controlling the La/(La + Al atomic ratio. In addition, gate-first n-MOSFETs with ultrathin EOT that use sulfur-implanted Schottky source/drain technology have been fabricated using a low-temperature process.

  9. Analysis of the X-ray spectra emitted by laser-produced plasma of highly ionized lanthanum and praseodymium in the 8. 4 to 12. 0 A wavelength range

    Energy Technology Data Exchange (ETDEWEB)

    Zigler, A [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel); Mandelbaum, P [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel); Schwob, J L [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel); Mitnik, D [Racah Inst. of Physics, Hebrew Univ., Jerusalem (Israel)

    1994-06-01

    A detailed analysis of the X-ray spectra emitted by laser produced plasma of lanthanum (8.5-12.5 A) and praseodymium (8.4-11.3 A) is given, using ab-initio calculations with the HULLAC relativistic code. Resonance 3d-nf (n 4, 5, 6) and 3p-4s, 4d transitions of the La XXX and Pr XXXII Ni I-like ions and neighbouring ionization states (La XXVIII to La XXXVI, Pr XXX to Pr XXXVI) have been identified. (orig.).

  10. Thermoluminescent kinetic parameters of the perovskite, KMgF{sub 3}, activated with lanthanum; Parametros cineticos termoluminiscentes de la perovskita, KMgF{sub 3}, activada con lantano

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda M, F. [ESFM-IPN, 07738 Mexico D.F. (Mexico); Azorin N, J.; Rivera M, T. [UAM-I, 09340 Mexico D.F. (Mexico); Furetta, C.; Sanipoli, C. [Physics Department, Universita di Roma ' ' La Sapienza' ' , Piazzale A. Moro 2, 00185 Roma (Italy)

    2004-07-01

    The thermoluminescent curves induced by the beta radiation in the perovskite KMgF{sub 3} were investigated activated with lanthanum. The classic methods were used to determine the kinetic parameters (the kinetic order b, the activation energy E and the frequency of escape intent s) associated with the peaks of the thermoluminescent curve (Tl) in the KMgF{sub 3} activated with lanthanum after the irradiation with beta rays. The method is based on the position of the thermoluminescent peaks, obtained of the temperature change of the peak in the maximum emission caused by the change in the heating rapidity to which the samples were measured. In this work, the samples in form of pellets were re cooked previously at 400 C during one hour before irradiating them with beta particles. The Tl measures were made with a Tl reader system using three different heating rapidities and storing the glow curves. To calculate the depth of the E traps and the frequency factor s, the parameters of the glow curve were determined experimentally of the shame of the glow curve by means of the mensuration of the shame of the maximum temperature of the peak, T{sub M} like a function of the heating rapidity. The results indicate that the values of the kinetic parameters are very near among if when they are obtained indistinctly of anyone of the different methods. (Author)

  11. Synthesis and characterization of Sr- and Mg-doped Lanthanum gallate electrolyte materials prepared via the Pechini method

    International Nuclear Information System (INIS)

    Shi Min; Xu Yudong; Liu Anping; Liu Ning; Wang Can; Majewski, P.; Aldinger, F.

    2009-01-01

    The powders of Sr- and Mg-doped lanthanum gallate (La 0.85 Sr 0.15 Ga 0.80 Mg 0.2 O 2.825 ; LSGM) were synthesized by the Pechini method. The XRD pattern indicates that the main phase (LaGaO 3 ) exists in the uncalcined powders. The LSGM materials are composed of the main phase without secondary phases when calcined at 1400 deg. C. The LSGM materials contain fewer amounts of secondary phases than those prepared by the sol-gel method and solid-state reaction method at the same calcination temperature. TEM image of the powders indicate that the average grain size is about 80 nm. The conductivity increases with the testing temperature increasing. The curve of ln(σT) vs 1/T exists two straight lines intersecting at T* (T* is about 602 deg. C). It indicates that activation energy of oxygen-vacancy motion at lower temperatures is greater than that at higher temperatures

  12. Synthesis and characterization of Sr- and Mg-doped Lanthanum gallate electrolyte materials prepared via the Pechini method

    Energy Technology Data Exchange (ETDEWEB)

    Shi Min [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)], E-mail: shimin@mail.hf.ah.cn; Xu Yudong; Liu Anping; Liu Ning; Wang Can [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Majewski, P.; Aldinger, F. [Max-Planck-Institut fur Metallforschung, Pulvermetallurgisches Laboratorium, Heisenbergstr. 5, D-70569 Stuttgart (Germany)

    2009-03-15

    The powders of Sr- and Mg-doped lanthanum gallate (La{sub 0.85}Sr{sub 0.15}Ga{sub 0.80}Mg{sub 0.2}O{sub 2.825}; LSGM) were synthesized by the Pechini method. The XRD pattern indicates that the main phase (LaGaO{sub 3}) exists in the uncalcined powders. The LSGM materials are composed of the main phase without secondary phases when calcined at 1400 deg. C. The LSGM materials contain fewer amounts of secondary phases than those prepared by the sol-gel method and solid-state reaction method at the same calcination temperature. TEM image of the powders indicate that the average grain size is about 80 nm. The conductivity increases with the testing temperature increasing. The curve of ln({sigma}T) vs 1/T exists two straight lines intersecting at T* (T* is about 602 deg. C). It indicates that activation energy of oxygen-vacancy motion at lower temperatures is greater than that at higher temperatures.

  13. Competitive binding affinity of two lanthanum(III) macrocycle complexes toward DNA and bovine serum albumin in water

    Energy Technology Data Exchange (ETDEWEB)

    Asadi, Zahra; Mosallaei, Hamta; Sedaghat, Moslem [Shiraz Univ. (Iran, Islamic Republic of). Dept. of Chemistry; Yousefi, Reza [Shiraz Univ. (Iran, Islamic Republic of). Protein Chemistry Lab. (PCL)

    2017-11-15

    In the present study, two water-soluble lanthanum(III) hexaaza Schiff base complexes were synthesized and characterized and also theoretically investigated. The interactions of these complexes with DNA and bovine serum albumin (BSA) were studied using different spectroscopic assessments and docking simulation analysis. The DNA docking studies suggested that these two complexes are able to interact with DNA through the minor groove, and also the binding affinity is in the order of La(L{sup 1}) > La(L{sup 2}). Furthermore, the spectral titration was carried out and viscosity measurements were taken. In this regard, protein-binding studies revealed that these complexes quench the intrinsic fluorescence of BSA, and indicated that the possible binding site is located on the vicinity of Trp 213, which is further validated by docking simulation analysis. The in vitro anticancer activities of these complexes indicated that the La(L{sup 1}) complex is more effective than the other one and also exhibits a better interaction with DNA.

  14. Fabrication of Lanthanum Strontium Cobalt Ferrite-Gadolinium-Doped Ceria Composite Cathodes Using a Low-Price Inkjet Printer.

    Science.gov (United States)

    Han, Gwon Deok; Choi, Hyung Jong; Bae, Kiho; Choi, Hyeon Rak; Jang, Dong Young; Shim, Joon Hyung

    2017-11-15

    In this work, we have successfully fabricated lanthanum strontium cobalt ferrite (LSCF)-gadolinium-doped ceria (GDC) composite cathodes by inkjet printing and demonstrated their functioning in solid oxide fuel cells (SOFCs). The cathodes are printed using a low-cost HP inkjet printer, and the LSCF and GDC source inks are synthesized with fluidic properties optimum for inkjet printing. The composition and microstructure of the LSCF and GDC layers are successfully controlled by controlling the color level in the printed images and the number of printing cycles, respectively. Anode-support type SOFCs with optimized LSCF-GDC composite cathodes synthesized by our inkjet printing method have achieved a power output of over 570 mW cm -2 at 650 °C, which is comparable to the performance of a commercial SOFC stack. Electrochemical impedance analysis is carried out to establish a relationship between the cell performance and the compositional and structural characteristics of the printed LSCF-GDC composite cathodes.

  15. A new quantum interferometer effect in superconducting oxide ceramics

    International Nuclear Information System (INIS)

    Chela Flores, J.; Shehata, L.N.

    1987-08-01

    On the basis of a phenomenological approach to type II high T c superconductivity, we suggest that in the lanthanum compounds the Mercereau effect for a coupled junction pair should display and ex-dependent shift in the period of modulation of the tunnelling current. (author). 14 refs

  16. Impact of a small amount of vacancy in both lanthanum and calcium on the physical properties of nanocrystalline La{sub 0.7}Ca{sub 0.3}MnO{sub 3} manganite

    Energy Technology Data Exchange (ETDEWEB)

    Makni-Chakroun, J., E-mail: makni.jihed@yahoo.fr [Material Physics Laboratory, Faculty of Sciences of Sfax, B. P. 1171, Sfax University, 3000 Sfax (Tunisia); Cheikhrouhou-Koubaa, W. [Material Physics Laboratory, Faculty of Sciences of Sfax, B. P. 1171, Sfax University, 3000 Sfax (Tunisia); Research Centre for Computing, Multimedia and Digital Data Processing, Sfax Technopark, BP 275, 3021 Sakiet-ezzit (Tunisia); Koubaa, M.; Cheikhrouhou, A. [Material Physics Laboratory, Faculty of Sciences of Sfax, B. P. 1171, Sfax University, 3000 Sfax (Tunisia)

    2015-11-25

    In this paper, we report the effect of both lanthanum and calcium (1%) on the structural and magnetic properties of nanocrystalline La{sub 0.7}Ca{sub 0.3}MnO{sub 3} manganite. Our powder specimens were synthesized using the sol–gel method with an annealing temperature of 850 °C. The X-ray diffraction patterns refined using Rietveld method confirms that our compounds are single phase and crystallize in the orthorhombic perovskite structure (Pbnm space group). The morphology of the samples, observed using a scanning electron microscope (SEM), reveals a spherical shape with an average grain size lower than 100 nm. Magnetization measurements versus temperature under low magnetic applied field (0.05T) show a paramagnetic–ferromagnetic transition for all compounds. The Curie temperature T{sub C} is found to increase with lacuna in both cases. In addition, the inverse of the susceptibility (1/χ) as a function of temperature indicates a deviation from the Curie Weiss lawn, signature of Griffiths phase occurrence. Experimental results for the critical β and γ exponents are typical of a behavior governed by the tricritical mean-field theory model. Using magnetization measurements as a function of magnetic applied field at several temperatures, we have deduced the magnetic entropy change, which undergoes an enlargement for both lacuna sites. The obtained results are compared to calculated ones based on the Landau theory and a good concordance is observed. - Graphical abstract: (a) Spontaneous magnetization and inverse of susceptibility versus T for La{sub 0.7}Ca{sub 0.29}□{sub 0.01}MnO{sub 3} compound. Inset the Ln–Ln plot used to determine the critical exponents β and γ. (b) M vs μ{sub 0}H isotherm measured at T{sub C} = 200 K. Inset the Ln–Ln plot for the critical exponent δ calculation as well as the modified Arrott plot for La{sub 0.7}Ca{sub 0.29}□{sub 0.01}MnO{sub 3} compound. - Highlights: • SEM images reveal a spherical shape with an average grain

  17. Synthesis and characterization of calcium doped lanthanum ...

    Indian Academy of Sciences (India)

    56

    The structural, morphological, and optical properties of the resulting powder was ... FESEM image indicates that the LCMO sample has nanowire ... This makes ABO3 compound as a superior catalyst for the degradation of pollutant by inducing.

  18. Synthesis and characterization of a new photoluminescent material (8-hydroxy quinoline) bis (2-2'bipyridine) lanthanum La(Bpy)2q

    Science.gov (United States)

    Kumar, Rahul; Bhargava, Parag

    2016-05-01

    A new photoluminescence material, (8-hydroxy quinoline) bis (2-2'bipyridine) lanthanum has been synthesized and characterized by different techniques. The prepared material La(Bpy)2q was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) shows the thermal stability up to 190°C.Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy)2q in ethanol showed absorption peak at 385nm, which may be attributed due to (π - π*) transitions. The photoluminescence spectra of La(Bpy)2q in ethanol solution showed intense peak at 490 nm

  19. Influence of milling and calcination steps on phase assemblage of strontium and magnesium doped lanthanum gallate

    International Nuclear Information System (INIS)

    Reis, S.L.; Muccillo, E.N.S.

    2011-01-01

    Sr- and Mg- doped lanthanum gallate (La_1_-_xSr_xGa_1_-_yMg_yO_3_δ) is one of the most promising solid electrolyte and electrode components for solid oxide fuel cells operating at low-temperature, due to its high electric conductivity and stability over a wide range of oxygen partial pressures. In this work, La_0_,_9Sr_0_,_1Ga_0_,_8Mg_0_,_2O_2_,_85 was prepared by different solid state reaction routes. The main purpose is to determine a suitable processing route that enables high sintering density along with free or negligible secondary phase contents. Phase analysis was carried out by X-ray diffraction and the sintered density was obtained from the water immersion method. Results on X-ray diffraction showed negligible secondary phases formed even for sintering at relatively high temperatures. The apparent density obtained was higher than 95% of the theoretical value for all routes. The main difference observed among the studied routes is the final contents of secondary phases. (author)

  20. Twinning induced by the rhombohedral to orthorhombic phase transition in lanthanum gallate (LaGaO3)

    Science.gov (United States)

    Wang, W. L.; Lu, H. Y.

    2006-10-01

    Phase-transformation-induced twins in pressureless-sintered lanthanum gallate (LaGaO3) ceramics have been analysed using the transmission electron microscopy (TEM). Twins are induced by solid state phase transformation upon cooling from the rhombohedral (r, Rbar{3}c) to orthorhombic ( o, Pnma) symmetry at ˜145°C. Three types of transformation twins {101} o , {121} o , and {123} o were found in grains containing multiple domains that represent orientation variants. Three orthorhombic orientation variants were distinguished from the transformation domains converged into a triple junction. These twins are the reflection type as confirmed by tilting experiment in the microscope. Although not related by group-subgroup relation, the transformation twins generated by phase transition from rhombohedral to orthorhombic are consistent with those derived from taking cubic Pm {bar {3}}m aristotype of the lowest common supergroup symmetry as an intermediate metastable structure. The r→ o phase transition of first order in nature may have occurred by a diffusionless, martensitic-type or discontinuous nucleation and growth mechanism.

  1. The phase stability and toughening effect of 3Y-TZP dispersed in the lanthanum zirconate ceramics

    International Nuclear Information System (INIS)

    Wang, Yanfei; Xiao, Ping

    2014-01-01

    The low fracture toughness of lanthanum zirconate (La 2 Zr 2 O 7 , LZ) greatly impedes its wide application as thermal barrier coatings (TBC). The 3 mol% Y 2 O 3 -stabilized tetragonal zirconia polycrystals (3Y-TZP) have been introduced to toughen the brittle LZ ceramics. The dispersive 3Y-TZP undergoes a simultaneous t–m transformation upon cooling below a critical volume fraction x of 3Y-TZP, above which its tetragonal phases can however be preserved. The different stabilities of 3Y-TZP second phases arise from a variation of residual tensile stress within them. The fracture toughness has been greatly improved by dispersing the tetragonal particulates (t-3YSZ) in the LZ matrix and the primary toughening mechanisms are phase transformations of the dispersive second phases and the residual compressive stress within the matrix. An anticipated increase of fracture toughness from the ferroelastic toughening and the residual compressive stress toughening highlights the great potentials to improve coating durability by depositing t′-3YSZ/LZ composite TBCs by the industrial non-equilibrium route

  2. Oxidative effects, nutrients and metabolic changes in aquatic macrophyte, Elodea nuttallii, following exposure to lanthanum.

    Science.gov (United States)

    Zhang, Jingjing; Zhang, Tingting; Lu, Qianqian; Cai, Sanjuan; Chu, Weiyue; Qiu, Han; Xu, Ting; Li, Feifei; Xu, Qinsong

    2015-05-01

    We investigated the phytoremediation potential of Elodea nuttallii to remove rare earth metals from contaminated water. The laboratory experiments were designed to assess the responses induced by lanthanum (5-20mgL(-1)) in E. nuttallii over a period of 7 days. The results showed that most La (approximately 85%) was associated with the cell wall. The addition of La to the culture medium reduced the concentration of K, Ca, Cu, Mg, and Mn. However, O2(·-) levels increased with a concomitant increase in the malondialdehyde (MDA) concentration as the La concentration increased, which indicated that the cells were under oxidative stress. Significant reductions in the levels of chlorophyll (Chl) a, b, and carotenoids (Car) were observed in a concentration-dependent manner. However, the levels of reduced glutathione (GSH), total non-protein thiols (TNP-SH) and phytochelatins (PCs) increased for all La concentrations. The results suggested that La was toxic to E. nuttallii because it induced oxidative stress and disturbed mineral uptake. However, E. nuttallii was able to combat La induced damage via an immobilization mechanism, which involved the cell wall and the activation of non-enzymatic antioxidant. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Osteoblast adhesion on novel machinable calcium phosphate/lanthanum phosphate composites for orthopedic applications.

    Science.gov (United States)

    Ergun, Celaletdin; Liu, Huinan; Webster, Thomas J

    2009-06-01

    Lanthanum phosphate (LaPO(4), LP) was combined with either hydroxyapatite (HA) or tricalcium phosphate (TCP) to form novel composites for orthopedic applications. In this study, these composites were prepared by wet chemistry synthesis and subsequent powder mixing. These HA/LP and TCP/LP composites were characterized in terms of phase stability and microstructure evolution during sintering using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Their machinability was evaluated using a direct drilling test. For HA/LP composites, LP reacted with HA during sintering and formed a new phase, Ca(8)La(2)(PO(4))(6)O(2), as a reaction by-product. However, TCP/LP composites showed phase stability and the formation of a weak interface between TCP and LP machinability when sintered at 1100 degrees C, which is crucial for achieving desirable properties. Thus, these novel TCP/LP composites fulfilled the requirements for machinability, a key consideration for manufacturing orthopedic implants. Moreover, the biocompatibility of these novel LP composites was studied, for the first time, in this paper. In vitro cell culture tests demonstrated that the LP and its composites supported osteoblast (bone-forming cell) adhesion similar to natural bioceramics (such as HA and TCP). In conclusion, these novel LP composites should be further studied and developed for more effectively treating bone related diseases or injuries. 2008 Wiley Periodicals, Inc.

  4. Removal of phosphate from water by activated carbon fiber loaded with lanthanum oxide

    International Nuclear Information System (INIS)

    Zhang Ling; Wan Lihua; Chang Ning; Liu Jianyong; Duan Chao; Zhou Qi; Li Xiangling; Wang Xinze

    2011-01-01

    Phosphate removal from wastewater is very important for the prevention of eutrophication. Adsorption of phosphate from water was investigated using activated carbon fiber loaded with lanthanum oxide (ACF-La) as a novel adsorbent. The effects of variables (La/ACF mass ratio, impregnation time, activation time, and activation temperature) have been studied by the single-factor method. Response surface methodology (RSM), based on three-variable-three-level Box-Behnken design (BBD), was employed to assess the individual and collective effects of the main independent parameters on the phosphate removal. The optimal conditions within the range studied for preparing ACF-La were found as follows: La/ACF mass ratio of 11.78%, activation time of 2.5 h and activation temperature at 650 ° C , respectively. The phosphate removal using the ACF-La prepared under the optimal conditions was up to 97.6% even when the phosphate concentration in water was 30 mg P/L, indicating that ACF-La may be an effective adsorbent. The results from Fourier transform infrared (FT-IR) spectroscopy and change of pH values associated with the adsorption process revealed that the probable mechanism of phosphate ions onto ACF-La was not only ion exchange and coulomb interaction, but also a result of Lewis acid-base interaction due to La-O coordination bonding.

  5. Synthesis of adsorbent from Tamarix hispida and modified by lanthanum metal for fluoride ions removal from wastewater: Adsorbent characteristics and real wastewater treatment data

    Directory of Open Access Journals (Sweden)

    Nasim Habibi

    2017-08-01

    Full Text Available This data article describes a facile method for production of an adsorbent from Tamarix hispida wasted wood and modified by lanthanum metal for fluoride ions removal from wastewater. The main characteristics of the adsorbent consist of BET surface area, functional groups, and elemental analysis is presented. The data for attenuating the pollutants from a real wastewater treatment which was provided from a glass factory is also represented. More than 90% of fluoride content of the real wastewater was treated by the adsorbent. Generally, these data would be informative for extend research aim to industrial wastewater treatment and those who work in the wastewater treatment plants.

  6. Synthesis and investigation of new heteronuclear [Zn-La] coordination compounds based on unsaturated lanthanum complex with N,N'-tetraethyl-N''-trichloacetylphosphortriamide

    International Nuclear Information System (INIS)

    Amyirkhanov, O.V.; Sliva, T.Yu.; Moroz, O.V.; Trush, Je.A.; Frits'kij, Yi.O.

    2011-01-01

    New heteronuclear [Zn-La] coordination compounds, perspective luminescent materials, with general formulas [Zn(Ve)La(X) 2 (Ac)] ({Zn-La;Ve;X}) and [Zn(Vp)La(X) 2 (Ac)] ({Zn-La;Vp;X}) have been synthesized HX=CCl 3 C(O)NHP(O)[N(C 2 H 5 ) 2 ] 2 - N,N'-tetraethyl-N''-trichloracetylphosphortriamide, H 2 Ve and H 2 Vp are products of the condensation of 1,2-diaminoethane and 1,3-diaminopropane with o-vanillin, respectively). The composition of [Zn-La] complexes has been determined, and the coordination mode of a phosphorylated ligand has been suggested by element analysis, IR- and 1 H, 31 P NMR-spectroscopy.

  7. Influence of lanthanum on the optomagnetic properties of zinc ferrite prepared by combustion method

    International Nuclear Information System (INIS)

    Tholkappiyan, R.; Vishista, K.

    2014-01-01

    Pure and lanthanum doped zinc ferrite nanoparticles were synthesized by a combustion method using glycine as fuel. The mechanism of formation of these nanoferrites is discussed briefly. The prepared nanoparticles characterized using powder X-ray diffraction analysis (XRD) revealed the formation of cubic spinel phase with high crystallinity. Average crystallite size, X-ray density and bulk density were found to decrease with an increase in La 3+ concentration. The chemical elements and states on the surface of these ferrites were determined using X-ray photoelectron spectroscopy (XPS). The detailed core level spectra of the photoelectron peaks of Zn 2p, Fe 2p, La 3d and O 1s were analyzed. The magnetic behavior of these nanoparticles was studied using a vibrating sample magnetometer (VSM) and corresponding changes in the saturation magnetization (Ms), coercivity (Hc) and remanent magnetization (Mr) were analyzed. The optical behavior of these ferrite nanoparticles was characterized by UV–Diffuse reflectance studies (UV–DRS). From the UV–DRS studies, the optical band gap was found to be in the range of 1.87–1.97 eV. The combustion method significantly produces large amount of products within a short time. Therefore, this method is potentially suitable for manufacturing industries for preparing the magnetic nanoparticles

  8. Dynamical properties of lanthanum monochalcogenides

    International Nuclear Information System (INIS)

    Varshney, Dinesh; Rathore, V.; Kaurav, N.; Choudhary, K.K.; Singh, R.K.

    2006-01-01

    We have employed an effective interionic interaction potential approach to describe the dynamical properties of LaS. This potential consists of the long-range Coulomb and three-body interactions (TBI) and the short-range van der Waals (vdW) interaction and the Hafemeister and Flygare type overlap repulsion extended up to the second neighbor ions. The elastic constants obtained from the model have been used to calculate the phonon dispersion relation in the symmetry direction. The phonon dispersion curves of LaS compound. calculated from the present model, agree with the measured data. We also report the two-phonon density of states of LaS. (author)

  9. Identification of solution products of lanthanoid (3) diethyldithiocarbamatohexamethyl phosphotriamide compounds from IR, electron and sup 1 H, sup 13 C, sup 31 P NMR absorption spectra. Identifikatsiya produktov rastvoreniya diehtilditiokarbamatogeksametil fosfotriamidnykh soedinenij lantanoidov (3) po IK, ehlektronnym i YaMR sup 1 H, sup 13 C, sup 31 P spektram pogloshcheniya

    Energy Technology Data Exchange (ETDEWEB)

    Skopenko, V V; Savost' yanova, A F; Trachevskij, V V; Gorbalyuk, A D; Sukhan, T A [Kievskij Gosudarstvennyj Univ., Kiev (Ukrainian SSR)

    1991-01-01

    By the methods of conductometry, IR, electron and {sup 1}H, {sup 13}C, {sup 31}P NMR spectroscopy nonaqueous solutions of the compounds (La(S{sub 2}CNEt{sub 2})Hmpa{sub 5})(BPh{sub 4}){sub 2}, Hmpa=OP(NMe{sub 2}){sub 3}; (Ln(S{sub 2}CNEt{sub 2}){sub 2}Hmpa{sub 3})BPh{sub 4}, Ln=Y, La-Lu; (Ln(S{sub 2}CNEt{sub 2}){sub 3}Hmpa{sub 2}), Ln=La-Gd, have been investigated. It is ascertained that bis-dithiocarbamate compounds are dissolved in all the studied solvents with preservation of composition and structure of lanthanide (3) inner coordination sphere. Tris-dithiocarbamates in nonaqueous solutions are subjected to reactions of ligand redistribution according to schemes depending on the solvent nature. In the process of dissolving of lanthanum monodithiocarbamate bond isomerization of dithiocarbamate groups occurs, which is pronounced in splitting of {sup 1}H and {sup 13}C NMR signals.

  10. Refinement of La1.5Ba1.5Cu3O7-x from a Twinned Crystal

    DEFF Research Database (Denmark)

    Hjorth, Michael

    1996-01-01

    The structure of the title compound (barium copper lanthanum oxide, Ba1.50Cu3La1.50O6.66) has been refined from a twinned crystal using single-crystal methods. The results of the present investigation show lower standard deviations than the results of earlier powder diffraction refinements...

  11. Synthesis and characterization of a new photoluminescent material (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum La(Bpy)2q

    International Nuclear Information System (INIS)

    Kumar, Rahul; Bhargava, Parag

    2016-01-01

    A new photoluminescence material, (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum has been synthesized and characterized by different techniques. The prepared material La(Bpy) 2 q was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) shows the thermal stability up to 190°C.Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy) 2 q in ethanol showed absorption peak at 385nm, which may be attributed due to (π – π*) transitions. The photoluminescence spectra of La(Bpy) 2 q in ethanol solution showed intense peak at 490 nm

  12. Superconductivity in the lanthanum-yttrium-manganese alloy system

    International Nuclear Information System (INIS)

    Stierman, R.J.

    1980-03-01

    An empirical approach involving lattice instabilities was investigated in the search for new superconducting materials. Pseudo-lanthanide compounds using La and Y were prepared for the system La/sub 1-x/Y/sub x/Mn 2 by arc melting and subsequent heat treatment. Low temperature magnetic susceptibility and low temperature heat capacity measurements were made. The unit cell lattice parameters were determined from x-ray powder patterns taken on most samples and metallographic examination was carried out on selected samples. Alloys with low La concentrations (x greater than or equal to 0.6) showed RMn 2 in the cubic C15 Laves phase as the major component with second phase material present. The magnetic susceptibility and x-ray data indicated a superconducting phase which seemed to be the RMn 2 phase, but heat capacity measurements showed the second phase material was the superconductor, while the RMn 2 was not. Failure to form compounds with higher La content was experienced and may be due to the lattice instability expected at x = 0.56. This indicates that perhaps more stingent conditions are required to form pseudo-lanthanide compounds than were previously considered. More systems should be investigated to see if this is true, and to determine the possibilities of this approach

  13. Electric properties and phase transition behavior in lead lanthanum zirconate stannate titanate ceramics with low zirconate content

    Science.gov (United States)

    Zeng, Tao; Lou, Qi-Wei; Chen, Xue-Feng; Zhang, Hong-Ling; Dong, Xian-Lin; Wang, Gen-Shui

    2015-11-01

    The phase transitions, dielectric properties, and polarization versus electric field (P-E) hysteresis loops of Pb0.97La0.02(Zr0.42Sn0.58-xTix)O3 (0.13≤ x ≤0.18) (PLZST) bulk ceramics were systematically investigated. This study exhibited a sequence of phase transitions by analyzing the change of the P-E hysteresis loops with increasing temperature. The antiferroelectric (AFE) to ferroelectric (FE) phase boundary of PLZST with the Zr content of 0.42 was found to locate at the Ti content between 0.14 and 0.15. This work is aimed to improve the ternary phase diagram of lanthanum-doped PZST with the Zr content of 0.42 and will be a good reference for seeking high energy storage density in the PLZST system with low-Zr content. Project supported by the National Natural Science Foundation of China (Grant Nos. 51202273, 11204304, and 11304334) and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 14DZ2261000).

  14. Use of fluoride systems for some fission product separation from residues of fast reactor spent fuel fluorination

    International Nuclear Information System (INIS)

    Shishkov, Yu.D.; Khomyakov, V.I.

    1977-01-01

    Investigated has been a possibility of the use of fluoride systems (acid nitrozyl fluoride and molten salts) for americium extraction from residues of fluorination of irradiated fuel containing mainly fluorides of rare earth compounds, alkali and alkaline earth elements. At treatment of fission product fluorides by acid nitrozyl fluoride only cesium and uranium fluorides dissolve, while americium and rare earth fluorides are practically non-soluble in it. The solubility of cesium, strontium, barium and fluorides of some other rare earth elements in molten cryolite at the temperature of 1000 deg C, Li-NaF and LiF-CaF 2 of eutectic content at 750 and 800 deg C are respectively 15-77 %. Cerium fluoride presents an exception, its solubility in cryolite being only 0.73%. At treatment of mixture of americium and lanthanum fluorides by molten salts in the weight ratio of 1:1, approximately 50% of lanthanum and 65-70% of americium turn into melt independent of the type of melt. The maximum melt output of americium is obtained at treatment of lanthanum and americium fluoride mixture by cryolite melt at the temperature of 1000 deg C. It is shown that the presence of rare earth of fluorides, except lanthanum fluoride, effect significantly of americium distribution over phases in the process of fluoride processing by the fluoride molten salts

  15. Development of proton conducting materials and membranes based on lanthanum tungstate for hydrogen separation from gas mixtures; Entwicklung protonenleitender Werkstoffe und Membranen auf Basis von Lanthan-Wolframat fuer die Wasserstoffabtrennung aus Gasgemischen

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Janka

    2013-07-01

    Lanthanum tungstate La{sub 6-x}WO{sub 12-δ} (named LWO) is a ceramic material with mixed protonic electronic conductivity. Thereby it is a good candidate membrane material for hydrogen separation from synthesis gas in a fossil pre-combustion power plant. This work shows a material optimization by substitution targeted to clearly enhance the mixed conductivity and thereby the hydrogen flow through the LWO membrane. The first part of the work shows the synthesis and characterization of unsubstituted LWO. It points out that monophase LWO powder can be reproducibly synthesized. The La/W-ratio has to be considerably smaller than the nominal ratio of La/W = 6.0. It also depends on the used sintering conditions. Different relevant properties of LWO like stability in conditions close to application, thermal expansion, sintering behavior or microstructure were determined. Furthermore, the electrical conductivity of the material was investigated. LWO exhibits a prevailing protonic conductivity up to 750 C in wet atmospheres. Under dry atmospheres n-type conductivity was dominating. Oxygen ion and n-type conductivity dominated in wet and dry atmospheres above 750 C. The main part of the work is concerned with the development of new LWO based materials by substitutions. The aim is to achieve an improved mixed protonic electronic conductivity. Substitution elements for lanthanum side were Mg, Ca, Sr, Ba, Ce, Nd, Tb, Y and Al, while for the tungsten side Mo, Re and Ir were used. The total conductivity of the developed materials was investigated and compared to that of the unsubstituted LWO. The substitution of lanthanum led to no appreciable enhancement of the conductivity whereas the substitution of tungsten with 20 mol% molybdenum or 20 mol% rhenium clearly improved it. This caused a hydrogen flow about seven times higher for 20 mol% molybdenum- and about ten times higher for 20 mol% rhenium-substituted LWO in comparison with the unsubstituted LWO at 700 C. In the last part

  16. Antioxidant response of soybean seedlings to joint stress of lanthanum and acid rain.

    Science.gov (United States)

    Liang, Chanjuan; Wang, Weimin

    2013-11-01

    Excess of rare earth elements in soil can be a serious environmental stress on plants, in particular when acid rain coexists. To understand how such a stress affects plants, we studied antioxidant response of soybean leaves and roots exposed to lanthanum (0.06, 0.18, and 0.85 mmol L(-1)) under acid rain conditions (pH 4.5 and 3.0). We found that low concentration of La3+ (0.06 mmol L(-1)) did not affect the activity of antioxidant enzymes (catalase and peroxidase) whereas high concentration of La3+ (≥0.18 mmol L(-1)) did. Compared to treatment with acid rain (pH 4.5 and pH 3.0) or La3+ alone, joint stress of La3+ and acid rain affected more severely the activity of catalase and peroxidase, and induced more H2O2 accumulation and lipid peroxidation. When treated with high level of La3+ (0.85 mmol L(-1)) alone or with acid rain (pH 4.5 and 3.0), roots were more affected than leaves regarding the inhibition of antioxidant enzymes, physiological function, and growth. The severity of oxidative damage and inhibition of growth caused by the joint stress associated positively with La3+ concentration and soil acidity. These results will help us understand plant response to joint stress, recognize the adverse environmental impact of rare earth elements in acidic soil, and develop measures to eliminate damage caused by such joint stress.

  17. Influence of Lanthanum Doping on the Structural and Optical Properties of Hematite Nanopowders

    Science.gov (United States)

    Justus, J. Sharmila; Dharma Roy, S. Dawn; Raj, A. Moses Ezhil

    2016-10-01

    Rare-earth elements are an attractive class of dopant elements, as they give easily trivalent cations that possibly altering the structure and other properties of the parent nanoparticles and creating multifunctional materials because of their f-electronic configurations. Herein, experimental evidence has been given for a better understanding of the factors that dictate the interactions of La doping on the structure and optical properties of iron oxide nanoparticles. For that, lanthanum doped hematite (α-Fe2O3) nanoparticles were prepared by a facile solution method using iron (III) chloride (FeCl3) as starting precursor and sodium hydroxide (NaOH) as reducing agent without templates at low temperature. As-prepared powders were subsequently calcined in air for 3 hr at 800 °C. Xray diffraction (XRD) technique was used to study the nanocrystal formation of α-Fe2O3 and Fourier Transform Raman (FT-Raman) spectral information identified the chemical bond structure of the nanoparticles. Morphology study of the nanoparticles was identified using Scanning Electron Microscope (SEM) and the incorporated La content was recognized from the Energy Dispersive X-ray Spectroscopy (EDS) analysis. The optical absorption spectrum was recorded in the wavelength range of 200-2000 nm and the optical parameters such as absorption coefficient and optical band gap energy of pure and doped Fe2O3 nanoparticles were determined. Obtained results are interpreted by considering the impregnation of trivalent La cations that replaced Fe cations of the host structure.

  18. Nd3+-doped lanthanum lead boro-tellurite glass for lasing and amplification applications

    Science.gov (United States)

    Madhu, A.; Eraiah, B.; Manasa, P.; Srinatha, N.

    2018-01-01

    Nd3+-doped lanthanum lead boro-tellurite glass samples were prepared by conventional melt quenching method and their structural, thermal, fluorescence, and decay times of the glasses were investigated. Prepared glass samples exhibits amorphous nature and shows good thermal stability in the temperature range of 100-800 °C. Judd-Ofelt (JO) analysis was carried out and the intensity parameters (Ωλ = 2, 4, 6) also spontaneous radiative probability and stimulated-.emission cross-sections were estimated. The magnitude of Ωλ confirms the covalency nature. The near infrared emission spectra were measured by 808 nm excitation in which the emission intensity is found to be high at 1060 nm for the 4F3/2 → 4F11/2 transition. The stimulated cross section, effective band width and branching ratios are found to be 8.910 × 10-20 cm2, 21.57 nm and 53.72 % respectively, for 4F3/2 → 4F11/2 transition. The derived gain bandwidth, figure of merit, threshold and saturation intensity found to be comparable to some of the glass systems. Furthermore, the time decay rate found to decrease from 100 μs to 27 μs when the concentration increased from 0.1 to 3.0 mol% of Nd3+ ions and also all follow the single exponential behaviour which is attributed to the self quenching effect due to the cross-relaxation channels.

  19. Thickness effect on the structure, grain size, and local piezoresponse of self-polarized lead lanthanum zirconate titanate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Melo, M.; Araújo, E. B., E-mail: eudes@dfq.feis.unesp.br [Departamento de Física e Química, Faculdade de Engenharia de Ilha Solteira, UNESP—Univ. Estadual Paulista, 15385-000 Ilha Solteira, SP (Brazil); Shvartsman, V. V. [Institute for Materials Science, University Duisburg-Essen, 45141 Essen (Germany); Shur, V. Ya. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kholkin, A. L. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Department of Physics and CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal)

    2016-08-07

    Polycrystalline lanthanum lead zirconate titanate (PLZT) thin films were deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates to study the effects of the thickness and grain size on their structural and piezoresponse properties at nanoscale. Thinner PLZT films show a slight (100)-orientation tendency that tends to random orientation for the thicker film, while microstrain and crystallite size increases almost linearly with increasing thickness. Piezoresponse force microscopy and autocorrelation function technique were used to demonstrate the existence of local self-polarization effect and to study the thickness dependence of correlation length. The obtained results ruled out the bulk mechanisms and suggest that Schottky barriers near the film-substrate are likely responsible for a build-in electric field in the films. Larger correlation length evidence that this build-in field increases the number of coexisting polarization directions in larger grains leading to an alignment of macrodomains in thinner films.

  20. Composition dependence of the ferroelectric properties of lanthanum-modified bismuth titanate thin films grown by using pulsed-laser deposition

    CERN Document Server

    Bu, S D; Park, B H; Noh, T W

    2000-01-01

    Lanthanum-modified bismuth titanate, Bi sub 4 sub - sub x La sub x Ti sub 3 O sub 1 sub 2 (BLT), thin films with a La concentration of 0.25<=x<=1.00 were grown on Pt/Ti/SiO sub 2 /Si substrates by using pulsed-laser deposition. The BLT films showed well-saturated polarization-electric field curves whose remnant polarizations were 16.1 mu C/cm sup 2 , 27.8 mu C/cm sup 2 , 19.6 mu C/cm sup 2 , and 2.7 mu C/cm sup 2 , respectively, for x=0.25, 0.05, 0.75, and 1.00. The fatigue characteristics became better with increasing x up to 0.75. The Au/BLT/Pt capacitor with a La concentration of 0.50 showed an interesting dependence of the remanent polarization on the number of repetitive read/write cycles. On the other hand, the capacitor with a La concentration of 0.75 showed fatigue-free characteristics.

  1. Sorption of lanthanum and erbium from aqueous solution by activated carbon prepared from rice husk

    International Nuclear Information System (INIS)

    Awwad, N.S.; Gad, H.M.H.; Ahmad, M.I.; Aly, H.F.

    2010-01-01

    A biomass agricultural waste material, rice husk (RH) was used for preparation of activated carbon by chemical activation using phosphoric acid. The effect of various factors, e.g. time, ph, initial concentration and temperature of carbon on the adsorption capacity of lanthanum and erbium were quantitatively determined. It was found that the monolayer capacity is 175.4 mg/g for La(III) and 250 mg/g for Er(III) . The calculated activation energy of La(III) adsorption on the activated carbon derived from rice husk was equal to 5.84 kJ/ mol while 14.6 kJ/ mol for Er(III), which confirm that the reaction is mainly particle-diffusion controlled. The kinetics of sorption was described by a model of a pseudo-second-order. External diffusion and intra-particular diffusion were examined. The experimental data show that the external diffusion and intra-particular diffusion are significant in the determination of the sorption rate. Therefore, the developed sorbent is considered as a better replacement technology for removal of La (III) and Er(III) ions from aqueous solution due to its low cost and good efficiency, fast kinetics, as well as easy to handle and thus no or small amount of secondary sludge is obtained in this application

  2. Effect of compositional variations in the lead lanthanum zirconate stannate titanate system on electrical properties

    International Nuclear Information System (INIS)

    Markowski, K.; Park, S.E.; Yoshikawa, Shoko; Cross, L.E.

    1996-01-01

    The purpose of this work was to evaluate the effect of compositional modifications on the electrical properties of lead lanthanum zirconate stannate titanate (PLZST) ceramics, as well as to examine their electrically induced phase-change behavior. Variations in the Ti:Sn ratio were evaluated. Increased Ti 4+ content produced the following: decreased switching field, related to an increased antiferroelectric-ferroelectric (AFE-FE) transition temperature; constant hysteresis (ΔE) correlated with a constant temperature of the maximum dielectric constant (T max ); a sharper dielectric-constant maximum peak; and increased room-temperature dielectric constant (K). Variations in the Zr:Sn ratio also were evaluated. Increased Zr 4+ content produced the following: increased hysteresis with increased T max , decreased maximum dielectric constant, and decreased switching field with increased AFE-FE transition temperature (T AFE-FE ). From these results, with respect to compositional modifications, the AFE-FE switching field (E AFE-FE ) and ΔE were observed to be dependent strongly on T AFE-FE and T max , respectively. Negligible change existed in the strain achievable at the switching field, which remained constant for all compositions at ∼0.16%. The significance of this research was the ability demonstrated to tailor the properties of phase-change materials through compositional modifications

  3. Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo, E-mail: jibojiang0506@163.com; Han, Sheng, E-mail: hansheng654321@sina.com

    2015-12-01

    Highlights: • The effective surface area of the modified CPE has been expanded after self-assembly. • The GO–La composite exhibited excellent electrocatalytic activity toward DA. • The GO–La/CPE presented high selectivity, sensitivity, excellent stability and repeatability. - Abstract: A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO–La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO–La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO–La/CPE electrode for determining DA was linear in the region of 0.01–0.1 μM and 0.1–400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

  4. Impedance analysis of a disk-type SOFC using doped lanthanum gallate under power generation

    Science.gov (United States)

    Kato, Tohru; Nozaki, Ken; Negishi, Akira; Kato, Ken; Monma, Akihiko; Kaga, Yasuo; Nagata, Susumu; Takano, Kiyonami; Inagaki, Toru; Yoshida, Hiroyuki; Hosoi, Kei; Hoshino, Koji; Akbay, Taner; Akikusa, Jun

    Impedance measurements were carried out under practical power generation conditions in a disk-type SOFC, which may be utilized as a small-scale power generator. The tested cell was composed of doped lanthanum gallate (La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ) as the electrolyte, Sm 0.5Sr 0.5CoO 3 as the cathode electrode and Ni/Ce 0.8Sm 0.2O 2 cermet as the anode electrode. The cell impedance was measured between 10 mHz and 10 kHz by varying the fuel utilization and gas flow rate and plotted in complex impedance diagrams. The observed impedance shows a large semi-circular pattern on the low frequency side. The semi-circular impedance, having a noticeably low characteristic frequency between 0.13 and 0.4 Hz, comes from the change in gas composition, originally caused by the cell reaction. The change in impedance with the fuel utilization (load current) and the gas flow rate agreed qualitatively well with the theoretical predictions from a simulation. This impedance was dominant under high fuel-utilization power-generation conditions. The impedance, which described the activation polarizations in the electrode reactions, was comparatively small and scarcely changed with the change in fuel utilization (load current) and gas flow rate.

  5. X-ray photoelectron spectroscopy study of the surface of solid electrolyte La0.88Sr0.12Ga0.82Mg0.18O3-α

    International Nuclear Information System (INIS)

    Shkerin, S.N.; Kalashnikova, N.A.; Kuznetsov, M.V.

    2003-01-01

    The composition and chemical state of elements on the surface of solid oxygen-conducting electrolyte La 0.88 Sr 0.12 Ga 0.82 Mg 0.18 O 3-α prior to and after high-temperature annealing (T = 973 K) in CO 2 atmosphere were studied by the method of X-ray photoelectron spectroscopy. It is shown that products of interaction between doped lanthanum gallate and carbon dioxide are localized in the surface layer 8-10 nm thick. Annealing in CO 2 atmosphere does not involve formation of carbon chemical compounds with metals on the electrolyte surface. Surface layers both in the initial electrolyte and after allowance to stay in CO 2 were enriched by strontium oxide, lanthanum hydroxide being present on the surface [ru

  6. Luminescent determination of trace amounts of terbium using diantipyrylmethane and salicylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tishchenko, M A; Gerasimenko, G I; Poluehktov, N S [AN Ukrainskoj SSR, Odessa. Inst. Obshchej i Neorganicheskoj Khimii

    1978-01-01

    To elucidate the possibility of using pyrazolone-5-diantipyril-methane (DAM) derivative for determination of terbium microimpurities, the conditions have been studied of luminescent determination of terbium in complex compounds containing an ion of rare-earth element, diantipyrilmethane, and salicylic acid (Sal.). The ratio between the components in the complex REE-DAM-Sal is 1:1:3. La, Y, Gd do not affect the luminescence intensity of terbium complex. A luminescent method of determining terbium traces in highly pure oxides of lanthanum, gadolinium, lutetium, and yttrium has been developed in which suspensions of complex precipitation are used. The amount of terbium determined in oxide of lanthanum, gadolinium, and lutetium is (1-5)x10/sup -6/% and (2-3)x10/sup -5/% in yttrium oxide.

  7. Electron Emission And Beam Generation Using Ferroelectric Cathodes (electron Beam Generation, Lead Lanthanum Zicronate Titanate, High Power Traveling Wave Tube Amplfier)

    CERN Document Server

    Flechtner, D D

    1999-01-01

    In 1989, researchers at CERN published the discovery of significant electron emission (1– 100 A/cm2) from Lead- Lanthanum-Zirconate-Titanate (PLZT). The publication of these results led to international interest in ferroelectric cathodes studies for use in pulsed power devices. At Cornell University in 1991, experiments with Lead-Zirconate-Titanate (PZT) compositions were begun to study the feasibility of using this ferroelectric material as a cathode in the electron gun section of High Power Traveling Wave Tube Amplifier Experiments. Current-voltage characteristics were documented for diode voltages ranging from 50– 500,000 V with anode cathode gaps of.5– 6 cm. A linear current-voltage relation was found for voltages less than 50 kV. For diode voltages ≥ 200 kV, a typical Child-Langmuir V3/2 dependence was observed...

  8. Synthesis and characterization of a new photoluminescent material (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum La(Bpy)2q

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rahul, E-mail: id-kumarrahul003@gmail.com; Bhargava, Parag [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology-Bombay, Mumbai-400076 (India)

    2016-05-06

    A new photoluminescence material, (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum has been synthesized and characterized by different techniques. The prepared material La(Bpy){sub 2}q was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) shows the thermal stability up to 190°C.Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy){sub 2}q in ethanol showed absorption peak at 385nm, which may be attributed due to (π – π*) transitions. The photoluminescence spectra of La(Bpy){sub 2}q in ethanol solution showed intense peak at 490 nm.

  9. Development and characterization of ceramic composites alumina-titania based reinforced with lanthanum oxide for fabrication of inert coatings for metallic tanks of the oil industry

    International Nuclear Information System (INIS)

    Bandeira, J.M.; Yadava, Y.P.; Silva, N.D.G.; Ferreira, R.A.S.

    2016-01-01

    Crude petroleum is highly corrosive causing superficial degradation in metallic tanks used for storage and transportation of this material, which causes a serious problem in the oil industry. An alternative to solve this problem is to use some kind of coating that is inert to this kind of corrosion. Alumina and titania are interesting materials for several engineering applications because, when compared with other ceramic materials, they present superior mechanical properties, e.g. high mechanical strength, good chemical stability and high fracture toughness combined with good wear resistance and a coefficient of thermal expansion close to the iron's, which makes them fit to use in ceramic hardening process and coating. In this paper, alumina-titania ceramic composites with 5%, 10%, 15% and 20% of titania (TiO2) and reinforced with 2% of lanthanum oxide of were produced by thermo-mechanical processing and sintering techniques at 1350 deg C. In these composites, microstructure and mechanical properties were analyzed using X-ray spectroscopy, optical microscopy, scanning electron microscopy and Vickers hardness in order to evaluate their applicability. X-ray spectroscopy showed the formation of composite without the presence of other phases. Optical microscopy and scanning electron microscopy showed a homogeneous microstructure in terms of particle size and distribution. Vickers hardness test showed a gradual decrease in hardness with the addition of titania. The composite with 5% of titania and 2% of lanthanum oxide is the best choice for structural applications. The composites were submerged in crude petroleum for 30 days to study their stability in such environment. Through the analysis of X-ray spectroscopy, optical microscopy and Vickers hardness before and after the submersion in crude petroleum, it was not observed structural or microstructural degradation nether alterations in mechanical properties. This way, it was concluded that these composites have good

  10. The special features of the crystal structure and properties of oxides with mixed conductivity based on lanthanum gallate

    Science.gov (United States)

    Politova, E. D.; Ivanov, S. A.; Kaleva, G. M.; Mosunov, A. V.; Rusakov, V. S.

    2008-10-01

    The paper presents a review of works on the synthesis, structural composition effects, phase transitions, and electrical conductivity properties of multicomponent solid solutions based on heterosubstituted lanthanum gallate (La,A)(Ga,M)O3 - y . High-temperature phase transitions and structural and charge ordering effects were studied. The presence of iron cations in different valence states was proved; the relative contents of these cations depended on the x parameter and nonstoichiometry parameter y of the base composition. For M = Fe, antiferromagnetic ordering was observed; its temperature interval was determined by the concentration of iron cations in the high-spin state. The total conductivity was found to increase as the concentration of transition metal cations grew because of an increase in the electronic conductivity component. The data on structural parameters and dc and ac conductivity substantiated the conclusion that the highest ionic conductivity and permeability to oxygen were characteristic of iron-containing oxides. The results obtained are evidence that crystal chemical factors play a determining role in the formation of the ion-conducting properties of anion-deficient perovskite-like oxides.

  11. Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate

    Science.gov (United States)

    Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar

    2014-09-01

    One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed.

  12. Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate

    International Nuclear Information System (INIS)

    Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar

    2014-01-01

    One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed. (orig.)

  13. Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate

    Energy Technology Data Exchange (ETDEWEB)

    Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar [Indian Institute of Technology (Banaras Hindu University), Department of Physics, Varanasi (India)

    2014-09-15

    One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-δ} (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed. (orig.)

  14. Investigation of the complex structure, comparative DNA-binding and DNA cleavage of two water-soluble mono-nuclear lanthanum(III) complexes and cytotoxic activity of chitosan-coated magnetic nanoparticles as drug delivery for the complexes

    Czech Academy of Sciences Publication Activity Database

    Asadi, Z.; Nasrollahi, N.; Karbalaei-Heidari, H.; Eigner, Václav; Dušek, Michal; Mobaraki, N.; Pournejati, R.

    2017-01-01

    Roč. 178, May (2017), s. 125-135 ISSN 1386-1425 R&D Projects: GA ČR(CZ) GA15-12653S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : lanthanum(III) * binding constant * molecular docking * DNA cleavage * cytotoxicity * chitosan Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.536, year: 2016

  15. Demonstration of high efficiency intermediate-temperature solid oxide fuel cell based on lanthanum gallate electrolyte

    International Nuclear Information System (INIS)

    Inagaki, Toru; Nishiwaki, Futoshi; Kanou, Jirou; Yamasaki, Satoru; Hosoi, Kei; Miyazawa, Takashi; Yamada, Masaharu; Komada, Norikazu

    2006-01-01

    The Kansai Electric Power Co., Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been jointly developing intermediate-temperature solid oxide fuel cells (SOFCs). The operation temperatures between 600 and 800 o C were set as the target, which enable SOFC to use less expensive metallic separators for cell-stacking and to carry out internal reforming of hydrocarbon fuels. The electrolyte-supported planar-type cells were fabricated using highly conductive lanthanum gallate-based electrolyte, La(Sr)Ga(Mg,Co)O 3-δ , Ni-(CeO 2 ) 1-x (SmO 1.5 ) x cermet anode, and Sm(Sr)CoO 3-δ cathode. The 1 kW-class power generation modules were fabricated using a seal-less stack of the cells and metallic separators. The 1 kW-class prototype power generation system with the module was developed with the high performance cell, which showed the thermally self-sustainability. The system included an SOFC module, a dc-ac inverter, a desulfurizer, and a heat recovery unit. It provided stable ac power output of 1 kW with the electrical efficiency of 45% LHV based on ac output by using city gas as a fuel, which was considered to be excellent for such a small power generation system. And the hot water of 90 o C was obtained using high temperature off-gas from SOFC

  16. Demonstration of high efficiency intermediate-temperature solid oxide fuel cell based on lanthanum gallate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, Toru [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan)]. E-mail: inagaki@rdd.kepco.co.jp; Nishiwaki, Futoshi [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan); Kanou, Jirou [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan); Yamasaki, Satoru [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan); Hosoi, Kei [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan); Miyazawa, Takashi [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan); Yamada, Masaharu [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan); Komada, Norikazu [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan)

    2006-02-09

    The Kansai Electric Power Co., Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been jointly developing intermediate-temperature solid oxide fuel cells (SOFCs). The operation temperatures between 600 and 800 {sup o}C were set as the target, which enable SOFC to use less expensive metallic separators for cell-stacking and to carry out internal reforming of hydrocarbon fuels. The electrolyte-supported planar-type cells were fabricated using highly conductive lanthanum gallate-based electrolyte, La(Sr)Ga(Mg,Co)O{sub 3-{delta}}, Ni-(CeO{sub 2}){sub 1-x}(SmO{sub 1.5}) {sub x} cermet anode, and Sm(Sr)CoO{sub 3-{delta}} cathode. The 1 kW-class power generation modules were fabricated using a seal-less stack of the cells and metallic separators. The 1 kW-class prototype power generation system with the module was developed with the high performance cell, which showed the thermally self-sustainability. The system included an SOFC module, a dc-ac inverter, a desulfurizer, and a heat recovery unit. It provided stable ac power output of 1 kW with the electrical efficiency of 45% LHV based on ac output by using city gas as a fuel, which was considered to be excellent for such a small power generation system. And the hot water of 90 {sup o}C was obtained using high temperature off-gas from SOFC.

  17. Effect of Lanthanum-Natural Zeolite, La/NZA catalyst on biodiesel production from crude palm oil

    Science.gov (United States)

    Setianingsih, A.; Wisrayetti; Khairat; Bahri, S.

    2018-04-01

    Biodiesel can be produced from vegetable oils through the trans-esterification process. In this study, potential vegetable oil of Crude Palm Oil (CPO) was used as sample. The purposes of this research were to produce biodiesel from CPO as an alternative fuel, having study the ratio of impregnation of Lanthanum on NZA, and its catalyst weight to the biodiesel yield. The La/NZA catalyst is made as followed, first the natural zeolite size was reduced using grinding, then activated using HCl 6 N and NH4Cl 1 N, followed with the drying process. La is impregnated into NZA as solution having variations of 1 and 3% (w/w) of NZA, then it was followed with dried in an oven, calcination, oxidation and reduction. Production of biodiesel is carried out through two stages of esterification and transesterification processes. In the trans-esterification process conducted with the various variation of catalyst weight i.e. 1, 2 and 3% of La/NZA (w/w) for a total weight of 80 grams of CPO sample, having the ratio of oil : methanol 1 : 9. Reaction was lasted for 60 minutes at 60°C having 400 rpm stirring speed. From the result, the conversion of 85.37% is given by the run on using 3% La/NZA catalyst having catalyst weight 1%.

  18. Effect of sputtered lanthanum hexaboride film thickness on field emission from metallic knife edge cathodes

    Science.gov (United States)

    Kirley, M. P.; Novakovic, B.; Sule, N.; Weber, M. J.; Knezevic, I.; Booske, J. H.

    2012-03-01

    We report experiments and analysis of field emission from metallic knife-edge cathodes, which are sputter-coated with thin films of lanthanum hexaboride (LaB6), a low-work function material. The emission current is found to depend sensitively on the thickness of the LaB6 layer. We find that films thinner than 10 nm greatly enhance the emitted current. However, cathodes coated with a thicker layer of LaB6 are observed to emit less current than the uncoated metallic cathode. This result is unexpected due to the higher work function of the bare metal cathode. We show, based on numerical calculation of the electrostatic potential throughout the structure, that the external (LaB6/vacuum) barrier is reduced with respect to uncoated samples for both thin and thick coatings. However, this behavior is not exhibited at the internal (metal/LaB6) barrier. In thinly coated samples, electrons tunnel efficiently through both the internal and external barrier, resulting in current enhancement with respect to the uncoated case. In contrast, the thick internal barrier in thickly coated samples suppresses current below the value for uncoated samples in spite of the lowered external barrier. We argue that this coating thickness variation stems from a relatively low (no higher than 1018 cm-3) free carrier density in the sputtered polycrystalline LaB6.

  19. Role of cerium, lanthanum, and strontium additions in an Al-Si-Mg (A356) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Nabawy, Ahmed M.; Samuel, Agnes M.; Samuel, Fawzy H. [Universite du Quebec, Chicoutimi (Canada). Dept. des Sciences Appliquees; Alkahtani, Saleh A.; Abuhasel, Khaled A. [Salman Bin Abdulaziz Univ., Riyadh (Saudi Arabia). Mechanical Engineering Dept.

    2016-05-15

    The effects of individual and combined additions of cerium (Ce), lanthanum (La), and strontium (Sr) on the eutectic modification and solidification characteristics of an Al-Si-Mg (A356) aluminum alloy were investigated using optical microscopy and thermal analysis techniques. Addition of Ce, La, and Sr resulted in different depression levels of the eutectic nucleation temperature and eutectic growth undercooling, generating modified eutectic structures exhibiting different levels of modification. Microstructural results showed that the best modification levels using individual additions were achieved by Sr which produced a fine fibrous eutectic structure, followed by La, which produced a refined lamellar structure, with Ce providing the lowest level of modification. On the other hand, a combined addition of Ce and Sr provided the highest modification level, with the production of a very fine fibrous eutectic silicon structure. In general, the addition of Sr helped to further increase the refinement obtained in the alloys containing La or Ce + La additions. In the latter alloy, the main intermetallic phases observed were La(Al,Si){sub 2} and Al{sub 20}(La,Ce)Ti{sub 2}Si. The improved modification levels were found to be proportional to the depression in the eutectic nucleation temperature and the eutectic growth undercooling. A high cooling rate also improved the modification level by at least one level.

  20. Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

    Science.gov (United States)

    Ahmad, R.; Asmael, M. B. A.

    2016-07-01

    The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

  1. Low-temperature sintering and electrical properties of strontium- and magnesium-doped lanthanum gallate with V2O5 additive

    Science.gov (United States)

    Ha, Sang Bu; Cho, Yoon Ho; Ji, Ho-Il; Lee, Jong-Ho; Kang, Yun Chan; Lee, Jong-Heun

    2011-03-01

    The effects of a V2O5 additive on the low-temperature sintering and ionic conductivity of strontium- and magnesium-doped lanthanum gallate (LSGM: La0.8Sr0.2Ga0.8Mg0.2O2.8) are studied. The LSGM powders prepared by the glycine nitrate method are mixed with 0.5-2 at.% of VO5/2 and then sintered at 1100-1400 °C in air for 4 h. The apparent density and phase purity of the LSGM specimens are increased with increasing sintering temperature and VO5/2 concentration due to the enhanced sintering and mass transfer via the intergranular liquid phase. The 1 at.% VO5/2-doped LSGM specimen sintered at 1300 °C exhibits a high oxide ion conductivity of ∼0.027 S cm-1 at 700 °C over a wide range of oxygen partial pressure (PO2 =10-27 - 1 atm), thereby demonstrating its potential as a useful electrolyte for anode-supported solid oxide fuel cells (SOFCs) without the requirement for any buffer layer between the electrolyte and anode.

  2. Binary and ternary chelates of scandium (III), Yttrium (III) and lanthanum (III) with ethyleneglycol-bis(. beta. -aminoethylether)-tetraacetic acid as primary and substituted salicylic acids as secondary ligands

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, A K; Chandra, M; Agarwala, B V; Dey, A K [Allahabad Univ. (India). Chemical Labs.

    1980-01-01

    Formation constants of binary and ternary complexes of the systems of the type: M-L and M-egta-L (M = scandium(III), yttrium(III) and lanthanum(III), egta = ethylene glycol-bis(..beta..-aminoethylether)-tetra acetic acid, L = o-cresotic acid (o-ca), m-cresotic acid (m-ca), 5-chlorosalicyclic acid(csa), and 3,5-dibromosalicylic acid (dbsa)) have been determined pH-metrically at 25deg and ..mu.. = 0.1M (KNO/sub 3/) in 50% (v/v) aqueous-ethanol medium. The order of stabilities of ternary complexes has been compared with those of corresponding binary complexes, and results discussed on the basis of coulombic interactions.

  3. Production and processing of spinel semi-porous sintered blocks to CAD-CAM with lanthanum-glass infiltration for dental applications; Producao e processamento de blocos sinterizados semi-porosos de espinelio para CAD-CAM com infiltracao de vidro de lantanio para aplicacoes dentarias

    Energy Technology Data Exchange (ETDEWEB)

    Lourenco, A.A.C.; Ogasawara, T.; Costa Neto, C.A.; Santos, F.V.C., E-mail: ogasawat@metalmat.ufrj.b [Universidade Federal do Rio de Janeiro (PEMM/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao em Engenharia. Programa de Engenharia Metalurgica e de Materiais

    2009-07-01

    The objective of this research was to obtain direct synthesis and sintering spinel by using powder mixing method for CAD-CAM ceramics manufacturing. Powders of alumina and magnesia (71.8 wt% Al2O3 and 28.2 wt% MgO) were mixed with 5 wt% of PVA and PEG binders and homogenized using ball mill (12h), then deagglomerated and submitted to uniaxial pressing into discs and plates (54 to 221.96 MPa), followed by isostatic pressing (186.03 MPa) and sintering at 1500 deg C(GrI) , 1600 C(GrII) and 1700 deg C(GrIII). Characterizations: XRD, density and four-point flexural strength and (for GrIII) elasticity modulus and Vickers microhardness. Lanthanum-glass was infiltrated into samples from all three Groups. Conclusions: (1) Plenty success for the pediatrician method; (2) Maximum density achieved for GrIII, best mechanical strength for GrII (compared to that of commercial product), this last one being the most indicated for In-Ceram manufacturing via CAD-CAM route; (3) The flexural strength of GrI might be improved a lot after Lanthanum-glass infiltration. (author)

  4. Physical properties of lanthanum monosulfide thin films grown on (100) silicon substrates

    Science.gov (United States)

    Cahay, M.; Garre, K.; Wu, X.; Poitras, D.; Lockwood, D. J.; Fairchild, S.

    2006-06-01

    Thin films of lanthanum monosulfide (LaS) have been deposited on Si (100) substrates by pulsed laser deposition. The films are golden yellow in appearance with a mirrorlike surface morphology and a sheet resistance around 0.1 Ω/□, as measured using a four-probe measurement technique. The thin films are characterized by atomic force microscopy (AFM), x-ray diffraction (XRD) analysis, high resolution transmission electron microscopy (HRTEM), ellipsometry, and Raman spectroscopy. The root-mean-square variation of (1 μm thick) film surface roughness measured over a 1 μm2 area by AFM was found to be 1.74 nm. XRD analysis of fairly thick films (micrometer size) reveals the growth of the cubic rocksalt structure with a lattice constant of 5.863(7) A˚, which is close to the bulk LaS value. HRTEM images reveal that the films are comprised of nanocrystals separated by regions of amorphous material. Two beam bright field TEM images show that there is a strain contrast in the Si substrate right under the interface with the LaS film and penetrating into the Si substrate. This suggests that there is an initial epitaxial-like growth of the LaS film on the Si substrate that introduces a strain as a result of the 8% lattice mismatch between the film and substrate. Ellipsometry measurements of the LaS films are well characterized by a Drude-Lorentz model from which an electron concentration of about 2.52×1022 cm-3 and a mobility around 8.5 cm2/V s are derived. Typical crystalline LaS features were evident in Raman spectra of the films, but the spectra also revealed their disordered (polycrystalline) nature.

  5. Peculiarities of electronic, phonon and magnon subsystems of lanthanum and samarium tetraborides

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, V.V., E-mail: vvnovikov@mail.ru; Mitroshenkov, N.V.; Matovnikov, A.V.

    2015-10-15

    Experimental research was carried out to study the temperature dependences of heat capacity C{sub p}(T = 2–300 K), lattice parameters a(T), and ≿(T), (5–300 K) of lanthanum and samarium tetraborides. A comparison with data obtained previously for LuB{sub 4} reveals the peculiar influence of lanthanide contraction and the rare-earths mass on the thermodynamic properties of rare earth tetraborides at low and high temperatures. Sharp anomalies were found in the heat capacity and thermal expansion for SmB{sub 4} at T{sub N} = 25.1 K, conditioned by the phase transition into antiferromagnetic state. The more poorly defined heat capacity anomaly around 7 K is referred to the quadrupole orbital fluctuation of the atomic magnetic moments for Sm{sup 3+} ions. The electronic, lattice, and magnetic contributions to the heat capacity and thermal expansion of samarium tetraboride were defined. Our approach makes it possible to adequately approximate the lattice components of heat capacity and thermal expansion by combining the Debye and Einstein contributions, which are based on the joint analysis of calorimetric and X-ray data. The influence of the frustration of the atomic magnetic moment system for Sm{sup 3+} ions on the thermodynamic characteristics of the samarium tetraboride magnetic phase transition was revealed. - Highlights: • The heat capacity and lattice parameters for LaB{sub 4} and SmB{sub 4} were determined at 2–300 K. • The anomalies of C{sub p}(T), a(T), c(T) for SmB{sub 4} due to the phase transition are revealed. • The lattice contributions to the thermal properties of LaB{sub 4} and SmB{sub 4} are analyzed.

  6. On the luminescence of perovskite type rare earth gallates

    International Nuclear Information System (INIS)

    Jianmei, Y.; Qingyuan, W.; Shuzhen, L.; Lianren, S.; Mingyu, C.

    1985-01-01

    It has been reported that perovskite type lanthanum gallates may be a good host material for laser and luminescence, but in the rare earth gallates studied, the numbers of perovskite type are less than that of the garnet type and there is less report on their spectroscopic properties in the literature. In this paper synthesis and spectroscopic properties of these compounds are studied

  7. Phase transition of La- chalcogenides under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Dinesh Chandra [Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior - 474 011 (India); Raypuria, Gajendra Singh, E-mail: gsraypuria@gmail.com [Department of Physics, Govt. K.R.G. P.G. Autonomous College, Gwalior - 474 001 (India)

    2014-04-24

    The lanthanum compounds have been found to undergo transition from their initial NaCl-type structure to high pressure body centered tetragonal (BCT) structure (distorted CsCl-type P4/mmm) using CTIP model. The calculated values of cohesive energy, lattice constant, phase transition pressure, relative volume collapse agree well with the available measured data and better than those computed by earlier workers.

  8. Evaluation of GdBaCo{sub 2}O{sub 5+{delta}} as cathode material for doped lanthanum gallate electrolyte IT-SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Tarancon, A. [Department of Inorganic Chemistry, University of La Laguna, La Laguna, Tenerife (Spain); EME/XaRMAE/IN, Department of Electronics, University of Barcelona (Spain); Marrero-Lopez, D.; Ruiz-Morales, J.C.; Nunez, P. [Department of Inorganic Chemistry, University of La Laguna, La Laguna, Tenerife (Spain); Pena-Martinez, J.

    2008-10-15

    The layered perovskite GdBaCo{sub 2}O{sub 5+{delta}} (GBCO), recently proposed for intermediate temperature solid oxide fuel cell applications, was investigated and compared with Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) cathode material using La{sub 0.9}A{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85} (A=Sr,Ba) as electrolytes. Area-specific resistance was measured by impendance spectroscopy in symmetrical cells. The cobaltites were prepared by a modified citrate sol-gel route and tested as cathode materials for doped lanthanum gallate-based cells using dry H{sub 2} as fuel and air as oxidant, rendering power density values of 180 and 240 mW cm {sup -2} at 1,073 K (1 mm thick pellets) for GBCO and BSCF fuel cells, respectively. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  9. Low temperature synthesis of nanocrystalline lanthanum monoaluminate powders by chemical coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, C.-L. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, C.-L. [Department of Materials Science and Engineering, I-Shou University, 1 Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung 840, Taiwan (China); Chen, T.-Y. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Chen, G.-J. [Department of Materials Science and Engineering, I-Shou University, 1 Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung 840, Taiwan (China); Hung, I-M. [Department of Chemical Engineering and Materials Science, Yuan Ze University, 135 Yuan-Tung Road, Chungli, Taoyuan 320, Taiwan (China); Shih, C.-J. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China)]. E-mail: CJShih@kmu.edu.tw; Fung, K.-Z. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China)

    2007-08-16

    Nanocrystalline lanthanum monoaluminate (LaAlO{sub 3}) powders were prepared by chemical coprecipitation using 25 vol.% of NH{sub 4}OH, 0.05 M La(NO{sub 3}){sub 3}.6H{sub 2}O and 0.05 M Al(NO{sub 3}){sub 3}.9H{sub 2}O aqueous solutions as the starting materials. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analyses (TGA/DTA), X-ray diffraction (XRD), Raman spectrometry, specific surface area (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) were utilized to characterize the LaAlO{sub 3} powders prepared by chemical coprecipitation. The crystallization temperature of the LaAlO{sub 3} precursor gels precipitated at pH 9 is estimated as 810 deg. C by TG/DTA. The XRD pattern of the LaAlO{sub 3} precursor gels precipitated at pH 8-12 and calcined at 700 deg. C for 6 h shows a broad arciform continuum exist between 24{sup o} and 32{sup o} and sharp peaks of LaAlO{sub 3} except the precursor gels precipitated at pH 9. For the LaAlO{sub 3} precursor gels precipitated at pH 9 and calcined at 700 deg. C for 6 h, the formation of the perovskite LaAlO{sub 3} phase occurs and the presence of crystalline impurities is not found. The crystallite size of LaAlO{sub 3} slightly increases from 37.8 to 41.5 nm with calcination temperature increasing from 700 to 900 deg. C for 6 h. The LaAlO{sub 3} powders prepared by chemical coprecipitation have a considerably large specific surface of 30 m{sup 2}/g. The relative density greater than 97% is obtained when these nanocrystalline LaAlO{sub 3} powders are sintered at 1550 deg. C for 2 h.

  10. X-ray intensifying screens

    International Nuclear Information System (INIS)

    Bossomaier, T.R.J.; Sangway, P.C.

    1979-01-01

    It is claimed that stabilization of X-ray intensifying screens against discolouration and hydrolysis of lanthanum or gadolinium oxyhalide phosphors can be achieved by incorporating into the phosphor/binder formulation a compound containing free epoxy groups. Suitable epoxy compounds include gamma glycidoxy trimethoxy silane and dimethyl di(m-glycidoxy methylphenyl) methane. The oxyhalide may be activated by Tb, Tm or Yb and may be mixed with other phosphors. Plasticisers and organo-tin stabilisers for the formulation are given. Many binders are specified, preferably these should not react with the free epoxy groups. (UK)

  11. Lanthanum (III) regulates the nitrogen assimilation in soybean seedlings under ultraviolet-B radiation.

    Science.gov (United States)

    Huang, Guangrong; Wang, Lihong; Zhou, Qing

    2013-01-01

    Ultraviolet-B (UV-B, 280-320 nm) radiation has seriously affected the growth of plants. Finding the technology/method to alleviate the damage of UV-B radiation has become a frontal topic in the field of environmental science. The pretreatment with rare earth elements (REEs) is an effective method, but the regulation mechanism of REEs is unknown. Here, the regulation effects of lanthanum (La(III)) on nitrogen assimilation in soybean seedlings (Glycine max L.) under ultraviolet-B radiation were investigated to elucidate the regulation mechanism of REEs on plants under UV-B radiation. UV-B radiation led to the inhibition in the activities of the key enzymes (nitrate reductase, glutamine synthetase, glutamate synthase) in the nitrogen assimilation, the decrease in the contents of nitrate and soluble proteins, as well as the increase in the content of amino acid in soybean seedlings. The change degree of UV-B radiation at the high level (0.45 W m(-2)) was higher than that of UV-B radiation at the low level (0.15 W m(-2)). The pretreatment with 20 mg L(-1) La(III) could alleviate the effects of UV-B radiation on the activities of nitrate reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase, promoting amino acid conversion and protein synthesis in soybean seedlings. The regulation effect of La(III) under UV-B radiation at the low level was better than that of UV-B radiation at the high level. The results indicated that the pretreatment with 20 mg L(-1) La(III) could alleviate the inhibition of UV-B radiation on nitrogen assimilation in soybean seedlings.

  12. Ferroelectric and Piezoelectric properties of (111) oriented lanthanum modified lead zirconate titanate film

    International Nuclear Information System (INIS)

    Dutta, Soma; Antony Jeyaseelan, A.; Sruthi, S.

    2014-01-01

    Lanthanum modified lead zirconate titanate (PLZT) thick film with molecular formula of Pb 0.92 La 0.08 (Zr 0.52 Ti 0.48 ) 0.98 O 3 was grown preferentially along (111) direction on Pt/SiO 2 /Si (platinum/silicon oxide/silicon) substrate by spin coating of chemical solution. The directional growth of the film was facilitated by platinum (Pt) (111) template and rapid thermal annealing. X-ray diffraction pattern and atomic force microscopy revealed the preferential growth of the PLZT film. The film was characterized for ferroelectric and detailed piezoelectric properties in a parallel plate capacitor (metal–PLZT–metal) configuration. Ferroelectric characterization of the film showed saturated hysteresis loop with remanent polarization and coercive electric field values of 10.14 μC/cm 2 and 42 kV/cm, respectively, at an applied field of 300 kV/cm. Longitudinal piezoelectric coefficient (d 33,f ) was measured by employing converse piezoelectric effect where electrical charge response and displacement were measured with electrical voltage excitation on the sample electrodes. The effective transverse piezoelectric coefficient (e 31,f ) was derived from charge measurement with an applied mechanical excitation strain by using the four point bending method. d 33,f and e 31,f coefficients of PLZT films were found to be 380 pm/V and − 0.831 C/m 2 respectively. - Highlights: • PLZT (111) film is prepared by spin coating of chemical sol on Pt (111) template. • Piezoelectric d 33 value (380 pm/V) of PLZT film is found 20% higher than PZT. • Transverse piezocoefficient e 31,f of PLZT film is reported for the first time

  13. Thermophysical Properties of Matter - The TPRC Data Series. Volume 6. Specific Heat - Nonmetallic Liquids and Gases

    Science.gov (United States)

    1970-01-01

    hexahydrate (ErClj-6H201 Erbium gallate (see Trierbium p«ntagallium dodecaoxide) Trierbium pentagallium dodecaoxide lErjGajO« (Garnet) J Erbium oxide (E...Freon 22) Isotron 113 (see Freon 113) Isotron 114 (see Freon 114) J odium (see Iodine) Kalium (see Potassium) Krypton Lanthana (see Lanthanum ...oxide) Lanthanum Lanthanum oxide (LajOj) Lanthanum sesquioxide (see Lanthanum oxide) Dilantanum trioxide (see Lanthanum oxide) T auehing gas (see

  14. Polarization fluctuation behavior of lanthanum substituted Bi{sub 4}Ti{sub 3}O{sub 12} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Ni; Xiang, Ping-Hua, E-mail: phxiang@ee.ecnu.edu.cn; Zhang, Yuan-Yuan; Wu, Xing; Tang, Xiao-Dong; Yang, Ping-Xiong; Duan, Chun-Gang; Chu, Jun-Hao [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

    2015-09-14

    Polarization fluctuation behavior of lanthanum substituted Bi{sub 4}Ti{sub 3}O{sub 12} (Bi{sub 4−x}La{sub x}Ti{sub 3}O{sub 12}, BLT) ferroelectric thin films has been examined. Remnant polarization exhibits an initial increase (P{sub up}, 1–10{sup 6} cycles) and a subsequent decrease (P{sub down}, 10{sup 6}–10{sup 9} cycles) with switching cycles, whereas the dielectric constant exhibits a continuous decrease. By careful investigations on the effect of switching frequency and annealing atmosphere on the polarization fluctuation characteristics, we propose that this polarization fluctuation characteristic of BLT films is attributed to the competition between domain pinning and passive layer growing effect, due to the redistribution of oxygen vacancy related defect under external applied field. P{sub up} behavior is dominated by the unpinning of pinned domain, while P{sub down} behavior is dominated by the reduction of applied field on BLT bulk layer, due to the growing of the passive layer between BLT and Pt electrode. By assuming the dielectric constant and initial thickness of passive layer, the passive layer was estimated to be about 2–5 times thicker than the initial state after 10{sup 9} cycling.

  15. The exploration of Lanthanum based perovskites and their complementary electrolytes for the supercapacitor applications

    Directory of Open Access Journals (Sweden)

    Nadarajan Arjun

    Full Text Available In this study, four different kinds of perovskite powders (LaMnO3, LaFeO3, LaCrO3, and LaNiO3 were prepared and investigated as anode materials for supercapacitor. The as-prepared powders were blended with active carbon and subsequently coated on the nickel plates as the collector layer of the supercapacitors. Three different types of the aqueous solutions (3 M KCl, 1 M LiOH, and 3 M LiOH were respectively served as the electrolytes for the supercapacitor. The morphology and crystalline phase were characterized by transmission electron microscopy and XRD. The electrical capacity and impedance were measured by the electrochemical capacitance voltage analyzer and impedance spectroscopy. The profiles of specific capacitance of the four different anodic electrodes and three different electrolytes were implemented. The impedance results indicated that four asymmetric pseudocapacitors didn’t show any Warburg-type line and semi-circle line in the low-frequency region. According to the CV profiles, the intrinsic LaNiO3 exhibits the highest specific capacitance of 106.58 F/g in 3 M LiOH. Furthermore, the 98% of the initial capacitance of LaNiO3 was retained after 500 charge-discharge life cycles at the maximum current density of 1 A/g. The efficient charge storage of LaNiO3 was attributed by the anion intercalated redox reactions along with the suitability of electrode-electrolyte interactions. Keywords: Perovskite, Lanthanum nickel oxide, Pseudocapacitance, Asymmetric supercapacitor, Oxygen de-intercalation

  16. Effects of lanthanum(III) on nitrogen metabolism of soybean seedlings under elevated UV-B radiation.

    Science.gov (United States)

    Cao, Rui; Huang, Xiao-hua; Zhou, Qing; Cheng, Xiao-ying

    2007-01-01

    The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum (La) on nitrogen metabolism under two different levels of elevated UV-B radiation (UV-B, 280-320 nm). The whole process of nitrogen metabolism involves uptake and transport of nitrate, nitrate assimilation, ammonium assimilation, amino acid biosynthesis, and protein synthesis. Compared with the control, UV-B radiation with the intensity of low level 0.15 W/m2 and high level 0.45 W/m2 significantly affected the whole nitrogen metabolism in soybean seedlings (p nitrogen-metabolism-related enzymes, such as: nitrate reductase (NR) to the nitrate reduction, glutamine systhetase (GS) and glutamine synthase (GOGAT) to the ammonia assimilation, while it increased the content of free amino acids and decreased that of soluble protein as well. The damage effect of high level of UV-B radiation on nitrogen metabolism was greater than that of low level. And UV-B radiation promoted the activity of the anti-adversity enzyme glutamate dehydrogenase (GDH), which reduced the toxicity of excess ammonia in plant. After pretreatment with the optimum concentration of La (20 mg/L), La could increase the activity of NR, GS, GOGAT, and GDH, and ammonia assimilation, but decrease nitrate and ammonia accumulation. In conclusion, La could relieve the damage effect of UV-B radiation on plant by regulating nitrogen metabolism process, and its alleviating effect under low level was better than that under the high one.

  17. Isotopically modified compounds

    International Nuclear Information System (INIS)

    Kuruc, J.

    2009-01-01

    In this chapter the nomenclature of isotopically modified compounds in Slovak language is described. This chapter consists of following parts: (1) Isotopically substituted compounds; (2) Specifically isotopically labelled compounds; (3) Selectively isotopically labelled compounds; (4) Non-selectively isotopically labelled compounds; (5) Isotopically deficient compounds.

  18. Application of artificial neural network in 3D imaging with lanthanum bromide calorimeter

    Science.gov (United States)

    Gostojic, A.; Tatischeff, V.; Kiener, J.; Hamadache, C.; Karkour, N.; Linget, D.; Grave, X.; Gibelin, L.; Travers, B.; Blin, S.; Barrillon, P.

    2015-07-01

    Gamma-ray astronomy in the energy range from 0.1 up to 100 MeV holds many understudied questions connected with e.g. stellar nucleosynthesis, the active Sun, neutron stars and black holes. To access the physics behind, a significant improvement in detection sensitivity is needed compared to previous missions, e.g. CGRO and INTEGRAL. One of the promising concepts for a future gamma-ray mission is an Advanced Compton Telescope. Under the project of creating a prototype of such instrument, we study the perspectives of using a novel inorganic scintillator as a calorimeter part. Modern inorganic crystal or ceramics scintillators are constantly improving on qualities such as energy resolution and radiation hardness, and this makes them a smart choice for a new space-borne telescope. At CSNSM Orsay, we have assembled a detection module from a 5 × 5cm2 area and 1 cm thick, cerium-doped lanthanum (III) bromide (LaBr3:Ce) inorganic scintillator coupled to a 64 channel multi-anode photomultiplier. The readout of the PMT signals is carried out with the ASIC MAROC, used previously for the luminometer of the ATLAS detector (CERN). Characterization, thorough measurements with various radioactive sources, as well as, single photoelectron detection have been done. Furthermore, we made a comparison of measurements with a detailed GEANT4-based simulation which includes tracking of the optical photons. Finally, we have studied the 3D reconstruction of the first interaction point of incident gamma rays, utilizing a neural network algorithm. This spatial position resolution plays a crucial part in the future implementations and, together with the other measured properties, it makes our detector module very interesting for the next generation of space telescopes operating in the MeV range.

  19. Magnetic structural effect (MSE in epitaxial films of cerium oxide and lanthanum zirconate

    Directory of Open Access Journals (Sweden)

    Fatima Kh. Chibirova

    2015-06-01

    Full Text Available Increasing the critical current density in the second generation high-temperature superconducting wires (2G HTS is the major challenge for researchers and manufacturers of 2G HTS wires all over the world. We proposed a new approach to increase the number of percolation paths for supercurrent, i.e. increasing the number of low angle grain boundaries (<5° in the epitaxial superconducting YBCO layer by magnetic structural processing (MSP of buffer layers. New experimental results have been presented on the application of MSP for improving the structure and increasing the texture sharpness of buffer in electrical conducting element of 2G HTS wire. The influence of MCO on the structural and textural properties has been investigated in a buffer consisting of epitaxial films of cerium oxide CeO2 and lanthanum zirconate La2Zr2O7 in the CeO2/4La2Zr2O7 architecture. The influence of the magnetic processing of the epitaxial La2Zr2O7 buffer film on the shape of grains has been found. An atomic force microscopical study has shown that after magnetic processing the shape of grains improved significantly. A multilayer CeO2/4La2Zr2O7 buffer each layer of which was processed in a magnetic field has a high degree of orientation: only one diffraction peak with (200 indexes is observed in the X-ray spectrum. The X-ray settings of the (200 diffraction peak indicate a well developed epitaxial structure of CeO2 and La2Zr2O7 layers. The texture of the buffer is by more than 2° sharper than that of the Ni–5 at% W substrate.

  20. Ferroelectric and Piezoelectric properties of (111) oriented lanthanum modified lead zirconate titanate film

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Soma, E-mail: som@nal.res.in; Antony Jeyaseelan, A.; Sruthi, S.

    2014-07-01

    Lanthanum modified lead zirconate titanate (PLZT) thick film with molecular formula of Pb{sub 0.92}La{sub 0.08}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.98}O{sub 3} was grown preferentially along (111) direction on Pt/SiO{sub 2}/Si (platinum/silicon oxide/silicon) substrate by spin coating of chemical solution. The directional growth of the film was facilitated by platinum (Pt) (111) template and rapid thermal annealing. X-ray diffraction pattern and atomic force microscopy revealed the preferential growth of the PLZT film. The film was characterized for ferroelectric and detailed piezoelectric properties in a parallel plate capacitor (metal–PLZT–metal) configuration. Ferroelectric characterization of the film showed saturated hysteresis loop with remanent polarization and coercive electric field values of 10.14 μC/cm{sup 2} and 42 kV/cm, respectively, at an applied field of 300 kV/cm. Longitudinal piezoelectric coefficient (d{sub 33,f}) was measured by employing converse piezoelectric effect where electrical charge response and displacement were measured with electrical voltage excitation on the sample electrodes. The effective transverse piezoelectric coefficient (e{sub 31,f}) was derived from charge measurement with an applied mechanical excitation strain by using the four point bending method. d{sub 33,f} and e{sub 31,f} coefficients of PLZT films were found to be 380 pm/V and − 0.831 C/m{sup 2} respectively. - Highlights: • PLZT (111) film is prepared by spin coating of chemical sol on Pt (111) template. • Piezoelectric d{sub 33} value (380 pm/V) of PLZT film is found 20% higher than PZT. • Transverse piezocoefficient e{sub 31,f} of PLZT film is reported for the first time.

  1. Transport kinetics of hydrogen permeable lanthanum tungstate

    Energy Technology Data Exchange (ETDEWEB)

    Falkenstein, Andreas

    2017-01-24

    The electrical conductivity relaxation technique is a widely used method to determine the oxygen transport parameters of mixed ionic-electronic conductors. In recent years, it has been modified to investigate the hydration behavior of proton conducting mixed conductors, giving access to up to four transport parameters in a single relaxation experiment, the diffusion coefficients and surface reaction rates of hydrogen and oxygen. In this work, the transport properties of the fluorite type protonic conductor lanthanum tungstate have been investigated by means of electrical conductivity relaxation. The experiments were performed in a temperature range from 650 C to 950 C, in a pO{sub 2} range from 3 mbar to 100 mbar and in a pH{sub 2}O range from 10 mbar to 100 mbar and in dry atmosphere. At high temperatures, the conductivity relaxation curve follows the expected two-fold non-monotonic behavior upon hydration. At low temperatures, however, the contribution of the fast hydrogen kinetic decreases and by a further decrease of the temperature, the relaxation shows two-fold monotonic behavior. The power factors - the contribution of each single fold relaxation curve to the resulting two-fold relaxation curve, which is a superposition - have been derived to explain the behavior mentioned above. The activation energy of the oxygen incorporation is rather low. Hence, oxidation experiments were performed in dry atmospheres in order to investigate if the origin of the oxygen species is relevant. The results revealed higher activation energies, which was expected, but also higher absolute values of the surface reaction rate and the diffusion coefficient. Oxidation experiments with increasing humidity revealed that the increased diffusivity cannot be attributed to the total concentrations of electron holes and proton interstitials. First experiments using spectroscopic relaxation, which is dependent on the concentration of hydroxy-anions only, were performed. Absorption bands

  2. Lanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV-visible light

    Science.gov (United States)

    Dal'Toé, Adrieli T. O.; Colpani, Gustavo Lopes; Padoin, Natan; Fiori, Márcio Antônio; Soares, Cíntia

    2018-05-01

    Lanthanum doped titanium dioxide decorated with silver plasmonic nanoparticles (Ag-La/TiO2 NPs) materials were prepared using a simple ultrasound-assisted wet impregnation method followed by silver photodeposition. The obtained photocatalysts with different Ag contents were characterized by XRD, FE-SEM, EDX, TEM, BET, XPS, DRS and PL techniques. Moreover, the size distribution of the nanoparticles aggregates was assessed. The characterization analysis revealed that La doping slightly changed the crystalline phase of TiO2, increased the amount of surface hydroxyl groups and interacted with TiO2 nanoparticles via Ti-O-La bond, while Ag photodeposition enhanced the absorption of visible light due to the effects of localized surface plamon resonance and significantly decreased electronic recombination rate by the Schottky junction. Furthermore, the combination of Ag-La induced the formation of oxygen vacancies, which increased the amount of adsorbed surface hydroxyl groups in Ag-La/TiO2. In addition, Ag-La possibly decreased the semiconductor surface energy, which acted positively in the reduction of NPs aggregation. These features along with better textural properties (greater surface areas) played a fundamental role in the enhancement of the photocatalytic activity of Ag-La/TiO2 composites for the decolorization of methylene blue under UV-visible irradiation compared to the mono-metallic (La/TiO2 and Ag/TiO2) modified photocatalysts. Finally, a mechanism for the transfer of charge carriers in Ag-La/TiO2 photocatalyst under UV-visible irradiation was proposed.

  3. Alterations in cytosol free calcium in horseradish roots simultaneously exposed to lanthanum(III) and acid rain.

    Science.gov (United States)

    Zhang, Xuanbo; Wang, Lihong; Zhou, Anhua; Zhou, Qing; Huang, Xiaohua

    2016-04-01

    The extensive use of rare earth elements (REEs) has increased their environmental levels. REE pollution concomitant with acid rain in many agricultural regions can affect crop growth. Cytosol free calcium ions (Ca(2+)) play an important role in almost all cellular activities. However, no data have been reported regarding the role of cytosol free Ca(2+) in plant roots simultaneously exposed to REE and acid rain. In this study, the effects of exposures to lanthanum(III) and acid rain, independently and in combination, on cytosol free Ca(2+) levels, root activity, metal contents, biomass, cytosol pH and La contents in horseradish roots were investigated. The simultaneous exposures to La(III) and acid rain increased or decreased the cytosol free Ca(2+) levels, depending on the concentration of La(III), and these effects were more evident than independent exposure to La(III) or acid rain. In combined exposures, cytosol free Ca(2+) played an important role in the regulation of root activity, metal contents and biomass. These roles were closely related to La(III) dose, acid rain strength and treatment mode (independent exposure or simultaneous exposure). A low concentration of La(III) (20 mg L(-1)) could alleviate the adverse effects on the roots caused by acid rain, and the combined exposures at higher concentrations of La(III) and acid rain had synergic effects on the roots. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Stress-dependent crystal structure of lanthanum strontium cobalt ferrite by in situ synchrotron X-ray diffraction

    Science.gov (United States)

    Geiger, Philipp T.; Khansur, Neamul H.; Riess, Kevin; Martin, Alexander; Hinterstein, Manuel; Webber, Kyle G.

    2018-02-01

    Lanthanum strontium cobalt ferrite La1-xSrxCo1-yFeyO3-δ (LSCF) is one of the most studied mixed ionic-electronic conductor materials due to electrical and transport properties, which are attractive for intermediate temperature solid oxide fuel cells (SOFCs), oxygen permeation membranes, and catalysis. The integration of such materials, however, depends on the thermal as well as mechanical behavior. LSCF exhibits nonlinear hysteresis during compressive stress-strain measurements, marked by a remanent strain and coercive stress, i.e., ferroelasticity. However, the origin of ferroelastic behavior has not been investigated under high compressive stress. This study, therefore, investigates the microscopic origin of stress-induced mechanical behavior in polycrystalline (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ using in situ synchrotron x-ray diffraction. The data presented here reveals that the strain response originates from the intrinsic lattice strain as well as the extrinsic domain switching strain without any apparent change in crystallographic symmetry. A comparison of the calculated microscopic strain contribution with that of a macroscopic measurement indicates a significant change in the relative contributions of intrinsic and extrinsic strain depending on the applied stress state, i.e., under maximum stress and after unloading. Direct evidence of the microscopic origin of stress-strain response outlined in this paper may assist in guiding materials design with the improved mechanical reliability of SOFCs.

  5. Synthesis, spectral characterization and in vitro antifungal activity of Lanthanum(III) and Praseodymium(III) complexes with Schiff bases derived from 5-substituted-4-amino-5-hydrazino-1,2,4-triazoles and isatin

    International Nuclear Information System (INIS)

    Singh, Shweta; Tripathi, Priti; Pandey, Om P.; Sengupta, Soumitra K.

    2013-01-01

    The new lanthanum(III) and praseodymium(III) complexes of the general formula (LnCl(L)(H 2 O) 2 ) (Ln = La III or Pr III ; H 2 L = Schiff bases derived from 3-substituted-4-amino-5-hydrazino-1,2,4-triazoles and isatin) have been prepared. The complexes have been characterized by elemental analyses, molecular weight by FAB-mass, thermogravimetry, electrical conductance, magnetic moment and spectral (electronic, infrared, far-infrared, 1 H NMR and 13 C NMR) data. The ligands and all prepared complexes were assayed for antifungal (Aspergillus niger and Helminthosporium oryzae) activities. The activities have been correlated with the structures of the complexes. (author)

  6. Comparison between methods using copper, lanthanum, and colorimetry for the determination of the cation exchange capacity of plant cell walls.

    Science.gov (United States)

    Wehr, J Bernhard; Blamey, F Pax C; Menzies, Neal W

    2010-04-28

    The determination of the cation exchange capacity (CEC) of plant cell walls is important for many physiological studies. We describe the determination of cell wall CEC by cation binding, using either copper (Cu) or lanthanum (La) ions, and by colorimetry. Both cations are strongly bound by cell walls, permitting fast and reproducible determinations of the CEC of small samples. However, the dye binding methods using two cationic dyes, Methylene Blue and Toluidine Blue, overestimated the CEC several-fold. Column and centrifugation methods are proposed for CEC determination by Cu or La binding; both provide similar results. The column method involves packing plant material (2-10 mg dry mass) in a chromatography column (10 mL) and percolating with 20 bed volumes of 1 mM La or Cu solution, followed by washing with deionized water. The centrifugation method uses a suspension of plant material (1-2 mL) that is centrifuged, and the pellet is mixed three times with 10 pellet volumes of 1 mM La or Cu solution followed by centrifugation and final washing with deionized water. In both methods the amount of La or Cu bound to the material was determined by spectroscopic methods.

  7. Investigation of concentration-dependence of thermodynamic properties of lanthanum, yttrium, scandium and terbium in eutectic LiCl-KCl molten salt

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yafei; Zhou, Wentao; Zhang, Jinsuo, E-mail: zhang.3558@osu.edu

    2016-09-15

    Thermodynamic properties of rare earth metals in LiCl-KCl molten salt electrolyte are crucial to the development of electrochemical separation for the treatment of used nuclear fuels. In the present study, activity coefficient, apparent potential, and diffusion coefficient of lanthanum, yttrium, scandium, and terbium in the molten salt (58 at% LiCl and 42 at% KCl) were calculated by the method of molecular dynamics simulation up to a concentration around 3 at% at temperatures of 723 K and 773 K. It was found that the activity coefficient and the apparent potential increase with the species concentration while diffusion coefficient shows a trend of increase followed by decrease. The calculated results were validated by available measurement data of dilution cases. This research extends the range of data to a wide component and would provide further insight to the pyroprocessing design and safeguards. - Highlights: • Investigation of activity coefficient, apparent potential and diffusion coefficient at different concentrations. • MD simulation was studied for the calculation of thermodynamic properties of rare earth elements in molten salt. • The present study is a pioneering work focusing on the concentration dependence of thermodynamic properties.

  8. Sanskrit Compound Processor

    Science.gov (United States)

    Kumar, Anil; Mittal, Vipul; Kulkarni, Amba

    Sanskrit is very rich in compound formation. Typically a compound does not code the relation between its components explicitly. To understand the meaning of a compound, it is necessary to identify its components, discover the relations between them and finally generate a paraphrase of the compound. In this paper, we discuss the automatic segmentation and type identification of a compound using simple statistics that results from the manually annotated data.

  9. Combined effects of lanthanum (III) chloride and acid rain on photosynthetic parameters in rice.

    Science.gov (United States)

    Wang, Lihong; Wang, Wen; Zhou, Qing; Huang, Xiaohua

    2014-10-01

    Rare earth elements (REEs) pollution and acid rain are environmental issues, and their deleterious effects on plants attract worldwide attention. These two issues exist simultaneously in many regions, especially in some rice-growing areas. However, little is known about the combined effects of REEs and acid rain on plants. Here, the combined effects of lanthanum chloride (LaCl3), one type of REE salt, and acid rain on photosynthesis in rice were investigated. We showed that the combined treatment of 81.6 μM LaCl3 and acid rain at pH 4.5 increased net photosynthetic rate (Pn), stomatic conductance (Gs), intercellular CO2 concentration (Ci), Hill reaction activity (HRA), apparent quantum yield (AQY) and carboxylation efficiency (CE) in rice. The combined treatment of 81.6 μM LaCl3 and acid rain at pH 3.5 began to behave toxic effects on photosynthesis (decreasing Pn, Gs, HRA, AQY and CE, and increasing Ci), and the maximally toxic effects were observed in the combined treatment of 2449.0 μM LaCl3 and acid rain at pH 2.5. Moreover, the combined effects of LaCl3 and acid rain on photosynthesis in rice depended on the growth stage of rice, with the maximal effects occurring at the booting stage. Furthermore, the combined treatment of high-concentration LaCl3 and low-pH acid rain had more serious effects on photosynthesis in rice than LaCl3 or acid rain treatment alone. Finally, the combined effect of LaCl3 and acid rain on Pn in rice resulted from the changes in stomatic (Gs, Ci) and non-stomatic (HRA, AQY and CE) factors. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. HIGH-RESOLUTION FOURIER TRANSFORM SPECTROSCOPY OF LANTHANUM IN Ar DISCHARGE IN THE NEAR-INFRARED

    Energy Technology Data Exchange (ETDEWEB)

    Güzelçimen, F.; Başar, Gö. [Faculty of Science, Physics Department, Istanbul University, Tr-34134 Vezneciler, Istanbul (Turkey); Tamanis, M.; Kruzins, A.; Ferber, R. [Laser Centre, The University of Latvia, Rainis Boulevard 19, LV-1586 Riga (Latvia); Windholz, L. [Institut für Experimentalphysik, Technische Universität Graz, A-8010 Graz, Petersgasse 16 (Austria); Kröger, S., E-mail: gbasar@istanbul.edu.tr, E-mail: sophie.kroeger@htw-berlin.de [Hochschule für Technik und Wirtschaft Berlin, Wilhelminenhofstr. 75A, D-12459 Berlin (Germany)

    2013-10-01

    A high-resolution spectrum of lanthanum has been recorded by a Fourier Transform spectrometer in the wavelength range from 833 nm to 1666 nm (6000 cm{sup –1} to 12,000 cm{sup –1}) using as light source a hollow cathode lamp operated with argon as the discharge carrier gas. In total, 2386 spectral lines were detected in this region, of which 555 lines could be classified as La I transitions and 10 lines as La II transitions. All La II transitions and 534 of these La I transitions were classified for the first time, and 6 of the La II transitions and 433 of the classified La I transitions appear to be new lines, which could not be found in the literature. The corresponding energy level data of classified lines are given. Additionally, 430 lines are assigned as Ar I lines and 394 as Ar II lines, of which 179 and 77, respectively, were classified for the first time. All 77 classified Ar II transitions as well as 159 of the classified Ar I transitions are new lines. Furthermore, the wavenumbers of 997 unclassified spectral lines were determined, 235 of which could be assigned as La lines, because of their hyperfine pattern. The remaining 762 lines may be either unclassified Ar lines or unresolved and unclassified La lines with only one symmetrical peak with an FWHM in the same order of magnitude as the Ar lines. The accuracy of the wavenumber for the classified lines with signal-to-noise-ratio higher than four is better than 0.006 cm{sup –1} which corresponds to an accuracy of 0.0004 nm at 830 nm and 0.0017 nm at 1660 nm, respectively.

  11. Synthesis, structural, optical and Raman studies of pure and lanthanum doped ZnSe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Pushpendra, E-mail: push.nac@gmail.com [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 11529, Taiwan (China); Singh, Jai [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Department of Materials Science and Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Pandey, Mukesh Kumar [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 11529, Taiwan (China); Jeyanthi, C.E. [Research and Development Centre, Bharathiar University, Coimbatore 641 046 (India); Siddheswaran, R. [Department of Materials Science and Engineering, University of Concepcion, Concepcion (Chile); Paulraj, M. [Department of Physics, Faculty of Physical sciences and Mathematics, University of Concepcion, Casilla 160, Concepcion (Chile); Hui, K.N. [Department of Materials Science and Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Hui, K.S., E-mail: kshui@hanyang.ac.kr [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2014-01-01

    Graphical abstract: - Highlights: • Template-free synthesis of ZnSe and ZnSe:La nanoparticles was developed at low temperature 100 °C. • Cubic ZnSe and ZnSe:La nanoparticles were obtained by chemical route. • As-synthesized ZnSe:La nanoparticles showed higher emission intensity than ZnSe nanoparticles. • Band gap (E{sub g}) of ZnSe nanoparticles was bigger than ZnSe nanoparticles due to nanosized effect. - Abstract: In this work, a simple, effective and reproducible chemical synthetic route for the production of high-quality, pure ZnSe nanoparticles (NPs), and lanthanum-doped ZnSe (ZnSe:La) NPs is presented. The wide bandgap, luminescent pure ZnSe and ZnSe:La NPs has been synthesized at a low temperature (100 °C) in a single template-free step. The size and optical bandgap of the NPs was analyzed from powder X-ray diffraction (XRD), UV–visible (UV–vis) spectroscopy, transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM). A broad photoluminescence (PL) emission across the visible spectrum has been demonstrated by a systematic blue-shift in emission due to the formation of small nanoparticles. Here, contribution to emission intensity from surface states of NPs increases with La doping. TEM data revealed that the average size of ZnSe and ZnSe:La NPs is 14 and 8 nm, respectively. On the other hand, band gap energy E{sub g} of ZnSe and ZnSe:La NPs were found to be 3.59 eV and 3.65 eV, respectively. Results showed that hydrazine hydrate played multiple roles in the formation of ZnSe and ZnSe:La NPs. A possible reaction mechanism for the growth of NPs is also discussed.

  12. Measurement and Analysis of Activation Induced in Lanthanum, Erbium and Tantalum by Fusion Peak Neutrons

    International Nuclear Information System (INIS)

    Klix, A.; Eichin, R.; Freiesleben, H.; Schomburg, K.; Seidel, K.; Unholzer, S.; Forrest, R.A.

    2006-01-01

    The large fluxes of neutrons in the materials of a fusion device during operation produce activation that is relevant to operational safety and decommissioning. Nuclides with a broad range of half-lives have to be included in the corresponding analyses. The activity with decay times ranging from the order of magnitude of minutes to weeks is of interest with respect to heat production and shut-down dose rates, whereas the long-term activity determines the waste management. The activity is mainly produced by two components of the neutron flux spectrum, by thermal neutrons and by the 14-MeV D-T fusion neutrons. Analyses of the material activation rely on calculations with inventory codes and libraries containing activation and decay data. To gain trust in the results of such calculations data and codes have to be validated experimentally. In the present work, the European Activation System (EASY, inventory code FISPACT and data library EAF) was tested in benchmark experiments on Lanthanum, Erbium and Tantalum. They are constituents of fusion reactor structural materials such as EUROFER and insulating coatings for liquid breeder systems. Small samples of the materials were irradiated in a D-T neutron field. The gamma-radioactivity following irradiation was measured several times during decay and nuclide activities were derived. For each of the measured activities the corresponding value was calculated with EASY, and the calculated-to-experimental ratios (C/E) were determined. The nuclear reactions producing the activities were also analysed. The C/E ratios obtained for the individual activities will be used for discussing the activation performance and the contact dose rate of the materials at fusion power plant conditions. (author)

  13. Fabrication of lanthanum-doped thorium dioxide by high-energy ball milling and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Spencer M.; Yao, Tiankai [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Lu, Fengyuan [Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States); Xin, Guoqing; Zhu, Weiguang [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Lian, Jie, E-mail: lianj@rpi.edu [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States)

    2017-03-15

    Abstract: High-energy ball milling was used to synthesize Th{sub 1-x}La{sub x}O{sub 2-0.5x} (x = 0.09, 0.23) solid solutions, as well as improve the sinterability of ThO{sub 2} powders. Dense La-doped ThO{sub 2} pellets with theoretical density above 94% were consolidated by spark plasma sintering at temperatures above 1400 °C for 20 min, and the densification behavior and the non-equilibrium effects on phase and structure were investigated. A lattice contraction of the SPS-densified pellets occurred with increasing ball milling duration, and a secondary phase with increased La-content was observed in La-doped pellets. A dependence on the La-content and sintering duration for the onset of localized phase segregation has been proposed. The effects of high-energy ball milling, La-content, and phase formation on the thermal diffusivity were also studied for La-doped ThO{sub 2} pellets by laser flash measurement. Increasing La-content and high energy ball milling time decreases thermal diffusivity; while the sintering peak temperature and holding time beyond 1600 °C dramatically altered the temperature dependence of the thermal diffusivity beyond 600 °C. - Highlights: • Lanthanum incorporation into ThO{sub 2} by high energy ball milling and rapid consolidation by spark plasma sintering. • Elucidation of phase behavior of the La-doped ThO{sub 2} and the contributions of La incorporation and SPS sintering conditions. • Investigation of the effects of La incorporation and high energy ball milling on the thermal behavior of La-doped ThO{sub 2}.

  14. Simulating the physicochemical properties of borosilicate and lanthanum borosilicate glasses using a polarizable force field

    International Nuclear Information System (INIS)

    Pacaud, Fabien

    2016-01-01

    as result of the nuclear waste vitrification, the knowledge and understanding of the dynamic and structural properties of glasses, including the behavior of radionuclides, is important (in liquid and solid phases). It can influence the glass waste properties, the lifetime of the vitrification process and the amount of radionuclides introduced in the glass matrix. Molecular dynamic simulations have been done to study the influence of the glass matrix composition into the structural and dynamic properties of the glass. a simplified glass, with 3 major oxides of the R7T7 glass such as SiO_2, B_2O_3 and Na_2O, have been used to simulate the R7T7 industrial nuclear glass (a 30 oxides glass). The inclusion of La_2O_3 allows us to simulate the impact of fission products and minor actinides into the properties of the glass matrix. Both systems, the SiO_2-B_2O_3-Na_2O and SiO_2-B_2O_3-Na_2O-La_2O_3, allow us to study the sodium and lanthanum effect on the properties of the glass. During this work, a polarizable force field has been developed to do these simulations. The results obtained at room temperature let us reproduce the experimental results of the structure, the distribution of BIII/BIV and the density. a study has been done on the viscosity and electrical conductivity of the liquid. The distribution BIV/BIII and the influence of the structural changes on the density along with the temperature have also been observed with thermal quenching. The current limits of this approach are also described. (author) [fr

  15. Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO_3) ceramics

    International Nuclear Information System (INIS)

    Billah, Masum; Ahmed, A.; Rahman, Md. Miftaur; Mahbub, Rubbayat; Gafur, M. A.; Bashar, M. Shahriar

    2016-01-01

    In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La_2O_3) doped Barium Titanate (BaTiO_3) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO_3 with 0.3, 0.5 and 0.7 mole% La_2O_3 under different sintering parameters. The raw materials used were La_2O_3 nano powder of ~80 nm grain size and 99.995% purity and BaTiO_3 nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO_3 ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La_2O_3) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La_2O_3 with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La"3"+ concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO_3 ceramics.

  16. Lanthanum oxyfluoride nanostructures prepared by modified sonochemical method and their use in the fields of optoelectronics and biotechnology

    Directory of Open Access Journals (Sweden)

    C. Suresh

    2018-02-01

    Full Text Available Dysprosium doped lanthanum oxyfluoride nanostructures were prepared by modified sonochemical method using Aloe Vera gel as a bio-surfactant. The morphology of the product was systematically studied by varying different experimental parameters including concentration of surfactant, sonication time, pH and sonication power. It was found that some of these above parameters play a key role in tuning the morphology of the product. The photoluminescence studies exhibited characteristic emission peaks at ∼483 nm, 574 nm and 674 nm attributed to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 transitions of Dy3+ ions respectively. The optimal concentration of Dy3+ ions was found to be ∼3 mol%. The photometric studies revealed that the prepared samples were quite useful for the fabrication of white light emitting diodes. The optimized product was also tested for their capability as an antigen against the bacterial and fungal pathogens. The present method of preparation may be scaled up easily to the larger production for industrial applications. The optimized sample showed an effective visualization of latent fingerprints on various forensic relevant materials and also showed effective antimicrobial potential for applications in nanobiotechnology.

  17. SEMICONDUCTOR DEVICES: Structural and electrical characteristics of lanthanum oxide gate dielectric film on GaAs pHEMT technology

    Science.gov (United States)

    Chia-Song, Wu; Hsing-Chung, Liu

    2009-11-01

    This paper investigates the feasibility of using a lanthanum oxide thin film (La2O3) with a high dielectric constant as a gate dielectric on GaAs pHEMTs to reduce gate leakage current and improve the gate to drain breakdown voltage relative to the conventional GaAs pHEMT. An E/D mode pHEMT in a single chip was realized by selecting the appropriate La2O3 thickness. The thin La2O3 film was characterized: its chemical composition and crystalline structure were determined by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. La2O3 exhibited good thermal stability after post-deposition annealing at 200, 400 and 600 °C because of its high binding-energy (835.6 eV). Experimental results clearly demonstrated that the La2O3 thin film was thermally stable. The DC and RF characteristics of Pt/La2O3/Ti/Au gate and conventional Pt/Ti/Au gate pHEMTs were examined. The measurements indicated that the transistor with the Pt/La2O3/Ti/Au gate had a higher breakdown voltage and lower gate leakage current. Accordingly, the La2O3 thin film is a potential high-k material for use as a gate dielectric to improve electrical performance and the thermal effect in high-power applications.

  18. The preparation and composition design of boron-rich lanthanum hexaboride target for sputtering

    International Nuclear Information System (INIS)

    Chen, Defang; Min, Guanghui; Wu, Yan; Yu, Huashun; Zhang, Lin

    2015-01-01

    Highlights: • High-purity LaB 6 powder was prepared due to significant reduction of residual B 4 C and effective purification process. • The effects of raw materials ratio on the size, morphology, phase structure and crystalline size of LaB 6 were studied. • The correlation of component between LaB 6 films and boron-rich targets was established. • The variation of densities of LaB 6 targets with sintering time and sintering temperature was investigated. - Abstract: Lanthanum Hexaboride (LaB 6 ) nano-film has been proved to be promising transparent thermal insulation material, while its properties are limited on purity and composition. High-purity LaB 6 polycrystalline powder was prepared through boron carbide reduction method in this work. A series of techniques such as scanning electron microscopy, X-ray diffraction, laser particle analyzer and inductively coupled plasma emission spectrometer were employed to characterize LaB 6 powder. As raising the content of La 2 O 3 in reactants, more uniform, finer (2.686 μm) and purer (99.5139 wt%) LaB 6 powder is prepared, with only 0.4434 wt% residual B 4 C. The density of targets increases with the rise of sintering temperature and the extension of sintering time, while crystallite size increases simultaneously with the extension of sintering time. The introduction of B powder in target is conductive to sintering process, increasing hardness and flexural strength of targets. X-ray photoelectron spectrometer was used to characterize the composition and microstructure of LaB 6 nano-film which is tentatively considered to be composed of LaB 6 nanocrystalline and amorphous microstructure of La and B atoms. The film LaB 6.0627±0.02 was obtained when the ratio of B and La of sputtering target reached 12.5. The thickness and deposition rate decrease with the increase of B content in targets

  19. Preparation of americium metal of high purity and determination of the heat of formation of the hydrated trivalent americium ion

    International Nuclear Information System (INIS)

    Spirlet, J.C.

    1975-10-01

    In order to redetermine some physical and chemical properties of americium metal, several grams of Am-241 have been prepared by two independent methods: lanthanum reduction of the oxide and thermal dissociation of the intermetallic compound Pt 5 Am. After its separation from excess lanthanum or alloy constituent by evaporation, americium metal was further purified by sublimation at 1100 deg C and 10 -6 Torr. Irrespective of the method of preparation, the americium samples displayed the same d.h.c.p. crystal structure. As determined by vacuum hot extraction, the oxygen, nitrogen and hydrogen contents are equal to or smaller than 250, 50 and 20 ppm, respectively. The heats of solution of americium metal (d.c.h.p. structure) in aqueous hydrochloric acid solutions have been measured at 298.15+-0.05K. The standard enthalpy of formation of Am 3+ (aq) is obtained as -616.7+-1.2 kJ mol -1 [fr

  20. Effect of preparation technique of hydrated zirconium(4) dioxide on sorption of microimpurities of nonferrous metals, iron(3) and thorium(4) from lanthanum(3) nitrate solutions

    International Nuclear Information System (INIS)

    Bekrenev, A.V.; Pyartman, A.K.; Belousov, E.A.

    1989-01-01

    A study was made on the effect of peculiarities of hydrated zirconium(4) dioxide (HZD) synthesis on reproducibility of its sorption properties. It is shown that change of zirconium(4) concentration in basic solution within the limits of 0-1.0 mol/dm 3 its HCl acidity from 0 up to 1.0 mol/dm 3 concentration of NaOH solution used for HZD precipitation within the limits of 1.0-10.0 mol/dm 3 the final pH value of HZD gel from 10 up to 14 affects slightly the impurity element sorption from lanthanum nitrate solution. Freezing of HZD leads to increase of capacity and decrease of selectivity of sorbent samples with respect to impurity ions (Ni 2+ , Co 2+ , Bi 3+ , Fe 3+ , Th 4+ ); increase of the time of gel ripening leads to decrease of capacity and growth of selectivity

  1. Inner-sphere and outer-sphere complexes of yttrium(III), lanthanum (III), neodymium(III), terbium(III) and thulium(III) with halide ions in N,N-dimethylformamide

    International Nuclear Information System (INIS)

    Takahashi, Ryouta; Ishiguro, Shin-ichi

    1991-01-01

    The formation of chloro, bromo and iodo complexes of yttrium(III), and bromo and iodo complexes of lanthanum(III), neodymium(III), terbium(III) and thulium(III) has been studied by precise titration calorimetry in N,N-dimethylformamide (DMF) at 25 o C. The formation of [YCl] 2+ , [YCl 2 ] + , [YCl 3 ] and [YCl 4 ] - , and [MBr] 2+ and [MBr 2 ] + (M = Y, La, Nd, Tb, Tm) was revealed, and their formation constants, enthalpies and entropies were determined. It is found that the formation enthalpies change in the sequence ΔH o (Cl) > ΔH o (l), which is unusual for hard metal (III) ions. This implies that, unlike the chloride ion, the bromide ion forms outer-sphere complexes with the lanthanide(III) and yttrium(III) ions in DMF. Evidence for either an inner- or outer-sphere complex was obtained from 89 Y NMR spectra for Y(ClO 4 ) 3 , YCl 3 and YBr 3 DMF solutions at room temperature. (author)

  2. Inhomogeneous Low Frequency Spin Dynamics in La1.65Eu0.2Sr0.15CuO4

    International Nuclear Information System (INIS)

    Curro, N. J.; Hammel, P. C.; Suh, B. J.; Huecker, M.; Buechner, B.; Ammerahl, U.; Revcolevschi, A.

    2000-01-01

    We report Cu and La nuclear magnetic resonance measurements in the title compound that reveal an inhomogeneous glassy behavior of the spin dynamics. A low temperature peak in the La spin lattice relaxation rate and the ''wipeout'' of Cu intensity both arise from these slow electronic spin fluctuations that reveal a distribution of activation energies. Inhomogeneous slowing of spin fluctuations appears to be a general feature of doped lanthanum cuprate. (c) 2000 The American Physical Society

  3. Delayed gamma-ray spectroscopy with lanthanum bromide detector for non-destructive assay of nuclear material

    Science.gov (United States)

    Favalli, Andrea; Iliev, Metodi; Ianakiev, Kiril; Hunt, Alan W.; Ludewigt, Bernhard

    2018-01-01

    High-energy delayed γ-ray spectroscopy is a potential technique for directly assaying spent fuel assemblies and achieving the safeguards goal of quantifying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Requirements for the γ-ray detection system, up to ∼6 MeV, can be summarized as follows: high efficiency at high γ-ray energies, high energy resolution, good linearity between γ-ray energy and output signal amplitude, ability to operate at very high count rates, and ease of use in industrial environments such as nuclear facilities. High Purity Germanium Detectors (HPGe) are the state of the art and provide excellent energy resolution but are limited in their count rate capability. Lanthanum Bromide (LaBr3) scintillation detectors offer significantly higher count rate capabilities at lower energy resolution. Thus, LaBr3 detectors may be an effective alternative for nuclear spent-fuel applications, where count-rate capability is a requirement. This paper documents the measured performance of a 2" (length) × 2" (diameter) of LaBr3 scintillation detector system, coupled to a negatively biased PMT and a tapered active high voltage divider, with count-rates up to ∼3 Mcps. An experimental methodology was developed that uses the average current from the PMT's anode and a dual source method to characterize the detector system at specific very high count rate values. Delayed γ-ray spectra were acquired with the LaBr3 detector system at the Idaho Accelerator Center, Idaho State University, where samples of ∼3g of 235U were irradiated with moderated neutrons from a photo-neutron source. Results of the spectroscopy characterization and analysis of the delayed γ-ray spectra acquired indicate the possible use of LaBr3 scintillation detectors when high count rate capability may outweigh the lower energy resolution.

  4. Simulated-sunlight-activated photocatalysis of Methyl Orange using carbon and lanthanum co-doped Bi{sub 2}O{sub 3}–TiO{sub 2} composite

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Hao [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Song, Mianxin, E-mail: songmianxin@swust.edu.cn [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Yi, Facheng [Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Bian, Liang [The Xinjiang Technical Institute of Physics & Chemistry, Urumqi 830011 (China); Liu, Pan [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Shuai [Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China)

    2016-09-25

    The C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite was prepared by sol-gel method. The physicochemical properties of as-synthesized samples were characterized by the TG-DSC, FESEM, EDS, XRD, XPS, TEM, HRTEM and UV–vis DRS. Besides, their photoactivities were valuated by degrading Methyl Orange. The experimental results showed that the C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite has anatase crystal structure and exhibits a remarkable optical absorption in UV–visible light region. In addition, carbon and lanthanum are deposited in the Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of amorphous carbon and oxide, respectively. When the concentration of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} loading was 2.5 g/L, the decomposition rate of 25 mg/L Methyl Orange reached 94.3% under the irradiation of the 500 W xenon lamp after 60 min. The corresponding degradation rate constant of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} was 2.1, 9.2, 1.3 and 6.8 times higher than that of P25, Bi{sub 2}O{sub 3}–TiO{sub 2}, C/Bi{sub 2}O{sub 3}–TiO{sub 2} and La/Bi{sub 2}O{sub 3}–TiO{sub 2}, respectively. The reuse evaluation of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} indicated that its photocatalytic activity has good stability. - Highlights: • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite was prepared by sol-gel method. • Carbon is deposited in Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of amorphous carbon. • Lanthanum is deposited in Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of oxide. • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} exhibited superior photocatalytic activity than Bi{sub 2}O{sub 3}–TiO{sub 2}, C/Bi{sub 2}O{sub 3}–TiO{sub 2} and La/Bi{sub 2}O{sub 3}–TiO{sub 2}. • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} has good stability.

  5. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS

    Science.gov (United States)

    Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

    2016-01-01

    Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs (89Y, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 157Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb and 175Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001–1.000 μg∙L−1 with r2 > 0.997. The limits of detection and quantification for this method were in the range of 0.009–0.010 μg∙L−1 and 0.029–0.037 μg∙L−1, the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg∙L−1), Ce (1.492 ± 0.995 μg∙L−1), Nd (0.014 ± 0.009 μg∙L−1) and Gd (0.023 ± 0.010 μg∙L−1) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a higher trend

  6. Enhancement of the piezoelectric properties of sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15) through modification with cobalt

    International Nuclear Information System (INIS)

    Wang Chunming; Wang Jinfeng; Zheng Limei; Zhao Minglei; Wang Chunlei

    2010-01-01

    The dielectric, piezoelectric, and electromechanical properties of B-site cobalt-modified sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) piezoelectric ceramics were investigated. The piezoelectric properties of NLBT ceramics can be enhanced by cobalt modifications. The NLBT ceramics modified with 0.2 wt.% cobalt trioxide (NLBT-C4) possess good piezoelectric properties, with piezoelectric coefficient d 33 of 27 pC/N, electromechanical coupling factors (k p and k t ) of 6.5% and 28.5%, and mechanical quality factor Q m (k p mode) of 3400. The Curie temperature T c of cobalt-modified NLBT ceramics was found to slightly higher than that of pure NLBT ceramics. A large dielectric abnormity in dielectric loss tan δ was observed in NLBT ceramics, which can be significantly suppressed by cobalt modification. Thermal annealing studies presented the cobalt-modified NLBT ceramics possess stable piezoelectric properties.

  7. Transesterification of Jatropha curcas crude oil to biodiesel on calcium lanthanum mixed oxide catalyst: Effect of stoichiometric composition

    International Nuclear Information System (INIS)

    Taufiq-Yap, Yun Hin; Teo, Siow Hwa; Rashid, Umer; Islam, Aminul; Hussien, Mohd Zobir; Lee, Keat Teong

    2014-01-01

    Highlights: • Biodiesel synthesis from Jatropha curcas oil catalyzed by CaO–La 2 O 3 mixed oxide. • Effects of Ca-to-La ratio, catalyst concentration, methanol/oil ratio and reaction temperature were optimized. • Biodiesel yield >85% was achieved at 65 °C temperature. • CaO–La 2 O 3 catalyst can be easy regenerated. - Abstract: Heterogeneous solid mixed oxide (CaO–La 2 O 3 ) catalysts with different molar ratios of calcium to lanthanum (Ca-to-La) were synthesized by co-precipitation method. The synthesized solid CaO–La 2 O 3 mixed metal oxide catalysts were utilized in transesterification of Jatropha curcus oil as feedstock to produce biodiesel. Under the optimized conditions at 65 °C, 4% catalyst dose with 24:1 MeOH to Jatropha oil molar ratio, the transesterification reaction exhibited 86.51% of biodiesel yield. The prepared catalysts were characterized using various techniques such as X-ray diffraction (XRD), nitrogen sorption with Brunauer–Emmer–Teller (BET) method, temperature-programmed desorption of CO 2 (CO 2 -TPD) and scanning electron microscopy (SEM). Influence of Ca-to-La atomic ratio in the mixed metal oxide catalyst, catalyst amount, methanol to oil molar ratio, reaction time, different oils on the fatty acid methyl ester (FAME) yield were appraised. Different catalyst regeneration procedures were also performed to investigate the reusability of the CaO–La 2 O 3 catalyst

  8. Solid oxide fuel cells with apatite-type lanthanum silicate-based electrolyte films deposited by radio frequency magnetron sputtering

    Science.gov (United States)

    Liu, Yi-Xin; Wang, Sea-Fue; Hsu, Yung-Fu; Wang, Chi-Hua

    2018-03-01

    In this study, solid oxide fuel cells (SOFCs) containing high-quality apatite-type magnesium doped lanthanum silicate-based electrolyte films (LSMO) deposited by RF magnetron sputtering are successfully fabricated. The LSMO film deposited at an Ar:O2 ratio of 6:4 on an anode supported NiO/Sm0.2Ce0·8O2-δ (SDC) substrate followed by post-annealing at 1000 °C reveals a uniform and dense c-axis oriented polycrystalline structure, which is well adhered to the anode substrate. A composite SDC/La0·6Sr0·4Co0·2Fe0·8O3-δ cathode layer is subsequently screen-printed on the LSMO deposited anode substrate and fired. The SOFC fabricated with the LSMO film exhibits good mechanical integrity. The single cell with the LSMO layer of ≈2.8 μm thickness reports a total cell resistance of 1.156 and 0.163 Ωcm2, open circuit voltage of 1.051 and 0.982 V, and maximum power densities of 0.212 and 1.490 Wcm-2 at measurement temperatures of 700 and 850 °C, respectively, which are comparable or superior to those of previously reported SOFCs with yttria stabilized zirconia electrolyte films. The results of the present study demonstrate the feasibility of deposition of high-quality LSMO films by RF magnetron sputtering on NiO-SDC anode substrates for the fabrication of SOFCs with good cell performance.

  9. Synthesis of pure and Sr-doped LaGaO3, LaFeO3 and LaCoO3 and Sr,Mg-doped LaGaO3 for ITSOFC application using different wet chemical routes

    International Nuclear Information System (INIS)

    Kumar, M.; Srikanth, S.; Ravikumar, B.; Alex, T.C.; Das, S.K.

    2009-01-01

    Pure and Sr-doped LaGaO 3 , LaFeO 3 and LaCoO 3 and Sr,Mg-doped LaGaO 3 were synthesized by various wet chemical routes, namely combustion, co-precipitation and citrate-gel methods. The effect of the various process parameters on the phase purity, particle size and surface area and morphology of the synthesized powders were determined by XRD, simultaneous TG-DTA, laser light scattering, BET and scanning electron microscopy. The stability of the synthesized pure phases in oxidizing and reducing atmosphere was also studied by thermogravimetry. It was observed that pure and Sr-doped single perovskite phases of lanthanum ferrite, cobaltite and gallate and Sr,Mg-doped lanthanum gallate could be synthesized by combustion and citrate-gel methods under suitable process conditions. Synthesis using the co-precipitation method yielded incomplete reaction irrespective of the calcination temperature adopted. The citrate-gel method yielded better powder properties in terms of particle size and morphology and surface area compared to combustion synthesis. It was found that pure and Sr-doped lanthanum ferrite, lanthanum cobaltite, lanthanum gallate and Sr,Mg-doped lanthanum gallate were stable in the oxidizing atmosphere. In the reducing atmosphere, pure and Sr-doped lanthanum ferrite and Sr,Mg-doped lanthanum gallate was found to be stable at least during the timeframe of the thermogravimetric experiment whereas pure and Sr-doped lanthanum cobaltite was partially reduced in hydrogen atmosphere

  10. Synthesis of pure and Sr-doped LaGaO{sub 3}, LaFeO{sub 3} and LaCoO{sub 3} and Sr,Mg-doped LaGaO{sub 3} for ITSOFC application using different wet chemical routes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M. [National Metallurgical Laboratory-Madras Center, CSIR Madras Complex, Chennai 600113 (India); Srikanth, S. [National Metallurgical Laboratory-Madras Center, CSIR Madras Complex, Chennai 600113 (India)], E-mail: s_srikanth_99@yahoo.com; Ravikumar, B.; Alex, T.C.; Das, S.K. [National Metallurgical Laboratory, Jamshedpur 831007 (India)

    2009-02-15

    Pure and Sr-doped LaGaO{sub 3}, LaFeO{sub 3} and LaCoO{sub 3} and Sr,Mg-doped LaGaO{sub 3} were synthesized by various wet chemical routes, namely combustion, co-precipitation and citrate-gel methods. The effect of the various process parameters on the phase purity, particle size and surface area and morphology of the synthesized powders were determined by XRD, simultaneous TG-DTA, laser light scattering, BET and scanning electron microscopy. The stability of the synthesized pure phases in oxidizing and reducing atmosphere was also studied by thermogravimetry. It was observed that pure and Sr-doped single perovskite phases of lanthanum ferrite, cobaltite and gallate and Sr,Mg-doped lanthanum gallate could be synthesized by combustion and citrate-gel methods under suitable process conditions. Synthesis using the co-precipitation method yielded incomplete reaction irrespective of the calcination temperature adopted. The citrate-gel method yielded better powder properties in terms of particle size and morphology and surface area compared to combustion synthesis. It was found that pure and Sr-doped lanthanum ferrite, lanthanum cobaltite, lanthanum gallate and Sr,Mg-doped lanthanum gallate were stable in the oxidizing atmosphere. In the reducing atmosphere, pure and Sr-doped lanthanum ferrite and Sr,Mg-doped lanthanum gallate was found to be stable at least during the timeframe of the thermogravimetric experiment whereas pure and Sr-doped lanthanum cobaltite was partially reduced in hydrogen atmosphere.

  11. CONCENTRATION OF Pu USING AN IODATE PRECIPITATE

    Science.gov (United States)

    Fries, B.A.

    1960-02-23

    A method is given for separating plutonium from lanthanum in a lanthanum fluoride carrier precipitation process for the recovery of plutonium values from an aqueous solution. The carrier precipitation process includes the steps of forming a lanthanum fluoride precipi- . tate, thereby carrying plutonium out of solution, metathesizing the fluoride precipitate to a hydroxide precipitate, and then dissolving the hydroxide precipitate in nitric acid. In accordance with the invention, the nitric acid solution, which contains plutonium and lanthanum, is made 0.05 to 0.15 molar in potassium iodate. thereby precipitating plutonium as plutonous iodate and the plutonous iodate is separated from the lanthanum- containing supernatant solution.

  12. Organolanthanoid compounds

    International Nuclear Information System (INIS)

    Schumann, H.

    1984-01-01

    Up to little more than a decade ago organolanthanoid compounds were still a curiosity. Apart from the description of an isolated number of cyclopentadienyl and indenyl derivatives, very few significant contributions had been made to this interesting sector of organometallic chemistry. However, subsequent systematic studies using modern preparative and analytical techniques, together with X-ray single crystal structure determinations, enabled the isolation and characterization of a large number of very interesting homoleptic and heteroleptic compounds in which the lanthanoid is bound to hydrogen, to substituted or unsubstituted cyclopentadienyl groups, to allyl or alkynyl groups, or even to phosphorus ylides, trimethylsilyl, and carbonylmetal groups. These compounds, which are all extremely sensitive to oxygen and water, open up new possibilities in the field of catalysis and have great potential in organic synthesis - as recent studies with pentamethylcyclopentadienyl derivatives, organolanthanoid(II) compounds, and hexamethyllanthanoid complexes have already shown. (orig.) [de

  13. Chemical compatibility of alternative perovskite oxide SOFC cathodes with doped lanthanum gallate solid electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Kostogloudis, G.C.; Ftikos, C. [Laboratory of Inorganic Materials Technology, Department of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou Str., Zografou Campus, GR-15780 Athens (Greece); Ahmad-Khanlou, A.; Naoumidis, A.; Stoever, D. [Research Centre Juelich, Institute for Materials and Processes in Energy Systems IWV1, D-52425 Juelich (Germany)

    2000-10-01

    This paper reports on the investigations of the chemical compatibility between SOFC cathode materials with compositions Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Mn{sub 0.8}O{sub 3-{delta}}, Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}}, Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.3}Mn{sub 0.7}O{sub 3-{delta}} and Pr{sub 0.75}Sr{sub 0.2}Co{sub 0.2}Mn{sub 0.8}O{sub 3-{delta}} and the electrolyte materials with compositions La{sub 0.8}Sr{sub 0.2}Ga{sub 0.9}Mg{sub 0.1}O{sub 3-{delta}}, and La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}}. The lanthanum gallate electrolyte with 20 mol.% Sr contained two additional phases, namely, LaSrGa{sub 3}O{sub 7} and LaSrGaO{sub 4}, while that with 10 mol.% Sr was formed in nearly single phase. Two types of experiments were performed: (a) reactivity experiments of powder mixtures and (b) diffusion experiments in cathode/electrolyte double-layer pellets. No reaction products were detected by XRD. High Co diffusion into the electrolyte was identified with SEM/EDX in all diffusion experiments examined. The transition metals diffuse in the order Mn

  14. Effect of La surface treatments on corrosion resistance of A3xx.x/SiC{sub p} composites in salt fog

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, A. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040 Madrid (Spain)]. E-mail: anpardo@quim.ucm.es; Merino, M.C. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040 Madrid (Spain); Arrabal, R. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040 Madrid (Spain); Merino, S. [Departamento de Tecnologia Industrial, Universidad Alfonso X El Sabio, Villanueva de la Canada, 28691 Madrid (Spain); Viejo, F. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040 Madrid (Spain); Coy, A.E. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040 Madrid (Spain)

    2006-02-15

    The influence of the SiC{sub p} proportion and the matrix concentration of four aluminium metal matrix composites (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p, A380/SiC/20p) modified by lanthanum-based conversion or electrolysis coating was evaluated in neutral salt fog according to ASTM B 117. Lanthanum-based conversion coatings were obtained by immersion in 50 deg. C solution of La(III) salt and lanthanum electrolysis treatments were performed in ethylene glycol mono-butyl ether solution. These treatments preferentially covered cathodic areas such as intermetallic compounds, Si eutectic and SiC{sub p}. The kinetic of the corrosion process was studied on the basis of gravimetric tests. Both coating microstructure and nature of corrosion products were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDS) and low angle X-ray diffraction (XRD) before and after accelerated testing to determine the influence of microstructural changes on corrosion behaviour during exposure to the corrosive environment. The corrosion process was more influenced by the concentration of alloy elements in the matrix than by the proportion of SiC{sub p} reinforcement. Both conversion and electrolysis surface treatments improved the behaviour to salt fog corrosion in comparison with original composites without treatment. Additionally, electrolysis provided a higher degree of protection than the conversion treatment because the coating was more extensive.

  15. Effect of La surface treatments on corrosion resistance of A3xx.x/SiCp composites in salt fog

    International Nuclear Information System (INIS)

    Pardo, A.; Merino, M.C.; Arrabal, R.; Merino, S.; Viejo, F.; Coy, A.E.

    2006-01-01

    The influence of the SiC p proportion and the matrix concentration of four aluminium metal matrix composites (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p, A380/SiC/20p) modified by lanthanum-based conversion or electrolysis coating was evaluated in neutral salt fog according to ASTM B 117. Lanthanum-based conversion coatings were obtained by immersion in 50 deg. C solution of La(III) salt and lanthanum electrolysis treatments were performed in ethylene glycol mono-butyl ether solution. These treatments preferentially covered cathodic areas such as intermetallic compounds, Si eutectic and SiC p . The kinetic of the corrosion process was studied on the basis of gravimetric tests. Both coating microstructure and nature of corrosion products were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDS) and low angle X-ray diffraction (XRD) before and after accelerated testing to determine the influence of microstructural changes on corrosion behaviour during exposure to the corrosive environment. The corrosion process was more influenced by the concentration of alloy elements in the matrix than by the proportion of SiC p reinforcement. Both conversion and electrolysis surface treatments improved the behaviour to salt fog corrosion in comparison with original composites without treatment. Additionally, electrolysis provided a higher degree of protection than the conversion treatment because the coating was more extensive

  16. Advanced Antireflection Coatings for High-Performance Solar Energy Applications

    Science.gov (United States)

    Pan, Noren

    2015-01-01

    Phase II objectives: Develop and refine antireflection coatings incorporating lanthanum titanate as an intermediate refractive index material; Investigate wet/dry thermal oxidation of aluminum containing semiconductor compounds as a means of forming a more transparent window layer with equal or better optical properties than its unoxidized form; Develop a fabrication process that allows integration of the oxidized window layer and maintains the necessary electrical properties for contacting the solar cell; Conduct an experimental demonstration of the best candidates for improved antireflection coatings.

  17. Electric conductivity of double fluorides in the systems M1F-Th(U)F4(M1=K, Tl) and M2F2-ThF4(M2=Ca, Sr, Ba)

    International Nuclear Information System (INIS)

    Murin, I.V.; Andreev, A.M.; Amelin, Yu.V.

    1982-01-01

    The temperature dependence of electric conductivity of some double fluorides formed in the systems M 1 F-Th(U)F 4 (M 1 =K, Tl) and M 2 F 2 -ThF 4 (M 2 =Ca, Sr, Ba) as well as UF 3 in a wide temperature range is studied. It is shown that the values of electric conductivity and activation energy of these fluorides depend on the compound structure and cation nature. The temperature electric conductivity dependence for double fluorides with the tysonite structure is close to the lanthanum fluoride dependence. Taking into account low electron electric conductivity component the conclusion is drawn that the investigated compounds can be used as solid electrolytes

  18. Structural and thermal studies of H2La2/3Ta2O7, a protonated layered perovskite

    International Nuclear Information System (INIS)

    Le Berre, F.; Crosnier-Lopez, M.P.; Fourquet, J.L.

    2006-01-01

    We have synthesised the new protonated layered perovskite H 2 La 2/3 Ta 2 O 7 which is related to the Ruddlesden-Popper family. This compound is obtained by ionic exchange starting from Li 2 La 2/3 Ta 2 O 7 maintained in dilute HNO 3 at 60 deg. C. Thermal X-ray diffraction and DTA/TGA revealed interesting dehydration properties with formation of a layered anhydrous phase leading at higher temperature (1550 deg. C) to La 1/3 TaO 3 . This latter compound exhibits the original lanthanum ordering expected similarly to that of the Li form, while at 900 deg. C a metastable form, presenting a disordered La distribution, is observed

  19. On fluorozirconates and fluorohafnates of rare earths

    International Nuclear Information System (INIS)

    Korenev, Yu.M.; Antipov, P.I.; Novoselova, A.V.

    1980-01-01

    It has been shown by the method of X-ray phase analysis that on interaction between rare-earth fluorides and zirconium and hafnium tetrafluorides, compounds with 1:1, 1:2, 1:3 molar ratios of components are formed. Compounds of the LnHfF 4 type are prepared for all rare-earths. Fluoro-metals of the LnHf 2 F 11 composition are typical only of light lanthanides from lanthanum to neodymium, while pentafluorated salts Ln(EF 5 ) 3 are formed in the reaction between EF 4 with fluorides of heavy rare-earth elements from samarium to lutecium, as well as with yttrium trifluoride. Parameters of unit cells of heptafluohafnates and pentafluometallates are determined

  20. The formation of lithium diarylargentates from arylsilver compounds and the corresponding aryllithium compounds

    NARCIS (Netherlands)

    Blenkers, J.; Hofstee, H.K.; Boersma, J.; Kerk, G.J.M. van der

    1979-01-01

    Diarylsilverlithium compounds of the type Ar2AgLi are formed by treating arylsilver compounds with the corresponding aryllithium compounds. Cryoscopy in benzene shows that the Ar2AgLi compounds are associated into dimers. NMR spectroscopic data indicate that only one type of aryl group is present in