Automatic Transmission Of Liquid Nitrogen

Directory of Open Access Journals (Sweden)

Sumedh Mhatre

2015-08-01

Full Text Available Liquid Nitrogen is one of the major substance used as a chiller in industry such as Ice cream factory Milk Diary Storage of blood sample Blood Bank etc. It helps to maintain the required product at a lower temperature for preservation purpose. We cannot fully utilise the LN2 so practically if we are using 3.75 litre LN2 for a single day then around 12 of LN2 450 ml is wasted due to vaporisation. A pressure relief valve is provided to create a pressure difference. If there is no pressure difference between the cylinder carrying LN2 and its surrounding it will results in damage of container as well as wastage of LN2.Transmission of LN2 from TA55 to BA3 is carried manually .So care must be taken for the transmission of LN2 in order to avoid its wastage. With the help of this project concept the transmission of LN2 will be carried automatically so as to reduce the wastage of LN2 in case of manual operation.

Fatigue crack nucleation of type 316LN stainless steel

International Nuclear Information System (INIS)

Kim, Dae Whan; Kim, Woo Gon; Hong, Jun Hwa; Ryu, Woo Seog

2000-01-01

Low Cycle Fatigue (LCF) life decreases drastically with increasing temperature but increases with the addition of nitrogen at room and high temperatures. The effect of nitrogen on LCF life may be related to crack nucleation at high temperatures in austenitic stainless steel because the fraction of crack nucleation in LCF life is about 40%. The influence of nitrogen on the crack nucleation of LCF in type 316LN stainless steel is investigated by observations of crack population and crack depth after testing at 40% of fatigue life. Nitrogen increases the number of cycles to nucleate microcracks of 100 μm but decreases the crack population

Contamination of liquid oxygen by pressurized gaseous nitrogen

Science.gov (United States)

Zuckerwar, Allan J.; King, Tracy K.; Ngo, Kim Chi

1989-01-01

The penetration of pressurized gaseous nitrogen (GN2) into liquid oxygen (LOX) was investigated experimentally in the 7-inch High Temperature Tunnel, the pilot tunnel for the 8-foot High Temperature Tunnel (8'HTT) at Langley Research Center. A preliminary test using a nuclear monitor revealed the extent of the liquid nitrogen (LN2) build-up at the LOX interface as a function of GN2 pressure. Then an adaptation of the differential flash vaporization technique was used to determine the binary diffusivity of the LOX-LN2 system at a temperature of 90.2 K. The measured value D equals 0.000086 sq cm/s + or - 25 percent together with two prior measurements at lower temperatures revealed an excellent fit to the Arrhenius equation, yielding a pre-exponential factor D sub 0 equals 0.0452 sq cm/s and an activation enthalpy H equals 1.08 kcal/mol. At a pressure of 1700 psi and holding time of 15 min, the penetration of LN2 into LOX (to a 1 percent contamination level) was found to be 0.9 cm, indicating but minimal impact upon 8'HTT operations.

Red emitting phosphors of Eu3+ doped Na2Ln2Ti3O10 (Ln = Gd, Y) for white light emitting diodes

International Nuclear Information System (INIS)

Zhang, Niumiao; Guo, Chongfeng; Yin, Luqiao; Zhang, Jianhua; Wu, Mingmei

2015-01-01

Highlights: • Layered red phosphors Na 2 Ln 2 Ti 3 O 10 (Ln = Gd, Y):Eu 3+ were prepared. • The synthesis parameters of phosphors were optimized. • PL and thermal stability of the samples were investigated. • LED devices were also fabricated including the present red phosphor. - Abstract: A series of Eu 3+ doped Na 2 Ln 2 Ti 3 O 10 (Ln = Gd, Y) red-emitting phosphors for application in ultraviolet based light emitting diodes (LEDs) were successfully synthesized by a modified sol–gel method. Their structure and luminescent properties were characterized by powder X-ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra and absorption spectra, according to these results the optimal compositions and synthesis parameters were determined. In addition, the thermal stabilities of the phosphors were investigated according to the temperature-dependent PL spectra. The red and white-LEDs (W-LEDs) comprising the Na 2 Ln 2 Ti 3 O 10 :Eu 3+ (Ln = Gd, Y) red emitting phosphors were fabricated with a near-ultraviolet (n-UV) chip. In comparison with Na 2 Y 1.4 Eu 0.6 Ti 3 O 10 , the Na 2 Gd 0.6 Eu 1.4 Ti 3 O 10 phosphor offers higher brightness, quantum efficiency, and excellent thermal stability. W-LEDs comprising Na 2 Gd 0.6 Eu 1.4 Ti 3 O 10 showed bright white emission with a color rendering index (Ra) of 82, a color temperature of 2151 K, and Commission Internationale de I’Eclairage (CIE) color coordinates of (0.34, 0.37). The phosphor Na 2 Gd 0.6 Eu 1.4 Ti 3 O 10 is more suitable candidate for application in LEDs

Magnetic interactions in rhenium-containing rare earth double perovskites Sr{sub 2}LnReO{sub 6} (Ln=rare earths)

Energy Technology Data Exchange (ETDEWEB)

Nishiyama, Atsuhide; Doi, Yoshihiro; Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp

2017-04-15

The perovskite-type compounds containing both rare earth and rhenium Sr{sub 2}LnReO{sub 6} (Ln=Y, Tb-Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln{sup 3+} and Re{sup 5+} ions are structurally ordered at the B site of the perovskite SrBO{sub 3}. Magnetic anomalies are found in their magnetic susceptibility and specific heat measurements at 2.6–20 K for Ln=Y, Tb, Dy, Yb, Lu compounds. They are due to magnetic interactions between Re{sup 5+} ions. The results of the magnetic hysteresis and remnant magnetization measurements for Sr{sub 2}YReO{sub 6} and Sr{sub 2}LuReO{sub 6} indicate that the antiferromagnetic interactions between Re{sup 5+} ions below transition temperatures have a weak ferromagnetic component. The analysis of the magnetic specific heat data for Sr{sub 2}YbReO{sub 6} shows that both the Yb{sup 3+} and Re{sup 5+} ions magnetically order at 20 K. For the case of Sr{sub 2}DyReO{sub 6}, magnetic ordering of the Re{sup 5+} moments occurs at 93 K, and with decreasing temperature, the moments of Dy{sup 3+} ferromagnetically order at 5 K from the measurements of magnetic susceptibility and specific heat. - Graphical abstract: Crystal structure of double perovskite Sr{sub 2}LnReO{sub 6}. Red and black lines show cubic and monoclinic unit cells, respectively. - Highlights: • Double perovskites Sr{sub 2}LnReO{sub 6} (Ln=rare earths) were prepared. • They show an antiferromagnetic transition at 2.6–20 K. • In Sr{sub 2}DyReO{sub 6}, Dy and Re moments magnetically order at 5 and 93 K, respectively.

Numerical simulation of Cr2N age-precipitation in high nitrogen stainless steels

International Nuclear Information System (INIS)

Dai, Q.X.; Yuan, Z.Z.; Luo, X.M.; Cheng, X.N.

2004-01-01

At the temperature raging from 700 to 950 deg. C, the Cr 2 N age-precipitation in high nitrogen austenitic stainless steels Fe24Mn18Cr3Ni0.62N was investigated in this paper. A qualitative mathematical model of Cr 2 N age-precipitation, ln t S = f (Me,1/T), was established based on the thermodynamics and kinetics and phase transformation theories. Satisfactory results were obtained by means of the test of artificial neural network. This mathematical model can be applied to the calculation design and predication of Cr 2 N age-precipitation in high nitrogen stainless steels

Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln==Sm, Eu, Gd) and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln==Tb, Dy, Ho)

Energy Technology Data Exchange (ETDEWEB)

Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian, E-mail: jiadingxian@suda.edu.cn

2013-10-15

Solvothermal reactions of Ln{sub 2}O{sub 3}, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln{sub 2}O{sub 3} oxides were converted to [Ln(dien){sub 2}]{sup 3+} complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS{sub 4} unit. In 1−3, the AsS{sub 4} units interconnect the [Ln(dien){sub 2}]{sup 3+} cations via Ln−S bonds as tridentate μ-1κ,2κ{sup 2}-AsS{sub 4} bridging ligands, resulting in the neutral coordination polymers [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln1). In 4−6, the AsS{sub 4} units coordinate with the Ln{sup 3+} ion of [Ln(dien){sub 2}]{sup 3+} as 1κ{sup 2}-AsS{sub 4} chelating ligands to form neutral coordination compounds [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln2). The Ln{sup 3+} ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln{sup 3+} ions. Optical absorption spectra showed that 1−6 have potential use as semiconductors with the band gaps in the range 2.18−3.21 eV. - Graphical abstract: Two types of Ln-thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] were prepared by solvothermal methods and the soft Lewis basic AsS{sub 4}{sup 3–} ligand to Ln(III) centers with polyamine co-ligand was obtained. Display Omitted - Highlights: • Lanthanide thioarsenates were prepared by solvothermal methods. • The soft Lewis basic AsS{sub 4} ligand coordinate Ln{sup 3+} ions with coexistence polyamine ligands. • Two structural types of Ln-thioarsenates with structural turnover at Tb were obtained along Ln series. • The Ln-thioarsenates are potential semiconductors

Formation of high oxide ion conductive phases in the sintered oxides of the system Bi2O3-Ln2O3 (Ln = La-Yb)

International Nuclear Information System (INIS)

Iwahara, H.; Esaka, T.; Sato, T.; Takahashi, T.

1981-01-01

The electrical conduction in various phases of the system Bi 2 O 3 -Ln 2 O 3 (Ln = La, Nd, Sm, Dy, Er, or Yb) was investigated by measuring ac conductivity and the emf of the oxygen gas concentration cell. High-oxide-ion conduction was observed in the rhombohedral and face-centered cubic (fcc) phase in these systems. The fcc phase could be stabilized over a wide range of temperature by adding a certain amount of Ln 2 O 3 . In these cases, the larger the atomic number of Ln, the lower the content of Ln 2 O 3 required to form the fcc solid solution, except in the case of Yb 2 O 3 . The oxide ion conductivity of this phase decreased with increasing content of Ln 2 O 3 . Maximum conductivity was obtained at the lower limit of the fcc solid solution formation range in each system, which was more than one order of magnitude higher than those of conventional stabilized zirconias. Lattice parameters of the fcc phase were calculated from the x-ray diffraction patterns. The relationship between the oxide ion conductivity and the lattice parameter was also discussed

Upgradation in SCADA and PLC of existing LN_2 control system for SST-1

International Nuclear Information System (INIS)

Panchal, Pradip; Mahesuria, Gaurang; Panchal, Rohit; Patel, Rakesh; Sonara, Dashrath; Pitroda, Dipen; Nimavat, Hiren; Tanna, Vipul; Pradhan, Subrata

2016-01-01

Highlights: • The control system of LN_2 Management System of SST-1 is designed on PLC and SCADA. • The implementation and results of up-gradation in PLC and SCADA are reported. • The up-gradation in PLC and SCADA has improved the reliability & availability of SST-1 LN_2 system. - Abstract: Helium Refrigerator/Liquefier system of Steady State Superconducting Tokamak (SST-1) incorporates Liquid Nitrogen (LN_2) pre-cooling system. LN_2 is used for 80 K thermal shields of SST-1, current feeder system and integrated flow distribution and control system. The LN_2 management system is distributed system and requires automatic control. Initially LN_2 control system had Citect based Supervisory Control and Data Acquisition (SCADA) and Koyo make Programmable Logic Controller (PLC). With the passage of time and due to unavailability of their hardware, it is being obsoleted. So, the requirements of new PLC and SCADA systems have been envisaged to make uninterruptable operation of SST-1 cryogenic system. Therefore, Wonderware SCADA and Schneider Electric make PLC is programmed to replace Citect SCADA and Koyo PLC. New control features have been added in upgraded control system for better management of LN_2 system. This upgradation of SCADA and PLC is completed, tested successfully and in operation. Operational performance highlights of the new upgraded system are presented in this paper.

Effect of Elevated CO2 Concentration, Elevated Temperature and No Nitrogen Fertilization on Methanogenic Archaeal and Methane-Oxidizing Bacterial Community Structures in Paddy Soil.

Science.gov (United States)

Liu, Dongyan; Tago, Kanako; Hayatsu, Masahito; Tokida, Takeshi; Sakai, Hidemitsu; Nakamura, Hirofumi; Usui, Yasuhiro; Hasegawa, Toshihiro; Asakawa, Susumu

2016-09-29

Elevated concentrations of atmospheric CO2 ([CO2]) enhance the production and emission of methane in paddy fields. In the present study, the effects of elevated [CO2], elevated temperature (ET), and no nitrogen fertilization (LN) on methanogenic archaeal and methane-oxidizing bacterial community structures in a free-air CO2 enrichment (FACE) experimental paddy field were investigated by PCR-DGGE and real-time quantitative PCR. Soil samples were collected from the upper and lower soil layers at the rice panicle initiation (PI) and mid-ripening (MR) stages. The composition of the methanogenic archaeal community in the upper and lower soil layers was not markedly affected by the elevated [CO2], ET, or LN condition. The abundance of the methanogenic archaeal community in the upper and lower soil layers was also not affected by elevated [CO2] or ET, but was significantly increased at the rice PI stage and significantly decreased by LN in the lower soil layer. In contrast, the composition of the methane-oxidizing bacterial community was affected by rice-growing stages in the upper soil layer. The abundance of methane-oxidizing bacteria was significantly decreased by elevated [CO2] and LN in both soil layers at the rice MR stage and by ET in the upper soil layer. The ratio of mcrA/pmoA genes correlated with methane emission from ambient and FACE paddy plots at the PI stage. These results indicate that the decrease observed in the abundance of methane-oxidizing bacteria was related to increased methane emission from the paddy field under the elevated [CO2], ET, and LN conditions.

Phase relations in Ca(Sr)MoO4-Ln2(NoO4)3 systems (Ln = Pr-Lu)

International Nuclear Information System (INIS)

Vakalyuk, V.V.; Evdokimov, A.A.; Berezina, T.A.

1982-01-01

Using the methods of X-ray phase and differential thermal analyses phase ratios in the systems Ca(Sr)MoO 4 -Ln 2 (MoO 4 ) 3 at Ln=Pr-Lu are studied and phase diagrams of the systems CaMoO 4 -Ln 2 (MoO 4 ) 3 , for Ln=Nd, Gd, Yb and SrMoO 4 -Sm 2 (MoO 4 ) 3 are built. It is shown that phase ratios in the systems are similar for the following groups of rare earths: Pr-Sm, Eu-Tb, Ho-Lu. In the first group of systems ordered phase over all subsolidus region are formed, in the second one - ordered phases with scheelite-like structure and wide regions of homogeneity on the basis of Ca(Sr)MoO 4 are formed above the temperature of polymorphous transformation of rare earth molybdates, for the third group of systems intermediate compounds are not detected

Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature

Energy Technology Data Exchange (ETDEWEB)

Flura, Aurélien; Dru, Sophie; Nicollet, Clément; Vibhu, Vaibhav; Fourcade, Sébastien; Lebraud, Eric; Rougier, Aline; Bassat, Jean-Marc; Grenier, Jean-Claude, E-mail: grenier@icmcb-bordeaux.cnrs.fr

2015-08-15

The chemical stability of lanthanide nickelates Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) has been studied in the temperature range 25–1300 °C, either in air or at low pO{sub 2} (down to 10{sup −4} atm). Thermal gravimetry analysis (TGA) measurements coupled with X-ray diffraction (XRD) characterization have shown that all compounds retain their K{sub 2}NiF{sub 4}-type structure in these conditions, while remaining over-stoichiometric in oxygen up to 1000 °C. Only Nd{sub 2}NiO{sub 4+δ} starts to decompose into Nd{sub 2}O{sub 3} and NiO above 1000 °C, at pO{sub 2}=10{sup −4} atm. In addition, a careful analysis of the lanthanide nickelates structural features has been performed by in situ XRD, as a function of temperature and pO{sub 2}. For all compounds, a structural transition has been always observed in the temperature range 200–400 °C, in air or at pO{sub 2}=10{sup −4} atm. In addition, their cell volume did not vary upon the variation of the oxygen partial pressure. Therefore, these materials do not exhibit a chemical expansion in these conditions, which is beneficial for a fuel cell application as cathode layers. Additional dilatometry measurements have revealed that a temperature as high as 950 °C for Pr{sub 2}NiO{sub 4+δ} or 1100 °C for La{sub 2}NiO{sub 4+δ} and Nd{sub 2}NiO{sub 4+δ} has to be reached in order to begin the sintering of the material particles, which is of primary importance to obtain an efficient electronic/ionic conduction in the corresponding designed cathode layers. Besides, excellent matching was found between the thermal expansion coefficients of lanthanide nickelates and SOFC electrolytes such as 8wt% yttria stabilized zirconia (8YSZ) or Ce{sub 0.8}Gd{sub 0.2}O{sub 2−δ} (GDC), at least from 400 °C up to 1400 °C in air or up to 1200 °C at pO{sub 2}=10{sup −4} atm. - Graphical abstract: This study reports the good chemical stability of oxygen overstoichiometric Ln2NiO4+δ(Ln = La, Pr or Nd) at high temperatures

A determination of the oxygen non-stoichiometry of the oxygen storage materials LnBaMn{sub 2}O{sub 5+δ} (Ln=Gd, Pr)

Energy Technology Data Exchange (ETDEWEB)

Jeamjumnunja, Kannika; Gong, Wenquan; Makarenko, Tatyana; Jacobson, Allan J., E-mail: ajjacob@uh.edu

2016-07-15

The A-site ordered double-perovskite oxides, LnBaMn{sub 2}O{sub 5+δ} (Ln=Gd, Pr), were synthesized and investigated to understand the effect of A site cation substitution on the oxygen storage properties of these materials. The present results are compared with our previous data for YBaMn{sub 2}O{sub 5+δ}. The results clearly reveal that changing the Ln cation strongly influences the oxidation/reduction behavior of LnBaMn{sub 2}O{sub 5+δ}. Based on thermogravimetric analysis data, oxygen uptake begins at lower temperatures in both air and oxygen in compounds with Ln{sup 3+} ions larger than Y{sup 3+}. These oxides exhibit almost complete and reversible oxygen uptake/release between fully-reduced LnBaMn{sub 2}O{sub 5} and fully-oxidized LnBaMn{sub 2}O{sub 6} during changes of the oxygen partial pressure between air and 1.99% H{sub 2}/Ar. In addition, the oxygen non-stoichiometries of GdBaMn{sub 2}O{sub 5+δ} and PrBaMn{sub 2}O{sub 5+δ} were determined as a function of pO{sub 2} at 600, 650, 700 and 750 °C by Coulometric titration at near-equilibrium conditions. The results confirm that these materials have two distinct phases on oxidation/reduction with δ≈0, 0.5 and a third phase with a range of composition with an oxygen content (5+δ) approaching ~6. The stabilities of the LnBaMn{sub 2}O{sub 5+δ} phases extend over a wide range of oxygen partial pressures (∼10{sup −25}≤pO{sub 2} (atm)≤∼1) depending on temperature. Isothermal experiments show that the larger the Ln{sup 3+} cation the lower pO{sub 2} for phase conversion. At some temperatures and pO{sub 2} conditions, the LnBaMn{sub 2}O{sub 5+δ} compounds are unstable with respect to decomposition to BaMnO{sub 3−δ} and LnMnO{sub 3}. This instability is more apparent in Coulometric titration experiments than in thermogravimetric analysis. The Coulometric titration experiments are necessarily slow in order to achieve equilibrium oxygen compositions. - Graphical abstract: Structure of Ln

Effect of nitrogen on creep properties of type 316L(N) stainless steels

International Nuclear Information System (INIS)

Kim, Dae Whan; Lee, Yoon Kyu; Kim, Woo Gon; Ryu, Woo Seog

2001-01-01

The effects of nitrogen on the creep properties of type 316(N) stainless steels with three different nitrogen contents from 0.04% to 0.15% were investigated. Creep tests were carried out using constant-load single-lever machines at 550∼650 .deg. C in the air. The time to rupture increased and the minimum creep rate decreased with the addition of nitrogen. At constant stress, the rupture elongation decreased with the addition of nitrogen. Intergranular and transgranular fracture mode were mixed in all specimens. Cavity and carbides were nucleated at grain boundary and the number of cavity and carbide at constant stress was increased with the addition of nitrogen because of the increase in the time to rupture and carbide precipitation due to the addition of nitrogen. The increase of rupture time with the addition of nitrogen for type 316L(N) stainless steel was attributed to the combined effect of the decrease of minimum creep rate due to the increase of tensile strength and the rupture elongation due to the precipitation at grain boundaries

Upgradation in SCADA and PLC of existing LN{sub 2} control system for SST-1

Energy Technology Data Exchange (ETDEWEB)

Panchal, Pradip, E-mail: pradip@ipr.res.in; Mahesuria, Gaurang; Panchal, Rohit; Patel, Rakesh; Sonara, Dashrath; Pitroda, Dipen; Nimavat, Hiren; Tanna, Vipul; Pradhan, Subrata

2016-11-15

Highlights: • The control system of LN{sub 2} Management System of SST-1 is designed on PLC and SCADA. • The implementation and results of up-gradation in PLC and SCADA are reported. • The up-gradation in PLC and SCADA has improved the reliability & availability of SST-1 LN{sub 2} system. - Abstract: Helium Refrigerator/Liquefier system of Steady State Superconducting Tokamak (SST-1) incorporates Liquid Nitrogen (LN{sub 2}) pre-cooling system. LN{sub 2} is used for 80 K thermal shields of SST-1, current feeder system and integrated flow distribution and control system. The LN{sub 2} management system is distributed system and requires automatic control. Initially LN{sub 2} control system had Citect based Supervisory Control and Data Acquisition (SCADA) and Koyo make Programmable Logic Controller (PLC). With the passage of time and due to unavailability of their hardware, it is being obsoleted. So, the requirements of new PLC and SCADA systems have been envisaged to make uninterruptable operation of SST-1 cryogenic system. Therefore, Wonderware SCADA and Schneider Electric make PLC is programmed to replace Citect SCADA and Koyo PLC. New control features have been added in upgraded control system for better management of LN{sub 2} system. This upgradation of SCADA and PLC is completed, tested successfully and in operation. Operational performance highlights of the new upgraded system are presented in this paper.

Ion-irradiation resistance of the orthorhombic Ln_2TiO_5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) series

International Nuclear Information System (INIS)

Aughterson, Robert D.; Lumpkin, Gregory R.; Ionescu, Mihail; Reyes, Massey de los; Gault, Baptiste; Whittle, Karl R.; Smith, Katherine L.; Cairney, Julie M.

2015-01-01

The response of Ln_2TiO_5 (where Ln is a lanthanide) compounds exposed to high-energy ions was used to test their suitability for nuclear-based applications, under two different but complementary conditions. Eight samples with nominal stoichiometry Ln_2TiO_5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy), of orthorhombic (Pnma) structure were irradiated, at various temperatures, with 1 MeV Kr"2"+ ions in-situ within a transmission electron microscope. In each case, the fluence was increased until a phase transition from crystalline to amorphous was observed, termed critical dose D_c. At certain elevated temperatures, the crystallinity was maintained irrespective of fluence. The critical temperature for maintaining crystallinity, T_c, varied non-uniformly across the series. The T_c was consistently high for La, Pr, Nd and Sm_2TiO_5 before sequential improvement from Eu to Dy_2TiO_5 with T_c's dropping from 974 K to 712 K. In addition, bulk Dy_2TiO_5 was irradiated with 12 MeV Au"+ ions at 300 K, 723 K and 823 K and monitored via grazing-incidence X-ray diffraction (GIXRD). At 300 K, only amorphisation is observed, with no transition to other structures, whilst at higher temperatures, specimens retained their original structure. The improved radiation tolerance of compounds containing smaller lanthanides has previously been attributed to their ability to form radiation-induced phase transitions. No such transitions were observed here. - Highlights: • First ion-irradiation studies on a number of novel compounds including Pr_2TiO_5, Eu_2TiO_5 and Tb_2TiO_5. • Systematic in-situ ion-irradiation study of almost complete Ln_2TiO_5 series (Ln = lanthanides) with orthorhombic crystal structure type. • The first grazing incidence study of bulk irradiated Dy_2TiO_5 looking for irradiation induced phase transition.

Study of LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) double perovskites as new cathode material for IT-SOFC

Energy Technology Data Exchange (ETDEWEB)

Chavez, E; Mueller, M; Mogni, L; Caneiro, A, E-mail: mogni@cab.cnea.gov.a [Centro Atomico Bariloche-CNEA, Instituto Balseiro. Av. Bustillo 9500, S. C. de Bariloche 8400 (Argentina)

2009-05-01

Oxides with double perovskites structures of general composition LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) were synthesized by solid state reaction with the purpose to evaluate new materials to be used as cathodes in intermediate temperature solid oxide fuel cell (IT-SOFC). A preliminary study about electrochemical properties was performed by impedance spectroscopy between 500 and 800 deg. C under atmosphere of pure O{sub 2}. Symmetrical cells were obtained by spray deposition of LnBaCo{sub 2}O{sub 6-d}elta (Ln = Pr, Nd, Sm and Gd) at both sides of a dense ceramic electrolyte. The impedance spectroscopy measurements as a function of temperatures show a hysteresis loop which could be associated to a tetragonal/orthorhombic phase transition. The existence of this transition was corroborated by high temperature X-Ray diffraction and Differential Scanning Calorimetry measurements.

First-principle calculations of the structural, elastic and bonding properties of Cs{sub 2}NaLnCl{sub 6} (Ln=La–Lu) cubic elpasolites

Energy Technology Data Exchange (ETDEWEB)

Ma, C.G.; Liu, D.X.; Feng, B.; Tian, Y.; Li, L. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Brik, M.G., E-mail: mikhail.brik@ut.ee [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14C, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland)

2016-01-15

For the first time the structural, elastic and bonding properties of 15 elpasolite crystals Cs{sub 2}NaLnCl{sub 6} (Ln denotes all lanthanides from La to Lu) were calculated systematically using the CRYSTAL09 program. Several trends in the variation of these properties in relation to the atomic number Z of the Ln ions were found; in particular, the lattice parameter of these compounds decreases with Z (which can lead to the increased crystal field splittings of the 5d states for the heavier Ln ions), whereas the elastic constants and Debye temperature increase. The degree of covalency of the Ln–Cl chemical bonds is increased toward the end of the lanthanide series. - Highlights: • Structural, elastic and bonding properties of 15 cubic elpasolites Cs{sub 2}NaLnCl{sub 6} (Ln=La,…,Lu) are calculated. • Relations between these quantities and Ln atomic number were found. • Possible correlation between the elastic properties and Stokes shift is proposed.

Lattice dynamics of cubic Cs2NaLnX6 and CsNaLn1-xLn'xX6 elpasolites

International Nuclear Information System (INIS)

Acevedo, R.; Poblete, V.; Alzamora, R.; Venegas, R.; Navarro, G.; Henriquez, C.

1999-01-01

Crystal lattice dynamics of stoichiometric Cs 2 NaLnX 6 and nonstoichiometric CsNaLn 1-x Ln' x X 6 , 0.01 ≤ x ≤ 0.10, Ln and Ln' are trivalent positive lanthanide ions and X is chlorine or bromine, were studied.. Phonon dispersion relations were computed for similar compound, Cs 2 UBr 6 , and vibronic absorption spectra with reduced number of required input parameters are considered on the basis of proposed model. (author)

A Study of Submicron Grain Boundary Precipitates in Ultralow Carbon 316LN Steels

Science.gov (United States)

Downey, S.; Han, K.; Kalu, P. N.; Yang, K.; Du, Z. M.

2010-04-01

This article reports our efforts in characterization of an ultralow carbon 316LN-type stainless steel. The carbon content in the material is one-third that in a conventional 316LN, which further inhibits the formation of grain boundary carbides and therefore sensitizations. Our primary effort is focused on characterization of submicron size precipitates in the materials with the electron backscatter diffraction (EBSD) technique complemented by Auger electron spectroscopy (AES). Thermodynamic calculations suggested that several precipitates, such as M23C6, Chi, Sigma, and Cr2N, can form in a low carbon 316LN. In the steels heat treated at 973 K (700 °C) for 100 hours, a combination of EBSD and AES conclusively identified the grain boundary precipitates (≥100 nm) as Cr2N, which has a hexagonal closed-packed crystallographic structure. Increases of the nitrogen content promote formation of large size Cr2N precipitates. Therefore, prolonged heat treatment at relatively high temperatures of ultralow carbon 316LN steels may result in a sensitization.

Plastic deformation and fracture behaviors of nitrogen-alloyed austenitic stainless steels

International Nuclear Information System (INIS)

Wang Songtao; Yang Ke; Shan Yiyin; Li Laifeng

2008-01-01

The plastic deformation and fracture behaviors of two nitrogen-alloyed austenitic stainless steels, 316LN and a high nitrogen steel (Fe-Cr-Mn-0.66% N), were investigated by tensile test and Charpy impact test in a temperature range from 77 to 293 K. The Fe-Cr-Mn-N steel showed ductile-to-brittle transition (DBT) behavior, but not for the 316LN steel. X-ray diffraction (XRD) confirmed that the strain-induced martensite occurred in the 316LN steel, but no such transformation in the Fe-Cr-Mn-N steel. Tensile tests showed that the temperature dependences of the yield strength for the two steels were almost the same. The ultimate tensile strength of the Fe-Cr-Mn-N steel displayed less significant temperature dependence than that of the 316LN steel. The strain-hardening exponent increased for the 316LN steel, but decreased for the Fe-Cr-Mn-N steel, with decreasing temperature. Based on the experimental results and the analyses, a modified scheme was proposed to explain the fracture behaviors of austenitic stainless steels

Syntheses, crystal structures and photoluminescence properties of two rare-earth molybdates CsLn(MoO{sub 4}){sub 2} (Ln=Eu, Tb)

Energy Technology Data Exchange (ETDEWEB)

Zhao, Dan; Ma, Fa-Xue; Liu, Bao-Zhong; Fan, Yun-Chang; Han, Xue-Feng; Zhang, Lei; Nie, Cong-Kui [Henan Polytechnic Univ. (China). College of Chemistry and Chemical Engineering

2018-04-01

Single crystals of two cesium rare-earth molybdates CsLn(MoO{sub 4}){sub 2} (Ln=Eu, Tb) have been prepared using the high temperature molten salt (flux) method. Single-crystal X-ray diffraction analyses reveal that they crystallize in the orthorhombic space group Pccm (No. 49) and features a 2D layer structure that is composed of [Ln(MoO{sub 4}){sub 2}]{sub ∞} and [Cs]{sub ∞} layers. Under near-UV light excitation, emission spectrum of CsEu(MoO{sub 4}){sub 2} consists of several sharp lines due to the characteristic electronic transitions of Eu{sup 3+} ions, whereas CsTb(MoO{sub 4}){sub 2} exhibits characteristic green emission of Tb{sup 3+} ions.

Low-Temperature Transformations of Protonic Forms of Layered Complex Oxides HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd)

International Nuclear Information System (INIS)

Abdulaeva, L.D.; Silyukov, O.I.; Zvereva, I.A.; Petrov, Yu.V.

2013-01-01

In the present work protonic forms of layered Ruddlesden-Popper oxides HLnTiO 4 and H 2 Ln 2 Ti 3 O 10 (Ln = La, Nd) were used as the starting point for soft chemistry synthesis of two series of perovskite-like compounds by acid leaching and exfoliation, promoted by vanadyl sulfate. The last route leads to the nano structured VO 2+ containing samples. Characterization by SEM, powder XRD, and TGA has been performed for the determination of the structure and composition of synthesized oxides

Mathematical prediction of freezing times of bovine semen in straws placed in static vapor over liquid nitrogen.

Science.gov (United States)

Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

2013-02-01

A widespread practice in cryopreservation is to freeze spermatozoa by suspending the straws in stagnant nitrogen vapor over liquid nitrogen (N(2)V/LN(2)) for variable periods of time before plunging into liquid nitrogen (-196°C) for indefinite storage. A mathematical heat transfer model was developed to predict freezing times (phase change was considered) required for bull semen and extender packaged in 0.5ml plastic straws and suspended in static liquid nitrogen vapor. Thermophysical properties (i.e. thermal conductivity, specific heat, density, initial freezing temperature) of bovine semen and extender as a function of temperature were determined considering the water change of phase. The non-stationary heat transfer partial differential equations with variable properties (nonlinear mathematical problem) were numerically solved considering in series thermal resistances (semen suspension-straw) and the temperature profiles were obtained for both semen suspension and plastic straw. It was observed both the external heat transfer coefficient in stagnant nitrogen vapor and its temperature (controlled by the distance from the surface of liquid nitrogen to the straw) affected freezing times. The accuracy of the model to estimate freezing times of the straws was further confirmed by comparing with experimental literature data. Results of this study will be useful to select "safe" holding times of bull semen in plastic straws placed N(2)V/LN(2) to ensure that complete freezing of the sample has occurred in the nitrogen vapor and avoid cryodamage when plunging in LN(2). Freezing times predicted by the numerical model can be applied to optimize freezing protocols of bull semen in straws. Copyright © 2012 Elsevier Inc. All rights reserved.

Carbonato-bridged Ni(II)2Ln(III)2 (Ln(III) = Gd(III), Tb(III), Dy(III)) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH or H2O)Ln(III)(NO3)}2]·solvent [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato].

Science.gov (United States)

Sakamoto, Soichiro; Fujinami, Takeshi; Nishi, Koshiro; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Re, Nazzareno

2013-06-17

Atmospheric CO2 fixation of [Ni(II)(3-MeOsaltn)(H2O)2]·2.5H2O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln(III)(NO3)3·6H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni(II)2Ln(III)2 complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH)Ln(III)(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(H2O)Ln(III)(NO3)}2]·2CH3CN·2H2O (2Gd, 2Tb, and 2Dy). For both series, each Ni(II)2Ln(III)2 structure can be described as two di-μ-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO3(2-) units to form a carbonato-bridged (μ4-CO3)2{Ni(II)2Ln(III)2} structure. The high-spin Ni(II) ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O9 donor atoms from Ni(II)(3-MeOsaltn), bidentate NO3(-), and one and two oxygen atoms of two CO3(2-) ions. The NO3(-) ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni(II) and Ln(III) ions (Ln(III) = Gd(III), Tb(III), Dy(III)) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb(III) or Dy(III) ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the Ni(II)2Gd(III)2 complexes but exhibited an out-of-phase signal for Ni(II)2Tb(III)2 and Ni(II)2Dy(III)2, indicative of slow relaxation of magnetization. The energy barriers, Δ/kB, for the spin flipping were estimated from the Arrhenius

Effect of the ion force on the stability constants of the complexes LnCl2+ and LnCl2+ of Europium and Lutetium

International Nuclear Information System (INIS)

Fernandez R, E.; Jimenez R, M.; Solache R, M.

2004-01-01

A study is presented on the determination of the constants of stability of those complex LnCI 3-n n (where Ln = Eu 3+ and Lu 3+ and n = 1 and 2), by means of a method of extraction with solvent, to constant temperature (303 K) and in means of high ionic force (1- 3M H CI/HCIO 4 ). It is also presented the application of the theory of the specific interaction of ions (SIT) of Bronsted-Guggenheim-Scatchard for the extrapolation of the values to infinite dilution. (Author)

Polymorphism of Bi1-xLnxO1.5 phases (04Ln2O9 (x=0.33; Ln=La, Pr, Nd)

International Nuclear Information System (INIS)

Drache, Michel; Huve, Marielle; Roussel, Pascal; Conflant, Pierre

2003-01-01

The Bi 1-x Ln x O 1.5 solid solutions (Ln=La, Pr, Nd), of the β 2 /β 1 /ε (Bi-Sr-O) structural type, have been investigated in their Ln-rich domains. For Ln=La, Pr, and Nd, the upper limits are 0.35, 0.35 and 0.33, respectively. The Bi 4 Ln 2 O 9 ε phase (x=0.33) appears to be the single definite compound. For Bi 4 La 2 O 9 , Bi 4 Pr 2 O 9 and Bi 4 Nd 2 O 9 , the ε-type cells are respectively: a=9.484(4) A, b=3.982(2) A, c=7.030(3) A, β=104.75(3) deg.; a=9.470(5) A, b=3.945(2) A, c=6.968(4) A, β=104.73(3) deg. and a=9.439(3) A, b=3.944(2) A, c=6.923(2) A, β=105.03(3) deg. . Upon heating, each monoclinic (ε) compound transforms successively into rhombohedral phases (β 2 /β 1 ) and finally into a cubic fluorite-type phase. For La- and Pr-based compounds, all transitions are reversible; for Nd, depending on the thermal treatment, the reversibility of ε→β 2 can be incomplete. These transformations are characterized using X-ray thermodiffractometry, differential thermal analysis, dilatometry and impedance spectroscopy versus temperature. Examination of Bi 4 (Ln, Ln') 2 O 9 samples allows to correlate the evolution of the thermal behavior and of the unit cell parameters, to the lanthanide size. A partial plot of the (Bi 2 O 3 ) 1-x -(La 2 O 3 ) x phase diagram (0≤x≤0.40) is proposed

Modelling thermodynamic properties of lanthanide (LnL)3+ and actinide (AnL)3+ complexes with tridentate planar nitrogen ligands (L)

International Nuclear Information System (INIS)

Ionova, G.; Rabbe, C.; Charbonnel, M.C.; Hill, C.; Guillaumont, D.; Guillaumont, R.; Ionov, S.; Madic, C.

2004-01-01

We report here the results obtained from a systematic theoretical study on the thermodynamic properties of trivalent lanthanide (Ln) and actinide (An) complexes with chelating nitrogen tridentate ligands. The mechanism of chelation has been investigated and the role of cation dissolution is investigated through a comparison of the thermodynamic properties of solvated cations and complexes. The difference in thermodynamic properties of LnL and AnL complexes is analyzed. (authors)

Red emitting phosphors of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) for white light emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Niumiao [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Guo, Chongfeng, E-mail: guocf@nwu.edu.cn [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Yin, Luqiao; Zhang, Jianhua [Key Laboratory of Advanced Display and System Applications (Shanghai University), Ministry of Education, Shanghai 200072 (China); Wu, Mingmei, E-mail: ceswmm@mail.sysu.edu.cn [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, No. 135, Xingang Xi Road, Guangzhou 510275 (China)

2015-06-25

Highlights: • Layered red phosphors Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y):Eu{sup 3+} were prepared. • The synthesis parameters of phosphors were optimized. • PL and thermal stability of the samples were investigated. • LED devices were also fabricated including the present red phosphor. - Abstract: A series of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) red-emitting phosphors for application in ultraviolet based light emitting diodes (LEDs) were successfully synthesized by a modified sol–gel method. Their structure and luminescent properties were characterized by powder X-ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra and absorption spectra, according to these results the optimal compositions and synthesis parameters were determined. In addition, the thermal stabilities of the phosphors were investigated according to the temperature-dependent PL spectra. The red and white-LEDs (W-LEDs) comprising the Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10}:Eu{sup 3+} (Ln = Gd, Y) red emitting phosphors were fabricated with a near-ultraviolet (n-UV) chip. In comparison with Na{sub 2}Y{sub 1.4}Eu{sub 0.6}Ti{sub 3}O{sub 10}, the Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} phosphor offers higher brightness, quantum efficiency, and excellent thermal stability. W-LEDs comprising Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} showed bright white emission with a color rendering index (Ra) of 82, a color temperature of 2151 K, and Commission Internationale de I’Eclairage (CIE) color coordinates of (0.34, 0.37). The phosphor Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} is more suitable candidate for application in LEDs.

Synthesis and characterization of charge-substituted garnets YCaLnGa5O12 (Ln = Ce,Pr,Tb)

International Nuclear Information System (INIS)

Gramsch, S.A.

1993-01-01

A low temperature method is described for the preparation of the new garnet compounds YCaLnGa 5 O l2 (Ln=Ce, Pr, Th). In this set of compounds (Ca 2+ + Ln 4+ ) replaces 2 Y 3+ in the parent gallium based garnet Y 3 Ga 5 O l2 in order to stabilize as effectively as possible the Ln 4+ species in the eight-coordinate ''A'' site of the garnet structure. Characterization of the oxides by x-ray powder diffraction and thermogravimetric analysis is discussed with regard to the structural relationship of the substituted compound to the parent material. The tetravalent ions Pr 4+ and Tb 4+ exhibit increased thermal stability in reducing conditions as compared to the Ln 4+ states in the fluorite (LnO 2 ) and perovskite (BaLnO 3 ) type structures. This result is discussed with reference to the complex crystal chemistry of these systems

Synthesis, structure, luminescent, and magnetic properties of carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2] (Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato).

Science.gov (United States)

Ehama, Kiyomi; Ohmichi, Yusuke; Sakamoto, Soichiro; Fujinami, Takeshi; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Tsuchimoto, Masanobu; Re, Nazzareno

2013-11-04

Carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [Zn(II)L(n)(H2O)2]·xH2O, Ln(III)(NO3)3·6H2O, and triethylamine, where Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each Zn(II)2Ln(III)2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO3(2-) ions. The Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of L(n) and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L(n), two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(II)2Ln(III)2 complexes are analyzed on the basis of the dicarbonato-bridged binuclear Ln(III)-Ln(III) structure, as the Zn(II) ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L(1)) and ZnGd2 (L(2)) show a ferromagnetic Gd(III)-Gd(III) interaction with J(Gd-Gd) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)ŜGd1·ŜGd2. The magnetic data of the Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of Zn(II)2Tb(III)2 complexes were observed, while those

Cryogenic system with the sub-cooled liquid nitrogen for cooling HTS power cable

Energy Technology Data Exchange (ETDEWEB)

Fan, Y.F. [Chinese Academy of Sciences, Beijing (China). Technical Institute of Physics and Chemistry; Graduate School of Chinese Academy of Sciences, Beijing (China); Gong, L.H.; Xu, X.D.; Li, L.F.; Zhang, L. [Chinese Academy of Sciences, Beijing (China). Technical Institute of Physics and Chemistry; Xiao, L.Y. [Chinese Academy of Sciences, Beijing (China). Institute of Electrical Engineering

2005-04-01

A 10 m long, three-phase AC high-temperature superconducting (HTS) power cable had been fabricated and tested in China August 2003. The sub-cooled liquid nitrogen (LN{sub 2}) was used to cool the HTS cable. The sub-cooled LN{sub 2} circulation was built by means of a centrifugal pump through a heat exchanger in the sub-cooler, the three-phase HTS cable cryostats and a LN{sub 2} gas-liquid separator. The LN{sub 2} was cooled down to 65 K by means of decompressing, and the maximum cooling capacity was about 3.3 kW and the amount of consumed LN{sub 2} was about 72 L/h at 1500 A. Cryogenic system design, test and some experimental results would be presented in this paper. (author)

Integrated design of cryogenic refrigerator and liquid-nitrogen circulation loop for HTS cable

Science.gov (United States)

Chang, Ho-Myung; Ryu, Ki Nam; Yang, Hyung Suk

2016-12-01

A new concept of cryogenic cooling system is proposed and investigated for application to long-length HTS cables. One of major obstacles to the cable length of 1 km or longer is the difficulty in circulating liquid nitrogen (LN) along the cables, since the temperature rise and pressure drop of LN flow could be excessively large. This study attempts a breakthrough by integrating the refrigerator with the LN circulation loop in order to eliminate the cryogenic LN pumps, and generate a large LN flow with the power of compressors at ambient temperature. A variety of thermodynamic structures are investigated on standard and modified Claude cycles, where nitrogen is used as refrigerant and the LN circulation loop is included as part of the closed cycle. Four proposed cycles are fully analyzed and optimized with a process simulator (Aspen HYSYS) to evaluate the FOM (figure of merit) and examine the feasibility. The modified dual-pressure cycle cooled with expander stream is recommended for long HTS cables.

Phase transition of the orthorhombic fluorite-related compounds Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, Eu)

Energy Technology Data Exchange (ETDEWEB)

Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.j [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Doi, Yoshihiro; Nishimine, Hiroaki; Wakeshima, Makoto [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Sato, Mineo [Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan)

2009-12-04

Rare earth iridium oxides Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) were prepared and their structures were determined by X-ray diffraction measurements. At room temperature, Pr{sub 3}IrO{sub 7} crystallized in an orthorhombic superstructure of cubic fluorite with space group Cmcm. The differential thermal analysis (DTA) and specific heat measurements for Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) showed a phase transition at 262, 342, 420, and 485 K, respectively. At low temperatures, Ln{sub 3}IrO{sub 7} crystallized in a monoclinic structure with the space group P2{sub 1}/n. The transition temperatures increased with decreasing the ionic radius of rare earths, which indicates that the transition is stress-induced and occurs with the lattice contraction on cooling. These results for Ln{sub 3}IrO{sub 7} were compared with the phase transitions observed for Ln{sub 3}MoO{sub 7}, Ln{sub 3}RuO{sub 7}, Ln{sub 3}ReO{sub 7}, and Ln{sub 3}OsO{sub 7}.

Synthesis and characterisation of the n = 2 Ruddlesden–Popper phases Ln2Sr(Ba)Fe2O7 (Ln = La, Nd, Eu)

International Nuclear Information System (INIS)

Gurusinghe, Nicola N.M.; Figuera, Juand de la; Marco, José F.; Thomas, Michael F.; Berry, Frank J.; Greaves, Colin

2013-01-01

Graphical abstract: - Highlights: • Some Ruddlesden–Popper phases have been characterised. • Substitution on the A site influences cationic order. • The magnetic moment redirects with temperature - Abstract: A series of n = 2 Ruddlesden–Popper phases A 2 B 2 O 7 of composition Ln 2 Sr(Ba)Fe 2 O 7 (Ln = La, Nd, Eu) have been prepared. La 2 SrFe 2 O 7 and La 2 BaFe 2 O 7 crystallise in the tetragonal space group I4/mmm. The structures of Eu 2 SrFe 2 O 7 and Nd 2 SrFe 2 O 7 are best described in space group P4 2 /mnm. Substitution on the A site with smaller lanthanide- and larger alkaline metal- ions leads to enhanced cationic order in these phases and reflects increasing differences in cationic radii. All the compounds are antiferromagnetically ordered between 298 and 2 K. In La 2 SrFe 2 O 7 the magnetic moment lies along [1 1 0] at all temperatures between 298 and 2 K whereas in La 2 BaFe 2 O 7 the magnetic moment at 298 K lies along the crystallographic x-axis but redirects from the [1 0 0] to the [1 1 0] direction between 210 and 190 K and is retained in this direction until 2 K. In Nd 2 SrFe 2 O 7 the magnetic moment at 298 K lies along [1 1 0] but rotates from [1 1 0] to [0 0 1] between 17 and 9 K. A series of 57 Fe Mössbauer spectra recorded from La 2 SrFe 2 O 7 between 290 and 600 K indicate a magnetic ordering temperature of T N ≥ 535 K

Utility of Lithium in Rare-Earth Metal Reduction Reactions to Form Nontraditional Ln2+ Complexes and Unusual [Li(2.2.2-cryptand)]1+ Cations.

Science.gov (United States)

Huh, Daniel N; Darago, Lucy E; Ziller, Joseph W; Evans, William J

2018-02-19

The utility of lithium compared to other alkali metals in generating Ln 2+ rare-earth metal complexes via reduction of Ln 3+ precursors in reactions abbreviated as LnA 3 /M (Ln = rare-earth metal; A = anionic ligand; M = alkali metal) is described. Lithium reduction of Cp' 3 Ln (Cp' = C 5 H 4 SiMe 3 ; Ln = Y, Tb, Dy, Ho) under Ar in the presence of 2.2.2-cryptand (crypt) forms new examples of crystallographically characterizable Ln 2+ complexes of these metals, [Li(crypt)][Cp' 3 Ln]. In each complex, lithium is found in an N 2 O 4 donor atom coordination geometry that is unusual for the cryptand ligand. Magnetic susceptibility data on these new examples of nontraditional divalent lanthanide complexes are consistent with 4f n 5d 1 electronic configurations. The Dy and Ho complexes have exceptionally high single-ion magnetic moments, 11.35 and 11.67 μ B , respectively. Lithium reduction of Cp' 3 Y under N 2 at -35 °C forms the Y 2+ complex (Cp' 3 Y) 1- , which reduces dinitrogen upon warming to room temperature to generate the (N 2 ) 2- complex [Cp' 2 Y(THF)] 2 (μ-η 2 :η 2 -N 2 ). These results provide insight on the factors that lead to reduced dinitrogen complexes and/or stable divalent lanthanide complexes as a function of the specific reducing agent and conditions.

Ternary phosphates in Ca3(PO4)2-Na3Ln(PO4)2 (Ln-Nd, Eu, Er) systems

International Nuclear Information System (INIS)

Lazoryak, B.I.; Ivanov, L.N.; Strunenkova, T.V.; Golubev, V.N.; Viting, B.N.

1990-01-01

Ternary phosphates, formed in Ca 3 (PO 4 ) 2 -Na 3 Ln(PO 4 ) 2 (Ln-Nd, Eu, Er) systems were investigated by the methods of X-ray phase, luminescent analyses and IR spectroscopy. 5 regions of homogeneity were found. Two of them (I and II) were distinguished for all systems. Samples in the region of up to 14.285 mol.% Na 3 Ln(PO 4 ) 2 crystallize on the basis of β-Ca 3 (PO 4 ) 2 structure, and in other homogeneity regions - on the basis of β-K 2 SO 4 structure

Crystallographic and infrared spectroscopic study of bond distances in Ln[Fe(CN)6].4H2O (Ln=lanthanide)

International Nuclear Information System (INIS)

Zhou Xianju; Wong, W.-T.; Faucher, Michele D.; Tanner, Peter A.

2008-01-01

Along with crystallographic data of Ln[Fe(CN) 6 ].4H 2 O (Ln=lanthanide), the infrared spectra are reassigned to examine bond length trends across the series of Ln. The changes in mean Ln-O, Ln-N, C≡N and Fe-C distances are discussed and the bond natures of Ln-N and Ln-O are studied by bond length linear or quadratic fitting and comparisons with relevant ionic radii. The two different C≡N bond distances have been simulated by the covalo-electrostatic model. - Graphical abstract: Crystallographic and FTIR data for Ln[Fe(CN) 6 ].4H 2 O enable the changes in Ln-O, Ln-N, C≡N and Fe-C distances to be determined and modeled across the lanthanide series

Estimation of tau1 for the host Kramers' Ln3+ ions (Ln = Nd, Sm and Yb) from the EPR linewidths of Gd3+ impurity ions in Ln2(SO4)3.8H2O

International Nuclear Information System (INIS)

Malhotra, V.M.; Buckmaster, H.A.

1981-01-01

It is shown that the EPR linewidth data published by Misra and Mikolajczak for Gd 3+ impurity ions in Ln 2 (SO 4 ) 3 .8H 2 O (Ln = Nd, Sm and Yb) single crystals at 77 and 300 K can be used to estimate the effective spin-lattice relaxation time of Kramers' host ions. The various relaxation mechanisms which are operative in the lanthanides are reviewed and discussed. The estimated relaxation times are shown to be a sensitive function of the host ion energy level splittings and the temperature. The estimated effective spin-lattice relaxation times in these hosts are in reasonable agreement with those expected from a resonance Orbach process

The phase transition of the incommensurate phases β-Ln(PO3)3(Ln=Y,Tb...Yb), crystal structures of α-Ln(PO3)3(Ln=Y,Tb...Yb) and Sc(PO3)3

International Nuclear Information System (INIS)

Hoeppe, Hennig A.

2009-01-01

The incommensurately modulated room-temperature phases β-Ln(PO 3 ) 3 (Ln=Y,Tb...Yb) undergo a topotactic phase transition monitored by vibrational spectroscopy below 180 K leading to α-Ln(PO 3 ) 3 (Ln=Y,Dy...Yb), above 200 K the incommensurate phases are reobtained. The low-temperature phases exhibit a new structure type (α-Dy(PO 3 ) 3 ,P2 1 /c,Z=12,a=14.1422(6),b=20.0793(9),c=10.1018(4)A, β=127.532(3) 0 ). α-Tb(PO 3 ) 3 is isotypic with Gd(PO 3 ) 3 (α-Tb(PO 3 ) 3 ,I2/a,Z=16,a=25.875(6),b=13.460(3),c=10.044(2)A, β=119.13(3) 0 ). The symmetry relations between the involved phases of the phase transition are discussed. The crystal structure of Sc(PO 3 ) 3 is isotypic with that of Lu(PO 3 ) 3 and C-type phosphates. The polyphosphates consist of infinite zig-zag chains of corner-sharing PO 4 tetrahedra, the cations are coordinated sixfold in an almost octahedral arrangement. To confirm the quality of the determined crystal structures the deviation of the phosphate tetrahedra from ideal symmetry was determined and discussed. - Abstract: Basic structure from which all crystal structures of the late lanthanoids' polyphosphates at room temperature and below can be derived.

Strain-rate dependent fatigue behavior of 316LN stainless steel in high-temperature water

Energy Technology Data Exchange (ETDEWEB)

Tan, Jibo [CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wu, Xinqiang, E-mail: xqwu@imr.ac.cn [CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Han, En-Hou; Ke, Wei; Wang, Xiang [CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Sun, Haitao [Nuclear and Radiation Safety Center, SEPA, Beijing 100082 (China)

2017-06-15

Low cycle fatigue behavior of forged 316LN stainless steel was investigated in high-temperature water. It was found that the fatigue life of 316LN stainless steel decreased with decreasing strain rate from 0.4 to 0.004 %s{sup −1} in 300 °C water. The stress amplitude increased with decreasing strain rate during fatigue tests, which was a typical characteristic of dynamic strain aging. The fatigue cracks mainly initiated at pits and slip bands. The interactive effect between dynamic strain aging and electrochemical factors on fatigue crack initiation is discussed. - Highlights: •The fatigue lives of 316LN stainless steel decrease with decreasing strain rate. •Fatigue cracks mainly initiated at pits and persistent slip bands. •Dynamic strain aging promoted fatigue cracks initiation in high-temperature water.

Nitrogen effect on precipitation and sensitization in cold-worked Type 316L(N) stainless steels

International Nuclear Information System (INIS)

Oh, Yong Jun; Hong, Jun Hwa

2000-01-01

The precipitation behavior and sensitization resistance of Type 316L(N) stainless steels containing different concentrations of nitrogen have been investigated at the aging condition of 700 deg. C for cold work (CW) levels ranging from 0% (as solution annealed) to 40% reduction in thickness. The precipitation of M 23 C 6 carbide and intermetallic compounds (χ, Laves and σ phase) was accelerated by increasing the CW level. Nitrogen in the deformed alloys retarded the inter- and intra-granular precipitation of the carbides at low and high CW levels respectively, whereas it increased the relative amount of the χ phase. Quantitative assessment of the degree of sensitization (DOS) using the double loop-electrochemical potentiokinetic reactivation (DL-EPR) tests indicated that CW levels up to 20% enhanced sensitization while 40% CW suppressed sensitization for all aging times. The increase in nitrogen content accelerated the sensitization at CW levels below 20%. This might be associated with the homogeneous distribution of dislocations and the lower tendency toward recrystallization exhibited in the alloys having higher nitrogen content

Structural, magnetic and electronic properties of rare earth ternary oxides Li Ln(II) 2 Ln(III)O4

International Nuclear Information System (INIS)

Malki, M.

1987-06-01

Properties of a new class of rare earth ternary oxides Li Ln(II) 2 Ln(III)O 4 where Ln(II) is a divalent metal (Sr, Eu) and Ln(III) a trivalent rare earth (Eu, Gd, Dy, Er and Y). These orthorhombic compounds (type Li Eu 3 O 4 ) allow the study of many magnetic phenomena and their evolution in function of the nature of Ln(II) and Ln(III): diamagnetic ions Sr 2+ , Y 3+ ; isotrope magnetic ions: Eu 2+ , Gd 3+ and anisotrope magnetic ions Dy 3+ , Er 3+ . Magnetic and electric properties are obtained by classical techniques and from hyperfine interaction by Moessbauer spectroscopy. The possibility to use several Moessbauer resonance (nuclei Eu 151, Gd 155, Dy 161 and Er 166) completes informations obtained by the macroscopic study [fr

Optical and crystal chemistry studies of Na3Ln(PO4)2-K3Ln(PO4)2 (Ln=Eu, Gd)

International Nuclear Information System (INIS)

Mesnaoui, M.; Maazaz, M.

1987-01-01

In these systems, large single phase domains are separated by two phase regions. The structural evolution as a function of composition is analysed both by X-ray diffraction and by using Eu 3+ and Gd 3+ as luminescent local structural probes. Due to layer type structure of the K 3 Ln(PO 4 ) 2 phases an exchange reaction resulting in total substitution of sodium for potassium can be carried out with formation of metastable Na 3 Ln(PO 4 ) 2 phases, the structure of which is close to those of the potassium compounds. 10 refs.; 18 figs [fr

Quantifying nitrogen leaching response to fertilizer additions in China's cropland

International Nuclear Information System (INIS)

Gao, Shuoshuo; Xu, Peng; Zhou, Feng; Yang, Hui; Zheng, Chunmiao; Cao, Wei; Tao, Shu; Piao, Shilong; Zhao, Yue; Ji, Xiaoyan; Shang, Ziyin

2016-01-01

Agricultural soils account for more than 50% of nitrogen leaching (L_N) to groundwater in China. When excess levels of nitrogen accumulate in groundwater, it poses a risk of adverse health effects. Despite this recognition, estimation of L_N from cropland soils in a broad spatial scale is still quite uncertain in China. The uncertainty of L_N primarily stems from the shape of nitrogen leaching response to fertilizer additions (N_r_a_t_e) and the role of environmental conditions. On the basis of 453 site-years at 51 sites across China, we explored the nonlinearity and variability of the response of L_N to N_r_a_t_e and developed an empirical statistical model to determine how environmental factors regulate the rate of N leaching (LR). The result shows that L_N-N_r_a_t_e relationship is convex for most crop types, and varies by local hydro-climates and soil organic carbon. Variability of air temperature explains a half (∼52%) of the spatial variation of LR. The results of model calibration and validation indicate that incorporating this empirical knowledge into a predictive model could accurately capture the variation in leaching and produce a reasonable upscaling from site to country. The fertilizer-induced L_N in 2008 for China's cropland were 0.88 ± 0.23 TgN (1σ), significantly lower than the linear or uniform model, as assumed by Food and Agriculture Organization and MITERRA-EUROPE models. These results also imply that future policy to reduce N leaching from cropland needs to consider environmental variability rather than solely attempt to reduce N_r_a_t_e. - Highlights: • L_N-N_r_a_t_e relationship is convex and varies by local hydro-climates and SOC. • Variability of temperature explains a half of spatial variation of N leaching rate. • L_N in 2008 were 0.88 ± 0.23 Tg, lower than the linear or uniform models. • Reducing L_N should consider background rather than decreasing N_r_a_t_e solely. - Variability of air temperature explains a half of

Catalytic Oligomerization of Terminal Alkynes by Lanthanide Carbyls (η5-C5Me5)2LnCH(SiMe3)2 (Ln = Y, La, Ce)

NARCIS (Netherlands)

Heeres, H.J.; Teuben, J.H.

1991-01-01

Lanthanide and group 3 carbyls Cp*2LnCH(SiMe3)2 (1, Ln = Y; 2, Ln = La; 3, Ln = Ce) are active catalyst precursors for the oligomerization of terminal alkynes HC≡CR (R = alkyl, aryl, SiMe3). The regioselectivity and the extent of oligomerization depend strongly on the lanthanide applied as well as

Phase relations and crystal structures in the systems (Bi,Ln)2WO6 and (Bi,Ln)2MoO6 (Ln=lanthanide)

International Nuclear Information System (INIS)

Berdonosov, Peter S.; Charkin, Dmitri O.; Knight, Kevin S.; Johnston, Karen E.; Goff, Richard J.; Dolgikh, Valeriy A.; Lightfoot, Philip

2006-01-01

Several outstanding aspects of phase behaviour in the systems (Bi,Ln) 2 WO 6 and (Bi,Ln) 2 MoO 6 (Ln=lanthanide) have been clarified. Detailed crystal structures, from Rietveld refinement of powder neutron diffraction data, are provided for Bi 1.8 La 0.2 WO 6 (L-Bi 2 WO 6 type) and BiLaWO 6 , BiNdWO 6 , Bi 0.7 Yb 1.3 WO 6 and Bi 0.7 Yb 1.3 WO 6 (all H-Bi 2 WO 6 type). Phase evolution within the solid solution Bi 2- x La x MoO 6 has been re-examined, and a crossover from γ(H)-Bi 2 MoO 6 type to γ-R 2 MoO 6 type is observed at x∼1.2. A preliminary X-ray Rietveld refinement of the line phase BiNdMoO 6 has confirmed the α-R 2 MoO 6 type structure, with a possible partial ordering of Bi/Nd over the three crystallographically distinct R sites. - Graphical abstract: A summary of phase relations in the lanthanide-doped bismuth tungstate and bismuth molybdate systems is presented, together with some additional structural data on several of these phases

New lanthanide hydrogen phosphites LnH (P03H)2 2H20

International Nuclear Information System (INIS)

Durand, J.; Tijani, N.; Cot, L.; Loukili, M.; Rafiq, M.

1988-01-01

LnH ((P0 3 H) 2 2H 2 0 is prepared from lanthanide oxide and phosphorous acid with Ln = La, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er or Tm. By thermal gravimetric analysis LnH (P0 3 H) 2 and LnH 2 P 2 0 5 (P0 3 H) 2 are obtained. The three salts are orthorhombic. Parameters and space groups are given for the three salts of each lanthanide. 4 tabs., 13 refs

Investigation of BaMoO4-Ln2(MoO4)3 systems (Ln = Nd, Sm, Yb)

International Nuclear Information System (INIS)

Vakulyuk, V.V.; Evdokimov, A.A.; Khomchenko, G.P.

1982-01-01

Using the methods of X-ray phase and differential-thermal analyses phase ratios in the systems BaMoO 4 -Ln 2 (MoO 4 ) 3 (Ln=Nd, Sm, Yb); BaNd 2 (MoO 4 ) 4 -MaGd 2 (MoO 4 ) are studied. Unit cell parameters and the character of melting of the compounds BaLn 2 (MoO 4 ) 4 are specified. Effect of growth conditions on laminated nature of BaGd 2 (MoO 4 ) 4 monocrystals is studied

K2Ln2As2Se9 (Ln = Sm, Gd): the first quaternary rare-earth selenoarsenate compounds with a 3D framework containing chairlike As2Se4 units.

Science.gov (United States)

Wu, Yuandong; Bensch, Wolfgang

2009-04-06

The new compounds K(2)Ln(2)As(2)Se(9) (Ln = Sm, Gd) were obtained by applying the reactive flux method. The structure consists of a three-dimensional (3D) [Ln(2)As(2)Se(9)](2-) framework with K(+) ion-filling tunnels running along the b axis. The two unique Ln(3+) cations are coordinated by two Se(2)(2-) dumbbells, two AsSe(3)(3-) pyramids, and one chairlike As(2)Se(4)(2-) unit in a bicapped trigonal-prismatic geometry. The Ln(3+)-centered trigonal prisms share triangular faces with neighboring prisms, forming one-dimensional chains along the b axis. These chains are linked to each other to form layers by sharing Se(2-) anions on the capped sites of the trigonal prisms. The As(2)Se(4) units connect these layers to form the 3D framework.

Rapid hydrogen hydrate growth from non-stoichiometric tuning mixtures during liquid nitrogen quenching.

Science.gov (United States)

Grim, R Gary; Kerkar, Prasad B; Sloan, E Dendy; Koh, Carolyn A; Sum, Amadeu K

2012-06-21

In this study the rapid growth of sII H(2) hydrate within 20 min of post formation quenching towards liquid nitrogen (LN(2)) temperature is presented. Initially at 72 MPa and 258 K, hydrate samples would cool to the conditions of ~60 MPa and ~90 K after quenching. Although within the stability region for H(2) hydrate, new hydrate growth only occurred under LN(2) quenching of the samples when preformed hydrate "seeds" of THF + H(2) were in the presence of unconverted ice. The characterization of hydrate seeds and the post-quenched samples was performed with confocal Raman spectroscopy. These results suggest that quenching to LN(2) temperature, a common preservation technique for ex situ hydrate analysis, can lead to rapid unintended hydrate growth. Specifically, guest such as H(2) that may otherwise need sufficiently long induction periods to nucleate, may still experience rapid growth through an increased kinetic effect from a preformed hydrate template.

Liquid to gas leak ratios with liquid nitrogen and liquid helium

International Nuclear Information System (INIS)

Batzer, T.H.; Call, W.R.

1985-01-01

To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (approx.750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases (G) at ambient pressure and room temperature were: GN 2 (1), LN 2 (18), GHe(1), and LHe(172). The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

Lanthanide stannate pyrochlores (Ln2Sn2O7; Ln = Nd, Gd, Er) at high pressure.

Science.gov (United States)

Turner, Katlyn M; Tracy, Cameron L; Mao, Wendy L; Ewing, Rodney C

2017-11-09

Lanthanide stannate pyrochlores (Ln2Sn2O7; Ln=Nd, Gd, and Er) were investigated in situ to 50 GPa in order to determine their structural response to compression and compare it to that of lanthanide titanate, zirconate, and hafnate pyrochlores. The cation radius ratio of A3+/B4+ in pyrochlore oxides (A2B2O7) is thought to be the dominant property that influences their compression response. The ionic radius of Sn4+ is intermediate to that of Ti4+, Zr4+, and Hf4+, but the bond in stannate pyrochlore is more covalent than the bonds in titanates, zirconate, and hafnates. In stannates, the pyrochlore cation and anion sublattices begin to disorder at 0.3 GPa. The extent of sublattice disorder vs. pressure is greater in stannates with a smaller Ln3+ cation. Stannate pyrochlores (Fd-3m) begin a sluggish transformation to a cotunnite-like structure (Pnma) at ~28 GPa; similar transitions have been observed in titanate, zirconate, and hafnate pyrochlore at varying pressures with cation radius ratio. The extent of the phase transition vs. pressure varies directly with the size of the Ln3+ cation. Post-decompression from ~50 GPa, Er2Sn2O7 and Gd2Sn2O7 adopt a pyrochlore structure, rather than the multiscale defect-fluorite + weberite structure adopted by Nd2Sn2O7 that is characteristic of titanate, zirconate, and hafnate pyrochlore treated to similar conditions. Like pyrochlore titanates, zirconates, and hafnates, the bulk modulus, B0, of stannates varies linearly and inversely with cation radius ratio. The trends of bulk moduli in stannates in this study are in excellent agreement with previous experimental studies on stannates, and suggest that the size of the Ln3+ cation is a primary determining factor of B0. Additionally, when normalized to rA/rB, the bulk moduli of stannates are comparable to those of zirconates and hafnates, which vary from titanates. Our results suggest that the cation radius ratio strongly influences the bulk moduli of stannates as well as

Magnetic properties and structural transitions of fluorite-related rare earth osmates Ln3OsO7 (Ln=Pr, Tb)

International Nuclear Information System (INIS)

Hinatsu, Yukio; Doi, Yoshihiro

2013-01-01

Ternary rare-earth osmates Ln 3 OsO 7 (Ln=Pr, Tb) have been prepared. They crystallize in an ortho-rhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr 3 OsO 7 exhibits magnetic transitions at 8 and 73 K, and Tb 3 OsO 7 magnetically orders at 8 and 60 K. The Os moments become one-dimensionally ordered, and when the temperature is furthermore decreased, it provokes the ordering in the Ln 3+ sublattice that simultaneously becomes three-dimensionally ordered with the Os sublattice. - Graphical abstract: Ternary rare-earth osmates Ln 3 OsO 7 (Ln=Pr, Tb) have been prepared. They crystallize in an orthorhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr 3 OsO 7 exhibits magnetic transitions at 8 and 73 K, and Tb 3 OsO 7 magnetically orders at 8 and 60 K. Highlights: ► Ternary rare-earth osmates Ln 3 OsO 7 (Ln=Pr, Tb) with an ordered defect-fluorite structure have been prepared. ► Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). ► These compounds show complex magnetic behavior at low temperatures due to magnetic ordering of Ln and Os.

The phase transition of the incommensurate phases β-Ln(PO3)3(Ln=Y,Tb…Yb), crystal structures of α-Ln(PO3)3(Ln=Y,Tb…Yb) and Sc(PO3)3

Science.gov (United States)

Höppe, Hennig A.

2009-07-01

The incommensurately modulated room-temperature phases β-Ln(PO3)3(Ln=Y,Tb…Yb) undergo a topotactic phase transition monitored by vibrational spectroscopy below 180 K leading to α-Ln(PO3)3(Ln=Y,Dy…Yb), above 200 K the incommensurate phases are reobtained. The low-temperature phases exhibit a new structure type (α-Dy(PO3)3, P21/c, Z=12,a=14.1422(6), b=20.0793(9),c=10.1018(4) A˚, β=127.532(3)∘). α-Tb(PO3)3 is isotypic with Gd(PO3)3(α-Tb(PO3)3, I2/a,Z=16,a=25.875(6), b=13.460(3), c=10.044(2) A˚, β=119.13(3)∘). The symmetry relations between the involved phases of the phase transition are discussed. The crystal structure of Sc(PO3)3 is isotypic with that of Lu(PO3)3 and C-type phosphates. The polyphosphates consist of infinite zig-zag chains of corner-sharing PO4 tetrahedra, the cations are coordinated sixfold in an almost octahedral arrangement. To confirm the quality of the determined crystal structures the deviation of the phosphate tetrahedra from ideal symmetry was determined and discussed.

Bi3+ sensitized Y2WO6:Ln3+ (Ln=Dy, Eu, and Sm) phosphors for solar spectral conversion.

Science.gov (United States)

Huang, M N; Ma, Y Y; Xiao, F; Zhang, Q Y

2014-01-01

The phosphors of Y2WO6:Bi3+, Ln3+ (Ln=Dy, Eu and Sm) were synthesized by solid-state reaction in this study. The crystal structure, photoluminescence properties and energy transfer mechanism were investigated. By introducing Bi3+ ions, the excitation band of the phosphors was broadened to be 250-380 nm, which could be absorbed by the dye-sensitized solar cells (DSSCs). The overlap between excitation of W-O groups/Bi3+ and the emission of Ln3+ (Dy, Eu, and Sm) indicated that the probability of energy transfer from W-O groups and Bi3+ to Ln3+. The energy transfer efficiency from Bi3+ to Ln3+ (Ln=Dy, Eu and Sm) are calculated to be 16%, 20% and 58%. This work suggested that Y2WO6:Bi3+, Ln3+ (Ln=Dy, Eu and Sm) might be a promising ultraviolet-absorbing luminescent converter to enhance the photoelectrical conversion efficiency of dye-sensitized solar cells (DSSCs). Copyright © 2013 Elsevier B.V. All rights reserved.

XPS study of the Ln 5p,4f-electronic states of lanthanides in Ln2O3

International Nuclear Information System (INIS)

Teterin, Yu.A.; Teterin, A.Yu.; Utkin, I.O.; Ryzhkov, M.V.

2004-01-01

The present work analyses the fine structure of the low binding energy (E b , 0-50 eV) X-ray photoelectron spectra XPS of lanthanide (La through Lu excepted for Pm) oxides, and compares it with the non-relativistic X α -discrete variation calculation results for the clusters reflecting the close environment of lanthanides in oxides. The obtained results show that the Ln 4f n -electrons of lanthanides in oxides by their spectral parameters have much in common with the M 3d-electrons in oxides of the 3d-transition metals. According to these data, the Ln 4f shell of lanthanides is rather outer and can participate in the formation of molecular orbitals in compounds. The XPS data at least do not contradict the theoretical suggestion about the significant participation of the Ln 4f-electrons in formation of the molecular orbitals in the studied materials. The spectra in the Ln 5p-O 2s binding energy region of the studied lanthanide oxides were found to exhibit the complicated structure instead of separated peaks due to the electrons of the Ln 5p 3/2,5/2 and O 2s atomic shells. Taking into account the energy differences between the inner (Ln 3d) and outer (Ln 5p) electronic shells for some metallic lanthanides and their oxides, the Ln 5p atomic shells were shown to participate in the formation of the inner valence molecular orbitals (IVMO). That agrees qualitatively with the calculation results

Development of electrolyte-supported intermediate-temperature single-chamber solid oxide fuel cells using Ln{sub 0.7}Sr{sub 0.3}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} (Ln = Pr, La, Gd) cathodes

Energy Technology Data Exchange (ETDEWEB)

Ruiz de Larramendi, I.; Ruiz de Larramendi, J.I.; Rojo, T. [Departamento de Quimica Inorganica, Universidad del Pais Vasco, Apdo.644, 48080 Bilbao (Spain); Lamas, D.G.; Cabezas, M.D.; Walsoee de Reca, N.E. [CINSO, CONICET-CITEFA, J.B. de La Salle 4397 (B1603ALO) Villa Martelli, Pcia. de Buenos Aires (Argentina)

2009-09-05

Iron-cobalt-based perovskite oxides with general formula Ln{sub 0.7}Sr{sub 0.3}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} (where Ln = La, Pr and Gd) have been investigated for their application as intermediate-temperature cathodes in solid oxide fuel cells (SOFCs). Powdered samples of these materials were synthesized by a novel gel combustion process and then characterized by X-ray powder diffraction (XPD) and scanning electron microscopy (SEM). XPD patterns were satisfactorily indexed with an orthorhombic GdFeO{sub 3}-type structure and, for all samples, a mean particle size of less than 1 {mu}m was estimated from the SEM data. Experimental single-chamber SOFCs using with these materials as cathodes and NiO-SDC (samaria-doped ceria) and SDC as anode and electrolyte, respectively, were evaluated at 600 C in a methane/oxygen mixtures. Peak power densities of 65.4, 48.7 and 46.2 mW cm{sup -2} were obtained for Ag vertical stroke Ln{sub 0.7}Sr{sub 0.3}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} vertical stroke SDC vertical stroke NiO-SDC vertical stroke Pt cells with Ln = Pr, La and Gd, respectively. The relatively high power density obtained for the Pr compound shows that it could be an interesting material for cathode of single-chamber SOFCs. (author)

Synthesis and characterisation of the n = 2 Ruddlesden–Popper phases Ln{sub 2}Sr(Ba)Fe{sub 2}O{sub 7} (Ln = La, Nd, Eu)

Energy Technology Data Exchange (ETDEWEB)

Gurusinghe, Nicola N.M. [School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Figuera, Juand de la; Marco, José F. [Instituto de Quimica-Fisica “Rocasolano”, CSIC, Serrano 119, 28006 Madrid (Spain); Thomas, Michael F. [Department of Physics, University of Liverpool, Liverpool. L69 3BX (United Kingdom); Berry, Frank J., E-mail: f.j.berry.1@bham.ac.uk [School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Greaves, Colin [School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

2013-09-01

Graphical abstract: - Highlights: • Some Ruddlesden–Popper phases have been characterised. • Substitution on the A site influences cationic order. • The magnetic moment redirects with temperature - Abstract: A series of n = 2 Ruddlesden–Popper phases A{sub 2}B{sub 2}O{sub 7} of composition Ln{sub 2}Sr(Ba)Fe{sub 2}O{sub 7} (Ln = La, Nd, Eu) have been prepared. La{sub 2}SrFe{sub 2}O{sub 7} and La{sub 2}BaFe{sub 2}O{sub 7} crystallise in the tetragonal space group I4/mmm. The structures of Eu{sub 2}SrFe{sub 2}O{sub 7} and Nd{sub 2}SrFe{sub 2}O{sub 7} are best described in space group P4{sub 2}/mnm. Substitution on the A site with smaller lanthanide- and larger alkaline metal- ions leads to enhanced cationic order in these phases and reflects increasing differences in cationic radii. All the compounds are antiferromagnetically ordered between 298 and 2 K. In La{sub 2}SrFe{sub 2}O{sub 7} the magnetic moment lies along [1 1 0] at all temperatures between 298 and 2 K whereas in La{sub 2}BaFe{sub 2}O{sub 7} the magnetic moment at 298 K lies along the crystallographic x-axis but redirects from the [1 0 0] to the [1 1 0] direction between 210 and 190 K and is retained in this direction until 2 K. In Nd{sub 2}SrFe{sub 2}O{sub 7} the magnetic moment at 298 K lies along [1 1 0] but rotates from [1 1 0] to [0 0 1] between 17 and 9 K. A series of {sup 57}Fe Mössbauer spectra recorded from La{sub 2}SrFe{sub 2}O{sub 7} between 290 and 600 K indicate a magnetic ordering temperature of T{sub N} ≥ 535 K.

Arcing time analysis of liquid nitrogen with respect to electrode materials

Science.gov (United States)

Junaid, Muhammad; Yang, Kun; Ge, Hanming; Wang, Jianhua

2018-03-01

Unlike sulphur hexafluoride (SF6), liquid nitrogen (LN2) is cost effective, environment friendly and cryogenic dielectric. It has astounding insulating properties with the potential to decrease power loss in switchgear applications due to its remarkably low temperatures. The basic research is however a necessity to observe the performance of LN2 subjected to high luminance arcs. So far, there are no findings that refer to the arcing time inside the LN2 environment. The objective of this work was to investigate the arcing times in LN2 and compare the results with open air conditions using different electrode materials. Experiments were conducted on different DC voltages and their arcing times were measured. Three different kinds of electrode materials, namely: pure copper (Cu), stainless used steel (SUS) and aluminium alloy (Al 6061) were tested under 1 atmospheric pressure. The results revealed that LN2 extinguishes arc in almost half the amount of time required by the open air insulation. With Al 6061 has the shortest arcing time, whilst Cu, the second best choice and SUS places last in the evaluation. It was encapsulated from the findings that LN2 is a better choice than air insulation in terms of arc quenching and a better alternative to SF6 when environment is the priority.

Experimental investigations on cryogenic cooling by liquid nitrogen in the end milling of hardened steel

Science.gov (United States)

Ravi, S.; Pradeep Kumar, M.

2011-09-01

Milling of hardened steel generates excessive heat during the chip formation process, which increases the temperature of cutting tool and accelerates tool wear. Application of conventional cutting fluid in milling process may not effectively control the heat generation also it has inherent health and environmental problems. To minimize health hazard and environmental problems caused by using conventional cutting fluid, a cryogenic cooling set up is developed to cool tool-chip interface using liquid nitrogen (LN 2). This paper presents results on the effect of LN 2 as a coolant on machinability of hardened AISI H13 tool steel for varying cutting speed in the range of 75-125 m/min during end milling with PVD TiAlN coated carbide inserts at a constant feed rate. The results show that machining with LN 2 lowers cutting temperature, tool flank wear, surface roughness and cutting forces as compared with dry and wet machining. With LN 2 cooling, it has been found that the cutting temperature was reduced by 57-60% and 37-42%; the tool flank wear was reduced by 29-34% and 10-12%; the surface roughness was decreased by 33-40% and 25-29% compared to dry and wet machining. The cutting forces also decreased moderately compared to dry and wet machining. This can be attributed to the fact that LN 2 machining provides better cooling and lubrication through substantial reduction in the cutting zone temperature.

Interplay of structural chemistry and magnetism in perovskites; A study of CaLn2Ni2WO9; Ln=La, Pr, Nd

Science.gov (United States)

Chin, Chun-Mann; Paria Sena, Robert; Hunter, Emily C.; Hadermann, Joke; Battle, Peter D.

2017-07-01

Polycrystalline samples of CaLn2Ni2WO9 (Ln=La, Pr, Nd) have been synthesized and characterised by a combination of X-ray and neutron diffraction, electron microscopy and magnetometry. Each composition adopts a perovskite-like structure with a 5.50, b 5.56, c 7.78 Å, β 90.1° in space group P21/n. Of the two crystallographically distinct six-coordinate sites, one is occupied entirely (Ln=Pr) or predominantly (Ln=La, Nd) by Ni2+ and the other by Ni2+ and W6+ in a ratio of approximately 1:2. None of the compounds shows long-range magnetic order at 5 K. The magnetometry data show that the magnetic moments of the Ni2+ cations form a spin glass below 30 K in each case. The Pr3+ moments in CaPr2Ni2WO9 also freeze but the Nd3+ moments in CaNd2Ni2WO9 do not. This behaviour is contrasted with that observed in other (A,A')B2B'O9 perovskites.

Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

Science.gov (United States)

Pathan, F. S.; Khan, Z.; Semwal, P.; Raval, D. C.; Joshi, K. S.; Thankey, P. L.; Dhanani, K. R.

2008-05-01

Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN2 panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN2 panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN2 panels during sniffer test and pressure drop test using helium gas.

Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

Energy Technology Data Exchange (ETDEWEB)

Pathan, F S; Khan, Z; Semwal, P; Raval, D C; Joshi, K S; Thankey, P L; Dhanani, K R [Institute for Plasma Research, Bhat, Gandhinagar - 382 428, Gujarat (India)], E-mail: firose@ipr.res.in

2008-05-01

Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN{sub 2} panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN{sub 2} panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN{sub 2} panels during sniffer test and pressure drop test using helium gas.

Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

International Nuclear Information System (INIS)

Pathan, F S; Khan, Z; Semwal, P; Raval, D C; Joshi, K S; Thankey, P L; Dhanani, K R

2008-01-01

Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN 2 panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN 2 panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN 2 panels during sniffer test and pressure drop test using helium gas

Structure and bulk modulus of Ln-doped UO{sub 2} (Ln = La, Nd) at high pressure

Energy Technology Data Exchange (ETDEWEB)

Rittman, Dylan R., E-mail: drittman@stanford.edu [Department of Geological Sciences, Stanford University, Stanford, CA 94305 (United States); Park, Sulgiye; Tracy, Cameron L. [Department of Geological Sciences, Stanford University, Stanford, CA 94305 (United States); Zhang, Lei [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California Davis, Davis, CA 95616 (United States); Department of Chemical Engineering and Materials Science, University of California Davis, Davis, CA 95616 (United States); Palomares, Raul I.; Lang, Maik [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Navrotsky, Alexandra [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California Davis, Davis, CA 95616 (United States); Department of Chemical Engineering and Materials Science, University of California Davis, Davis, CA 95616 (United States); Mao, Wendy L. [Department of Geological Sciences, Stanford University, Stanford, CA 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Ewing, Rodney C. [Department of Geological Sciences, Stanford University, Stanford, CA 94305 (United States)

2017-07-15

The structure of lanthanide-doped uranium dioxide, Ln{sub x}U{sub 1-x}O{sub 2-0.5x+y} (Ln = La, Nd), was investigated at pressures up to ∼50–55 GPa. Samples were synthesized with different lanthanides at different concentrations (x ∼ 0.2 and 0.5), and all were slightly hyperstoichiometric (y ∼ 0.25–0.4). In situ high-pressure synchrotron X-ray diffraction was used to investigate their high-pressure phase behavior and determine their bulk moduli. All samples underwent a fluorite-to-cotunnite phase transformation with increasing pressure. The pressure of the phase transformation increased with increasing hyperstoichiometry, which is consistent with results from previous computational simulations. Bulk moduli are inversely proportional to both the ionic radius of the lanthanide and its concentration, as quantified using a weighted cationic radius ratio. This trend was found to be consistent with the behavior of other elastic properties measured for Ln-doped UO{sub 2}, such as Young's modulus. - Highlights: •Ln-doped UO{sub 2} transforms from fluorite to cotunnite at high pressure. •Transition pressure increases with increasing hyperstoichiometry. •Bulk modulus decreases with increasing Ln-dopant radius and concentration.

Test of a cryogenic set-up for a 10 meter long liquid nitrogen cooled superconducting power cable

DEFF Research Database (Denmark)

Træholt, Chresten; Rasmussen, Carsten; Kühle (fratrådt), Anders Van Der Aa

2000-01-01

High temperature superconducting power cables may be cooled by a forced flow of sub-cooled liquid nitrogen. One way to do this is to circulate the liquid nitrogen (LN2) by means of a mechanical pump through the core of the cable and through a sub-cooler.Besides the cooling station, the cryogenics...... cable. We report on our experimental set-up for testing a 10 meter long high temperature superconducting cable with a critical current of 3.2 kA at 77K. The set-up consists of a custom designed cable end termination, current lead, coolant feed-through, liquid nitrogen closed loop circulation system...

Magnetic properties and structural transitions of fluorite-related rare earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb)

Energy Technology Data Exchange (ETDEWEB)

Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Doi, Yoshihiro [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan)

2013-02-15

Ternary rare-earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb) have been prepared. They crystallize in an ortho-rhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr{sub 3}OsO{sub 7} exhibits magnetic transitions at 8 and 73 K, and Tb{sub 3}OsO{sub 7} magnetically orders at 8 and 60 K. The Os moments become one-dimensionally ordered, and when the temperature is furthermore decreased, it provokes the ordering in the Ln{sup 3+} sublattice that simultaneously becomes three-dimensionally ordered with the Os sublattice. - Graphical abstract: Ternary rare-earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb) have been prepared. They crystallize in an orthorhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr{sub 3}OsO{sub 7} exhibits magnetic transitions at 8 and 73 K, and Tb{sub 3}OsO{sub 7} magnetically orders at 8 and 60 K. Highlights: Black-Right-Pointing-Pointer Ternary rare-earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb) with an ordered defect-fluorite structure have been prepared. Black-Right-Pointing-Pointer Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). Black-Right-Pointing-Pointer These compounds show complex magnetic behavior at low temperatures due to magnetic ordering of Ln and Os.

Influence of prior deformation on the sensitization of AISI Type 316LN stainless steel

Energy Technology Data Exchange (ETDEWEB)

Parvathavarthini, N. (Metallurgy Div., Indira Gandhi Centre for Atomic Research, Tamilnadu (India)); Dayal, R.K. (Metallurgy Div., Indira Gandhi Centre for Atomic Research, Tamilnadu (India)); Gnanamoorthy, J.B. (Metallurgy Div., Indira Gandhi Centre for Atomic Research, Tamilnadu (India))

1994-02-01

The sensitization behaviour of a nuclear grade AISI 316LN stainless steel (SS) was studied for various cold-work levels ranging from 0% (mill-annealed) to 25% reduction in thickness. ASTM standard A262 Practices A and E were adopted to detect the susceptibility to intergranular corrosion. The results obtained in these tests were used to construct time-temperature-sensitization (TTS) diagrams. Using these data, the critical linear cooling rate was calculated, above which there is no risk of sensitization. In order to predict the sensitization behaviour during practical cooling conditions, Continuous-cooling-sensitization (CCS) diagrams were established utilising the TTS diagrams by a mathematical method. The influences of prior deformation and nitrogen in the alloy on the sensitization kinetics are discussed. It was found that nitrogen addition retards the sensitization kinetics and that t[sub min] (minimum time required for sensitization at nose temperature) increases by two orders of magnitude in Type 316LN SS compared to that of Type 316 SS at the different prior deformation levels. Cold-working up to 15% accelerates the onset of carbide precipitation and on further cold working there is not much difference in the kinetics. Desensitization is faster in highly cold-worked material, especially at high temperatures. (orig.)

High Energy Cutting and Stripping Utilizing Liquid Nitrogen

Science.gov (United States)

Hume, Howard; Noah, Donald E.; Hayes, Paul W.

2005-01-01

The Aerospace Industry has endeavored for decades to develop hybrid materials that withstand the rigors of mechanized flight both within our atmosphere and beyond. The development of these high performance materials has led to the need for environmentally friendly technologies for material re-work and removal. The NitroJet(TM) is a fluid jet technology that represents an evolution of the widely used, large-scale water jet fluid jet technology. It involves the amalgamation of fluid jet technology and cryogenics technology to create a new capability that is applicable where water jet or abrasive jet (water jet plus entrained abrasive) are not suitable or acceptable because of technical constraints such as process or materials compatibility, environmental concerns and aesthetic or legal requirements. The NitroJet(TM) uses ultra high-pressure nitrogen to cut materials, strip numerous types of coatings such as paint or powder coating, clean surfaces and profile metals. Liquid nitrogen (LN2) is used as the feed stream and is pressurized in two stages. The first stage pressurizes sub cooled LN2 to an intermediate pressure of between 15,000 and 20,000 psi at which point the temperature of the LN2 is about -250 F. The discharge from this stage is then introduced as feed to a dual intensifier system, which boosts the pressure from 15,000 - 20,000 psi up to the maximum operating pressure of 55,000 psi. A temperature of about -220 F is achieved at which point the nitrogen is supercritical. In this condition the nitrogen cuts, strips and abrades much like ultra high-pressure water would but without any residual liquid to collect, remove or be contaminated. Once the nitrogen has performed its function it harmlessly flashes back into the atmosphere as pure nitrogen gas. The system uses heat exchangers to control and modify the temperature of the various intake and discharge nitrogen streams. Since the system is hydraulically operated, discharge pressures can be easily varied over

High-pressure synthesis and magnetic behavior of A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd)

Energy Technology Data Exchange (ETDEWEB)

Shimura, Gen; Niwa, Ken; Shirako, Yuichi; Hasegawa, Masashi [Department of Crystalline Materials Science, Nagoya University, 464-8601, Nagoya (Japan)

2017-01-26

A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd), were successfully synthesized under high pressure and high temperature (6 GPa, 1375 K). From the synchrotron powder X-ray diffraction patterns, all of the diffraction peaks can be indexed by the P4{sub 2}/nmc space group with lattice parameters a, c ∼ 2a{sub p} (a{sub p}: primitive cubic perovskite lattice) and no ordering of the B-site cations. Rietveld analysis of the synchrotron powder X-ray diffraction patterns and Curie-Weiss fitting of their magnetizations reveal that the ionic formulae of these perovskites are Ln{sup 3+}Mn{sup 2+}(Ga{sup 3+}{sub 0.5}Ti{sup 4+}{sub 0.5}){sub 2}O{sup 2-}{sub 6}. SmMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} shows canted-antiferromagnetic behavior, whereas GdMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} exhibits two different magnetic states at low temperature depending on the applied magnetic field and shows an unusual magnetization curve. These magnetic behaviors originate by decreasing the antiferromagnetic interaction by substituting Ga{sup 3+}(d{sup 10}) for Ti{sup 4+}(d{sup 0}) and by decreasing the ferromagnetic interaction between columnar-ordered Ln{sup 3+} and Mn{sup 2+}. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Phase equilibria in the MgMoO4-Ln2(MoO4)3 (Ln=La,Gd) systems

International Nuclear Information System (INIS)

Fedorov, N.F.; Ipatov, V.V.; Kvyatkovskij, O.V.

1980-01-01

Phase equilibria in the MgMoO 4 -Ln 2 (MoO 4 ) 3 systems (Ln=La, Gd) have been studied by static and dynamic methods of the physico-chemical analysis, using differential thermal, visual-polythermal, crystal-optical, X-ray phase, and infrared spectroscopic methods, and their phase diagrams have been constructed. Phase equilibria in the systems studied are characterized by limited solubility of components in the liquid state, formation of solid solutions on the base of α- and β-forms of Gd 2 (MoO 4 ) 3 . Eutectics in the MgMoO 4 -Ln 2 (MoO 4 ) 3 (Ln=La, Gd) systems corresponds to the composition of 71 mode % La 2 (MoO 4 ) 3 -29 mole % MgMoO 4 , tsub(melt)--935+-5 deg C and 57 mole % Gd 2 (MoO 4 ) 3 -43 mole % MgMoO 4 , tsub(melt)=1020+-5 deg C. The region of glass formation has been established [ru

Structures, magnetic, and thermal properties of Ln3MoO7 (Ln=La, Pr, Nd, Sm, and Eu)

International Nuclear Information System (INIS)

Nishimine, Hiroaki; Wakeshima, Makoto; Hinatsu, Yukio

2005-01-01

Ternary lanthanide-molybdenum oxides Ln 3 MoO 7 (Ln=La, Pr, Nd, Sm, Eu) have been prepared. Their structures were determined by X-ray diffraction measurements. They crystallize in a superstructure of cubic fluorite and the space group is P2 1 2 1 2 1 . The Mo ion is octahedrally coordinated by six oxygens and the slightly distorted octahedra share corners forming a zig-zag chain parallel to the b-axis. These compounds have been characterized by magnetic susceptibility and specific heat measurements. The La 3 MoO 7 shows complex magnetic behavior at 150 and 380K. Below these temperatures, there is a large difference in the temperature-dependence of the magnetic susceptibility measured under zero-field-cooled condition and under field-cooled condition. The Nd 3 MoO 7 show a clear antiferromagnetic transition at 2.5K. From the susceptibility measurements, both Pr 3 MoO 7 and Sm 3 MoO 7 show the existence of magnetic anomaly at 8.0 and 2.5K, respectively. The results of the specific heat measurements also show anomalies at the corresponding magnetic transition temperatures. The differential scanning calorimetry measurements indicate that two phase-transitions occur for any Ln 3 MoO 7 compound in the temperature range between 370 and 710K

Digital LN2 control system for superconducting linac at PLF, Mumbai

International Nuclear Information System (INIS)

Karande, J.N.; Dhumal, P.; Takke, A.N.; Pal, S.; Nanal, V.; Pillay, R.G.

2013-01-01

The superconducting LINAC at PLF, Mumbai has a modular structure with eight cryostats divided in two groups. Each cryostat has a LN2 vessel of ∼ 40L capacity, which serves as a thermal shield for helium vessel. A coaxial capacitance type sensor is developed in house to measure the LN2 level. Monostable multi-vibrator based readout electronics is designed to measure the change in capacitance due to LN2 level change. The sensor capacitance with a fixed value resistor decides the 'ON' time of the monostable multi-vibrator. A 16 bit timer of microcontroller 8051 is used to measure the pulse width. The change in pulse width is converted into a LN2 level and displayed on a 4*20 LCD screen. The control unit is also equipped with automatic control of LN2 filling valves triggered by levels. The digital LN2 control can be operated locally or remotely via a serial RS232 communication line.Two control stations are designed and developed to take care of eight cryostats. (author)

Heterospin systems constructed from [Cu2Ln]3+ and [Ni(mnt)2]1-,2- Tectons: First 3p-3d-4f complexes (mnt = maleonitriledithiolato).

Science.gov (United States)

Madalan, Augustin M; Avarvari, Narcis; Fourmigué, Marc; Clérac, Rodolphe; Chibotaru, Liviu F; Clima, Sergiu; Andruh, Marius

2008-02-04

New heterospin complexes have been obtained by combining the binuclear complexes [{Cu(H(2)O)L(1)}Ln(O(2)NO)(3)] or [{CuL(2)}Ln(O(2)NO)(3)] (L(1) = N,N'-propylene-di(3-methoxysalicylideneiminato); L(2) = N,N'-ethylene-di(3-methoxysalicylideneiminato); Ln = Gd(3+), Sm(3+), Tb(3+)), with the mononuclear [CuL(1)(2)] and the nickel dithiolene complexes [Ni(mnt)(2)](q)- (q = 1, 2; mnt = maleonitriledithiolate), as follows: (1)infinity[{CuL(1)}(2)Ln(O(2)NO){Ni(mnt)(2)}].Solv.CH(3)CN (Ln = Gd(3+), Solv = CH(3)OH (1), Ln = Sm(3+), Solv = CH(3)CN (2)) and [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)][Ni(mnt)(2)] (3) with [Ni(mnt)2]2-, [{(CH(3)CN)CuL(1)}(2)Ln(H(2)O)][Ni(mnt)(2)]3.2CH(3)CN (Ln = Gd(3+) (4), Sm(3+) (5), Tb(3+) (6)), and [{(CH(3)OH)CuL(2)}{CuL(2)}Gd(O(2)NO){Ni(mnt)(2)}][Ni(mnt)(2)].CH(2)Cl(2) (7) with [Ni(mnt))(2]*-. Trinuclear, almost linear, [CuLnCu] motifs are found in all the compounds. In the isostructural 1 and 2, two trans cyano groups from a [Ni(mnt)2]2- unit bridge two trimetallic nodes through axial coordination to the Cu centers, thus leading to the establishment of infinite chains. 3 is an ionic compound, containing discrete [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)](2+) cations and [Ni(mnt)(2)](2-) anions. Within the series 4-6, layers of discrete [CuLnCu](3+) motifs alternate with stacks of interacting [Ni(mnt)(2)](*-) radical anions, for which two overlap modes, providing two different types of stacks, can be disclosed. The strength of the intermolecular interactions between the open-shell species is estimated through extended Hückel calculations. In compound 7, [Ni(mnt)(2)](*-) radical anions coordinate group one of the Cu centers of a trinuclear [Cu(2)Gd] motif through a CN, while discrete [Ni(mnt)(2)](*-) units are also present, overlapping in between, but also with the coordinated ones. Furthermore, the [Cu(2)Gd] moieties dimerize each other upon linkage by two nitrato groups, both acting as chelate toward the gadolinium ion from one unit and monodentate toward a

Magnetic properties and structural transitions of fluorite-related rare earth osmates Ln3OsO7 (Ln=Pr, Tb)

Science.gov (United States)

Hinatsu, Yukio; Doi, Yoshihiro

2013-02-01

Ternary rare-earth osmates Ln3OsO7 (Ln=Pr, Tb) have been prepared. They crystallize in an ortho-rhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr3OsO7 exhibits magnetic transitions at 8 and 73 K, and Tb3OsO7 magnetically orders at 8 and 60 K. The Os moments become one-dimensionally ordered, and when the temperature is furthermore decreased, it provokes the ordering in the Ln3+ sublattice that simultaneously becomes three-dimensionally ordered with the Os sublattice.

The solubility of carbon in low-nitrogen liquid lithium

International Nuclear Information System (INIS)

Yonco, R.M.; Homa, M.I.

1986-01-01

The solubility of carbon in liquid lithium containing 0 C and compared with the solubility in lithium containing proportional 2600 wppm nitrogen in that same temperature range. A direct sampling method was employed in which filtered samples of the saturated solution were taken at randomly selected temperatures. The entire sample was analyzed for carbon by the acetylene evolution method. The analytical method was examined critically and it was found that (1) all of the carbon in solution, including carbon introduced as lithium cyanamide is detected and (2) ethylene and ethane must also be measured and included with the acetylene to get complete recovery of the carbon content of the sample. The solubility of carbon in low-nitrogen lithium can be expressed by the equations ln S=6.731-8617T -1 and log Ssup(*)=7.459-3740T -1 , where S is the mole percent Li 2 C 2 and Ssup(*) is in weight parts per million carbon. The presence of proportional 2600 wppm nitrogen does not affect the solubility of carbon in lithium at temperatures above proportional 350 0 C, but at lower temperatures it increased the solubility by as much as an order of magnitude compared to the solubility in low-nitrogen lithium. (orig.)

New family of lanthanide-based inorganic-organic hybrid frameworks: Ln2(OH)4[O3S(CH2)nSO3]·2H2O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4) and their derivatives.

Science.gov (United States)

Liang, Jianbo; Ma, Renzhi; Ebina, Yasuo; Geng, Fengxia; Sasaki, Takayoshi

2013-02-18

We report the synthesis and structure characterization of a new family of lanthanide-based inorganic-organic hybrid frameworks, Ln(2)(OH)(4)[O(3)S(CH(2))(n)SO(3)]·2H(2)O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4), and their oxide derivatives. Highly crystallized samples were synthesized by homogeneous precipitation of Ln(3+) ions from a solution containing α,ω-organodisulfonate salts promoted by slow hydrolysis of hexamethylenetetramine. The crystal structure solved from powder X-ray diffraction data revealed that this material comprises two-dimensional cationic lanthanide hydroxide {[Ln(OH)(2)(H(2)O)](+)}(∞) layers, which are cross-linked by α,ω-organodisulfonate ligands into a three-dimensional pillared framework. This hybrid framework can be regarded as a derivative of UCl(3)-type Ln(OH)(3) involving penetration of organic chains into two {LnO(9)} polyhedra. Substitutional modification of the lanthanide coordination promotes a 2D arrangement of the {LnO(9)} polyhedra. A new hybrid oxide, Ln(2)O(2)[O(3)S(CH(2))(n)SO(3)], which is supposed to consist of alternating {[Ln(2)O(2)](2+)}(∞) layers and α,ω-organodisulfonate ligands, can be derived from the hydroxide form upon dehydration/dehydroxylation. These hybrid frameworks provide new opportunities to engineer the interlayer chemistry of layered structures and achieve advanced functionalities coupled with the advantages of lanthanide elements.

Theoretical analysis and experimental investigation on performance of the thermal shield of accelerator cryomodules by thermo-siphon cooling of liquid nitrogen

Science.gov (United States)

Datta, T. S.; Kar, S.; Kumar, M.; Choudhury, A.; Chacko, J.; Antony, J.; Babu, S.; Sahu, S. K.

2015-12-01

Five beam line cryomodules with total 27 superconducting Radio Frequency (RF) cavities are installed and commissioned at IUAC to enhance the energy of heavy ion from 15 UD Pelletron. To reduce the heat load at 4.2 K, liquid nitrogen (LN2) cooled intermediate thermal shield is used for all these cryomodules. For three linac cryomodules, concept of forced flow LN2 cooling is used and for superbuncher and rebuncher, thermo-siphon cooling is incorporated. It is noticed that the shield temperature of superbuncher varies from 90 K to 110 K with respect to liquid nitrogen level. The temperature difference can't be explained by using the basic concept of thermo-siphon with the heat load on up flow line. A simple thermo-siphon experimental set up is developed to simulate the thermal shield temperature profile. Mass flow rate of liquid nitrogen is measured with different heat load on up flow line for different liquid levels. It is noticed that small amount of heat load on down flow line have a significant effect on mass flow rate. The present paper will be investigating the data generated from the thermosiphon experimental set up and a theoretical analysis will be presented here to validate the measured temperature profile of the cryomodule shield.

Cutting characteristics and deformed layer of type 316LN stainless steel

International Nuclear Information System (INIS)

Oh, Sun Sae; Yi, Won

2004-01-01

The cutting characteristics and the deformed layer of Nitrogen(N)-added type 316LN stainless steel were comparatively investigated to type 316L stainless steel. The cutting force, the surface roughness(Ra) and the tool wear in face milling works were measured with cutting conditions, and the deformed layers were obtained from micro-hardness testing method. The cutting resistance of type 316LN was similar to type 316L in spite of its high strength. The surface roughness of type 316LN was superior to type 316L for all the cutting conditions. In particular, in the high cutting speed above 345m/min, the surface roughness of the two stainless steels was closely same. The deformed layer thickness of the two stainless steels was generated in the 150μm-300μm ranges, and its value of type 316LN was lower than that of type 316L. This is due to the high strength properties by nitrogen effect. It was found that type 316LN was higher in the tool wear than that type 316L, and flank wear was dominant to crater wear. In face milling works of type 316LN steel, tool wear is regarded as a important problem

Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

Science.gov (United States)

Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

2013-11-01

High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN2). Electrical conductivity of PPLP in LN2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

Brush Seals for Cryogenic Applications: Performance, Stage Effects, and Preliminary Wear Results in LN2 and LH2

Science.gov (United States)

Proctor, Margaret P.; Walker, James F.; Perkins, H. Douglas; Hoopes, Joan F.; Williamson, G. Scott

1996-01-01

Brush seals are compliant contacting seals and have significantly lower leakage than labyrinth seals in gas turbine applications. Their long life and low leakage make them candidates for use in rocket engine turbopumps. Brush seals, 50.8 mm (2 in.) in diameter with a nominal 127-micron (0.005-in.) radial interference, were tested in liquid nitrogen (LN2) and liquid hydrogen (LH2) at shaft speeds up to 35,000 and 65,000 rpm, respectively, and at pressure drops up to 1.21 MPa (175 psid) per brush. A labyrinth seal was also tested in liquid nitrogen to provide a baseline. The LN2 leakage rate of a single brush seal with an initial radial shaft interference of 127 micron (0.005 in.) measured one-half to one-third the leakage rate of a 12-tooth labyrinth seal with a radial clearance of 127 micron (0.005 in.). Two brushes spaced 7.21 micron (0.248 in.) apart leaked about one-half as much as a single brush, and two brushes tightly packed together leaked about three-fourths as much as a single brush. The maximum measured groove depth on the Inconel 718 rotor with a surface finish of 0.81 micron (32 microinch) was 25 micron (0.0010 in.) after 4.3 hr of shaft rotation in liquid nitrogen. The Haynes-25 bristles wore approximately 25 to 76 micron (0.001 to 0.003 in.) under the same conditions. Wear results in liquid hydrogen were significantly different. In liquid hydrogen the rotor did not wear, but the bristle material transferred onto the rotor and the initial 127 micron (0.005 in.) radial interference was consumed. Relatively high leakage rates were measured in liquid hydrogen. More testing is required to verify the leakage performance, to validate and calibrate analysis techniques, and to determine the wear mechanisms. Performance, staging effects, and preliminary wear results are presented.

Insertion of water into rare earth oxocuprates (Ln)Ba 2Cu 3O 7-δ

Science.gov (United States)

Günther, Wulf; Schöllhorn, Robert

1996-02-01

The solid state reaction of LnBa 2Cu 3O 7-δ bulk material with water vapour corresponds to a quantitative topotactic reaction of the solid with H 2O to a maximum stoichiometry of LnBa 2Cu 3O 7-δ(H 2O) 1. The reaction proceeds in a temperature window which depends upon the oxygen content (δ) of the starting phase and is correlated with a structural transition via intermediate states. Although the integral copper oxidation state is not affected by the water intercalation, electronic and transport properties are strongly influenced. The insertion of water into these defect perovskites has to be described as a topotactic acid/base process.

Comparison of heat transfer in liquid and slush nitrogen by numerical simulation of cooling rates for French straws used for sperm cryopreservation.

Science.gov (United States)

Sansinena, M; Santos, M V; Zaritzky, N; Chirife, J

2012-05-01

Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was used to predict cooling rates. Calculations performed using heat transfer coefficients in the range of film boiling confirmed the main benefit of plunging a straw in slush over LN(2) did not arise from their temperature difference (-207 vs. -196 °C), but rather from an increase in the external heat transfer coefficient. Numerical simulations using high heat transfer (h) coefficients (assumed to prevail in SN(2)) suggested that plunging in SN(2) would increase cooling rates of French straw. This increase of cooling rates was attributed to a less or null film boiling responsible for low heat transfer coefficients in liquid nitrogen when the straw is placed in the solid-liquid mixture or slush. In addition, predicted cooling rates of French straws in SN(2) tended to level-off for high h values, suggesting heat transfer was dictated by heat conduction within the liquid filled plastic straw. Copyright © 2012 Elsevier Inc. All rights reserved.

Reaction of (CP(2)asterisk-lnH)(2) (ln=Y, La) and CP(2)asterisk-Y(2-C(6)H(4)CH(2)NMe(2)) with esters and amides and molecular-structure of [CP(2)asterisk-Y(mu- ocme=chc(oet)o)](2)

NARCIS (Netherlands)

Deelman, B.J; Wierda, F.; Meetsma, A.; Teuben, J.H

1995-01-01

The activation of esters and amides by (Cp(2)*LnH)(2) [Ln = Y (1a), Ln = La (1b), Cp*=C(5)Me] and Cp(2)*Y(2-C(6)H(4)CH(2)NMe(2)) (2) is described. Compounds 1a and 1b react with ethyl acetate to form Cp(2)*YOEt (3a) and Cp(2)*LaOEt (30). With 1a and ethyl benzoate a 1:1 mixture of 3a and

Investigation of phase relationships in subsolidus region of Ln2O3-MoO3-B2O3 systems

International Nuclear Information System (INIS)

Lysanova, C.V.; Dzhurinskij, B.F.; Komova, M.G.; Tananaev, I.V.

1983-01-01

Phase formation in subsolidus region of Ln 2 O 3 -MoO 3 B 2 O 3 systems (Ln-La, Nd) is studied. Three compounds with mixed oxyanions-boratomolybdates of LnMoBO 6 composition (Ln-La, Ce, Pr, Nd), Ln 2 MoB 2 O 9 (Ln-La, Ce, Pr, Nd, Sm, EU, Gde Tb) Ln 6 Mo 3 B 4 0 24 (Ln-Pr, Nd) are revealed and described

An explanation for why it is difficult to form slush nitrogen from liquid nitrogen used previously for this purpose.

Science.gov (United States)

Baker, Michael J; Denton, Travis T; Herr, Charles

2013-02-01

Slush nitrogen (SN) is used to avoid the Leidenfrost effect, which is problematic when using liquid nitrogen (LN). Slush nitrogen's usefulness has been demonstrated by its requirement for the successful cryopreservation of insect embryos. To convert LN to SN, typically, the pressure above a Dewar of LN is reduced, using a vacuum pump in a sealed system until conversion occurs. It has been observed that LN from a fresh tank will readily produce SN; however, repeated use of the same LN results in the inability to form SN in subsequent trials. The current experiments were designed to identify the cause of this phenomenon. The hypothesis is that gaseous oxygen from the surrounding, ambient air condenses and mixes with the LN to form a mixture with a lower freezing point and; therefore, prevents the formation of SN. The hypothesis was tested and found to be true. Copyright © 2012. Published by Elsevier Inc.

Synthesis and Structures of Two Lanthanide Complexes Containing a Mixed Ligand System: [Ln(Phen)2(L)3(HL)]·H2O [Ln = La, Ce; Phen = Phenanthroline; HL = Salicylic Acid

International Nuclear Information System (INIS)

Iravani, Effat; Nami, Navabeh; Nabizadeh, Fatemeh; Bayani, Elham; Neumueller, Bernhard

2013-01-01

The reaction of LnCl 3 ·7H 2 O [Ln = La (1), Ce (2)] with salicylic acid (HL) and 1,10-phenanthroline (Phen) at 20 .deg. C in H 2 O/ethanol gave after work-up and recrystallization two novel lanthanide complexes with general formula [Ln(Phen) 2 (L) 3 (HL)]·H 2 O. Compounds 1 and 2 were characterized by IR and UV-Vis spectroscopy, TGA, CHN as well as by X-ray analysis. According to these results, compounds 1 and 2 are isostructural and contain Ln 3+ ions with coordination number nine. Complexes 1 and 2 consist of two Phen, one neutral HL and three L anions (two L anions act as monodentate ligands and the third one is chelating to Ln 3+ ). Thermal decomposition led to primary loss of the Phen molecules. Then HL molecules and finally L moieties left the material to give Ln 2 O 3

Study on feasibility of replacing 321 with 316LN stainless steel for main reactor coolant pipe material

International Nuclear Information System (INIS)

Luo Yijun

2013-01-01

The metallurgical, physical and mechanical performance, and the corrosion and welding properties of 00Cr17Ni12Mo2 (controlled Nitrogen, ANSI316LN) and 0Cr18Ni10Ti (ANSI321SS) for main pipe material were analyzed comparatively in this paper. The feasibility of 316LN pipe material manufacturing was studied too. The analysis results showed that under the operation condition of the nuclear reactor, the general properties of 316LN are better than that of 321SS. Therefore, 316LN could be used for main pipe material, replacing 321SS. (authors)

Development of liquid nitrogen Centrifugal Pump

International Nuclear Information System (INIS)

Abe, M; Sagiyama, R; Tsuchiya, H; Takayama, T; Torii, Y; Nakamura, M; Hoshino, Y; Odashima, Y

2009-01-01

Usually liquid nitrogen (LN 2 ) transfer from a container to a laboratory equipment takes place by applying pressure to the container to push out liquid or pouring liquid into the cryostat directly by lifting the container. In order to overcome inconvenience of pressuring or lifting containers, we have been developing the Liquid Nitrogen Centrifugal Pump of a small electric turbine pump. Significant advantages that both reducing time to fill LN 2 and controlling the flow rate of liquid into the cryostat are obtained by introducing this pump. We have achieved the lift of about 800mm with the vessel's opening diameter of 28mm.

Effect of ligand substitution on the SMM properties of three isostructural families of double-cubane Mn4Ln2 coordination clusters.

Science.gov (United States)

Akhtar, Muhammad Nadeem; Lan, Yanhua; AlDamen, Murad A; Zheng, Yan-Zhen; Anson, Christopher E; Powell, Annie K

2018-03-06

Three isostructural lanthanide series with a core of MnMnLn 2 are reported. These three families have the formulae of [MnMnLn 2 (μ 4 -O) 2 (H 2 edte) 2 (piv) 6 (NO 3 ) 2 ] {no crystallization solvent, Ln = La, Ce, Pr, Nd, Eu (1-4, 6); solv = 3MeCN, Ln = Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y (5, 7-13)}, where H 2 edte = N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine and piv = pivalate; [MnMnLn 2 (μ 4 -O) 2 (H 2 edte) 2 (benz) 6 (NO 3 ) 2 ], where benz = benzoate, or [MnMnLn 2 (μ 4 -O) 2 (edteH 2 ) 2 (benz) 6 (NO 3 ) 2 ]·2MeCN {Ln = Gd, Tb, Dy (14-16); and [MnMnLn 2 (μ 4 -O) 2 (edteH 2 ) 2 (piv) 8 ].solv {solv = 4MeCN, Ln = La (17); solv = 2MeCN·tol·H 2 O, Ln = Pr, Nd, Sm, Tb (18-20, 22); solv = 2MeCN·H 2 O, Ln = Gd (21). These compounds crystallize in two different systems, namely, monoclinic in the space groups P2 1 /n for 1-4, 6, and 14-16 and C2/c for 5, 7-13, 18-20, and 22 and triclinic in the space group P1[combining macron] for 17 and 21. The crystal structures of these compounds display a face-fused dicubane structure connected by different types of bridged oxygen atoms. Solid-state dc magnetic susceptibility characterization was carried out for 1-22, and fitting showed that Mn III Mn III is antiferromagnetically (AF) coupled and Mn II Mn III , Mn II Ln and Mn III Ln are weakly ferromagnetically coupled. In addition, ac measurements were carried out and showed that only 7, 15, and 22 for Tb, 8 and 16 for Dy, and 20 for Sm exhibited slow magnetization relaxation. In the case of 15, it was possible to determine the energy barrier of the slow-relaxation behavior by fitting peak temperatures to the Arrhenius law, which gave a value of U eff = 21.2 K and a pre-exponential factor of τ 0 = 4.0 × 10 -9 s.

Synthesis and electronic properties of LnRhAsO and LnIrAsO compositions

International Nuclear Information System (INIS)

Muir, Sean; Sleight, A.W.; Subramanian, M.A.

2011-01-01

The synthesis and characterization of the new compositions LnRhAsO (Ln=Ce, Nd) and LnIrAsO (Ln=La, Ce, Nd) are reported. These compounds crystallize in the ZrCuSiAs type structure, isostructural to iron pnictide LnFeAsO materials. Upon substitution of Rh for Fe, both a and c lattice parameters increase relative to 3d transition metal compounds; however, when Ir is substituted for Rh the a-parameter decreases slightly while the c-parameter expands. The decrease in a lattice parameter corresponds to a short metal-metal distance in Ir compounds. CeRhAsO and CeIrAsO compositions show abrupt decreases in resistivity at 7 and 10 K, respectively, coinciding with a small shift in magnetization at the transition temperature. - Graphical abstract: LnIrAsO (Ln=La, Ce, Nd) and LnRhAsO (Ln=Ce, Rh) have been synthesized. These new transition metal oxypnictide compositions are isostructural to LaFeAsO. The 5d Ir compositions demonstrate a shorter metal-metal interaction than the 4d Rh compositions. Highlights: → LnIrAsO (Ln=La, Ce, Nd) and LnRhAsO (Ln=Ce, Nd) have been synthesized. → Ir compositions show a decreased a-parameter and increased c-parameter relative to Rh compositions. → All LnIrAsO and LnRhAsO compositions are metallic while CeIrAsO and CeRhAsO show a sudden drop in resistivity at 10 and 7 K, respectively.

Room temperature ferromagnetism and absorption red-shift in nitrogen-doped TiO2 nanoparticles

International Nuclear Information System (INIS)

Gómez-Polo, C.; Larumbe, S.; Monge, M.

2014-01-01

Highlights: • N-doped TiO 2 anatase nanoparticles were obtained by sol–gel. • The nanoparticle size, controlled by the N doping, determines lattice parameters. • Correlation between room temperature ferromagnetism and absorption red-shift. • Oxygen vacancies reinforce both phenomena. • Metal transition impurities contribute to the room temperature ferromagnetism. - Abstract: In this work, room-temperature ferromagnetism and the red-shift of the optical absorption is analyzed in nitrogen doped TiO 2 semiconductor nanoparticles. The nanoparticles were synthesized by the sol–gel method using urea as the nitrogen source. Titanium Tetraisopropoxide (TTIP) was employed as the alkoxyde precursor and dissolved in ethanol. The as prepared gels were dried and calcined in air at 300 °C. Additionally, post-annealing treatments under vacuum atmosphere were performed to modify the oxygen stoichiometry of the samples. The anatase lattice parameters, analyzed by means of powder X-ray diffractometry, depend on the nanometer grain size of the nanoparticles (increase and decrease, respectively, of the tetragonal a and c lattice parameters with respect to the bulk values). The diffuse reflectance ultraviolet–visible (UV–Vis) absorbance spectra show a clear red-shift as consequence of the nitrogen and the occurrence of intragap energy levels. The samples display ferromagnetic features at room temperature that are reinforced with the nitrogen content and after the post annealings in vacuum. The results indicate a clear correlation between the room temperature ferromagnetism and the shift of the absorbance spectrum. In both phenomena, oxygen vacancies (either induced by the nitrogen doping or by the post vacuum annealings) play a dominant role. However, we conclude the existence of very low concentration of diluted transition metal impurities that determine the room ferromagnetic response (bound magnetic polaron BMP model). The contraction of the c soft axis of the

Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

International Nuclear Information System (INIS)

Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

2013-01-01

Highlights: •The electrical conductivity of PPLP in LN 2 was successfully measured. •Based on the measured value of PPLP, DC field analysis was performed. •The electric field distribution was altered according to the DC applying stages. •The maximum electric field was observed during polarity reversal situation. •DC field analysis is important to determine the optimum design of DC HTS devices. -- Abstract: High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN 2 ). Electrical conductivity of PPLP in LN 2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN 2 were presented in this paper. Based on the experimental works, DC electric field distribution of

Thermochemistry of rare earth doped uranium oxides Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} (Ln = La, Y, Nd)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lei; Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu

2015-10-15

Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10–50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO{sub 1.5}, UO{sub 2} and UO{sub 3} in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3} for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U{sup 5+}, U{sup 6+}, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements. - Highlights: • We synthesize, characterize Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} solid solutions (Ln = La, Y, Nd). • Formation enthalpies become more exothermic with increasing rare earth content. • Oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3}. • Direct calorimetric measurements are in good agreement with free energy data.

A reliable procedure for decontamination before thawing of human specimens cryostored in liquid nitrogen: three washes with sterile liquid nitrogen (SLN2).

Science.gov (United States)

Parmegiani, Lodovico; Accorsi, Antonio; Bernardi, Silvia; Arnone, Alessandra; Cognigni, Graciela Estela; Filicori, Marco

2012-10-01

To report a washing procedure, to be performed as frozen specimens are taken out of cryobanks, to minimize the risk of hypothetical culture contamination during thawing. Basic research. Private assisted reproduction center. Two batches of liquid nitrogen (LN(2)) were experimentally contaminated, one with bacteria (Pseudomonas aeruginosa, Escherichia coli, Stenotrophomonas maltophilia) and the other with fungi (Aspergillus niger). Two hundred thirty-two of the most common human gamete/embryo vitrification carriers (Cryotop, Cryoleaf, Cryopette) were immersed in the contaminated LN(2) (117 in the bacteria and 25 in the fungi-contaminated LN(2)). The carriers were tested microbiologically, one group without washing (control) and the other after three subsequent washings in certified ultraviolet sterile liquid nitrogen (SLN(2)). The carriers were randomly allocated to the "three-wash procedure" (three-wash group, 142 carriers) or "no-wash" (control group, 90 carriers) using a specific software tool. Assessment of microorganism growth. In the no-wash control group, 78.6% of the carriers were contaminated by the bacteria and 100% by the fungi. No carriers were found to be contaminated, either by bacteria or fungi, after the three-wash procedure. The three-wash procedure with SLN(2) produced an efficient decontamination of carriers in extreme experimental conditions. For this reason, this procedure could be routinely performed in IVF laboratories for safe thawing of human specimens that are cryostored in nonhermetical cryocontainers, particularly in the case of open or single-straw closed vitrification systems. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Predictable self-assembled [2×2] Ln(III)4 square grids (Ln = Dy,Tb)-SMM behaviour in a new lanthanide cluster motif.

Science.gov (United States)

Anwar, Muhammad Usman; Thompson, Laurence Kenneth; Dawe, Louise Nicole; Habib, Fatemah; Murugesu, Muralee

2012-05-14

The ditopic carbohydrazone ligand (L1) produces the square, self-assembled [2×2] grids [Dy(4)(L1)(4)(OH)(4)]Cl(2) (1) and [Ln(4)(L1)(4)(μ(4)-O)(μ(2)-1,1-N(3))(4)] (Ln = Dy (2), Tb (3)), with 2 exhibiting SMM behaviour. Two relaxation processes occur with U(eff) = 51 K, 91 K in the absence of an external field, and one with U(eff) = 270 K in the presence of a 1600 Oe optimum field. This journal is © The Royal Society of Chemistry 2012

Liquid to gas leak ratios with liquid nitrogen and liquid helium

International Nuclear Information System (INIS)

Batzer, T.H.; Call, W.R.

1985-01-01

To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (about 750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases at ambient pressure and room temperature are presented. The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

Effect of crystalline electric field on heat capacity of LnBaCuFeO5 (Ln = Gd, Ho, Yb)

Science.gov (United States)

Lal, Surender; Mukherjee, K.; Yadav, C. S.

2018-02-01

Structural, magnetic and thermodynamic properties of layered perovskite compounds LnBaCuFeO5 (Ln = Ho, Gd, Yb) have been investigated. Unlike the iso-structural compound YBaCuFeO5, which shows commensurate antiferromagnetic to incommensurate antiferromagnetic ordering below ∼200 K, the studied compounds do not show any magnetic transition in measured temperature range of 2-350 K. The high temperature heat capacity of the compounds is understood by employing contributions from both optical and acoustic phonons. At low temperature, the observed upturn in the heat capacity is attributed to the Schottky anomaly. The magnetic field dependent heat capacity shows the variation in position of the anomaly with temperature, which appears due to the removal of ground state degeneracy of the rare earth ions, by the crystalline electric field.

Phase formation in the Li2MoO4-Rb2MoO4-Ln2(MoO4)3 systems and the properties of LiRbLn2(MoO4)4

International Nuclear Information System (INIS)

Basovich, O.M.; Khajkina, E.G.; Vasil'ev, E.V.; Frolov, A.M.

1995-01-01

Phase equilibria within subsolidus range of ternary salt systems Li 2 MoO 4 -Rb 2 MoO 4 -Ln 2 (MoO 4 ) 4 (Ln - Nd, Er) are analyzed. Formation of ternary molybdate LiRbNd 2 (MoO 4 ) 4 is proved along LiNd(MoO 4 ) 2 -RbNd(MoO 4 )-2 cross-section. Phase diagram of this cross-section is plotted. Similar compounds are synthesized for Ln = La-Eu. The parameters of their monoclinic elementary cells are determined. Luminescent properties of LiRbLa 2 (MoO 4 ) 4 -Nd 3+ are studied. 17 refs., 4 figs., 2 tabs

Systematics in the electron transport and magnetic properties of LnBO3 perovskites

International Nuclear Information System (INIS)

Ganguly, P.; Rao, C.N.R.

1980-01-01

Systematics in the electrical and magnetic properties of transition metal perovskites LnBO 3 (Ln = rare-earth ion, B = 3d transition metal) with the variation of Ln and B ions are reviewed. The electrical resistivity and activation energy of LnBO 3 compounds increase with the decreasing size of the Ln 3+ ion for a given B ion. The low-spin to high-spin transition temperature of Co 3+ ion in LnCoO 3 similarly increase with the decrease in size of Ln 3+ while the magnetic ordering temperatures in LnVO 3 , LnFeO 3 , LnCrO 3 and LnSrCo 2 O 6 decrease with decreasing size of the rare-earth ion. These results may be understood in terms of the increasing acidity of the rare earth ion with decreasing size and the competition between the Ln 3+ and the B 3+ ions for covalency with the oxygen ions. The effect of this competition on the metal oxygen covalency and crystal field parameter is discussed in relation to the results obtained and Goodenough's phase diagram. The possibility of d-f exchange interaction in Lasub(1-x)Lnsub(x)NiOsub(3) is also discussed in the light of ESR results. (auth.)

Ectopic phytocystatin expression increases nodule numbers and influences the responses of soybean (Glycine max) to nitrogen deficiency.

Science.gov (United States)

Quain, Marian D; Makgopa, Matome E; Cooper, James W; Kunert, Karl J; Foyer, Christine H

2015-04-01

Cysteine proteases and cystatins have many functions that remain poorly characterised, particularly in crop plants. We therefore investigated the responses of these proteins to nitrogen deficiency in wild-type soybeans and in two independent transgenic soybean lines (OCI-1 and OCI-2) that express the rice cystatin, oryzacystatin-I (OCI). Plants were grown for four weeks under either a high (5 mM) nitrate (HN) regime or in the absence of added nitrate (LN) in the absence or presence of symbiotic rhizobial bacteria. Under the LN regime all lines showed similar classic symptoms of nitrogen deficiency including lower shoot biomass and leaf chlorophyll. However, the LN-induced decreases in leaf protein and increases in root protein tended to be smaller in the OCI-1 and OCI-2 lines than in the wild type. When LN-plants were grown with rhizobia, OCI-1 and OCI-2 roots had significantly more crown nodules than wild-type plants. The growth nitrogen regime had a significant effect on the abundance of transcripts encoding vacuolar processing enzymes (VPEs), LN-dependent increases in VPE2 and VPE3 transcripts in all lines. However, the LN-dependent increases of VPE2 and VPE3 transcripts were significantly lower in the leaves of OCI-1 and OCI-2 plants than in the wild type. These results show that nitrogen availability regulates the leaf and root cysteine protease, VPE and cystatin transcript profiles in a manner that is in some cases influenced by ectopic OCI expression. Moreover, the OCI-dependent inhibition of papain-like cysteine proteases favours increased nodulation and enhanced tolerance to nitrogen limitation, as shown by the smaller LN-dependent decreases in leaf protein observed in the OCI-1 and OCI-2 plants relative to the wild type. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Response of rice grain quality traits to free-air CO2 enrichment].

Science.gov (United States)

Dong, Guichun; Wang, Yulong; Huang, Jianye; Yang, Hongjian; Gu, Hui; Peng, Bin; Ju, Jing; Yang, Lianxin; Zhu, Jianguo; Shan, Yuhua

2004-07-01

The study showed that under field condition, when the CO2 concentration was elevated 200 micromol x mol(-1) above control, the average brown rice rate of japonica variety Wuxiangjing 14 was 1.4% higher, while lead milled rice rate was 12.3% lower than control. The brown rice rate increased at lower nitrogen supply level (LN), while lead milled rice rate increased at higher nitrogen supply level (HN). The percentage of chalky grain was 11.9% higher, and chalkiness degree was 2.8% higher than control, but no obvious difference was found in chalkiness area between the FACE and the control. The chalkiness area, percentage of chalky grain and chalkiness degree decreased at HN plus higher phosphorus supply level (HP). The gelatinization temperature was elevated 0.52 degrees C, gel consistency increased, while amylose content was not statistically significant. The amylose content decreased at HN plus HP, while gel consistency and gelatinization temperature decreased at LN plus HP and at LN, respectively. The protein content was decreased 0.6% under FACE treatment and at LN plus lower phosphorus supply level.

NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes.

Science.gov (United States)

Adam, Christian; Beele, Björn B; Geist, Andreas; Müllich, Udo; Kaden, Peter; Panak, Petra J

2015-02-01

C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15 N labeling and characterized by NMR and LIFDI-MS methods. 15 N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15 N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal-ligand bonding in Am(C5-BPP) 3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP) 3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species.

First principles investigation of structural, electronic, elastic and thermal properties of rare-earth-doped titanate Ln2TiO5

Directory of Open Access Journals (Sweden)

Hui Niu

2012-09-01

Full Text Available Systematic first-principles calculations based on density functional theory were performed on a wide range of Ln2TiO5 compositions (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Y in order to investigate their structural, elastic, electronic, and thermal properties. At low temperature, these compounds crystallize in orthorhombic structures with a Pnma symmetry, and the calculated equilibrium structural parameters agree well with experimental results. A complete set of elastic parameters including elastic constants, Hill's bulk moduli, Young's moduli, shear moduli and Poisson's ratio were calculated. All Ln2TiO5 are ductile in nature. Analysis of densities of states and charge densities and electron localization functions suggests that the oxide bonds are highly ionic with some degree of covalency in the Ti-O bonds. Thermal properties including the mean sound velocity, Debye temperature, and minimum thermal conductivity were obtained from the elastic constants.

Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon [Hanyang University, 408-2, 4th Engineering Bldg, Sa 3-dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of); Cho, Jeon-Wook; Ryoo, Hee-Suk [Korea Electrotechnology Research Institute, Changwon, Gyungnam 641-120 (Korea, Republic of); Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr [Hanyang University, 408-2, 4th Engineering Bldg, Sa 3-dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of)

2013-11-15

Highlights: •The electrical conductivity of PPLP in LN{sub 2} was successfully measured. •Based on the measured value of PPLP, DC field analysis was performed. •The electric field distribution was altered according to the DC applying stages. •The maximum electric field was observed during polarity reversal situation. •DC field analysis is important to determine the optimum design of DC HTS devices. -- Abstract: High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN{sub 2}). Electrical conductivity of PPLP in LN{sub 2} has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN{sub 2} were presented in this paper. Based on the experimental works, DC electric

Remote refilling of LN2 cryostats for high sensitivity astronomical applications

Science.gov (United States)

l'Allemand, J. L. Lizon a.

2017-12-01

The most sensitive observation mode of the ESO VLT (European Southern Observatory Very Large Telescope) is the interferometric mode, where the 4 Units Telescopes are directed to the same stellar object in order to operate as a gigantic interferometer. The beam is then re-combined in the main interferometry laboratory and fed into the analyzing instruments. In order not to disturb the performance of the Interferometer, this room is considered as a sanctuary where one enters only in case of extreme need. A simple opening of the door would create air turbulences affecting the stability for hours. Any cold spot in the room could also cause convection which might change the optical path by fraction of a micron. Most of the instruments are operating at cryogenic temperatures using passive cooling based on LN2 bath cryostat. For this reason, dedicated strategy has been developed for the transfer of LN2 to the various instruments. The present document describes the various aspects and care taken in order to guarantee the very high thermal and mechanical environmental stability.

Formation of simple nitrogen hydrides NH and NH2 at cryogenic temperatures through N + NH3→ NH + NH2 reaction: dark cloud chemistry of nitrogen.

Science.gov (United States)

Nourry, Sendres; Krim, Lahouari

2016-07-21

Although NH3 molecules interacting with ground state nitrogen atoms N((4)S) seem not to be a very reactive system without providing additional energy to initiate the chemical process, we show through this study that, in the solid phase, at very low temperature, NH3 + N((4)S) reaction leads to the formation of the amidogen radical NH2. Such a dissociation reaction previously thought to occur exclusively through UV photon or energetic particle irradiation is in this work readily occurring just by stimulating the mobility of N((4)S)-atoms in the 3-10 K temperature range in the solid sample. The N((4)S)-N((4)S) recombination may be the source of metastable molecular nitrogen N2(A), a reactive species which might trigger the NH3 dissociation or react with ground state nitrogen atoms N((4)S) to form excited nitrogen atoms N((4)P/(2)D) through energy transfer processes. Based on our obtained results, it is possible to propose reaction pathways to explain the NH2 radical formation which is the first step in the activation of stable species such as NH3, a chemical induction process that, in addition to playing an important role in the origin of molecular complexity in interstellar space, is known to require external energy supplies to occur in the gas phase.

CooLN2Car: An Experimental Car Which Uses Liquid Nitrogen as Its Fuel

Science.gov (United States)

Parker, M. E.; Plummer, M. C.; Ordonez, C. A.

1997-10-01

A ``cryogenic" heat engine which operates using the atmosphere as a heat source and a cryogenic medium as a heat sink has been incorporated as the power system for an automobile. A 1973 Volkswagen Beetle has been converted and uses liquid nitrogen as its ``fuel." A Dewar was mounted in the car and provides nitrogen under pressure to two heat exchangers connected in parallel which use atmospheric heat to heat the nitrogen. The heat exchangers deliver compressed nitrogen gas to a vane-type pneumatic motor mounted in place of the original gasoline engine. Pressure in the tank is maintained internally at 1.2 MPa and is reduced to 0.7 MPa before the motor by a pressure regulator. A throttle, composed of a butterfly valve, is mounted between the regulator and the motor and is connected to the driver's accelerator peddle. The vehicle has good acceleration, a maximum range of 15 miles, and a maximum speed of 25 mph. A demonstration with the vehicle is planned.

In pursuit of the rhabdophane crystal structure: from the hydrated monoclinic LnPO{sub 4}.0.667H{sub 2}O to the hexagonal LnPO{sub 4} (Ln = Nd, Sm, Gd, Eu and Dy)

Energy Technology Data Exchange (ETDEWEB)

Mesbah, Adel, E-mail: adel.mesbah@cea.fr [ICSM, UMR 5257 CNRS – CEA – ENSCM – Université de Montpellier, Site de Marcoule - Bât 426, BP 17171, 30207 Bagnols/Cèze (France); Clavier, Nicolas [ICSM, UMR 5257 CNRS – CEA – ENSCM – Université de Montpellier, Site de Marcoule - Bât 426, BP 17171, 30207 Bagnols/Cèze (France); Elkaim, Erik [Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France); Szenknect, Stéphanie; Dacheux, Nicolas [ICSM, UMR 5257 CNRS – CEA – ENSCM – Université de Montpellier, Site de Marcoule - Bât 426, BP 17171, 30207 Bagnols/Cèze (France)

2017-05-15

The dehydration process of the hydrated rhabdophane LnPO{sub 4}.0.667H{sub 2}O (Ln = La to Dy) was thoroughly studied over the combination of in situ high resolution synchrotron powder diffraction and TGA experiments. In the case of SmPO{sub 4}.0.667H{sub 2}O (monoclinic, C2), a first dehydration step was identified around 80 °C leading to the formation of SmPO{sub 4}.0.5H{sub 2}O (Monoclinic, C2) with Z =12 and a =17.6264(1) Å, b =6.9704(1) Å, c =12.1141(1) Å, β=133.74(1) °, V =1075.33(1) Å{sup 3}. In agreement with the TGA and dilatometry experiments, all the water molecules were evacuated above 220 °C yielding to the anhydrous form, which crystallizes in the hexagonal P3{sub 1}21 space group with a =7.0389(1) Å, c =6.3702(1) Å and V =273.34(1) Å{sup 3}. This study was extended to selected LnPO{sub 4}.0.667H{sub 2}O samples (Ln= Nd, Gd, Eu, Dy) and the obtained results confirmed the existence of two dehydration steps before the stabilization of the anhydrous form, with the transitory formation of LnPO{sub 4}.0.5H{sub 2}O. - Graphical abstract: The dehydration process of the rhabdophane SmPO{sub 4}.0.667H{sub 2}O was studied over combination of in situ high resolution synchrotron powder diffraction and TGA techniques, a first dehydration was identified around 80 °C leading to the formation of SmPO{sub 4}.0.5H{sub 2}O (Monoclinic, C2). Then above 220 °C, the anhydrous form of the rhabdophane SmPO{sub 4} was stabilized and crystallizes in the hexagonal P3{sub 1}21 space group. - Highlights: • In situ synchrotron powder diffraction was carried out during the dehydration of the rhabdopahe LnPO{sub 4}.0.667H{sub 2}O. • The heat of the rhabdophane LnPO{sub 4}.0.667H{sub 2}O leads to LnPO{sub 4}.0.5H{sub 2}O then to anhydrous rhabdophane LnPO{sub 4}. • LnPO{sub 4}.0.5H{sub 2}O (monoclinic, C2) and LnPO{sub 4} (Hexagonal, P3{sub 1}21) were solved over the use of direct methods.

Room temperature ferromagnetism and absorption red-shift in nitrogen-doped TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Gómez-Polo, C., E-mail: gpolo@unavarra.es [Departamento de Física, Universidad Pública de Navarra, Campus de Arrosadia, 31006 Pamplona (Spain); Larumbe, S. [Departamento de Física, Universidad Pública de Navarra, Campus de Arrosadia, 31006 Pamplona (Spain); Monge, M. [Departamento de Química, Universidad de la Rioja, Centro de Investigación en Síntesis Química (CISQ), Complejo Científico Tecnológico, 26006 Logroño (Spain)

2014-11-05

Highlights: • N-doped TiO{sub 2} anatase nanoparticles were obtained by sol–gel. • The nanoparticle size, controlled by the N doping, determines lattice parameters. • Correlation between room temperature ferromagnetism and absorption red-shift. • Oxygen vacancies reinforce both phenomena. • Metal transition impurities contribute to the room temperature ferromagnetism. - Abstract: In this work, room-temperature ferromagnetism and the red-shift of the optical absorption is analyzed in nitrogen doped TiO{sub 2} semiconductor nanoparticles. The nanoparticles were synthesized by the sol–gel method using urea as the nitrogen source. Titanium Tetraisopropoxide (TTIP) was employed as the alkoxyde precursor and dissolved in ethanol. The as prepared gels were dried and calcined in air at 300 °C. Additionally, post-annealing treatments under vacuum atmosphere were performed to modify the oxygen stoichiometry of the samples. The anatase lattice parameters, analyzed by means of powder X-ray diffractometry, depend on the nanometer grain size of the nanoparticles (increase and decrease, respectively, of the tetragonal a and c lattice parameters with respect to the bulk values). The diffuse reflectance ultraviolet–visible (UV–Vis) absorbance spectra show a clear red-shift as consequence of the nitrogen and the occurrence of intragap energy levels. The samples display ferromagnetic features at room temperature that are reinforced with the nitrogen content and after the post annealings in vacuum. The results indicate a clear correlation between the room temperature ferromagnetism and the shift of the absorbance spectrum. In both phenomena, oxygen vacancies (either induced by the nitrogen doping or by the post vacuum annealings) play a dominant role. However, we conclude the existence of very low concentration of diluted transition metal impurities that determine the room ferromagnetic response (bound magnetic polaron BMP model). The contraction of the c soft axis

Coordination polyhedra LnFn (Ln=La-Lu) in crystal structure

International Nuclear Information System (INIS)

Vologzhanina, A.V.; Pushkin, D.V.; Serezhkin, V.N.

2006-01-01

Peculiarities of stereochemistry of lanthanides (Ln) surrounded by fluorine atoms were studied by means of the Voronoi-Dirichlet polyhedra (PVD) and method of crossing spheres, 118 compounds are presented in the structure. It has been found that coordination numbers (CN) of Ln atoms change from 6 to 12, nine types of LnF n coordination polyhedra are formed in the process, Ln-F bond lengths have changes by 0.2-0.7 A in accordance to CN. It is found that in spite of significant variation of bond lengths volume of PVD Ln atoms is determined by their nature and oxidation state. It has been found that the change in radii of spherical domains, which volume is equal to the volume of PVD Ln atoms, is accompanied by tetrad-effect [ru

Family of defect-dicubane Ni4Ln2 (Ln = Gd, Tb, Dy, Ho) and Ni4Y2 complexes: rare Tb(III) and Ho(III) examples showing SMM behavior.

Science.gov (United States)

Zhao, Lang; Wu, Jianfeng; Ke, Hongshan; Tang, Jinkui

2014-04-07

Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of χ″ signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes.

Formation enthalpies of LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) interlanthanide perovskites

Energy Technology Data Exchange (ETDEWEB)

Qi, Jianqi [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Laboratory of High Energy Density Physics of Ministry of Education, Sichuan University, Chengdu 610064 (China); Guo, Xiaofeng [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Mielewczyk-Gryn, Aleksandra [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Faculty of Applied Physics and Mathematics, Department of Solid State Physics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States)

2015-07-15

High-temperature oxide melt solution calorimetry using 3Na{sub 2}O·MoO{sub 3} at 802 °C was performed for interlanthanide perovskites LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) and lanthanide oxides (La{sub 2}O{sub 3}, Ho{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, Tm{sub 2}O{sub 3} and Yb{sub 2}O{sub 3}). The enthalpies of formation of these interlanthanide perovskites from binary lanthanide oxides at room temperature (25 °C) were determined to be −8.3±3.4 kJ/mol for LaHoO{sub 3}, −9.9±3.0 kJ/mol for LaErO{sub 3}, −10.8±2.7 kJ/mol for LaTmO{sub 3} and −12.3±2.9 kJ/mol for LaYbO{sub 3}. There is a roughly linear relationships between these enthalpy values and the tolerance factor for these and for other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites, confirming that the distortion of the perovskites as results from ionic radius difference of A-site and B-site cations, is the main factor determining the stability of these compounds. - Graphical abstract: A linear relationship between the enthalpy of formation and the tolerance factor for interlanthanide LaLn'O{sub 3} (Ln'=Ho, Er, Tm, and Yb) and other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites. - Highlights: • Interlanthanide perovskites were synthesized by solid state reactions. • Their enthalpies of formation were measured by oxide melt solution calorimetry. • ΔH{sub f,ox} shows a linear relationship with tolerance factor.

Synthesis and Structures of Two Lanthanide Complexes Containing a Mixed Ligand System: [Ln(Phen){sub 2}(L){sub 3}(HL)]·H{sub 2}O [Ln = La, Ce; Phen = Phenanthroline; HL = Salicylic Acid

Energy Technology Data Exchange (ETDEWEB)

Iravani, Effat [UNiv. of Applied Science and Technology, Tehran (Iran, Islamic Republic of); Nami, Navabeh; Nabizadeh, Fatemeh; Bayani, Elham [Islamic Azad Univ., Mazandaran (Iran, Islamic Republic of); Neumueller, Bernhard [Philipps-Universitat Marburg, Marburg (Germany)

2013-11-15

The reaction of LnCl{sub 3}·7H{sub 2}O [Ln = La (1), Ce (2)] with salicylic acid (HL) and 1,10-phenanthroline (Phen) at 20 .deg. C in H{sub 2}O/ethanol gave after work-up and recrystallization two novel lanthanide complexes with general formula [Ln(Phen){sub 2}(L){sub 3}(HL)]·H{sub 2}O. Compounds 1 and 2 were characterized by IR and UV-Vis spectroscopy, TGA, CHN as well as by X-ray analysis. According to these results, compounds 1 and 2 are isostructural and contain Ln{sup 3+} ions with coordination number nine. Complexes 1 and 2 consist of two Phen, one neutral HL and three L anions (two L anions act as monodentate ligands and the third one is chelating to Ln{sup 3+}). Thermal decomposition led to primary loss of the Phen molecules. Then HL molecules and finally L moieties left the material to give Ln{sub 2}O{sub 3}.

Tricolor emission Ca3Si2O7:Ln (Ln=Ce, Tb, Eu) phosphors for near-UV white light-emitting-diode

International Nuclear Information System (INIS)

Mao, Zhi-yong; Zhu, Ying-chun; Gan, Lin; Zeng, Yi; Xu, Fang-fang; Wang, Yang; Tian, Hua; Li, Jian; Wang, Da-jian

2013-01-01

Tricolor emission in a same Ca 3 Si 2 O 7 host with independent Ln (Ln=Ce 3+ , Eu 2+ , Tb 3+ ) dopants is demonstrated to construct a near-UV white light emitting diode (LED). The luminescence properties and thermal quenching properties, as well as the applications in near-UV white LED are investigated. These phosphors show typical blue, red, and green, three-basal-color, luminescence in the CIE chromaticity diagram for Ce 3+ , Eu 2+ and Tb 3+ dopants, respectively. Thermal quenching properties show that the luminescence thermal stability strongly depends on the different dopant types; better thermal quenching property of Ce 3+ and Tb 3+ is recorded in comparison with that of Eu 2+ . The white LED prototype fabricated with near-UV chip and as-prepared tricolor phosphors exhibits acceptable CIE chromaticity coordinates (0.32, 0.30) with a CCT of 6000 K and a CRI of 87, indicating the potential application of Ca 3 Si 2 O 7 :Ln phosphors in near-UV white LED. - Highlights: ► Tricolor Ca 3 Si 2 O 7 : Ln phosphors were demonstrated to construct near-UV white LED. ► Eu 2+ doped Ca 3 Si 2 O 7 red-emitting phosphor was confirmed by this work once again. ► Thermal quenching properties for Ca 3 Si 2 O 7 :Ln phosphors were reported for the first time. ► Performances of fabricated white LED indicated the potential application of phosphors.

Influence of lead oxide addition on LnTiTaO6 (Ln = Ce, Pr and Nd) microwave ceramics

International Nuclear Information System (INIS)

Padma Kumar, H.; Thomas, J.K.; John, Annamma; Solomon, Sam

2011-01-01

The effect of PbO addition on the structural, processing and microwave dielectric properties of LnTiTaO 6 (Ln = Ce, Pr and Nd) ceramics are reported. Conventional solid state ceramic route was used for the preparation of samples. Phase pure LnTiTaO 6 (Ln = Ce, Pr and Nd) ceramics are prepared at a calcination temperature of 1300 deg C. The samples are sintered at optimized temperatures. Addition of PbO reduces the sintering temperature. The crystal structure of the materials was analysed using X-ray diffraction techniques and the surface morphology of the sintered samples was analysed using scanning electron microscopy. The dielectric constant at microwave frequency range decreases for higher PbO addition for all the samples but the quality factor improves on small PbO addition. The thermal stability of resonant frequency was also improved with PbO addition on all the systems. A number of samples with improved microwave dielectric properties were obtained on all the systems suitable for practical applications. (author)

Systems Ln-Fe-O ( Ln=Eu, Gd): thermodynamic properties of ternary oxides using solid-state electrochemical cells

Science.gov (United States)

Parida, S. C.; Rakshit, S. K.; Dash, S.; Singh, Ziley; Prasad, R.; Venugopal, V.

2003-05-01

The standard molar Gibbs energies of formation of LnFeO 3(s) and Ln3Fe 5O 12(s) where Ln=Eu and Gd have been determined using solid-state electrochemical technique employing different solid electrolytes. The reversible e.m.f.s of the following solid-state electrochemical cells have been measured in the temperature range from 1050 to 1255 K. Cell (I): (-)Pt / { LnFeO 3(s)+ Ln2O 3(s)+Fe(s)} // YDT/CSZ // {Fe(s)+Fe 0.95O(s)} / Pt(+); Cell (II): (-)Pt/{Fe(s)+Fe 0.95O(s)}//CSZ//{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}/Pt(+); Cell (III): (-)Pt/{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}//YSZ//{Ni(s)+NiO(s)}/Pt(+); and Cell(IV):(-)Pt/{Fe(s)+Fe 0.95O(s)}//YDT/CSZ//{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}/Pt(+). The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the e.m.f. data. The standard Gibbs energies of formation of solid EuFeO 3, Eu 3Fe 5O 12, GdFeO 3 and Gd 3Fe 5O 12 calculated by the least-squares regression analysis of the data obtained in the present study are given by Δ fG°m(EuFeO 3, s) /kJ mol -1 (± 3.2)=-1265.5+0.2687( T/K) (1050 ⩽ T/K ⩽ 1570), Δ fG°m(Eu 3Fe 5O 12, s)/kJ mol -1 (± 3.5)=-4626.2+1.0474( T/K) (1050 ⩽ T/K ⩽ 1255), Δ fG°m(GdFeO 3, s) /kJ mol -1 (± 3.2)=-1342.5+0.2539( T/K) (1050 ⩽ T/K ⩽ 1570), and Δ fG°m(Gd 3Fe 5O 12, s)/kJ·mol -1 (± 3.5)=-4856.0+1.0021( T/K) (1050 ⩽ T/K ⩽ 1255). The uncertainty estimates for Δ fG°m include the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagrams for the systems Eu-Fe-O and Gd-Fe-O and chemical potential diagrams for the system Gd-Fe-O were computed at 1250 K.

Mixed phosphates of the Na3PO4 - LnPO4 systems

International Nuclear Information System (INIS)

Slivko, T.A.; Smirnova, I.N.; Zimina, G.V.; Spiridonov, F.M.; Chudinova, N.N.

2002-01-01

The phase relationships in the systems Na 3 PO 4 - LnPO 4 (subsolidus 950 Deg C cross-sections), where Ln=Sm, Eu, Tb, Dy, Ho, Tm, Yb, Lu, were studied by X-ray analysis. Reactions of the components were deduced, formed phases were separated and identified. The Na 6 Ln 3 (PO 4 ) 5 (Ln=Dy, Ho, Tm), Na 3 Ln 2 (PO 4 ) 3 (Ln=Tm, Yb, Lu) compounds and phases of the unstable composition Na 6+x Ln 3-x/3 (PO 4 ) 5 (Ln=Yb, Lu, 0 ≤ x ≤ 1.5) were detected for the first time. In all systems the existence of the Na 3-x Ln x/3 PO 4 unstable composition phase on the basis of the high temperature modification of sodium phosphate (sp. gr. Fm3m) is established, suggesting that stabilization of this modification by rare earth ions is possible [ru

The automatic liquid nitrogen filling system for GDA detectors

Indian Academy of Sciences (India)

. Abstract. An indigenously developed automatic liquid nitrogen (LN2) filling system has been installed in gamma detector array (GDA) facility at Nuclear Science Centre. Electro-pneumatic valves are used for filling the liquid nitrogen into the ...

AgLnSb/sub 2/O/sub 7/ compounds with weberite structure

Energy Technology Data Exchange (ETDEWEB)

Lopatin, S S; Aver' yanova, L N; Belyaev, I N; Zvyagintsev, B I; Dyatlov, Eh V [Rostovskij-na-Donu Gosudarstvennyj Univ. (USSR)

1982-11-01

The interaction between AgSbO/sub 3/ and LnSbO/sub 4/ in the solid phase at 1100-1150 deg C has been investigated. AgLnSb/sub 2/O/sub 7/ compounds with weberite crystal structure are formed in Ln=La, Pr, Nd, Sm cases but in Ln=Eu, Cd, Dy, Er cases the formation of termary oxides of the indicated composition has not been observed. Inasmuch as compounds of the general formula A/sub 2/B/sub 2/O/sub 7/ with average cation radii Rsub(B) >0.60 A and 1.65 <= Rsub(A)/Rsub(B) <= 2.20 can crystallize in weberite, pyrochlore and laminated perovskite-like structurer, conditions of the existence of the above mentioned structures depending on A and B dimensions and electronegativity are discussed.

Temperature effects on lithium-nitrogen reaction rates

International Nuclear Information System (INIS)

Ijams, W.J.; Kazimi, M.S.

1985-08-01

A series of experiments have been run with the aim of measuring the reaction rate of lithium and nitrogen over a wide spectrum of lithium pool temperatures. In these experiments, pure nitrogen was blown at a controlled flow rate over a preheated lithium pool. The pool had a surface area of approximately 4 cm 2 and a total volume of approximately 6 cm 3 . The system pressure varied from 0 to 4 psig. The reaction rate was very small - approximately 0.002 to 0.003 g Li min cm 2 for lithium temperatures below 500 0 C. Above 500 0 C the reaction rate began to increase sharply, and reached a maximum of approximately 0.80 g Li min cm 2 above 700 0 C. It dropped off beyond 1000 0 C and seemed to approach zero at 1150 0 C. The maximum reaction rate observed in these forced convection experiments was higher by 60% than those previously observed in experiments where the nitrogen flowed to the reaction site by means of natural convection. During a reaction, a hard nitride layer built up on the surface of the lithium pool - its effect on the reaction rate was observed. The effect of the nitrogen flow rate on the reaction rate was also observed

Synthesis and characterization of K2Ln2/3Ta2O7·nH2O (Ln= La, Pr, Nd), layered tantalates photo catalysts for water splitting

International Nuclear Information System (INIS)

Valencia S, H.; Tavizon, G.; Pfeiffer, H.; Acosta, D.; Negron M, A.

2015-01-01

Three compounds of the K 2 Ln 2/3 Ta 2 O 7 (Ln = La, Nd, Pr) cation-deficient Ruddlesden-Popper series were prepared by the Pechini (polymeric complex) method. The crystal structures of the hydrated form of these compounds were determined by Rietveld analysis of the X-ray power diffraction data and High Resolution Transmission Electron Microscopy (HRTEM). The samples were also analyzed to determine specific area (Bet), degree of hydration (Thermogravimetric analysis), and photo catalytic activity for hydrogen evolution from water and aqueous methanol solution. (Author)

Room temperature synthesis of hydrophilic Ln(3+)-doped KGdF4 (Ln = Ce, Eu, Tb, Dy) nanoparticles with controllable size: energy transfer, size-dependent and color-tunable luminescence properties.

Science.gov (United States)

Yang, Dongmei; Li, Guogang; Kang, Xiaojiao; Cheng, Ziyong; Ma, Ping'an; Peng, Chong; Lian, Hongzhou; Li, Chunxia; Lin, Jun

2012-06-07

In this paper, we demonstrate a simple, template-free, reproducible and one-step synthesis of hydrophilic KGdF(4): Ln(3+) (Ln = Ce, Eu, Tb and Dy) nanoparticles (NPs) via a solution-based route at room temperature. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the samples. The results indicate that the use of water-diethyleneglycol (DEG) solvent mixture as the reaction medium not only allows facile particle size control but also endows the as-prepared samples with good water-solubility. In particular, the mean size of NPs is monotonously reduced with the increase of DEG content, from 215 to 40 nm. The luminescence intensity and absolute quantum yields for KGdF(4): Ce(3+), Tb(3+) NPs increase remarkably with particle sizes ranging from 40 to 215 nm. Additionally, we systematically investigate the magnetic and luminescence properties of KGdF(4): Ln(3+) (Ln = Ce, Eu, Tb and Dy) NPs. They display paramagnetic and superparamagnetic properties with mass magnetic susceptibility values of 1.03 × 10(-4) emu g(-1)·Oe and 3.09 × 10(-3) emu g(-1)·Oe at 300 K and 2 K, respectively, and multicolor emissions due to the energy transfer (ET) process Ce(3+)→ Gd(3+)→ (Gd(3+))(n)→ Ln(3+), in which Gd(3+) ions play an intermediate role in this process. Representatively, it is shown that the energy transfer from Ce(3+) to Tb(3+) occurs mainly via the dipole-quadrupole interaction by comparison of the theoretical calculation and experimental results. This kind of magnetic/luminescent dual-function materials may have promising applications in multiple biolabels and MR imaging.

Structures and magnetic properties of rare earth double perovskites containing antimony or bismuth Ba{sub 2}LnMO{sub 6} (Ln=rare earths; M=Sb, Bi)

Energy Technology Data Exchange (ETDEWEB)

Otsuka, Shumpei, E-mail: m-nis-s-o@ec.hokudai.ac.jp; Hinatsu, Yukio

2015-07-15

A series of double perovskite-type oxides Ba{sub 2}LnMO{sub 6} (Ln=lanthanides; M=Sb, Bi) were synthesized and their structures were studied. The Ln and M are structurally ordered in the rock-salt type at the B-site of the perovskite ABO{sub 3}. For Ba{sub 2}PrBiO{sub 6} and Ba{sub 2}TbBiO{sub 6}, it has been found that the disordering between Ln ion and Bi ion occurs at the B-site of the double perovskite and both the Pr (Tb) and Bi exist in two oxidation state in the same compound from the analysis of the X-ray diffraction and magnetic susceptibility data. Magnetic susceptibility measurements show that all these compounds are paramagnetic and have no magnetic ordering down to 1.8 K. - Graphical abstract: Tolerance factor for Ba{sub 2}LnMO{sub 6} (M=Sb, Bi) plotted against the ionic radius of Ln{sup 3+}. We have found that there is a clear relation between crystal structures and tolerance factors. - Highlights: • The Ln and M ions are structurally ordered in the rock-salt type at the B-site. • The disordering between Pr (Tb) ion and Bi ion occurs at the B-site. • Ba{sub 2}LnMO{sub 6} (M=Sb, Bi) have no magnetic ordering down to 1.8 K.

Enhanced visible light-responsive photocatalytic activity of LnFeO3 (Ln = La, Sm) nanoparticles by synergistic catalysis

International Nuclear Information System (INIS)

Li, Li; Wang, Xiong; Zhang, Yange

2014-01-01

Highlights: • LnFeO 3 (Ln = La, Sm) nanoparticles were prepared by a facile sol–gel method. • The samples exhibit superior visible-light-responsive photocatalytic activity. • Synergistic effect will enhance the photodegradation of RhB under visible light. - Abstract: LnFeO 3 (Ln = La, Sm) nanoparticles were prepared by a facile sol–gel method with assistance of glycol at different calcination temperatures. The as-synthesized LnFeO 3 was characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimeter and thermogravimetric analysis, and UV–vis absorption spectroscopy. The photocatalytic behaviors of LnFeO 3 nanoparticles were evaluated by photodegradation of rhodamine B under visible light irradiation. The results indicate that the visible light-responsive photocatalytic activity of LnFeO 3 nanoparticles was enhanced remarkably by the synergistic effect between the semiconductor photocatalysis and Fenton-like reaction. And a possible catalytic mechanism was also proposed based on the experimental results

Dynamics of low-temperature acclimation in temperate and boreal conifer foliage in a mild winter climate

Science.gov (United States)

G. Richard Strimbeck; Trygve D. Kjellsen; Paul G. Schaberg; Paula F. Murakami

2008-01-01

To provide baseline data for physiological studies of extreme low-temperature (LT) tolerance in boreal conifers, we profiled LT stress responses, liquid nitrogen (LN2)-quench tolerance, and sugar concentrations in foliage of boreal-temperate species pairs in the genera Abies, Picea and Pinus, growing in an...

Liquid nitrogen vapor is comparable to liquid nitrogen for storage of cryopreserved human sperm: evidence from the characteristics of post-thaw human sperm.

Science.gov (United States)

Hu, Jingmei; Zhao, Shidou; Xu, Chengyan; Zhang, Lin; Lu, Shaoming; Cui, Linlin; Ma, Jinlong; Chen, Zi-Jiang

2015-11-01

To compare the differences in the characteristics of post-thaw human sperm after storage in either liquid nitrogen (LN2; -196 °C) or LN2 vapor (-167 °C). Experimental study. University hospital. Thirty healthy volunteers who agreed to donate their normal semen samples for infertility or research were included in the study. Semen samples (n = 30) were divided into eight aliquots and frozen. Four aliquots of each human semen sample were stored in LN2 (-196 °C), and the other four aliquots were stored in LN2 vapor (-167 °C). After 1, 3, 6, or 12 months, samples were thawed and analyzed. The motility was evaluated by the manual counting method. The viability was estimated by eosin staining. The morphology was analyzed by Diff-Quik staining. The sperm DNA integrity was determined with acridine orange fluorescent staining, and acrosin activity was assayed by the modified Kennedy method. The characteristics of post-thaw human sperm, including motility, viability, morphology, DNA integrity, and acrosin activity, showed no significant difference between LN2 and LN2 vapor storage for the different time periods. LN2 vapor was comparable to LN2 in post-thaw sperm characteristics, suggesting that LN2 vapor may be substituted for LN2 for the long-term storage of human sperm. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Li{sub 35}Ln{sub 9}Si{sub 30}N{sub 59}O{sub 2}F with Ln = Ce, Pr - highly condensed nitridosilicates

Energy Technology Data Exchange (ETDEWEB)

Lupart, Saskia; Durach, Dajana; Schnick, Wolfgang [Department Chemie, Lehrstuhl fuer Anorganische Festkoerperchemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

2011-10-15

The isotypic nitridosilicates Li{sub 35}Ln{sub 9}Si{sub 30}N{sub 59}O{sub 2}F (Ln = Ce, Pr) were synthesized by reaction of LnF{sub 3} and LiN{sub 3} with Si(NH){sub 2} in liquid lithium flux in weld shut tantalum ampoules. The crystal structures of the isotypic compounds were solved and refined on the basis of single-crystal X-ray diffraction (P anti 3c1 (no. 165), Z = 2; Li{sub 35}Ce{sub 9}Si{sub 30}N{sub 59}O{sub 2}F:, a = 1479.9(2), c = 1538.3(3) pm, R{sub 1} = 0.0526, 1671 data, 175 parameters; Li{sub 35}Pr{sub 9}Si{sub 30}N{sub 59}O{sub 2}F: a = 1477.3(2), c = 1533.9(3) pm, R{sub 1} = 0.0441, 1331 data, 175 parameters). The silicate substructure represents a 3D network of all side corner sharing SiN{sub 4} tetrahedra. At one discrete and not condensed mixed anion position an atomic ratio O:F = 2:1 is assumed in order to achieve charge neutrality. With an atomic ratio Si:N = 30:59, the degree of condensation of the silicate substructure is slightly above κ = 1/2. Accordingly, there are triply crosslinking N{sup [3]} atoms in the silicate substructure. The obtained structures prove that by employing the lithium flux technique not only nitridosilicates with a low degree of condensation can be obtained by using rather mild reaction conditions at low temperatures. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical composition. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

1,3-thiazole as suitable antenna ligand for lanthanide photoluminescence in [LnCl{sub 3}(thz){sub 4}].0.5thz, Ln = Sm, Eu, Gd, Tb, Dy

Energy Technology Data Exchange (ETDEWEB)

Dannenbauer, Nicole; Mueller-Buschbaum, Klaus [Wuerzburg Univ. (Germany). Inst. for Inorganic Chemistry; Kuzmanoski, Ana; Feldmann, Claus [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Inorganic Chemistry

2014-02-15

The series of luminescent monomeric lanthanide thiazole complexes [LnCl{sub 3}(thz){sub 4}].0.5thz (Ln = Sm, Eu, Gd, Tb, Dy; thz = 1,3-thiazole) has been synthesised and characterised by powder and single-crystal X-ray diffraction, IR and photoluminescence spectroscopy, DTA/TG as well as elemental analysis. The colourless compounds exhibit photoluminescence in the visible region with varying quantum efficiencies up to QY = 48 % for [LnCl{sub 3}(thz){sub 4}].0.5thz. Both, the lanthanide ions as well as the thiazole ligand contribute to the luminescence. Excitation can be achieved via intra-4f transitions and by exciting the ligand, emission is observed mainly from the lanthanide ions again by 4f transitions. Thiazole can transfer energy to the lanthanide ions, which further feeds the lanthanide emission by an efficient antenna effect even at room temperature. The lanthanide ions show pentagonal-bipyramidal coordination by three chloride anions and four N atoms of 1,3-thiazole, which leads to a strong {sup 5}D{sub 0} → {sup 7}F{sub 4} transition for europium. Significant differences arise as compared to thiophene complexes because no sulphur atom is involved in the metal coordination, as the thiazole ligand is solely coordinated via its nitrogen function. (orig.)

High-pressure syntheses of lanthanide polysulfides and polyselenides LnX_1_._9 (Ln = Gd-Tm, X = S, Se)

International Nuclear Information System (INIS)

Mueller, Carola J.; Schwarz, Ulrich; Doert, Thomas

2012-01-01

The polysulfides LnS_1_._9 and polyselenides LnSe_1_._9 of the lanthanide metals from gadolinium to thulium were prepared by high-pressure high-temperature synthesis. The compounds adopt the tetragonal CeSe_1_._9 structure type in space group P4_2/n (No. 86) with lattice parameters of 8.531 Aa ≤ a ≤ 8.654 Aa and 15.563 Aa ≤ c ≤ 15.763 Aa for the sulfides and 8.869 Aa ≤ a ≤ 9.076 Aa and 16.367 Aa ≤ c ≤ 16.611 Aa for the selenides. The atomic pattern consists of puckered double slabs [LnX]"+ and planar chalcogenide layers with ten possible chalcogen positions, of which eight are occupied by chalcogen atoms forming dinuclear X_2"2"- dianions, one by a single X"2"- ion and one remaining vacant. This resembles a √5 x √5 x 2 superstructure of the ZrSSi aristotype. Structural relationships to the aristotype and the related lanthanide polychalcogenides LnX_2_-_δ (Ln = La-Tm, X = S-Te, δ = 0 - 0.3) are discussed. The samples synthesized under high-pressure conditions (p > 1 GPa) decompose slowly under release of sulfur or selenium at ambient conditions. The crystal structure of a partially degraded thulium-polysulfide sample can be described as an incommensurate variant of the original TmS_1_._9 motif. Additionally, the isostructural ternary compound Gd(S_1_-_xSe_x)_1_._9 was synthesized and characterized by powder X-ray diffraction. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

On the structure of rare earth periodates of LnIO5x4H2O (Ln=Pr-Lu, Y)

International Nuclear Information System (INIS)

Shamraj, N.B.; Varfolomeev, M.B.; Saf'yanov, Yu.N.; Kuz'min, Eh.A.; Ilyukhin, V.V.; AN SSSR, Moscow. Inst. Kristallografii)

1977-01-01

The crystal structure of three representatives of an isotypic series of monoclinic periodates of rare earth elements in the series from Pr to Lu and Y was deciphered. The monoclinic cell for all LnIO 5 x4H 2 O contains Z=4 formula units. The architectural motif consists in layers of octahedra of IO 4 (OH) 2 and polyhedra of LnO 5 (H 2 O 3 ) parallel to the (100) plane. Adhesion between the layers is achieved through H-bonds

Protonation and structural/chemical stability of Ln{sub 2}NiO{sub 4+δ} ceramics vs. H{sub 2}O/CO{sub 2}: High temperature/water pressure ageing tests

Energy Technology Data Exchange (ETDEWEB)

Upasen, S. [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France); Batocchi, P.; Mauvy, F. [ICMCB, ICMCB-CNRS-IUT-Université de Bordeaux, 33608 Pessac Cedex (France); Slodczyk, A. [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France); Colomban, Ph., E-mail: philippe.colomban@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France)

2015-02-15

Highlights: • High temperature/water pressure autoclave is used to study the reaction/corrosion at SOFC/HTSE electrode. • High stability of Pr{sub 2}NiO{sub 4+δ} (PNO) and Nd{sub 2}NiO{sub 4+δ} (NNO) dense ceramics vs. water pressure is demonstrated. • Protonated rare-earth nickelates retain the perovskite-type structure and their H-content is determined. • Very low laser illumination power is required to avoid RE nickelate phase transition. • Nickelates show increasing stability from La to Pr/Nd vs. CO{sub 2}-rich high temperature water vapor. - Abstract: Mixed ionic-electronic conductors (MIEC) such as rare-earth nickelates with a general formula Ln{sub 2}NiO{sub 4+δ} (Ln = La, Pr, Nd) appear as potential for energy production and storage systems: fuel cells, electrolysers and CO{sub 2} converters. Since a good electrode material should exhibit important stability in operating conditions, the structural and chemical stability of different nickelate-based, well-densified ceramics have been studied using various techniques: TGA, dilatometry, XRD, Raman scattering and IR spectroscopy. Consequently, La{sub 2}NiO{sub 4+δ} (LNO), Pr{sub 2}NiO{sub 4+δ} (PNO) and Nd{sub 2}NiO{sub 4+δ} (NNO) have been exposed during 5 days to high water vapor pressure (40 bar) at intermediate temperature (550 °C) in an autoclave device, the used water being almost free or saturated with CO{sub 2}. Such protonation process offers an accelerating stability test and allows the choice of the most pertinent composition for industrial applications requiring a selected material with important life-time. In order to understand any eventual change of crystal structure, the ceramics were investigated in as-prepared, pristine state as well as after protonation and deprotonation (due to thermal treatment till 1000 °C under dry atmosphere). The results show the presence of traces or second phases originating from undesirable hydroxylation and carbonation, detected in the near

Hydrothermal synthesis of 4ZnO·B2O3·H2O:Ln3 + (Ln = Eu, Tb) phosphors: Morphology-tunable and luminescence properties

Science.gov (United States)

Cao, Shiwei; Jiao, Yang; Han, Weifang; Ge, Chunhua; Song, Bo; Wang, Jie; Zhang, Xiangdong

2018-02-01

4ZnO·B2O3·H2O:Ln3 + (Ln = Eu, Tb) phosphors with different morphologies have been successfully synthesized via one-step hydrothermal method through regulating the molar amount of Eu3 + and Tb3 +. Comprehensive scanning electron microscopy (SEM), X-ray diffraction (XRD) Fourier transform infrared spectrum (FT-IR) and inductively coupled plasma atomic emission spectrometer (ICP-AES) characterizations all confirm that obtained products are 4ZnO·B2O3·H2O:Ln3 + (Ln = Eu, Tb). The experimental results displayed that the morphology and photoluminescence of compounds is regularly changed with increased the molar amount of rare earth ions. For the Eu3 +-doped, Tb3 +-doped and Eu3 +/Tb3 + co-doped 4ZnO·B2O3·H2O phosphors of morphologies, the rod-like structures gradually changed to flower-like structures, fine wire-like structure and hybrid structure, respectively. To their photoluminescence, the Eu3 + shows a red emission (615 nm); the Tb3 + shows a green emission (545 nm); for the Eu3 +/Tb3 + co-doped 4ZnO·B2O3·H2O phosphors, a combination of blue (5d-4f of Eu2 +), green (5D4-7F5 of Tb3 +) and red (5D0-7F2 of Eu3 +) emissions emerges to achieve white emission. In addition, the energy transfer among Eu3 +, Eu2 + and Tb3 + ions was also discussed.

A new promising phosphor, Na3La2(BO3)3:Ln (Ln=Eu, Tb)

International Nuclear Information System (INIS)

Li Zhihua; Zeng Jinghui; Zhang Guochun; Li Yadong

2005-01-01

We present an efficient way to search a host for ultraviolet (UV) phosphor from UV nonlinear optical (NLO) materials. With the guidance, Na 3 La 2 (BO 3 ) 3 (NLBO), as a promising NLO material with a broad transparency range and high damage threshold, was adopted as a host material for the first time. The lanthanide ions (Tb 3+ and Eu 3+ )-doped NLBO phosphors have been synthesized by solid-state reaction. Luminescent properties of the Ln-doped (Ln=Tb 3+ , Eu 3+ ) sodium lanthanum borate were investigated under UV ray excitation. The emission spectrum was employed to probe the local environments of Eu 3+ ions in NLBO crystal. For red phosphor, NLBO:Eu, the measured dominating emission peak was at 613 nm, which is attributed to 5 D - 7 F 2 transition of Eu 3+ . The luminescence indicates that the local symmetry of Eu 3+ in NLBO crystal lattice has no inversion center. Optimum Eu 3+ concentration of NLBO:Eu 3+ under UV excitation with 395 nm wavelength is about 30 mol%. The green phosphor, NLBO:Tb, showed bright green emission at 543 with 252 nm excited light. The measured concentration quenching curve demonstrated that the maximum concentration of Tb 3+ in NLBO was about 20%. The luminescence mechanism of Ln-doped NLBO (Tb 3+ and Eu 3+ ) was analyzed. The relative high quenching concentration was also discussed

LN2 Dewar 42 Delivery Overfill Inlet Solution

Energy Technology Data Exchange (ETDEWEB)

Wu, J.; Mulholland, G.T.; /Fermilab

1991-02-26

Pressure vessels must be protected against overpressure scenarios. A scenario of particular concern is that from a high pressure LN2 pump, now standard on LN2 delivery trailers. A safety mechanism must be in place to prevent the overfilling, and subsequent overpressure from occurring because these pumps have a higher mass flow output than reasonably sized relief valves provide. The original solution to the problem was to close a valve on the fill line when a certain liquid level in the dewar is reached. The valve remains closed until the level drops below that threshold. The trigger level was about 13,000 gallons for the 20,000 gallon capacity dewar. The solution was in place from 1989 until present, 2004.

Vibrational spectra of mixed oxides of Ln2MgTiO6 composition

International Nuclear Information System (INIS)

Porotnikov, N.V.; German, M.; Kovba, L.M.

1984-01-01

In the range 33-4000 cm -1 IR and Raman spectra of complex oxides of the composition Ln 2 MgTiO 6 (Ln=La-Yb and Y) have been studied. Using the Magnesium isotope-substituted compositions Lasub(2)sup(24,26)MgTiOsub(6), Smsub(2)sup(24,26)MgTiOsub(6) and Ybsub(2)sup(24,26)MgTiOsub(6), it has been shoWn that in Ln 2 MgTiO 6 titanium and magnesium ions are located in sites With octahedral coordination, of rare earth ions highly-coordinated polyhedrons with coordination number 10-12 are characteristic

Commissioning of the Liquid Nitrogen Thermo-Siphon System for NASA-JSC Chamber-A

Science.gov (United States)

Homan, J.; Montz, M.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Garcia, S.; Garza, J.

2013-01-01

NASA's Space Environment Simulation Laboratory's (SESL) Chamber A, located at the Johnson Space Center in Houston Texas has recently implemented major enhancements of its cryogenic and vacuum systems. The new liquid nitrogen (LN2) thermo-siphon system was successfully commissioned in August of 2012. Chamber A, which has 20 K helium cryo-panels (or shrouds ) which are shielded by 80 K nitrogen shrouds, is capable of simulating a deep space environment necessary to perform ground testing of NASA s James Webb Space Telescope (JWST). Chamber A s previous system used forced flow LN2 cooling with centrifugal pumps, requiring 200,000 liters of LN2 to cool-down and consuming 180,000 liters per day of LN2 in steady operation. The LN2 system did not have the reliability required to meet the long duration test of the JWST, and the cost estimate provided in the initial approach to NASA-JSC by the sub-contractor for refurbishment of the system to meet the reliability goals was prohibitive. At NASA-JSC's request, the JLab Cryogenics Group provided alternative options in 2007, including a thermo-siphon, or natural flow system. This system, eliminated the need for pumps and used one tenth of the original control valves, relief valves, and burst disks. After the thermo-siphon approach was selected, JLab provided technical assistance in the process design, mechanical design, component specification development and commissioning oversight, while the installation and commissioning operations of the system was overseen by the Jacobs Technology/ESC group at JSC. The preliminary commissioning data indicate lower shroud temperatures, 70,000 liters to cool-down and less than 90,000 liters per day consumed in steady operation. All of the performance capabilities have exceeded the design goals. This paper will outline the comparison between the original system and the predicted results of the selected design option, and the commissioning results of thermo-siphon system.

Thermal decomposition of heavy rare-earth butanoates, Ln(C₃H₇CO₂)₃ (Ln = Er, Tm, Yb and Lu) in argon

DEFF Research Database (Denmark)

Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao

2016-01-01

was observed in all four compounds, but its course depends on the rare-earth element. Decomposition to sesquioxides proceeds via the formation of dioxymonocarbonates (Ln2O2CO3) and release of 4-heptanone (C3H7COC3H7) as well as carbon dioxide (CO2) without evidence for an intermediate oxobutanoate stage...... of Ln2O2CO3 and Ln2O3. The stability of this intermediate state seems to decrease with the mass of the rare-earth elements. Complete conversion to Ln2O3 is reached at about 1100 °C. The overall thermal decomposition behaviour of the title compounds is different from previous reports for other rare....... During the decomposition of Ln2O2CO3 into the respective sesquioxides (Ln2O3), an intermediate plateau extending from approximately 550 to 850 °C appears in the TG traces. The overall composition during this stage corresponds approximately to Ln2O2.8(CO3)0.2, but the state is more probably a mixture...

Efficient NIR (near-infrared) luminescent ZnLn-grafted (Ln=Nd, Yb or Er) PNBE (Poly(norbornene))

Energy Technology Data Exchange (ETDEWEB)

Liu, Lin; Feng, Hei-Ni; Fu, Guo-Rui; Li, Bao-Ning [School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi’an 710069, Shaanxi (China); Lü, Xing-Qiang, E-mail: lvxq@nwu.edu.cn [School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi’an 710069, Shaanxi (China); Wong, Wai-Kwok [Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong (China); Jones, Richard A. [Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165 (United States)

2017-06-15

Through the ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with each of allyl-containing complex monomers [Zn(L){sub 2}(µ{sub 1}-OAc)Ln(µ{sub 2}-OAc){sub 2}] (Ln=La, 1; Nd, 2; Yb, 3; Er, 4 or Gd, 5; HL=4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol), a series of ZnLn-grafted polymers Poly([Zn(L){sub 2}(µ{sub 1}-OAc)Ln(µ{sub 2}-OAc){sub 2}]-co-NBE) with desired physical properties were obtained, respectively. Within near-infrared (NIR) luminescent polymers, Poly(3-co-NBE) endows an attractive quantum yield of 1.47% in solid state, and exhibits an effective prevention of high-concentration self-quenching. - Graphical abstract: Through grafting of [Zn(L){sub 2}(µ{sub 1}-OAc)Ln(µ{sub 2}-OAc){sub 2}] (Ln=Nd, 2; Yb, 3 or Er, 4) into PNBE with desired physical properties including NIR luminescence, Poly(3-co-NBE) exhibits an attractive quantum yield of 1.47% and an effective emitters' clustering prevention.

β-Y(BO{sub 2}){sub 3}. A new member of the β-Ln(BO{sub 2}){sub 3} (Ln = Nd, Sm, Gd-Lu) structure family

Energy Technology Data Exchange (ETDEWEB)

Schmitt, Martin K.; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

2017-07-01

β-Y(BO{sub 2}){sub 3} was synthesized in a Walker-type multianvil module at 5.9 GPa/1000 C. The crystal structure has been elucidated through single-crystal X-ray diffraction. β-Y(BO{sub 2}){sub 3} crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 15.886(2), b = 7.3860(6), and c = 12.2119(9) Aa. Its crystal structure will be discussed in the context of the isotypic lanthanide borates β-Ln(BO{sub 2}){sub 3} (Ln = Nd, Sm, Gd-Lu).

Characteristic charge transport in oxygen-deficiency-controlled LnFeAsO1-y (Ln = La and Nd)

International Nuclear Information System (INIS)

Ishida, Shigeyuki; Nakajima, Masamichi; Tomioka, Yasuhide; Ito, Toshimitsu; Miyazawa, Kiichi; Kito, Hijiri; Lee, Chul-Ho; Ishikado, Motoyuki; Shamoto, Shin-ichi; Iyo, Akira; Eisaki, Hiroshi; Kojima, Kenji M.; Uchida, Shin-ichi

2010-01-01

We have investigated the transport properties of LnFeAsO 1-y (Ln = La, Nd) over a wide range of doping. When we compare the exponent n of resistivity ρ(T)∼T n , a marked difference is found between La and Nd system. In the La system with lower T C ,ρ(T) is always dominated by a T 2 term at low temperatures, showing relatively large magnetoresistance. On the other hand, in the Nd system with higher T C ,ρ(T) is linear on T with a small magnetoresistance. These results indicate that the carriers are subject to stronger scattering in NdFeAsO 1-y , which might be linked to the higher T C .

Air conditioning and power generation for residential applications using liquid nitrogen

International Nuclear Information System (INIS)

Ahmad, Abdalqader; Al-Dadah, Raya; Mahmoud, Saad

2016-01-01

Highlights: • Using liquid nitrogen to provide power and air conditioning for domestic applications. • The proposed system leads to save energy and reduce the peak electricity demands. • Compared with conventional AC saving up to 36% was achieved at the current LN2 price. • The widespread of this technology leads to lower LN2 price and saving up to 81%. • The last configuration was the efficient system with overall thermal efficiency 74%. - Abstract: Current air conditioning (AC) systems consume a significant amount of energy, particularly during peak times where most electricity suppliers face difficulties to meet the users’ demands, and the global demands for AC systems have increased rapidly over the last few decades leading to significant power consumption and carbon dioxide emissions. This paper presents a new technique that uses liquid nitrogen (LN2) produced from renewable energy sources, or surplus electricity at off peak times, to provide cooling and power for domestic houses. Thermodynamic analyses of various cryogenic cycles have been carried out to achieve the most effective configuration that produces the maximum power output with minimum LN2 flow rate, to meet the required cooling of a 170 m"2 dwelling in Libya. A comparison with a conventional AC system was also made. Results showed that at the current LN2 prices, using LN2 to provide cooling and power demands of residential buildings is feasible and saves up to 36% compared to conventional air conditioning systems with an overall thermal efficiency of 74%. However, as the LN2 price decreases to around 1.3 pence per kg, the proposed technology will have significant advantages compared to conventional AC systems with savings of up to 81%.

Prism inside. Spectroscopic and magnetic properties of the lanthanide(III) chloride oxidotungstates(VI) Ln{sub 3}Cl{sub 3}[WO{sub 6}] (Ln = La - Nd, Sm - Tb)

Energy Technology Data Exchange (ETDEWEB)

Dorn, Katharina V.; Blaschkowski, Bjoern; Hartenbach, Ingo [Institute for Inorganic Chemistry, University of Stuttgart (Germany); Foerg, Katharina; Netzsch, Philip; Hoeppe, Henning A. [Institute for Physics, University of Augsburg (Germany)

2017-11-17

The lanthanide(III) chloride oxidotungstates(VI) with the formula Ln{sub 3}Cl{sub 3}[WO{sub 6}] for Ln = La - Nd, Sm - Tb were synthesized by solid-state reactions utilizing the respective lanthanide trichloride, lanthanide sesquioxide (where available), and tungsten trioxide together with lithium chloride as flux. The title compounds crystallize hexagonally in space group P6{sub 3}/m (no. 176, a = 941-909, c = 543-525 pm, Z = 2). The structures comprise crystallographically unique Ln{sup 3+} cations surrounded by six O{sup 2-} and four Cl{sup -} anions (C.N. = 10) forming distorted tetracapped trigonal prisms as well as rather uncommon trigonal prismatic [WO{sub 6}]{sup 6-} units, whose edges are coordinated by nine Ln{sup 3+} cations. Thus, a {sup 3}{sub ∞}{([WO_6]Ln"e_9_/_3)"3"+} framework (e = edge-sharing) is created, which contains tube-shaped channels along [001] lined with chloride anions. To elucidate the spectroscopic and magnetic properties of the obtained pure phase samples, single-crystal Raman (for Ln = La - Nd, Sm-Tb), diffuse reflectance (for Ln = La, Pr, Nd, Gd), and luminescence spectroscopy (for bulk Ln{sub 3}Cl{sub 3}[WO{sub 6}] (Ln = La, Eu, Gd, Tb) and Eu{sup 3+}- or Tb{sup 3+}-doped derivatives of La{sub 3}Cl{sub 3}[WO{sub 6}] and Gd{sub 3}Cl{sub 3}[WO{sub 6}], respectively) were performed and their temperature-dependent magnetic moments (for Ln = Pr, Nd, Gd) were determined. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Corrections to O(α7(lnα)mc2) fine-structure splittings and O(α6(lnα)mc2) energy levels in helium

International Nuclear Information System (INIS)

Zhang, T.

1996-01-01

Fully relativistic formulas for the energy-level shifts arising from no-pair exchange diagrams of two transverse photons plus an arbitrary number of Coulomb photons are derived in closed form within the external potential Bethe-Salpeter formalism. O(α 7 (lnα)mc 2 ) corrections to the fine-structure splittings of helium are obtained and expressed in terms of expectation values of nonrelativistic operators. O(α 7 mc 2 ) operators from exchange diagrams are found in nonrelativistic approximation. O(α 6 m 2 c 2 /M) nucleus-electron operators contributing to the fine-structure splittings are derived. Nonrelativistic operators of O(α 6 mc 2 ) corrections to the triplet levels of helium are presented. Nonrelativistic operators of O(α 6 (lnα)mc 2 ) corrections to the helium singlet levels and to positronium S levels are derived. O(α 6 m 2 c 2 /M) hydrogen and O(α 6 mc 2 ) positronium P levels, and O(α 6 (lnα)mc 2 ) corrections of first order to positronium S levels, are calculated using the derived operators for helium, in agreement with those obtained previously by others, except for one term in corrections to positronium P levels. In addition, the O(α 6 mc 2 ) Dirac energies for hydrogenic non-S levels are exactly reproduced in a perturbative calculation. copyright 1996 The American Physical Society

Magnetic characterization of microcrystalline Na3Ln0.99–xEr0.01Crx(PO42 orthophosphates synthesized by Pechini method (Ln = La, Gd

Directory of Open Access Journals (Sweden)

Kaczmarek S.M.

2018-03-01

Full Text Available Na3Ln(PO42 orthophosphates (Ln = La, Gd doped with Er3+ and co-doped with Cr3+ ions were synthesized by Pechini method and characterized by electron paramagnetic resonance (EPR and magnetic susceptibility measurements. Low temperature EPR spectra were detected and analyzed in terms of temperature dependence and the structure of the obtained materials. They show that erbium and chromium ions substitute Ln3+ and also Na+ ions or Na+ channels forming complex EPR spectra. Both kinds of ions reveal ferromagnetic type of interaction which shows some anomaly at the temperature between 10 K and 15 K. Magnetic susceptibility reveals a weak antiferromagnetic kind of interaction dominating in the whole temperature range, from 3.5 to 300 K.

A method for the estimation of the enthalpy of formation of mixed oxides in Al2O3-Ln2O3 systems

International Nuclear Information System (INIS)

Vonka, P.; Leitner, J.

2009-01-01

A new method is proposed for the estimation of the enthalpy of formation (Δ ox H) of various Al 2 O 3 -Ln 2 O 3 mixed oxides from the constituent binary oxides. Our method is based on Pauling's concept of electronegativity and, in particular, on the relation between the enthalpy of formation of a binary oxide and the difference between the electronegativities of the oxide-forming element and oxygen. This relation is extended to mixed oxides with a simple formula given for the calculation of Δ ox H. The parameters of this equation were fitted using published experimental values of Δ ox H derived from high-temperature oxide melt solution calorimetry. Using our proposed method, we obtained a standard deviation (σ) of 4.87 kJ mol -1 for this data set. Taking into account regularities within the lanthanide series, we then estimated the Δ ox H values for Al 2 O 3 -Ln 2 O 3 mixed oxides. The values estimated using our method were compared with those obtained by Aronson's and Zhuang's empirical methods, both of which give significantly poorer results. - Graphical abstract: Enthalpy of formation of Ln-Al-O oxides from the constituent binary ones.

Small-x behavior of the structure function F2 and its slope ∂lnF2/∂ln(1/x) for ''frozen'' and analytic strong-coupling constants

International Nuclear Information System (INIS)

Cvetic, G.; Kniehl, B.A.; Kotikov, A.V.

2009-06-01

Using the leading-twist approximation of the Wilson operator product expansion with ''frozen'' and analytic versions of the strong-coupling constant, we show that the Bessel-inspired behavior of the structure function F 2 and its slope ∂lnF 2 /∂ln(1/x) at small values of x, obtained for a at initial condition in the DGLAP evolution equations, leads to good agreement with experimental data of deep-inelastic scattering at DESY HERA. (orig.)

FATIGUE PROPERTIES OF MODIFIED 316LN STAINLESS STEEL AT 4 K FOR HIGH FIELD CABLE-IN-CONDUIT APPLICATIONS

International Nuclear Information System (INIS)

Toplosky, V. J.; Walsh, R. P.; Han, K.

2010-01-01

Cable-In-Conduit-Conductor (CICC) alloys, exposed to Nb 3 Sn reaction heat-treatments, such as modified 316LN require a design specific database. A lack of fatigue life data (S-n curves) that could be applied in the design of the ITER CS and the NHMFL Series Connected Hybrid magnets is the impetus for the research presented here. The modified 316LN is distinguished by a lower carbon content and higher nitrogen content when compared to conventional 316LN. Because the interstitial alloying elements affect the mechanical properties significantly, it is necessary to characterize this alloy in a systematic way. In conjunction, to ensure magnet reliability and performance, several criteria and expectations must be met, including: high fatigue life at the operating stresses, optimal stress management at cryogenic temperatures and thin walled conduit to reduce coil mass. Tension-tension load control axial fatigue tests have good applicability to CICC solenoid magnet design, thus a series of 4 K strength versus fatigue life curves have been generated. In-situ samples of 316LN base metal, seam welded, butt welded and seam plus butt welded are removed directly from the conduit in order to address base and weld material fatigue life variability. The more than 30 fatigue tests show good grouping on the fatigue life curve and allow discretionary 4 K fatigue life predictions for conduit made with modified 316LN.

ALnS2:RE (A=K, Rb; Ln=La, Gd, Lu, Y): New optical materials family

International Nuclear Information System (INIS)

Jarý, V.; Havlák, L.; Bárta, J.; Mihóková, E.; Buryi, M.; Nikl, M.

2016-01-01

In the presented review paper, new potentially interesting material family, RE-doped ternary sulfides ALnS 2 (RE=Ce, Pr, Sm, Eu, Tb, Tm; A=Rb, K; Ln=La, Gd, Lu, Y) is discussed. Their synthesis is described and the structural and optical properties, characterized by methods of X-ray diffraction, time-resolved luminescence spectroscopy and electron paramagnetic resonance, are summarized and reviewed especially with respect to the influence of their composition. All samples discussed were synthesized in the form of transparent crystalline hexagonal platelets by chemical reaction under the flow of hydrogen sulfide. Their luminescence characteristics, including absorption, radioluminescence, photoluminescence excitation and emission spectra and decay kinetics, were measured and evaluated in a broad temperature (8–800 K) and concentration (0.002–20% of dopants) range. The application potential of mentioned compounds in the field of white LED solid state lightings or X-ray phosphors is thoroughly discussed. - Highlights: • RE-doped ALnS 2 (A=K, Rb; Ln=La, Gd, Lu, Y) were synthesized. • Their optical characteristics are summarized. • Concentration and temperature dependences of luminescence features investigated. • EPR technique is employed to explain Eu 2+ incorporation into KLuS 2 host. • The application potential in white LED and X-ray phosphors is discussed.

Síntesis hidrotermal de monocristales LnMn2O5 (Ln= Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho y Er

Directory of Open Access Journals (Sweden)

Señarís Rodríguez, M. A.

2008-08-01

Full Text Available Ten single crystals of the series LnMn2O5 (Ln= Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er were synthesized by hydrothermal synthesis in a single step and without subsequent thermal treatments from aqueous solutions of metals salts at 240 ºC. The obtained single crystals have a size of various micrometers and their morphology changes throughout the serie: they are polygonal in the case of the compounds with Ln= Pr, Nd, Sm, Eu and Gd and needle-like in the case of the compounds with Ln= Y, Tb, Dy, Ho and Er. After the analysis of the obtained products employing different conditions of synthesis we attributed the different morphology to a greater growth rate along the c axis when the smaller ions (Y, Tb, Dy, Ho y Er are involved, due to their better adaptation to the compound’s crystal structure.Se han conseguido preparar monocristales de 10 óxidos mixtos de la serie LnMn2O5 (Ln= Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho y Er mediante síntesis hidrotermal optimizada, en un único paso y sin tratamientos térmicos posteriores partiendo de las correspondientes sales metálicas en disolución acuosa a 240 ºC. Los monocristales obtenidos son relativamente grandes, de varias micras y su morfología varía a lo largo de la serie: es poligonal en el caso de los compuestos de los lantánidos del inicio de la serie (Ln= Pr, Nd, Sm, Eu y Gd y acicular en el caso de los compuestos de Y y de los lantánidos del final de la serie (Ln= Tb, Dy, Ho y Er. Tras el análisis de los productos obtenidos empleando distintas condiciones de síntesis atribuimos la diferente morfología a una mayor velocidad de crecimiento cristalino a lo largo del eje c cuando intervienen los iones más pequeños (Y, Tb, Dy, Ho y Er debido a la mejor adaptación de éstos últimos a la estructura cristalina del compuesto.

A series of noncentrosymmetric antimony sulfides Ln{sub 8}Sb{sub 2}S{sub 15} (Ln = La, Pr, Nd) - syntheses, crystal and electronic structures, and NLO properties

Energy Technology Data Exchange (ETDEWEB)

Zhao, Hua-Jun [Laboratory of Applied Research on the Characteristic Resources in the North of Guizhou Province, School of Chemistry and Chemical Engineering, Zunyi Normal College, Guizhou (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China); Zhou, Liu-Jiang [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China)

2015-02-15

A series of noncentrosymmetric sulfides Ln{sub 8}Sb{sub 2}S{sub 15} (Ln = La, Pr, Nd) were prepared from stoichiometric mixtures of the elements at 1223 K in an evacuated silica tube. The compounds Ln{sub 8}Sb{sub 2}S{sub 15} with Ln = La and Nd are isostructural to Pr{sub 8}Sb{sub 2}S{sub 15} and crystallize in the tetragonal noncentrosymmetric space group I4{sub 1}cd. Their structure contains discrete [SbS{sub 3}]{sup 3-} trigonal pyramids separated by Ln{sup 3+} cations and S{sup 2-} anions. La{sub 8}Sb{sub 2}S{sub 15} shows second harmonic generation with intensities 1.2 times that of the commercially used IR NLO (nonlinear optics) material AgGaS{sub 2} (at 2.05 μm laser). It exhibits excellent thermal stability up to 663 C. Studies with UV/Vis-NIR diffuse reflectance spectroscopy show that La{sub 8}Sb{sub 2}S{sub 15} has an optical gap of around 2.3 eV, and a DFT study indicates a direct band gap with an electronic transfer excitation of S 3p electrons to a La 5d orbital. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

An investigation of an uninterruptible power supply (UPS) based on supercapacitor and liquid nitrogen hybridization system

International Nuclear Information System (INIS)

Zhang, Xinjing; Xue, Haobai; Xu, Yujie; Chen, Haisheng; Tan, Chunqing

2014-01-01

Highlights: • A hybrid UPS based on supercapacitor and liquid nitrogen engine is proposed. • The dynamic modelling of the hybrid UPS system is conducted. • The dynamic working performance is obtained and analysed based on the simulation. • The hybrid UPS enjoys environmental benignity, long life and easy maintenance. • It is a highly possible solution to replace conventional UPS systems. - Abstract: An uninterruptible power supply (UPS) system based on supercapacitor and liquid nitrogen (LN 2 ) hybridization is first introduced in this paper. Of the newly designed UPS, the supercapacitor reacts instantaneously once the main supply fails, and it also starts the LN 2 power system to produce continuing electricity for the customer. This hybrid UPS system is of environment cleanness, long life time, easy maintenaince, etc. A 10 kW model is analyzed in this study. A two-stage nitrogen expander is designed with the rated speed of 900 rpm as the long time power generation device of the LN 2 cycle. The UPS starting process calculation is carried out. The results reveal that commercial supercapacitors could fulfill this request. This UPS could be a competent choice for the UPS application. Further discussion indicates the LN 2 power system could be used widely from UPS to low carbon vehicles

Facile in-situ reduction: Crystal growth and magnetic studies of reduced vanadium (III/IV) silicates CaxLn1-xVSiO5 (Ln = Ce-Nd, Sm-Lu, Y)

Science.gov (United States)

Abeysinghe, Dileka; Smith, Mark D.; Morrison, Gregory; Yeon, Jeongho; zur Loye, Hans-Conrad

2018-04-01

A series of lanthanide containing mixed-valent vanadium (III/IV) silicates of the type CaxLn1-xVSiO5 (Ln = Ce-Nd, Sm-Lu, Y) was synthesized as high quality single crystals from a molten chloride eutectic flux, BaCl2/NaCl. Utilizing Ca metal as the reducing agent, an in-situ reduction of V5+ to V3+/4+ as well as of Ce4+ to Ce3+ was achieved. The structures of 14 reported isostructural compounds were determined by single crystal X-ray diffraction. They crystallize in the tilasite (CaMgAsO4F) structure type in the monoclinic space group C2/c. The extended structure contains 1D chains of VO6 octahedra that are connected to each other via SiO4 groups and (Ca/Ln)O7 polyhedra. The magnetic susceptibility and the field dependent magnetization data were measured for CaxLn1-xVSiO5 (Ln = Ce-Nd, Sm, Gd-Lu, Y), and support the existence of antiferromagnetic behavior at low temperatures.

Synthesis and characterization of K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7}·nH{sub 2}O (Ln= La, Pr, Nd), layered tantalates photo catalysts for water splitting

Energy Technology Data Exchange (ETDEWEB)

Valencia S, H.; Tavizon, G. [UNAM, Instituto de Quimica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Pfeiffer, H. [UNAM, Instituto de Investigaciones en Materiales, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Acosta, D. [UNAM, Instituto de Fisica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Negron M, A., E-mail: hvalencia@utp.edu.co [UNAM, Instituto de Ciencias Nucleares, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico)

2015-07-01

Three compounds of the K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7} (Ln = La, Nd, Pr) cation-deficient Ruddlesden-Popper series were prepared by the Pechini (polymeric complex) method. The crystal structures of the hydrated form of these compounds were determined by Rietveld analysis of the X-ray power diffraction data and High Resolution Transmission Electron Microscopy (HRTEM). The samples were also analyzed to determine specific area (Bet), degree of hydration (Thermogravimetric analysis), and photo catalytic activity for hydrogen evolution from water and aqueous methanol solution. (Author)

A high-power narrow-linewidth optical parametric oscillator based on PPMgLN

International Nuclear Information System (INIS)

Peng, Y F; Wei, X B; Xie, G; Gao, J R; Li, D M; Wang, W M

2013-01-01

A high-power and narrow-linewidth tunable optical parametric oscillator based on PPMgLN is presented. The phase matching type e → e + e is used to avoid the walk-off effect and utilize the maximum nonlinear coefficient d 33 (27.4 pm V −1 ) of the PPMgLN crystal (5 mol% MgO doped). When the pump power of the 1064 nm laser is 50 W and the temperature of the PPMgLN crystal is 100 °C, average output power of 15.8 W is obtained with a slope efficiency of 40.6%. The 1.655 μm signal and 2.98 μm idler output powers are 9.5 W and 6.3 W, respectively. The linewidth of the 1.655 μm signal laser is 1.00 nm before compression and 0.05 nm after compression. The compression ratio is 20. The linewidth of the 2.98 μm idler laser is within 0.30–0.63 nm based on theoretical analysis of the linewidth of the 1064 nm pump laser and 1.655 μm signal laser. The output wavelength can be tuned from 1.6 to 1.8 μm and from 3.1 to 2.7 μm by changing the temperature of the 31.2 μm PPMgLN crystal from 30 to 200 °C. (paper)

Rhombus-shaped tetranuclear [Ln4] complexes [Ln = Dy(III) and Ho(III)]: synthesis, structure, and SMM behavior.

Science.gov (United States)

Chandrasekhar, Vadapalli; Hossain, Sakiat; Das, Sourav; Biswas, Sourav; Sutter, Jean-Pascal

2013-06-03

The reaction of a new hexadentate Schiff base hydrazide ligand (LH3) with rare earth(III) chloride salts in the presence of triethylamine as the base afforded two planar tetranuclear neutral complexes: [{(LH)2Dy4}(μ2-O)4](H2O)8·2CH3OH·8H2O (1) and [{(LH)2Ho4}(μ2-O)4](H2O)8·6CH3OH·4H2O (2). These neutral complexes possess a structure in which all of the lanthanide ions and the donor atoms of the ligand remain in a perfect plane. Each doubly deprotonated ligand holds two Ln(III) ions in its two distinct chelating coordination pockets to form [LH(Ln)2](4+) units. Two such units are connected by four [μ2-O](2-) ligands to form a planar tetranuclear assembly with an Ln(III)4 core that possesses a rhombus-shaped structure. Detailed static and dynamic magnetic analysis of 1 and 2 revealed single-molecule magnet (SMM) behavior for complex 1. A peculiar feature of the χM" versus temperature curve is that two peaks that are frequency-dependent are revealed, indicating the occurrence of two relaxation processes that lead to two energy barriers (16.8 and 54.2 K) and time constants (τ0 = 1.4 × 10(-6) s, τ0 = 7.2 × 10(-7) s). This was related to the presence of two distinct geometrical sites for Dy(III) in complex 1.

Relating surface chemistry and oxygen surface exchange in LnBaCo2O(5+δ) air electrodes.

Science.gov (United States)

Téllez, Helena; Druce, John; Kilner, John A; Ishihara, Tatsumi

2015-01-01

The surface and near-surface chemical composition of electroceramic materials often shows significant deviations from that of the bulk. In particular, layered materials, such as cation-ordered LnBaCo2O(5+δ) perovskites (Ln = lanthanide), undergo surface and sub-surface restructuring due to the segregation of the divalent alkaline-earth cation. These processes can take place during synthesis and processing steps (e.g. deposition, sintering or annealing), as well as at temperatures relevant for the operation of these materials as air electrodes in solid oxide fuel cells and electrolysers. Furthermore, the surface segregation in these double perovskites shows fast kinetics, starting at temperatures as low as 400 °C over short periods of time and leading to a decrease in the transition metal surface coverage exposed to the gas phase. In this work, we use a combination of stable isotope tracer labeling and surface-sensitive ion beam techniques to study the oxygen transport properties and their relationship with the surface chemistry in ordered LnBaCo2O(5+δ) perovskites. Time-of-Flight Secondary-Ion Mass Spectrometry (ToF-SIMS) combined with (18)O isotope exchange was used to determine the oxygen tracer diffusion (D*) and surface exchange (k*) coefficients. Furthermore, Low Energy Ion Scattering (LEIS) was used for the analysis of the surface and near surface chemistry as it provides information from the first mono-atomic layer of the materials. In this way, we could relate the compositional modifications (e.g. cation segregation) taking place at the electrochemically-active surface during the exchange at high temperatures and the oxygen transport properties in double perovskite electrode materials to further our understanding of the mechanism of the surface exchange process.

Superconductivity in Multiple Phase Sr2Ln1–xCaxGaCu2O7 and Characterization of La2–xSrxCaCu2O6+δ

NARCIS (Netherlands)

Cava, R.J.; Dover, R.B. van; Batlogg, B.; Krajewski, J.J.; Schneemeyer, L.F.; Siegrist, T.; Hessen, B.; Chen, H.; Peck, Jr.; Rupp, Jr. L.W.

1991-01-01

We have observed the occurrance of superconductivity at temperatures between 40 and 50K for multiple phase samples of Sr2Ln1–xCaxGaCu2O7 treated at 950-1000°C at 25 atmospheres oxygen pressure. We have not been able to find conditions at oxygen pressures of 25 atmospheres or below which make single

Modified Cooling System for Low Temperature Experiments in a 3000 Ton Multi-Anvil Press

Science.gov (United States)

Secco, R.; Yong, W.

2017-12-01

A new modified cooling system for a 3000-ton multi-anvil press has been developed to reach temperatures below room temperature at high pressures. The new system is much simpler in design, easier to make and use, and has the same cooling capability as the previous design (Secco and Yong, RSI, 2016). The key component of the new system is a steel ring surrounding the module wedges that contains liquid nitrogen (LN2) which flows freely through an entrance port to flood the interior of the pressure module. Upper and lower O-rings on the ring seal in the liquid while permitting modest compression and an thermally insulating layer of foam is attached to the outside of the ring. The same temperature of 220 K reached with two different cooling systems suggests that thermal equilibrium is reached between the removal of heat by LN2 and the influx of heat through the massive steel components of this press.

Crystallization of rare earth germanates in the K2O-Ln2O3-GeO2-H2O at 280 deg C

International Nuclear Information System (INIS)

Panasenko, E.B.; Begunova, R.G.; Sklokina, N.F.

1980-01-01

Crystallization of rare earth germanates in potassium hydroxide solutions is studied at 280 deg C. Stability limits for different crystalline phases are established. Diorthogermanates Ln 2 O 3 x2GeO 3 (three structural modifications) are formed with all lanthanides except lanthanum. Germanates-apatites 7Ln 2 O 3 x9GeO 2 are characteristic for ''large'' lanthanides La-Nd. Alkali germanate of the composition 0.5 K 2 OxLn 2 O 3 xGeO 2 xnH 2 O is realized with the elements of the end of rare earth series, i.e., Tm-Lu. Some properties of the germanates synthesized are considered [ru

The role of Ln

NARCIS (Netherlands)

Katayama, Y.; Kayumi, T.; Ueda, J.; Dorenbos, P.; Viana, B; Tanabe, S

2017-01-01

In this paper, Mn2+ and Ln3+ (Ln = Eu, Yb) co-doped MgGeO3 phosphors were prepared using a solid state reaction technique, and their optical properties were investigated. Mn2+-doped samples exhibit persistent luminescence in the red region, peaking at 677 nm, because of the 4T1 → 6A1 transition of

2-D and 3-D phosphotungstate-based TM-Ln heterometallic derivatives constructed from dimeric [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} fragments and copper-organic complex linkers

Energy Technology Data Exchange (ETDEWEB)

Shang, Sensen [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Zhao, Junwei, E-mail: zhaojunwei@henu.edu.cn [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen, Lijuan [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Basic Experiment Teaching Center, Henan University, Kaifeng, Henan 475004 (China); Li, Yuye; Zhang, Jingli; Li, Yanzhou [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Niu, Jingyang, E-mail: jyniu@henu.edu.cn [Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

2012-12-15

Three organic-inorganic hybrid TM-Ln heterometallic phosphotungstates [Cu(dap){sub 2}(H{sub 2}O)][Cu(dap){sub 2}]{sub 3.5}[La({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (1) [Cu(dap){sub 2}(H{sub 2}O)]{sub 0.5}[Cu(dap){sub 2}]{sub 4}[Nd({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}4H{sub 2}O (2) and [Cu(dap){sub 2}(H{sub 2}O)]{sub 2}[Cu(dap){sub 2}]{sub 3.5}[Eu({alpha}-PW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (3) (dap=1,2-diaminopropane) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analyses and single-crystal X-ray diffraction. Their common features are that 1-3 all consist of asymmetric sandwich-type subunits [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} and [Cu(dap){sub 2}]{sup 2+} bridges. Both 1 and 2 display the 2-D (4,4)-topological sheets whereas 3 exhibits the 3-D 5-connected (4{sup 6}{center_dot}6{sup 4}) topological framework. The magnetic properties of 2 and 3 and the luminescence performance of 3 have been measured. - Graphical Abstract: Three TM-Ln heterometallic phosphotungstates 1-3 have been synthesized and characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, X-ray diffraction, thermogravimetric analyses magnetic susceptibility and luminescent properties. Highlights: Black-Right-Pointing-Pointer Cu{sup II}-Ln{sup III} heterometallic polyoxometalates. Black-Right-Pointing-Pointer 2-D and 3-D organic-inorganic hybrid phosphotungstates. Black-Right-Pointing-Pointer 2-D and 3-D structures consisting of Cu{sup II}-Ln{sup III} heterometals.

Rare earth ruthenium gallides with the ideal composition Ln_2Ru_3Ga_5 (Ln = La-Nd, Sm) crystallizing with U_2Mn_3Si_5 (Sc_2Fe_3Si_5) type structure

International Nuclear Information System (INIS)

Jeitschko, Wolfgang; Schlueter, Martin

2010-01-01

The rare earth ruthenium gallides Ln_2Ru_3Ga_5 (Ln = La, Ce, Pr, Nd, Sm) were prepared by arc-melting of cold-pressed pellets of the elemental components. They crystallize with a tetragonal structure (P4/mnc, Z = 4) first reported for U_2Mn_3Si_5. The crystal structures of the cerium and samarium compounds were refined from single-crystal X-ray data, resulting in significant deviations from the ideal compositions: Ce_2Ru_2_._3_1_(_1_)Ga_5_._6_9_(_1_), a = 1135.10(8) pm, c = 580.58(6) pm, R_F = 0.022 for 742 structure factors; Sm_2Ru_2_._7_3_(_2_)Ga_5_._2_7_(_2_), a = 1132.95(9) pm, c = 562.71(6) pm, R_F = 0.026 for 566 structure factors and 32 variable parameters each. The deviations from the ideal compositions 2:3:5 are discussed. A mixed Ru/Ga occupancy occurs only for one atomic site. The displacement parameters are relatively large for atoms with mixed occupancy within their coordination shell and small for atoms with no neighboring sites of mixed occupancy. Chemical bonding is analyzed on the basis of interatomic distances. Ln-Ga bonding is stronger than Ln-Ru bonding. Ru-Ga bonding is strong and Ru-Ru bonding is weak. The Ga-Ga interactions are of similar strength as in elemental gallium. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

The effect of lanthanides on color properties of the (Bi2O30.7(Ln2O30.3 compounds

Directory of Open Access Journals (Sweden)

Šulcová P.

2008-01-01

Full Text Available (Bi2O30.7(Ln2O30,3 solid solutions were synthesized as new inorganic yellow and orange pigments and their color properties have been investigated as possible ecological materials. The pigments were prepared by the solid state reaction of mixed oxides (Bi2O30.7(Ln2O30.3 of various rare earth cations (Ln = Eu, Gd, Tm, Yb and Lu. All the synthesized pigment samples were found to have color coordinates, low a* and high b* and exhibit the color from pale light yellow to orange. Reflectance spectra of the samples show high reflectance percentage in the 600 - 700 nm range. Characterization of the (Bi2O30.7(Ln2O30,3 solid solutions suggests that they have a potential to be alternative yellow colorants for paints, inks, plastics, and ceramics.

Tensile Deformation Temperature Impact on Microstructure and Mechanical Properties of AISI 316LN Austenitic Stainless Steel

Science.gov (United States)

Xiong, Yi; He, Tiantian; Lu, Yan; Ren, Fengzhang; Volinsky, Alex A.; Cao, Wei

2018-03-01

Uniaxial tensile tests were conducted on AISI 316LN austenitic stainless steel from - 40 to 300 °C at a rate of 0.5 mm/min. Microstructure and mechanical properties of the deformed steel were investigated by optical, scanning and transmission electron microscopies, x-ray diffraction, and microhardness testing. The yield strength, ultimate tensile strength, elongation, and microhardness increase with the decrease in the test temperature. The tensile fracture morphology has the dimple rupture feature after low-temperature deformations and turns to a mixture of transgranular fracture and dimple fracture after high-temperature ones. The dominating deformation microstructure evolves from dislocation tangle/slip bands to large deformation twins/slip bands with temperature decrease. The deformation-induced martensite transformation can only be realized at low temperature, and its quantity increases with the decrease in the temperature.

Increasing thermal drying temperature of biosolids reduced nitrogen mineralisation and soil N2O emissions

DEFF Research Database (Denmark)

Case, Sean; Gomez Muñoz, Beatriz; Magid, Jakob

2016-01-01

Previous studies found that thermally dried biosolids contained more mineralisable organic nitrogen (N) than the raw or anaerobically digested (AD) biosolids they were derived from. However, the effect of thermal drying temperature on biosolid N availability is not well understood. This will be o......Previous studies found that thermally dried biosolids contained more mineralisable organic nitrogen (N) than the raw or anaerobically digested (AD) biosolids they were derived from. However, the effect of thermal drying temperature on biosolid N availability is not well understood...

Liquid Nitrogen Removal of Critical Aerospace Materials

Science.gov (United States)

Noah, Donald E.; Merrick, Jason; Hayes, Paul W.

2005-01-01

Identification of innovative solutions to unique materials problems is an every-day quest for members of the aerospace community. Finding a technique that will minimize costs, maximize throughput, and generate quality results is always the target. United Space Alliance Materials Engineers recently conducted such a search in their drive to return the Space Shuttle fleet to operational status. The removal of high performance thermal coatings from solid rocket motors represents a formidable task during post flight disassembly on reusable expended hardware. The removal of these coatings from unfired motors increases the complexity and safety requirements while reducing the available facilities and approved processes. A temporary solution to this problem was identified, tested and approved during the Solid Rocket Booster (SRB) return to flight activities. Utilization of ultra high-pressure liquid nitrogen (LN2) to strip the protective coating from assembled space shuttle hardware marked the first such use of the technology in the aerospace industry. This process provides a configurable stream of liquid nitrogen (LN2) at pressures of up to 55,000 psig. The performance of a one-time certification for the removal of thermal ablatives from SRB hardware involved extensive testing to ensure adequate material removal without causing undesirable damage to the residual materials or aluminum substrates. Testing to establish appropriate process parameters such as flow, temperature and pressures of the liquid nitrogen stream provided an initial benchmark for process testing. Equipped with these initial parameters engineers were then able to establish more detailed test criteria that set the process limits. Quantifying the potential for aluminum hardware damage represented the greatest hurdle for satisfying engineers as to the safety of this process. Extensive testing for aluminum erosion, surface profiling, and substrate weight loss was performed. This successful project clearly

Solid-phase synthesis of compounds of europium and terbium with nitrogen-containing heterocyclic compounds under mechanical activation

International Nuclear Information System (INIS)

Kalinovskaya, I.V.; Karasev, V.E.

2000-01-01

Effect of solvents and parameters of mechanical treatment on basic regularities of synthesis of rare earth compounds with nitrogen-containing heterocyclic compounds is studied. It is shown that interaction on europium (3) and terbium (3) nitrates with nitrogen-containing heterocyclic compounds leads to formation of compounds of Ln(NO 3 )·2D composition, where Ln=Eu, Tb; D=2,2-dipyridyl, 1,10-phenanthroline, diphenylguanidine. Effect of conditions of mechanical treatment and different additions on process and yield of products is studied. Compounds prepared are characterized by the methods of chemical element analysis, IR spectroscopy and luminescent spectroscopy [ru

Single-ion 4f element magnetism: an ab-initio look at Ln(COT)2(-).

Science.gov (United States)

Gendron, Frédéric; Pritchard, Benjamin; Bolvin, Hélène; Autschbach, Jochen

2015-12-14

The electron densities associated with the Ln 4f shell, and spin and orbital magnetizations ('magnetic moment densities'), are investigated for the Ln(COT)2(-) series. The densities are obtained from ab-initio calculations including spin-orbit coupling. For Ln = Ce, Pr the magnetizations are also derived from crystal field models and shown to agree with the ab-initio results. Analysis of magnetizations from ab-initio calculations may be useful in assisting research on single molecule magnets.

Estudo de alguns compostos organolantanídeos: [LnCp2Cl.PPh3

Directory of Open Access Journals (Sweden)

Gatti Paula M.

2000-01-01

Full Text Available In this work we present the synthesis and characterization of some organolanthanide compounds [LnCp2Cl.PPh3], Ln = La, Nd, Eu, Yb and Lu. The catalytic activity of these compounds has been verified in cyclohexene hydrogenation. Cyclohexane was identified by¹H NMR analysis in the reaction products.

Phase transformations during HLnTiO{sub 4} (Ln=La, Nd) thermolysis and photocatalytic activity of obtained compounds

Energy Technology Data Exchange (ETDEWEB)

Silyukov, Oleg I., E-mail: olegsilyukov@yandex.ru; Abdulaeva, Liliia D.; Burovikhina, Alena A.; Rodionov, Ivan A.; Zvereva, Irina A.

2015-03-15

Layered HLnTiO{sub 4} (Ln=La, Nd) compounds belonging to Ruddlesden–Popper phases were found to form partially hydrated compounds Ln{sub 2}Ti{sub 2}O{sub 7}·xH{sub 2}O during thermal dehydration as well as defect oxides Ln{sub 2}□Ti{sub 2}O{sub 7} as final products. Further heating of metastable defect Ln{sub 2}□Ti{sub 2}O{sub 7} substances leads to the formation of pyrochlore-type oxides Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}, with subsequent transformation under higher temperatures to stable layered 110-type perovskites Ln{sub 2}Ti{sub 2}O{sub 7}. The occurring structure transformations lead to an increase of photocatalytic activity in the order of HLnTiO{sub 4}<Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O<Ln{sub 2}□Ti{sub 2}O{sub 7}<Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}<Ln{sub 2}Ti{sub 2}O{sub 7} in the reaction of hydrogen evolution from aqueous isopropanol solution. - Graphical abstract: Layered HLnTiO{sub 4} (Ln=La, Nd) compounds form partially hydrated Ln{sub 2}Ti{sub 2}O{sub 7}·xH{sub 2}O compounds during thermal dehydration, further heating results to the formation to defect oxides Ln{sub 2}□Ti{sub 2}O{sub 7}, pyrochlor-type oxides Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}, with subsequent transformation to layered 110-type perovskites Ln{sub 2}Ti{sub 2}O{sub 7}. Structure transformations lead to an increase of photocatalytic activity in the order of HLnTiO{sub 4}<Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O<Ln{sub 2}□Ti{sub 2}O{sub 7}<Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}<Ln{sub 2}Ti{sub 2}O{sub 7}. - Highlights: • We studied dehydration and further thermolysis of HLnTiO{sub 4} (Ln=La, Nd) compounds. • XRD, STA and solid state IR studies were carried out. • A new series of metastable Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O compounds was obtained. • We examined the photocatalytic activity of all obtained compounds. The hydrogen evolution rate increased in the course of the structure changes during thermolysis.

Synthesis, crystal structure, optical and thermal properties of lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho).

Science.gov (United States)

Förg, Katharina; Höppe, Henning A

2015-11-28

Lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho) were synthesised as colourless (Ln = Tb, Dy) and light pink (Ln = Ho) crystalline powders by reaction of Tb4O7/Dy2O3/Ho2O3 with H3PO3 at 380 °C. All compounds crystallise isotypically (P2(1)/c (no. 14), Z = 4, a(Tb) = 1368.24(4) pm, b(Tb) = 710.42(2) pm, c(Tb) = 965.79(3) pm, β(Tb) = 101.200(1)°, 3112 data, 160 parameters, wR2 = 0.062, a(Ho) = 1363.34(5) pm, b(Ho) = 709.24(3) pm, c(Ho) = 959.07(4) pm, β(Ho) = 101.055(1)°, 1607 data, 158 parameters, wR2 = 0.058). The crystal structure comprises two different infinite helical chains of corner-sharing phosphate tetrahedra. In-between these chains the lanthanide ions are located, coordinated by seven oxygen atoms belonging to four different polyphosphate chains. Vibrational, UV/Vis and fluorescence spectra of Ln[H(PO3)4] (Ln = Tb, Dy, Ho) as well as Dy[H(PO3)4]:Ln (Ln = Ce, Eu) and the magnetic and thermal behaviour of Tb[H(PO3)4] are reported.

Effect of nitrogen in austenitic stainless steel on deformation behavior and stress corrosion cracking susceptibility in BWR simulated environment

International Nuclear Information System (INIS)

Roychowdhury, S.; Kain, V.; Dey, G.K.

2012-01-01

Intergranular stress corrosion cracking (IGSCC) of austenitic stainless steel (SS) components in boiling water reactor (BWR has been a serious issue and is generic in nature. Initial cracking incidences were attributed to weld induced sensitisation and low temperature sensitisation which was mitigated by the use of low carbon grade of SS and molybdenum and nitrogen containing nuclear grade SS. However, IGSCC has occurred in these SS in the non-sensitised condition which was attributed to residual weld induced strain. Strain hardening in SS has been identified as a major cause for enhanced IGSCC susceptibility in BWR environment. Nitrogen in SS has a significant effect on the strain hardening characteristics and has potential to affect the IGSCC susceptibility in BWR environment. Type 304LN stainless steel is a candidate material for use in future reactors with long design life like the Advanced Heavy Water Reactor (AHWR), in which the operating conditions are similar to BWR. This study reports the effect of nitrogen in type 304LN stainless steel on the strain hardening behaviour and deformation characteristics and its effect on the IGSCC susceptibility in BWR/AHWR environment. Two heats of type 304LN stainless steel were used containing different levels of nitrogen, 0.08 and 0.16 wt % (SS alloys A and B, respectively). Both the SS was strain hardened by cross rolling at 200℃ to simulate the strain hardened regions having higher IGSCC susceptibility in BWRs. Tensile testing was done at both room temperature and 288℃(temperature simulating operating BWR conditions) and the effect of nitrogen on the tensile properties were established. Tensile testing was done at strain rates similar to the crack tip strain rates associated with a growing IGSCC in SS. Detailed transmission electron microscopic (TEM) studies were done to establish the effect of nitrogen on the deformation modes. Results indicated twinning was the major mode of deformation during cross rolling while

Combined Effects of Ocean Acidification and Light or Nitrogen Availabilities on 13C Fractionation in Marine Dinoflagellates.

Science.gov (United States)

Hoins, Mirja; Eberlein, Tim; Groβmann, Christian H; Brandenburg, Karen; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy; Van de Waal, Dedmer B

2016-01-01

Along with increasing oceanic CO2 concentrations, enhanced stratification constrains phytoplankton to shallower upper mixed layers with altered light regimes and nutrient concentrations. Here, we investigate the effects of elevated pCO2 in combination with light or nitrogen-limitation on 13C fractionation (εp) in four dinoflagellate species. We cultured Gonyaulax spinifera and Protoceratium reticulatum in dilute batches under low-light ('LL') and high-light ('HL') conditions, and grew Alexandrium fundyense and Scrippsiella trochoidea in nitrogen-limited continuous cultures ('LN') and nitrogen-replete batches ('HN'). The observed CO2-dependency of εp remained unaffected by the availability of light for both G. spinifera and P. reticulatum, though at HL εp was consistently lower by about 2.7‰ over the tested CO2 range for P. reticulatum. This may reflect increased uptake of (13C-enriched) bicarbonate fueled by increased ATP production under HL conditions. The observed CO2-dependency of εp disappeared under LN conditions in both A. fundyense and S. trochoidea. The generally higher εp under LN may be associated with lower organic carbon production rates and/or higher ATP:NADPH ratios. CO2-dependent εp under non-limiting conditions has been observed in several dinoflagellate species, showing potential for a new CO2-proxy. Our results however demonstrate that light- and nitrogen-limitation also affect εp, thereby illustrating the need to carefully consider prevailing environmental conditions.

Host composition dependent tunable multicolor emission in the single-phase Ba2(Ln1-zTbz)(BO3)2Cl:Eu phosphors

NARCIS (Netherlands)

Xia, Z.; Zhuang, J.; Meijerink, A.; Jing, X.

2013-01-01

A new strategy based on the host composition design has been adopted to obtain efficient color-tunable emission from Ba2Ln0.97−zTbz(BO3)2Cl:0.03Eu (Ln = Y, Gd and Lu, z = 0–0.97) phosphors. This study reveals that the single-phase Ba2Ln1−zTbz(BO3)2Cl compounds can be applied to use allowed Eu2+

Characteristics of poly- and mono-crystalline BeO and SiO2 as thermal and cold neutron filters

Science.gov (United States)

Adib, M.; Habib, N.; Bashter, I. I.; Morcos, H. N.; El-Mesiry, M. S.; Mansy, M. S.

2015-09-01

A simple model along with a computer code "HEXA-FILTERS" is used to carry out the calculation of the total cross-sections of BeO and SiO2 having poly or mono-crystalline form as a function of neutron wavelength at room (R.T.) and liquid nitrogen (L.N.) temperatures. An overall agreement is indicated between the calculated neutron cross-sections and experimental data. Calculation shows that 25 cm thick of polycrystalline BeO cooled at liquid nitrogen temperature was found to be a good filter for neutron wavelengths longer than 0.46 nm. While, 50 cm of SiO2, with much less transmission, for neutrons with wavelengths longer than 0.85 nm. It was also found that 10 cm of BeO and 15 cm SiO2 thick mono-crystals cut along their (0 0 2) plane, with 0.5° FWHM on mosaic spread and cooled at L.N., are a good thermal neutron filter, with high effect-to-noise ratio.

Enhancement of superconductivity near the pressure-induced semiconductor-metal transition in the BiS₂-based superconductors LnO₀.₅F₀.₅BiS₂ (Ln = La, Ce, Pr, Nd).

Science.gov (United States)

Wolowiec, C T; White, B D; Jeon, I; Yazici, D; Huang, K; Maple, M B

2013-10-23

Measurements of electrical resistivity were performed between 3 and 300 K at various pressures up to 2.8 GPa on the BiS2-based superconductors LnO0.5F0.5BiS2 (Ln=Pr, Nd). At lower pressures, PrO0.5F0.5BiS2 and NdO0.5F0.5BiS2 exhibit superconductivity with critical temperatures Tc of 3.5 and 3.9 K, respectively. As pressure is increased, both compounds undergo a transition at a pressure Pt from a low Tc superconducting phase to a high Tc superconducting phase in which Tc reaches maximum values of 7.6 and 6.4 K for PrO0.5F0.5BiS2 and NdO0.5F0.5BiS2, respectively. The pressure-induced transition is characterized by a rapid increase in Tc within a small range in pressure of ∼0.3 GPa for both compounds. In the normal state of PrO0.5F0.5BiS2, the transition pressure Pt correlates with the pressure where the suppression of semiconducting behaviour saturates. In the normal state of NdO0.5F0.5BiS2, Pt is coincident with a semiconductor-metal transition. This behaviour is similar to the results recently reported for the LnO0.5F0.5BiS2 (Ln=La, Ce) compounds. We observe that Pt and the size of the jump in Tc between the two superconducting phases both scale with the lanthanide element in LnO0.5F0.5BiS2 (Ln=La, Ce, Pr, Nd).

Synthesis, structure, and polymorphism of A{sub 3}LnSi{sub 2}O{sub 7} (A=Na, K; Ln=Sm, Ho, Yb)

Energy Technology Data Exchange (ETDEWEB)

Latshaw, Allison M.; Yeon, Jeongho; Smith, Mark D.; Loye, Hans-Conrad zur, E-mail: zurloye@mailbox.sc.edu

2016-03-15

Four new members of the A{sub 3}LnSi{sub 2}O{sub 7} family, K{sub 3}SmSi{sub 2}O{sub 7}, Na{sub 3}HoSi{sub 2}O{sub 7}, and two polymorphs of Na{sub 3}YbSi{sub 2}O{sub 7}, are reported. K{sub 3}SmSi{sub 2}O{sub 7} crystallizes in the hexagonal space group P6{sub 3}/mcm, Na{sub 3}HoSi{sub 2}O{sub 7} and Na{sub 3}YbSi{sub 2}O{sub 7} crystallize in the hexagonal space group P6{sub 3}/m, and Na{sub 3}YbSi{sub 2}O{sub 7} crystallizes in the trigonal space group P31c. The Na{sub 3}YbSi{sub 2}O{sub 7} composition that crystallizes in P31c is a new structure type. The magnetic properties for the Ho and Yb analogs are reported. - Graphical abstract: The different structure types and polymorphs of the A{sub 3}LnSi{sub 2}O{sub 7} family reported. - Highlights: • Four new members of the A{sub 3}LnSi{sub 2}O{sub 7} family are presented. • Na{sub 3}YbSi{sub 2}O{sub 7} is reported as two polymorphs, one is a new structure type. • Crystals synthesized out of molten fluoride fluxes.

Changes in transcript expression patterns as a result of cryoprotectant treatment and liquid nitrogen exposure in Arabidopsis shoot tips.

Science.gov (United States)

Gross, Briana L; Henk, Adam D; Bonnart, Remi; Volk, Gayle M

2017-03-01

Transcripts related to abiotic stress, oxidation, and wounding were differentially expressed in Arabidopsis shoot tips in response to cryoprotectant and liquid nitrogen treatment. Cryopreservation methods have been implemented in genebanks as a strategy to back-up plant genetic resource collections that are vegetatively propagated. Cryopreservation is frequently performed using vitrification methods, whereby shoot tips are treated with cryoprotectant solutions, such as Plant Vitrification Solution 2 (PVS2) or Plant Vitrification Solution 3 (PVS3); these solutions remove and/or replace freezable water within the meristem cells. We used the model system Arabidopsis thaliana to identify suites of transcripts that are up- or downregulated in response to PVS2 and PVS3 treatment and liquid nitrogen (LN) exposure. Our results suggest that there are many changes in transcript expression in shoot tips as a result of cryoprotection and that these changes exceed the number detected as a result of LN exposure. In total, 180 transcripts showed significant changes in expression level unique to treatment with either the cryoprotectant or cryopreservation followed by recovery. Of these 180 transcripts, 67 were related to stress, defense, wounding, lipid, carbohydrate, abscisic acid, oxidation, temperature (cold/heat), or osmoregulation. The responses of five transcripts were confirmed using qPCR methods. The transcripts responding to PVS2 + LN suggest an oxidative response to this treatment, whereas the PVS3 + LN treatment invoked a more general metabolic response. This work shows that the choice of cryoprotectant can have a major influence on the patterns of transcript expression, presumably due to the level and extent of stress experienced by the shoot tip. As a result, there may be divergent responses of study systems to PVS2 and PVS3 treatments.

Mechanical properties of electron beam welds of 316LN austenitic steels at low temperature for ITER gravity support system

International Nuclear Information System (INIS)

Lee, P.Y.; Huo, B.L.; Kuai, K.W.

2007-01-01

The gravity support system in ITER not only sustains magnet system, the vacuum vessel and in-vessel components, but also endures several large forces, such as electromagnetic force, thermal load and seismic loads. Based on the ITER design report, the maximum displacement of the gravity support system is estimated to be 32 mm in radial direction at the top flange of the flexible plates during the TF coil cool down from room temperature to 80 k. Welds are located in the peak stress region and subject to cyclic loads in the top flange is a potential problem. Therefore, the mechanical properties of the welds are extremely important for this system. 316LN austenitic stainless steel has been selected as the gravity support structure materials. However, there is still lack of the related mechanical data of the welding components of 316LN stainless steel at present. In this study, we are systematically investigated the mechanical properties of the welding components at low temperature. (authors)

Intergranular Corrosion Behavior of 304LN Stainless Steel Heat Treated at 623 K (350 °C)

Science.gov (United States)

Singh, Raghuvir; Kumar, Mukesh; Ghosh, Mainak; Das, Gautam; Singh, P. K.; Chattoraj, I.

2013-01-01

Low temperature sensitization of 304LN stainless steel from the two pipes, differing slightly in chemical composition, has been investigated; specimens were aged at 623 K (350 °C) for 20,000 hours and evaluated for intergranular corrosion and degree of sensitization. The base and heat-affected zone (HAZ) of the 304LN-1 appear resistant to sensitization, while 304LN-2 revealed a "dual" type microstructure at the transverse section and HAZ. The microstructure at 5.0-mm distance from the fusion line indicates qualitatively less sensitization as compared to that at 2.0 mm. The 304LN-2 base alloy shows overall lower degree of sensitization values as compared to the 304LN-1. A similar trend of degree of sensitization was observed in the HAZ where it was higher in the 304LN-1 as compared to the 304LN-2. The weld zone of both the stainless steels suffered from cracking during ASTM A262 practice E, while the parent metals and HAZs did not show such fissures. A mottled image within the ferrite lamella showed spinodal decomposition. The practice E test and transmission electron microscopy results indicate that the interdendritic regions may suffer from failure due to carbide precipitation and due to the evolution of brittle phase from spinodal decomposition.

Magnetic upconverting fluorescent NaGdF4:Ln3+ and iron-oxide@NaGdF4:Ln3+ nanoparticles

Science.gov (United States)

Shrivastava, Navadeep; Rocha, Uéslen; Muraca, Diego; Jacinto, Carlos; Moreno, Sergio; Vargas, J. M.; Sharma, S. K.

2018-05-01

Microwave assisted solvothermal method has been employed to synthesize multifunctional upconverting β-NaGdF4:Ln3+ and magnetic-upconverting Fe3O4/γ-Fe2O3@NaGdF4:Ln3+ (Ln = Yb and Er) nanoparticles. The powder x-ray diffraction data confirms the hexagonal structure of NaGdF4:Ln3+ and high resolution transmission electron microscopy shows the formation of rod shaped NaGdF4:Ln3+ (˜ 20 nm) and ovoid shaped Fe3O4/γ-Fe2O3@NaGdF4:Ln3+ (˜ 15 nm) nanoparticles. The magnetic hysteresis at 300 K for β-NaGdF4:Ln3+ demonstrates paramagnetic features, whereas iron-oxide@β-NaGdF4:Ln3+ exhibits superparamagnetic behavior along with a linear component at large applied field due to paramagnetic NaGdF4 matrix. Both nanoparticle samples provide an excellent green emitting [(2H11/2, 4S3/2)→4I15/2 (˜ 540 nm)] upconversion luminescence emission under excitation at 980 nm. The energy migration between Yb and Er in NaGdF4 matrix has been explored from 300-800 nm. Intensity variation of blue, green and red lines and the observed luminescence quenching due to the presence of Fe3O4/γ-Fe2O3 in the composite has been proposed. These kinds of materials contain magnetic and luminescence characteristics into single nanoparticle open new possibility for bioimaging applications.

Phase diagrams for the M2MoO4–Ln2(MoO43–Hf(MoO42 systems, where M = Li–Cs, Tl and Ln = La–Lu

Directory of Open Access Journals (Sweden)

Zh. G. Bazarova

2017-12-01

Full Text Available In this paper, the results of systematic studies of complex molybdate systems M2MoO4–Ln2(MoO43–Hf(MoO42 (M = Li–Cs, Tl; Ln = La–Lu are presented. Subsolidus phase diagrams of ternary systems were constructed and new triple molybdates were obtained. The optimum synthesis conditions for poly- and monocrystalline form were determined. According to single-crystal data, the structure of one of the representatives of triple molybdates was determined.

Liquid Nitrogen (Oxygen Simulant) Thermodynamic Vent System Test Data Analysis

Science.gov (United States)

Hedayat, A.; Nelson, S. L.; Hastings, L. J.; Flachbart, R. H.; Tucker, S. P.

2005-01-01

In designing systems for the long-term storage of cryogens in low-gravity (space) environments, one must consider the effects of thermal stratification on tank pressure that will occur due to environmental heat leaks. During low-gravity operations, a Thermodynamic Vent System (TVS) concept is expected to maintain tank pressure without propellant resettling. A series of TVS tests was conducted at NASA Marshall Space Flight Center (MSFC) using liquid nitrogen (LN2) as a liquid oxygen (LO2) simulant. The tests were performed at tank til1 levels of 90%, 50%, and 25%, and with a specified tank pressure control band. A transient one-dimensional TVS performance program is used to analyze and correlate the test data for all three fill levels. Predictions and comparisons of ullage pressure and temperature and bulk liquid saturation pressure and temperature with test data are presented.

Structure of trihydrated rare-earth acid diphosphates LnHP2O7·3H2O (Ln=La, Er)

International Nuclear Information System (INIS)

Ben Moussa, S.; Ventemillas, S.; Cabeza, A.; Gutierrez-Puebla, E.; Sanz, J.

2004-01-01

In trihydrated lanthanum acid-diphosphates LnHP 2 O 7 ·3H 2 O, prepared from acid LnCl 3 and Na 4 P 2 O 7 solutions (pH=1), two crystal forms were obtained. Layered structures of two representative members of this family have been determined by single-crystal X-ray diffraction (XRD) technique. In the case of orthorhombic LaHP 2 O 7 ·3H 2 O (type I), lanthanum cations are ninefold coordinated and diphosphate groups adopt a staggered (alternated) configuration. In the case of triclinic ErHP 2 O 7 ·3H 2 O (type II), erbium cations are eightfold coordinated and diphosphate groups adopt an eclipsed configuration. In agreement with Infrared (IR) spectroscopic data, a bended configuration for diphosphate groups has been deduced. In both structures, one-dimensional chains of edge-sharing rare-earth polyhedra are linked together by diphosphate groups to form the phosphate layers. In both diphosphates, PO 4 and HPO 4 environments have been identified by 31 P MAS-NMR technique. In the two compounds, OH groups of HPO 4 tetrahedra point out of diphosphate planes interacting with adjacent layers. In La-diphosphate, the interaction between HPO 4 groups and water molecules of adjacent layers is favored; however, in Er-diphosphate, the interaction between phosphate acid groups of contiguous layers is produced. Based on structural information deduced, differences detected in IR and NMR spectra of two disphosphates are discussed

Influence of temperature upon the mobilization of nitrogen in peat

Directory of Open Access Journals (Sweden)

Armi Kaila

1953-01-01

Full Text Available The preliminary experiments the results of which are recorded in the present paper, have been carried out in order to obtain some information on the microbiological and chemical mobilization of peat nitrogen at various temperatures. In the incubation experiment at 5°, 20°, 35°, 50°, and 65CC the accumulation of ammonia nitrogen increased with a rising temperature except in the limed series where a minimum was found at 20°. The maximum of nitrate-nitrogen lay at 20 in both the series. The amount of nitrite-nitrogen was almost negligible in all the samples. The mineral nitrogen in the samples incubated at 50° and 65° represented 10—20 % of the total nitrogen. Thus, the organic nitrogen in peat soils can be mobilized to a marked extent, if the conditions are favourable. Accumulation of mineral nitrogen could be stated also at the lower temperatures where the reutilization of released nitrogen in the synthesis of new microbial substance is always more intensive than in the range of thermophilic organisms. Even at 5° a release of nitrogen was noticable. In these experiments liming did not show any beneficial effect upon the accumulation of mineral nitrogen, on the contrary, the values for total nitrogen and ammonia nitrogen were lower in the limed series. The nitrate formation was generally somewhat higher in the limed samples than in the corresponding unlimed ones. It was supposed that the considerable increase in the ammonia content of the samples incubated at 50° and 65° was partly due to purely chemical transformations, since the mere heating of moist samples at 75° for two hours brought about a marked accumulation of ammonia nitrogen. The treatment with dry heat was less effective except when the temperature was raised to 200° in which case a carbonization of the peat took place. The losses of organic matter and of total nitrogen due to the heating were almost negligible at the temperatures below 150°. At 150° and at 200�

Effect of Ca substitution on the electrochemical properties of the Ruddlesden-Popper oxides Sr3.2-xCaxLn0.8Fe1.5Co1.5O10-δ

Science.gov (United States)

Padmasree, K. P.; Lai, Ke-Yu; Kaveevivitchai, Watchareeya; Manthiram, Arumugam

2018-01-01

The Ruddlesden-Popper (R-P) oxides Sr3.2-xCaxLn0.8Fe1.5Co1.5O10-δ with x = 0 and 0.4 and Ln = La, Pr, and Nd, have been synthesized and the effect of Ca on their electrochemical properties as cathodes in solid oxide fuel cells (SOFC) has been investigated. The substitution of Ca for Sr in Sr3.2-xCaxLn0.8Fe1.5Co1.5O10-δ decreases the amount of oxygen loss on heating and the thermal expansion coefficient (TEC). The phase instability of these materials at high temperature is a significant issue that restricts their application as SOFC cathodes, and the substitution of Ca effectively stabilizes the Sr3.2-xCaxLn0.8Fe1.5Co1.5O10-δ phase at 800 °C. Among the different lanthanides with and without Ca in Sr3.2-xCaxLn0.8Fe1.5Co1.5O10-δ, the Ln = Nd samples exhibit an enhancement in cathode performance in SOFC compared to Ln = La and Pr samples, which may be attributed to the higher concentration of oxygen vacancies in the Ln = Nd samples. Comparing the various compositions studied, the Sr2.8Ca0.4Nd0.8Fe1.5Co1.5O10-δ cathode material exhibits superior performance in SOFC with good phase stability.

スクッテルド鉱型化合物LnRu4P12(Ln=ランタニド)の構造と電子物性

OpenAIRE

内海, 貴徳; 関根, ちひろ; 木村, 繁之; 井上, 雅士; 城谷, 一民

1999-01-01

Ternary ruthenium phosphides LnRu4P12 (Ln=La,Ce,Pr,Nd,Sm,Eu,Gd and Tb) with the filled skutterudite-type structure have been prepared at high temperatures and high pressures. The crystal structure of a new compound TbRu4P12 is refined by the Rietveld analysis of the powder X-ray diffraction data. The physical properties of LnRu4P12 have been studied by means of electrical resistivity, magnetic susceptibility, magnetization and specific-heat measurements at low temperatures. LaRu4P12 is a supe...

Nitrogen Removal by Anammox Biofilm Column Reactor at Moderately Low Temperature

Directory of Open Access Journals (Sweden)

Tuty Emilia Agustina

2017-10-01

Full Text Available The anaerobic ammonium oxidation (anammox as a new biological approach for nitrogen removal has been considered to be more cost-effective compared with the combination of nitrification and denitrification process. However, the anammox bioreactors are mostly explored at high temperature (>300C in which temperature controlling system is fully required. This research was intended to develop and to apply anammox process for high nitrogen concentration removal at ambient temperature used for treating wastewater in tropical countries. An up-flow biofilm column reactor, which the upper part constructed with a porous polyester non-woven fabric material as a carrier to attach the anammox bacteria was operated without heating system. A maximum nitrogen removal rate (NRR of 1.05 kg-N m3 d-1 was reached in the operation days of 178 with a Total Nitrogen (TN removal efficiency of 74%. This showed the biofilm column anammox reactor was successfully applied to moderate high nitrogen removal from synthetic wastewater at moderately low temperature. Keywords: Anammox, biofilm column reactor, ambient temperature, nitrogen removal

Characterisation of Ceramic-Coated 316LN Stainless Steel Exposed to High-Temperature Thermite Melt and Molten Sodium

Science.gov (United States)

Ravi Shankar, A.; Vetrivendan, E.; Shukla, Prabhat Kumar; Das, Sanjay Kumar; Hemanth Rao, E.; Murthy, S. S.; Lydia, G.; Nashine, B. K.; Mallika, C.; Selvaraj, P.; Kamachi Mudali, U.

2017-11-01

Currently, stainless steel grade 316LN is the material of construction widely used for core catcher of sodium-cooled fast reactors. Design philosophy for core catcher demands its capability to withstand corium loading from whole core melt accidents. Towards this, two ceramic coatings were investigated for its application as a layer of sacrificial material on the top of core catcher to enhance its capability. Plasma-sprayed thermal barrier layer of alumina and partially stabilised zirconia (PSZ) with an intermediate bond coat of NiCrAlY are selected as candidate material and deposited over 316LN SS substrates and were tested for their suitability as thermal barrier layer for core catcher. Coated specimens were exposed to high-temperature thermite melt to simulate impingement of molten corium. Sodium compatibility of alumina and PSZ coatings were also investigated by exposing samples to molten sodium at 400 °C for 500 h. The surface morphology of high-temperature thermite melt-exposed samples and sodium-exposed samples was examined using scanning electron microscope. Phase identification of the exposed samples was carried out by x-ray diffraction technique. Observation from sodium exposure tests indicated that alumina coating offers better protection compared to PSZ coating. However, PSZ coating provided better protection against high-temperature melt exposure, as confirmed during thermite melt exposure test.

Monodisperse and core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln=Eu, Tb, Dy, Sm, Er, Ho, and Tm) spherical particles: A facile synthesis and luminescent properties

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhenhe, E-mail: xuzh056@163.com [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Feng, Bin [China National Aviation Fuel Group Corporation, Planning and Development Department, Beijing 100088 (China); Bian, Shasha; Liu, Tao; Wang, Mingli; Gao, Yu; Sun, Di; Gao, Xin [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Sun, Yaguang, E-mail: yaguangsun@yahoo.com.cn [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China)

2012-12-15

The core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles were realized by coating the Lu{sub 2}O{sub 3}:Ln{sup 3+} phosphors onto the surface of non-aggregated, monodisperse and spherical SiO{sub 2} particles by the Pechini sol-gel method. The as-synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photolumiminescence (PL), and low-voltage cathodoluminescence (CL). The results indicate that the 800 Degree-Sign C annealed sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores, in spherical shape with a narrow size distribution. The as-obtained particles show strong light emission with different colors corresponding to different Ln{sup 3+} ions under ultraviolet-visible light excitation and low-voltage electron beams excitation, which have potential applications in fluorescent lamps and field emission displays. - Graphical Abstract: Representative SEM and TEM images of the core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Eu{sup 3+} particles; CIE chromaticity diagram showing the emission colors for SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+}; Multicolor emissions of SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles. Highlights: Black-Right-Pointing-Pointer The core-shell particles were realized by coating the phosphors onto the surface of SiO{sub 2} particles. Black-Right-Pointing-Pointer The sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores. Black-Right-Pointing-Pointer The particles show different light emission colors corresponding to Ln{sup 3+} ions. Black-Right-Pointing-Pointer They have potential applications in fluorescent lamps and field emission displays.

Syntheses, structures and properties of three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers based on 2,2'-dipyridyl-5,5'-dicarboxylate ligands.

Science.gov (United States)

Zhao, Junwei; Cheng, Yamin; Shang, Sensen; Zhang, Fang; Chen, Li; Chen, Lijuan

2013-12-01

Three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers [Ln(III)Cu2(I)(Hbpdc)4] · Cl · xH2O [Ln(III) = La(III), x = 8 (1); Ln(III) = Pr(III), x=9 (2); Ln(III) = Eu(III), x = 8 (3)] (H2bpdc = 2,2'-bipyridyl-5,5'-dicarboxylic acid) have been prepared under hydrothermal conditions and structurally characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses, IR spectra, X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. X-ray diffraction indicates that the isomorphic 1-3 display the two-dimensional sheet structure constructed from [Cu(I)(Hbpdc)2](-) fragments through Ln(3+) connectors. Moreover, the solid-state photoluminescence measurements of 3 indicate that the Eu(III) ions, Hbpdc(-) ligands and Cu(I) cations make contributions to its luminescent properties simultaneously. Copyright © 2013 Elsevier B.V. All rights reserved.

Increased nitrogen availability counteracts climatic change feedback from increased temperature on boreal forest soil organic matter degradation

Science.gov (United States)

Erhagen, Bjorn; Nilsson, Mats; Oquist, Mats; Ilstedt, Ulrik; Sparrman, Tobias; Schleucher, Jurgen

2014-05-01

Over the last century, the greenhouse gas concentrations in the atmosphere have increased dramatically, greatly exceeding pre-industrial levels that had prevailed for the preceding 420 000 years. At the same time the annual anthropogenic contribution to the global terrestrial nitrogen cycle has increased and currently exceeds natural inputs. Both temperature and nitrogen levels have profound effects on the global carbon cycle including the rate of organic matter decomposition, which is the most important biogeochemical process that returns CO2 to the atmosphere. Here we show for the first time that increasing the availability of nitrogen not only directly affects the rate of organic matter decomposition but also significantly affects its temperature dependence. We incubated litter and soil organic matter from a long-term (40 years) nitrogen fertilization experiment in a boreal Scots pine (Pinus silvestris L.) forest at different temperatures and determined the temperature dependence of the decomposition of the sample's organic matter in each case. Nitrogen fertilization did not affect the temperature sensitivity (Q10) of the decomposition of fresh plant litter but strongly reduced that for humus soil organic matter. The Q10 response of the 0-3 cm soil layer decreased from 2.5±0.35 to an average of 1.9±0.21 over all nitrogen treatments, and from 2.2±0.19 to 1.6±0.16 in response to the most intense nitrogen fertilization treatment in the 4-7 cm soil layer. Long-term nitrogen additions also significantly affected the organic chemical composition (as determined by 13C CP-MAS NMR spectroscopy) of the soil organic matter. These changes in chemical composition contributed significantly (p<0.05) to the reduced Q10 response. These new insights into the relationship between nitrogen availability and the temperature sensitivity of organic matter decomposition will be important for understanding and predicting how increases in global temperature and rising anthropogenic

Ln28Ti2O7 (Ln = La, Nd, Sm, Gd): a novel series of defective Ruddlesden–Popper phases formed by topotactic dehydration of HLnTiO4

OpenAIRE

Thangadurai, V; Subbanna, GN; Gopalakrishnan, J

1998-01-01

Topotactic dehydration of HLnTiO4 (Ln = La, Nd, Sm or Gd) around 480–500 °C yields a new series of metastable layered perovskite oxides, Ln28Ti2O7, that possess a defective Sr3Ti2O7 structure, where the cubooctahedral sites within the double-perovskite layers are most likely vacant.

Combined Effects of Ocean Acidification and Light or Nitrogen Availabilities on 13C Fractionation in Marine Dinoflagellates.

Directory of Open Access Journals (Sweden)

Mirja Hoins

Full Text Available Along with increasing oceanic CO2 concentrations, enhanced stratification constrains phytoplankton to shallower upper mixed layers with altered light regimes and nutrient concentrations. Here, we investigate the effects of elevated pCO2 in combination with light or nitrogen-limitation on 13C fractionation (εp in four dinoflagellate species. We cultured Gonyaulax spinifera and Protoceratium reticulatum in dilute batches under low-light ('LL' and high-light ('HL' conditions, and grew Alexandrium fundyense and Scrippsiella trochoidea in nitrogen-limited continuous cultures ('LN' and nitrogen-replete batches ('HN'. The observed CO2-dependency of εp remained unaffected by the availability of light for both G. spinifera and P. reticulatum, though at HL εp was consistently lower by about 2.7‰ over the tested CO2 range for P. reticulatum. This may reflect increased uptake of (13C-enriched bicarbonate fueled by increased ATP production under HL conditions. The observed CO2-dependency of εp disappeared under LN conditions in both A. fundyense and S. trochoidea. The generally higher εp under LN may be associated with lower organic carbon production rates and/or higher ATP:NADPH ratios. CO2-dependent εp under non-limiting conditions has been observed in several dinoflagellate species, showing potential for a new CO2-proxy. Our results however demonstrate that light- and nitrogen-limitation also affect εp, thereby illustrating the need to carefully consider prevailing environmental conditions.

Synthesis, Structure, and Magnetism of Tris(amide) {Ln[N(SiMe3)2]3}1- Complexes of the Non-Traditional +2 Lanthanide Ions.

Science.gov (United States)

Ryan, Austin Jack; Darago, Lucy E; Balasubramini, Sree Ganesh; Chen, Guo P; Ziller, Joseph W; Furche, Filipp; Long, Jeffrey R; Evans, William J

2018-02-28

A new series of Ln2+ complexes has been synthesized that overturns two previous generalizations in rare-earth metal reduction chemistry: that amide ligands do not form isolable complexes of the highly-reducing non-traditional Ln2+ ions and that yttrium is a good model for the late lanthanides in these reductive reactions. Reduction of Ln(NR2)3 (R = SiMe3) complexes in THF under Ar with M = K or Rb in the presence of 2.2.2-cryptand (crypt) forms crystallographically-characterizable [M(crypt)][Ln(NR2)3] complexes not only for the traditional Tm2+ ion and the configurational crossover ions, Nd2+ and Dy2+, but also for the non-traditional Gd2+, Tb2+, Ho2+, and Er2+ ions. Crystallographic data as well as UV-visible, magnetic susceptibility, and density functional theory studies are consistent with the accessibility of 4fn5d1 configurations for Ln2+ ions in this tris(silylamide) ligand environment. The Dy2+ complex, [K(crypt)][Dy(NR2)3], has a higher magnetic moment than previously observed for any monometallic complex: 11.67 µB. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An anti CuO{sub 2}-type metal hydride square net structure in Ln{sub 2}M{sub 2}As{sub 2}H{sub x} (Ln = La or Sm, M = Ti, V, Cr, or Mn)

Energy Technology Data Exchange (ETDEWEB)

Mizoguchi, Hiroshi; Park, SangWon; Hosono, Hideo [Tokyo Institute of Technology, Yokohama (Japan). Materials Research Center for Element Strategy; Hiraka, Haruhiro; Ikeda, Kazutaka; Otomo, Toshiya [High-Energy Accelerator Research Organization (KEK), Tsukuba (Japan). Inst. of Materials Structure Science

2015-03-02

Using a high pressure technique and the strong donating nature of H{sup -}, a new series of tetragonal La{sub 2}Fe{sub 2}Se{sub 2}O{sub 3}-type layered mixed-anion arsenides, Ln{sub 2}M{sub 2}As{sub 2}H{sub x}, was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x∼3). In these compounds, an unusual M{sub 2}H square net, which has anti CuO{sub 2} square net structures accompanying two As{sup 3-} ions, is sandwiched by (LaH){sub 2} fluorite layers. Notably, strong metal-metal bonding with a distance of 2.80 Aa was confirmed in La{sub 2}Ti{sub 2}As{sub 2}H{sub 2.3}, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters.

Ab-initio calculation and experimental observation of room temperature ferromagnetism in 50 keV nitrogen implanted rutile TiO2

Science.gov (United States)

Luitel, Homnath; Chakrabarti, Mahuya; Sarkar, A.; Dechoudhury, S.; Bhowmick, D.; Naik, V.; Sanyal, D.

2018-02-01

Room temperature magnetic properties of 50 keV N4+ ion beam implanted rutile TiO2 have been theoretically and experimentally studied. Ab-initio calculation under the frame work of density functional theory has been carried out to study the magnetic properties of the different possible nitrogen related defects in TiO2. Spin polarized density of states calculation suggests that both Ninst and NO can induce ferromagnetic ordering in rutile TiO2. In both cases the 2p orbital electrons of nitrogen atom give rise to the magnetic moment in TiO2. The possibility of the formation of N2 molecule in TiO2 system is also studied but in this case no significant magnetic moment has been observed. The magnetic measurements, using SQUID magnetometer, results a ferromagnetic ordering even at room temperature for the 50 keV N4+ ion beam implanted rutile TiO2.

Decanuclear Ln10 Wheels and Vertex-Shared Spirocyclic Ln5 Cores: Synthesis, Structure, SMM Behavior, and MCE Properties.

Science.gov (United States)

Das, Sourav; Dey, Atanu; Kundu, Subrata; Biswas, Sourav; Narayanan, Ramakirushnan Suriya; Titos-Padilla, Silvia; Lorusso, Giulia; Evangelisti, Marco; Colacio, Enrique; Chandrasekhar, Vadapalli

2015-11-16

The reaction of a Schiff base ligand (LH3) with lanthanide salts, pivalic acid and triethylamine in 1:1:1:3 and 4:5:8:20 stoichiometric ratios results in the formation of decanuclear Ln10 (Ln = Dy (1), Tb (2), and Gd (3)) and pentanuclear Ln5 complexes (Ln = Gd (4), Tb (5), and Dy (6)), respectively. The formation of Ln10 and Ln5 complexes are fully governed by the stoichiometry of the reagents used. Detailed magnetic studies on these complexes (1-6) have been carried out. Complex 1 shows a SMM behavior with an effective energy barrier for the reversal of the magnetization (Ueff) = 16.12(8) K and relaxation time (τo) = 3.3×10(-5) s under 4000 Oe direct current (dc) field. Complex 6 shows the frequency dependent maxima in the out-of-phase signal under zero dc field, without achieving maxima above 2 K. Complexes 3 and 4 show a large magnetocaloric effect with the following characteristic values: -ΔSm = 26.6 J kg(-1) K(-1) at T = 2.2 K for 3 and -ΔSm = 27.1 J kg(-1) K(-1) at T = 2.4 K for 4, both for an applied field change of 7 T. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental investigation on No-Vent Fill (NVF) process using liquid Nitrogen

International Nuclear Information System (INIS)

Kim, Young Cheol; Seo, Man Su; Yoo, Dong Gyu; Jeong, Sang Kwon

2014-01-01

For a long-term space mission, filling process of cryogenic liquid propellant is operated on a space vehicle in space. A vent process during transfer and filling of cryogenic propellant is needed to maintain the fuel tank pressure at a safe level due to its volatile characteristic. It is possible that both liquid and vapor phases of the cryogenic propellant are released simultaneously to outer space when the vent process occurs under low gravity environment. As a result, the existing filling process with venting not only accompanies wasting liquid propellant, but also consumes extra fuel to compensate for the unexpected momentum originated from the vent process. No-Vent Fill (NVF) method, a filling procedure without a venting process of cryogenic liquid propellant, is an attractive technology to perform a long-term space mission. In this paper, the preliminary experimental results of the NVF process are described. The experimental set-up consists of a 9-liter cryogenic liquid receiver tank and a supply tank. Liquid nitrogen (LN2) is used to simulate the behavior of cryogenic propellant. The whole situation in the receiver tank during NVF is monitored. The major experimental parameter in the experiment is the mass flow rate of the liquid nitrogen. The experimental results demonstrate that as the mass flow rate is increased, NVF process is conducted successfully. The quality and the inlet temperature of the injected LN2 are affected by the mass flow rate. These parameters determine success of NVF.

X-ray photoelectron spectroscopic study of direct reforming catalysts Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) for high temperature-operating solid oxide fuel cell

Energy Technology Data Exchange (ETDEWEB)

Kim, Keunsoo [Department of Engine Research, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon 305-343 (Korea, Republic of); Jeong, Jihoon [Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Azad, Abul K. [Faculty of Integrated Technologies, University Brunei Darussalam, Jalan Tunku Link, Gadong BE1410 (Brunei Darussalam); Jin, Sang Beom [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of); Kim, Jung Hyun, E-mail: jhkim2011@hanbat.ac.kr [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of)

2016-03-01

Graphical abstract: Measured Ti 2p peaks and deconvolution peaks of Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} under oxidizing condition (left) and NSTM under reducing condition (right). - Highlights: • Chemical states of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm) were analyzed. • Charge compensation occurred with the reduction of Mn and Ti. • The Nd substitution effect allowed some Ti to convert into a metallic behavioral component. • NSTM and SSTM had a large amount of lattice oxygen; however, LSTM retained a large quantity of adsorbed oxygen. - Abstract: Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}; Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}, some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} from the O 1s spectra; a high portion of lattice oxygen was observed in both Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (NSTM) and Sm{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O

Crystal structure and phase transition studies in perovskite-type oxides using powder-diffraction techniques and symmetry-mode analysis : SrLnMRuO6 (Ln=La,Pr,Nd; M=Zn,Co,Mg,Ni,Fe) and ALn2CuTi2O9 (A=Ca,Ba; Ln=La,Pr,Nd,Sm)

OpenAIRE

Iturbe Zabalo, Edurne

2013-01-01

La tesis se ha centrado en la síntesis y caracterización estructural de materiales tipo perovskita: SrLnMRuO6 (Ln=La,Pr,Nd; M=Zn,Co,Mg,Ni,Fe) y ALn2CuTi2O9 (A=Ca,Ba; Ln=La,Pr,Nd,Sm). El estudio de las estructuras de los materiales se ha realizado mediante el análisis de los patrones de difracción en polvo de rayos-X, sincrotrón y/o neutrones. En el refinamiento por el método de Rietveld de las estructuras se han sustituido las coordenadas atómicas (el método más común), por coordenadas colect...

Can there be a T3 ln T kind of behaviour of the low temperature specific heat of liquid 3He without the paramagnons?

International Nuclear Information System (INIS)

Tripathy, D.N.; Mishra, S.

1996-01-01

It is shown that even without invoking the concepts like paramagnons, the temperature dependence of the interparticle correlations in a system of liquid 3 He can give rise a T 3 ln T kind of behaviour of its low temperature fermionic specific heat. It is found to be coming from the self-energy corrections to the bare single particle energy involving the particle-hole propagator. Looking at the similar kind of behaviour observed by us recently for an electron liquid, one may conclude that the T 3 ln T behaviour is perhaps universal for all fermi systems, although for liquid 3 He the very dependence also follows from the paramagnon effects. It is interesting to see that unlike earlier theories, an extremely good fit is obtained with the experimental data over the entire range of low temperatures. (orig.)

An anti CuO{sub 2}-type metal hydride square net structure in Ln{sub 2}M{sub 2}As{sub 2}H{sub x} (Ln = La or Sm, M = Ti, V, Cr, or Mn)

Energy Technology Data Exchange (ETDEWEB)

Mizoguchi, Hiroshi; Park, SangWon; Hosono, Hideo [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Hiraka, Haruhiro; Ikeda, Kazutaka; Otomo, Toshiya [Institute of Materials Structure Science, High-Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan)

2015-03-02

Using a high pressure technique and the strong donating nature of H{sup -}, a new series of tetragonal La{sub 2}Fe{sub 2}Se{sub 2}O{sub 3}-type layered mixed-anion arsenides, Ln{sub 2}M{sub 2}As{sub 2}H{sub x}, was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x∼3). In these compounds, an unusual M{sub 2}H square net, which has anti CuO{sub 2} square net structures accompanying two As{sup 3-} ions, is sandwiched by (LaH){sub 2} fluorite layers. Notably, strong metal-metal bonding with a distance of 2.80 Aa was confirmed in La{sub 2}Ti{sub 2}As{sub 2}H{sub 2.3}, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Covalency in lanthanides. An X-ray absorption spectroscopy and density functional theory study of LnCl6(x-) (x = 3, 2).

Science.gov (United States)

Löble, Matthias W; Keith, Jason M; Altman, Alison B; Stieber, S Chantal E; Batista, Enrique R; Boland, Kevin S; Conradson, Steven D; Clark, David L; Lezama Pacheco, Juan; Kozimor, Stosh A; Martin, Richard L; Minasian, Stefan G; Olson, Angela C; Scott, Brian L; Shuh, David K; Tyliszczak, Tolek; Wilkerson, Marianne P; Zehnder, Ralph A

2015-02-25

Covalency in Ln-Cl bonds of Oh-LnCl6(x-) (x = 3 for Ln = Ce(III), Nd(III), Sm(III), Eu(III), Gd(III); x = 2 for Ln = Ce(IV)) anions has been investigated, primarily using Cl K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT); however, Ce L3,2-edge and M5,4-edge XAS were also used to characterize CeCl6(x-) (x = 2, 3). The M5,4-edge XAS spectra were modeled using configuration interaction calculations. The results were evaluated as a function of (1) the lanthanide (Ln) metal identity, which was varied across the series from Ce to Gd, and (2) the Ln oxidation state (when practical, i.e., formally Ce(III) and Ce(IV)). Pronounced mixing between the Cl 3p- and Ln 5d-orbitals (t2g* and eg*) was observed. Experimental results indicated that Ln 5d-orbital mixing decreased when moving across the lanthanide series. In contrast, oxidizing Ce(III) to Ce(IV) had little effect on Cl 3p and Ce 5d-orbital mixing. For LnCl6(3-) (formally Ln(III)), the 4f-orbitals participated only marginally in covalent bonding, which was consistent with historical descriptions. Surprisingly, there was a marked increase in Cl 3p- and Ce(IV) 4f-orbital mixing (t1u* + t2u*) in CeCl6(2-). This unexpected 4f- and 5d-orbital participation in covalent bonding is presented in the context of recent studies on both tetravalent transition metal and actinide hexahalides, MCl6(2-) (M = Ti, Zr, Hf, U).

Nitrogen availability from residues-based biochar at two pyrolisis temperatures

Science.gov (United States)

Coscione, Aline Renee; Silveira Bibar, Maria Paula; de Andrade, Cristiano Alberto

2014-05-01

Biochar has been studied for several applications, such as soil quality improvement, heavy metals remediation and N2O mitigation. Considering the soil quality improvement aspect it is desirable to evaluate if the nitrogen content in biochar samples obtained from several residues used as the biomass sources could be available for plants. Samples of sewage sludge (SS), coffee grounds (CG), chicken manure (CM) and fungi mycelia (FM) were pyrolyzed at two temperatures, 400 and 700 oC (indicated by the number 4 and 7 in this abstract, respectively), in order to obtain the biochar samples. The Kjeldahl nitrogen of biochar was (% m/m): 3.0 (CM4, CG7, FM7 and CG4); 2.0 (CM7 e SS4); 3.4 (FM7); 1.4 (SS7), with organic carbon (potassium dichromate method) ranging from 2.0 to 3.0% for all but CG4 (6%). The C/N ratio of biochar samples was: 9 (CM4, SS4 and CG7); 11 (CM7); 15 (SS7); 7 (FM4 and FM7); 21 (CG4). The eight soil + biochar resulting mixtures, prepared using the equivalent to 60 t/ha of biochar (about 3% w/w), and one additional control treatment (no biochar added) were incubated for 90 days, with four replications of each treatment per time evaluated. Inorganic nitrogen and soil pH measurements were performed for all treatments at 0, 5, 15, 30, 60 and 90 days of incubation. Soil moisture was kept at 40% soil water holding capacity, by weighting, during the experiment. The data was submitted to ANOVA with Tukey's average comparison test (p organic residues with C/N ratios lower than 20 applied to the soil a fast degradation, with the corresponding increase in inorganic nitrogen availability is expect. Although all the biochar samples tested had C/N ratios below that cutting point, just 2 of 8 presented inorganic nitrogen available in the soil+biochar mixtures. These results show that soil incubation tests are ultimate for the evaluation of the nitrogen potential release to the soil. Low temperature SS based biochar may offer additional nitrogen release to soil besides

The oxonitridoborate Eu{sub 5}(BO{sub 2.51(7)}N{sub 0.49(7)}){sub 4} and the mixed-valent borates Sr{sub 3}Ln{sub 2}(BO{sub 3}){sub 4} (Ln = Ho, Er)

Energy Technology Data Exchange (ETDEWEB)

Hoeppe, Henning A.; Kazmierczak, Karolina; Grumbt, Christine; Schindler, Lisa [Institut fuer Physik, Universitaet Augsburg (Germany); Schellenberg, Inga; Poettgen, Rainer [Westfaelische Wilhelms-Universitaet Muenster, Institut fuer Anorganische und Analytische Chemie (Germany)

2013-11-04

The crystal structures of the mixed borates Sr{sub 3}Er{sub 2}(BO{sub 3}){sub 4} [Pnma, no. 62, Z = 4, a = 738.08(2), b = 1588.94(4), c = 867.81(2) pm, 683 reflections, 70 parameters, R1 = 0.037, wR2 = 0.077] and Sr{sub 3}Ho{sub 2}(BO{sub 3}){sub 4} [Pnma, no. 62, Z = 4, a = 738.45(7), b = 1591.55(12), c = 871.03(9) pm, 691 reflections, 59 parameters, R1 = 0.069, wR2 = 0.098] and europium oxonitridoborate Eu{sub 5}(BO{sub 2.51(7)}N{sub 0.49(7)}){sub 4} [Pnma, no. 62, Z = 12, a = 2232.2(5), b = 1603.1(3), c = 879.59(18) pm, 2880 reflections, 313 parameters, R1 = 0.027, wR2 = 0.059] were solved from single-crystal X-ray diffraction data. Eu{sub 5}(BO{sub 2.51(7)}N{sub 0.49(7)}){sub 4} adopts a threefold superstructure of the structure of Sr{sub 3}Ln{sub 2}(BO{sub 3}){sub 4} (Ln = Ho, Er). In both structure types, the different cations are situated on common sites with a pronounced preferential occupation but no complete ordering. These conclusions are based on the crystal structure refinement, {sup 151}Eu Moessbauer spectroscopy and MAPLE (Madelung part of lattice energy) calculations. The proposed Eu{sub 5}(BO{sub 3}){sub 4} contains nitrogen and has a formula Eu{sub 5}(BO{sub 2.51(7)}N{sub 0.49(7)}){sub 4} as confirmed by {sup 151}Eu Moessbauer spectroscopy. The optical reflectance spectrum of Eu{sub 5}(BO{sub 2.51(7)}N{sub 0.49(7)}){sub 4} is in accordance with the yellow colour of the compound. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Magnetic properties of Aurivillius lanthanide-bismuth (LnFeO3nBi4Ti3O12 (n = 1,2 layered titanates

Directory of Open Access Journals (Sweden)

Tartaj, J.

2008-06-01

Full Text Available Bismuth titanates of Aurivillius layer-structure (BiFeO3nBi4Ti3O12, are of great technological interest because of their applications as non-volatile ferroelectric memories and high-temperature piezoelectric materials. The synthesis and crystallographic characterization of a new family of compounds (LnFeO3nBi4Ti3O12 was recently reported, in which the layers consist of LnFeO3 perovskites with a lanthanide Ln3+ substituting diamagnetic Bi3+. We report herein the magnetic properties of bulk samples, with Ln = Nd, Eu, Gd and Tb, and n = 1 and 2. Single-layer materials are paramagnetic, similar to non-substituted bismuth titanate Bi5FeTi3O15, and show crystal field effects due to the crystallographic environment of Eu3+ and Tb3+. Several anomalies are detected in the magnetization M(T of double-layer (LnFeO32Bi4Ti3O12 compounds, related to the strong magnetism of Tb and Gd, since they weakly appear for Nd and they are absent in the VanVleck Eu3+ ion and in the parent Bi6Fe2Ti3O18 compound.Los titanatos de hierro y bismuto con estructura laminar tipo Aurivillius, (BiFeO3nBi4Ti3O12, tienen un gran interés tecnológico debido a sus aplicaciones como memorias ferroeléctricas no volátiles y como piezoeléctrico cerámico de alta temperatura. La síntesis y la caracterización cristalina de una nueva familia de compuestos (LnFeO3nBi4Ti3O12 han sido recientemente reportadas, en la que el catión diamagnético Bi3+ ha sido sustituido por los paramagnéticos Ln3+ en los bloques de perovskita. Se estudian las propiedades magnéticas de muestras cerámicas en volumen con Ln = Nd, Eu, Gd y Tb, y n = 1 y 2. Los materiales con n=1 son paramagnéticos y similares al no sustituido Bi5FeTi3O15, y muestran efectos de campo cristalino debido al entorno cristalino de Eu3+ y Tb3+. Se han detectado algunas anomalías en la magnetización M(T de los compuestos n=2 (LnFeO32Bi4Ti3O12 que están relacionadas con el fuerte magnetismo de Tb y Gd, que aparecen d

Sm2Fe17Nx with discontinuous nitrogen profiles

International Nuclear Information System (INIS)

Skomski, R.; Kobayashi, K.; Brennan, S.; Coey, J.M.D.

1995-01-01

Microprobe analysis and theoretical calculations based on Hooke's law are used to investigate Sm 2 Fe 17 N x nitrides produced by N 2 and NH 3 interstitial modification. In the case of molecular nitrogen, stress and strain as well as Curie temperature, magnetization and anisotropy exhibit a smooth spatial variation, while nitrogen overloading due to the presence of ammonia leads to large excess strain and lattice incoherency. Discontinuous nitrogen profiles are associated with the occurrence of microcracks. ((orig.))

High nitrogen stainless steels for nuclear industry

International Nuclear Information System (INIS)

Kamachi Mudali, U.

2016-01-01

Nitrogen alloying in stainless steels (SS) has myriad beneficial effects, including solid solution strengthening, precipitation effects, phase control and corrosion resistance. Recent years have seen a rapid development of these alloys with improved properties owing to advances in processing technologies. Furthermore, unlimited demands for high-performance advanced steels for special use in advanced applications renewed the interest in high nitrogen steels (HNS). The combination of numbers of attractive properties such as strength, fracture toughness, wear resistance, workability, magnetic properties and corrosion resistance of HNS has given a unique advantage and offers a number of prospective applications in different industries. Based on extensive studies carried out at IGCAR, nitrogen alloyed type 304LN SS and 316LN SS have been chosen as materials of construction for many engineering components of fast breeder reactor (FBR) and associated reprocessing plants. HNS austenitic SS alloys are used as structural/reactor components, i.e., main vessel, inner vessel, control plug, intermediate heat exchanger and main sodium piping for fast breeder reactor. HNS type 304LN SS is a candidate material for continuous dissolver, nuclear waste storage tanks, pipings, etc. for nitric acid service under highly corrosive conditions. Recent developments towards the manufacturing and properties of HNS alloys for application in nuclear industry are highlighted in the presentation. (author)

Change in gene abundance in the nitrogen biogeochemical cycle with temperature and nitrogen addition in Antarctic soils.

Science.gov (United States)

Jung, Jaejoon; Yeom, Jinki; Kim, Jisun; Han, Jiwon; Lim, Hyoun Soo; Park, Hyun; Hyun, Seunghun; Park, Woojun

2011-12-01

The microbial community (bacterial, archaeal, and fungi) and eight genes involved in the nitrogen biogeochemical cycle (nifH, nitrogen fixation; bacterial and archaeal amoA, ammonia oxidation; narG, nitrate reduction; nirS, nirK, nitrite reduction; norB, nitric oxide reduction; and nosZ, nitrous oxide reduction) were quantitatively assessed in this study, via real-time PCR with DNA extracted from three Antarctic soils. Interestingly, AOB amoA was found to be more abundant than AOA amoA in Antarctic soils. The results of microcosm studies revealed that the fungal and archaeal communities were diminished in response to warming temperatures (10 °C) and that the archaeal community was less sensitive to nitrogen addition, which suggests that those two communities are well-adapted to colder temperatures. AOA amoA and norB genes were reduced with warming temperatures. The abundance of only the nifH and nirK genes increased with both warming and the addition of nitrogen. NirS-type denitrifying bacteria outnumbered NirK-type denitrifiers regardless of the treatment used. Interestingly, dramatic increases in both NirS and NirK-types denitrifiers were observed with nitrogen addition. NirK types increase with warming, but NirS-type denitrifiers tend to be less sensitive to warming. Our findings indicated that the Antarctic microbial nitrogen cycle could be dramatically altered by temperature and nitrogen, and that warming may be detrimental to the ammonia-oxidizing archaeal community. To the best of our knowledge, this is the first report to investigate genes associated with each process of the nitrogen biogeochemical cycle in an Antarctic terrestrial soil environment. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Comparative magnetic studies of (Sm, Nd) trichloroacetates and their heteronuclear CuLn2(CCl3COO)8.6H2O systems: structure and spectroscopy of a new type of Eu trichloroacetate

International Nuclear Information System (INIS)

Wojciechowski, W.; Legendziewicz, J.; Puchalska, M.; Ciunik, Z.

2004-01-01

Two series of compounds: heteronuclear CuLn 2 (CCl 3 COO) 8 .6H 2 O (Ln = Nd and Sm) and their simple analogues Ln(CCl 3 COO) 3 .2H 2 O (Ln = Eu, Nd, Sm) were synthesized. New Eu(III) trichloroacetate; Eu(CCl 3 COO) 3 .3H 2 O.CH 3 OH was obtained, its molecular structure was determined by X-ray diffraction and compared with the data of respective systems reported earlier. Magnetization was measured and the susceptibility was derived in the limit of low field. Magnetic susceptibilities were calculated and discussed for series of homo- and hetero-nuclear chloroacetates.Untypical hysteresis was found (two loops) in samarium trichloroacetate. This phenomenon is most probably the effect of flops of spins in magnetic fields of 30,000Oe and very weak (if any) interaction intermediated by weak hydrogen bonding between the chains. A similar magnetic behavior was observed in neodymium carboxylate where the magnetic ordering was observed as a result of Nd-Nd interaction at low temperature (1.6K). For this system, the magnetic moment depends on magnitude of the magnetic field and ferromagnetic ordering appears at low temperatures. The strongest interactions of coupled ions and antiferromagnetic ordering with T N =6.5K were found in CuSm 2 (CCl 3 COO) 8 .6H 2 O single crystals.Heisenberg model was applied in the calculations for three interacting ions located linearly. The following relation was derived: χ M =Ng 2 μ β 2 kT(12)+(12)exp(J 2 /kT)+5exp(J 2 /kT)-exp(1,5J 1 /kT)2+2exp(J 2 /kT)+4exp(J 2 /kT)-exp(1,5J 1 /kT) and applied in calculations of the exchange integrals. Mechanism of the exchange interaction was discussed on the basis of the obtained results.

Series of isostructural planar lanthanide complexes [Ln(III)4(mu3-OH)2(mdeaH)2(piv)8] with single molecule magnet behavior for the Dy4 analogue.

Science.gov (United States)

Abbas, Ghulam; Lan, Yanhua; Kostakis, George E; Wernsdorfer, Wolfgang; Anson, Christopher E; Powell, Annie K

2010-09-06

A series of five isostructural tetranuclear lanthanide complexes of formula [Ln(4)(mu(3)-OH)(2)(mdeaH)(2)(piv)(8)], (mdeaH(2) = N-methyldiethanolamine; piv = pivalate; Ln = Tb (1), Dy (2), Ho (3), Er (4), and Tm (5)) have been synthesized and characterized. These clusters have a planar "butterfly" Ln(4) core. Magnetically, the Ln(III) ions are weakly coupled in all cases; the Dy(4) compound 2 shows Single Molecule Magnet (SMM) behavior.

Hetero-metallic {3d-4f-5d} complexes: preparation and magnetic behavior of trinuclear [(L(Me2)Ni-Ln){W(CN)(8)}] compounds (Ln = Gd, Tb, Dy, Ho, Er, Y; L(Me2) = Schiff base) and variable SMM characteristics for the Tb derivative.

Science.gov (United States)

Sutter, Jean-Pascal; Dhers, Sébastien; Rajamani, Raghunathan; Ramasesha, S; Costes, Jean-Pierre; Duhayon, Carine; Vendier, Laure

2009-07-06

Assembling bimetallic {Ni-Ln}(3+) units and {W(CN)(8)}(3-) is shown to be an efficient route toward heteronuclear {3d-4f-5d} compounds. The reaction of either the binuclear [{L(Me2)Ni(H(2)O)(2)}{Ln(NO(3))(3)}] complexes or their mononuclear components [L(Me2)Ni] and Ln(NO(3))(3) with (HNBu(3))(3){W(CN)(8)} in dmf followed by diffusion of tetrahydrofuran yielded the trinuclear [{L(Me2)NiLn}{W(CN)(8)}] compounds 1 (Ln = Y), 2a,b (Gd), 3a,b (Tb), 4 (Dy), 5 (Ho), and 6 (Er) as crystalline materials. All of the derivatives possess the trinuclear core resulting from the linkage of the {W(CN)(8)} to the Ni center of the {Ni-Ln} unit. Differences are found in the solvent molecules acting as ligands and/or in the lattice depending on the crystallization conditions. For all the compounds ferromagnetic {Ni-W} and {Ni-Ln} (Ln = Gd, Tb, Dy, and Er} interactions are operative resulting in high spin ground states. Parameterization of the magnetic behaviors for the Y and Gd derivatives confirmed the strong cyano-mediated {Ni-W} interaction (J(NiW) = 27.1 and 28.5 cm(-1)) compared to the {Ni-Gd} interaction (J(NiGd) = 2.17 cm(-1)). The characteristic features for slow relaxation of the magnetization are observed for two Tb derivatives, but these are modulated by the crystal phase. Analysis of the frequency dependence of the alternating current susceptibility data yielded U(eff)/k(B) = 15.3 K and tau(0) = 4.5 x 10(-7) s for one derivative whereas no maxima of chi(M)'' appear above 2 K for the second one.

Synthesis, structures, and luminescent properties of sodium rare-earth metal(III) chloride oxotellurates(IV), Na{sub 2}Ln{sub 3}Cl{sub 3}[TeO{sub 3}]{sub 4} (Ln = Sm, Eu, Gd, Tb, Dy, and Ho)

Energy Technology Data Exchange (ETDEWEB)

Charkin, Dmitri O.; Dorofeev, Sergey G.; Berdonosov, Peter S.; Dolgikh, Valery A. [Department of Chemistry, Lomonosov Moscow State University (Russian Federation); Zitzer, Sabine; Greiner, Stefan; Schleid, Thomas [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany); Olenev, Andrei V. [Department of Chemistry, Lomonosov Moscow State University (Russian Federation); Sine Theta Ltd., Moscow (Russian Federation)

2017-11-17

Six sodium rare-earth metal(III) chloride oxotellurates(IV), Na{sub 2}Ln{sub 3}Cl{sub 3}[TeO{sub 3}]{sub 4}, isostructural to Na{sub 2}Y{sub 3}Cl{sub 3}[TeO{sub 3}]{sub 4}, were synthesized by flux techniques and characterized by single-crystal XRD. The compounds crystallize in the monoclinic space group C2/c with lattice constants a = 23.967(1), b = 5.6342(3), c = 16.952(1) Aa, β = 134.456(5) for Ln = Sm, a = 23.932(2), b = 5.6044(5), c = 17.134(1) Aa, β = 135.151(6) for Ln = Eu, a = 23.928(1), b = 5.5928(1), c = 17.1133(8) Aa, β = 135.366(3) for Ln = Gd, a = 23.907(1), b = 5.569(3), c = 16.745(1) Aa, β = 134.205(3) for Ln = Tb, a = 23.870(1), b = 5.547(3), c = 16.665(1) Aa, β = 134.102(3) for Ln = Dy, and a = 23.814(1), b = 5.526(3), c = 16.626(1) Aa, β = 134.016(3) for Ln = Ho and Z = 4. Their crystal structure can be considered as a framework built of intergrowing Ln-O and Na-(O,Cl) slabs with channel walls decorated by tellurium atoms of [TeO{sub 3}]{sup 2-} groups. The luminescent properties of the new compounds due to the Ln{sup 3+} cations are described and discussed. We also discuss the crystal chemistry of various alkali-metal rare-earth metal(III) halide oxochalcogenates(IV). (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Structural properties of nitrogenated amorphous carbon films: Influence of deposition temperature and radiofrequency discharge power

International Nuclear Information System (INIS)

Lazar, G.; Bouchet-Fabre, B.; Zellama, K.; Clin, M.; Ballutaud, D.; Godet, C.

2008-01-01

The structural properties of nitrogenated amorphous carbon deposited by radiofrequency magnetron sputtering of graphite in pure N 2 plasma are investigated as a function of the substrate temperature and radiofrequency discharge power. The film composition is derived from x-ray photoemission spectroscopy, nuclear reaction analysis and elastic recoil detection measurements and the film microstructure is discussed using infrared, Raman, x-ray photoemission and near edge x-ray absorption fine structure spectroscopic results. At low deposition temperature and low radiofrequency power, the films are soft, porous, and easily contaminated with water vapor and other atmospheric components. The concentration of nitrogen in the films is very large for low deposition temperatures (∼33.6 at. % N at 150 deg. C) but decreases strongly when the synthesis temperature increases (∼15 at. % N at 450 deg. C). With increasing deposition temperature and discharge power values, the main observed effects in amorphous carbon nitride alloys are a loss of nitrogen atoms, a smaller hydrogen and oxygen contamination related to the film densification, an increased order of the aromatic sp 2 phase, and a strong change in the nitrogen distribution within the carbon matrix. Structural changes are well correlated with modifications of the optical and transport properties

Microbial contamination of embryos and semen during long term banking in liquid nitrogen.

Science.gov (United States)

Bielanski, A; Bergeron, H; Lau, P C K; Devenish, J

2003-04-01

We report on microbial contamination of embryos and semen cryopreserved in sealed plastic straws and stored for 6-35 years in liquid nitrogen. There were 32 bacterial and 1 fungal species identified from randomly drawn liquid nitrogen, frozen semen, and embryos samples stored in 8 commercial and 8 research facility liquid nitrogen (LN) tanks. The identified bacteria represented commensal or environmental microorganisms and some, such as Escherichia coli, were potential or opportunistic pathogens for humans and animals. Stenotrophomonas maltophilia was the most common contaminant identified from the samples and was further shown to significantly suppress fertilization and embryonic development in vitro. Analysis of the strains by pulsed field gel electrophoresis revealed restriction patterns with no relatedness indicating that there was no apparent cross-contamination of S. maltophilia strains between the germplasm and liquid nitrogen samples. In addition, no transmission of bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BHV-1) from infected semen and embryos straws to clean germplasm stored in the same LN tanks or LN was detected.

Corrosion behavior of low energy, high temperature nitrogen ion ...

Indian Academy of Sciences (India)

Corrosion behavior of low energy, high temperature nitrogen ion-implanted AISI 304 stainless steel. M GHORANNEVISS1, A SHOKOUHY1,∗, M M LARIJANI1,2,. S H HAJI HOSSEINI 1, M YARI1, A ANVARI4, M GHOLIPUR SHAHRAKI1,3,. A H SARI1 and M R HANTEHZADEH1. 1Plasma Physics Research Center, Science ...

Orbital storage and supply of subcritical liquid nitrogen

Science.gov (United States)

Aydelott, John C.

1990-01-01

Subcritical cryogenic fluid management has long been recognized as an enabling technology for key propulsion applications, such as space transfer vehicles (STV) and the on-orbit cryogenic fuel depots which will provide STV servicing capability. The LeRC Cryogenic Fluids Technology Office (CFTO), under the sponsorship of OAST, has the responsibility of developing the required technology via a balanced program involving analytical modeling, ground based testing, and in-space experimentation. Topics covered in viewgraph form include: cryogenic management technologies; nitrogen storage and supply; cryogenic nitrogen cooling capability; and LN2 system demonstration technical objectives.

Rovibrational coupling in molecular nitrogen at high temperature: An atomic-level study

Energy Technology Data Exchange (ETDEWEB)

Valentini, Paolo, E-mail: vale0142@umn.edu; Norman, Paul, E-mail: norma198@umn.edu; Zhang, Chonglin, E-mail: zhang993@umn.edu; Schwartzentruber, Thomas E., E-mail: schwart@aem.umn.edu [Department of Aerospace Engineering and Mechanics, College of Science and Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2014-05-15

This article contains an atomic-level numerical investigation of rovibrational relaxation in molecular nitrogen at high temperature (>4000 K), neglecting dissociation. We conduct our study with the use of pure Molecular Dynamics (MD) and Classical Trajectory Calculations (CTC) Direct Simulation Monte Carlo (DSMC), verified to produce statistically identical results at the conditions of interest here. MD and CTC DSMC solely rely on the specification of a potential energy surface: in this work, the site-site Ling-Rigby potential. Additionally, dissociation is prevented by modeling the N–N bond either as a harmonic or an anharmonic spring. The selected molecular model was shown to (i) recover the shear viscosity (obtained from equilibrium pure MD Green-Kubo calculations) of molecular nitrogen over a wide range of temperatures, up to dissociation; (ii) predict well the near-equilibrium rotational relaxation behavior of N{sub 2}; (iii) reproduce vibrational relaxation times in excellent accordance with the Millikan-White correlation and previous semi-classical trajectory calculations in the low temperature range, i.e., between 4000 K and 10 000 K. By simulating isothermal relaxations in a periodic box, we found that the traditional two-temperature model assumptions become invalid at high temperatures (>10 000 K), due to a significant coupling between rotational and vibrational modes for bound states. This led us to add a modification to both the Jeans and the Landau-Teller equations to include a coupling term, essentially described by an additional relaxation time for internal energy equilibration. The degree of anharmonicity of the N{sub 2} bond determines the strength of the rovibrational coupling. Although neglecting N{sub 2} dissociation only provides a partial description of a nitrogen system at very high temperatures, high-energy trends for bound-bound transitions are essential to understand nonequilibrium gas flows, with possible implications on rovibration

Rovibrational coupling in molecular nitrogen at high temperature: An atomic-level study

International Nuclear Information System (INIS)

Valentini, Paolo; Norman, Paul; Zhang, Chonglin; Schwartzentruber, Thomas E.

2014-01-01

This article contains an atomic-level numerical investigation of rovibrational relaxation in molecular nitrogen at high temperature (>4000 K), neglecting dissociation. We conduct our study with the use of pure Molecular Dynamics (MD) and Classical Trajectory Calculations (CTC) Direct Simulation Monte Carlo (DSMC), verified to produce statistically identical results at the conditions of interest here. MD and CTC DSMC solely rely on the specification of a potential energy surface: in this work, the site-site Ling-Rigby potential. Additionally, dissociation is prevented by modeling the N–N bond either as a harmonic or an anharmonic spring. The selected molecular model was shown to (i) recover the shear viscosity (obtained from equilibrium pure MD Green-Kubo calculations) of molecular nitrogen over a wide range of temperatures, up to dissociation; (ii) predict well the near-equilibrium rotational relaxation behavior of N 2 ; (iii) reproduce vibrational relaxation times in excellent accordance with the Millikan-White correlation and previous semi-classical trajectory calculations in the low temperature range, i.e., between 4000 K and 10 000 K. By simulating isothermal relaxations in a periodic box, we found that the traditional two-temperature model assumptions become invalid at high temperatures (>10 000 K), due to a significant coupling between rotational and vibrational modes for bound states. This led us to add a modification to both the Jeans and the Landau-Teller equations to include a coupling term, essentially described by an additional relaxation time for internal energy equilibration. The degree of anharmonicity of the N 2 bond determines the strength of the rovibrational coupling. Although neglecting N 2 dissociation only provides a partial description of a nitrogen system at very high temperatures, high-energy trends for bound-bound transitions are essential to understand nonequilibrium gas flows, with possible implications on rovibration

Syntheses, crystal structures and solid-state properties of the lanthanoid-containing nanoclusters [(Ln{sub 2}PW{sub 10}O{sub 38}){sub 4}(W{sub 3}O{sub 8})(OH){sub 4}(H{sub 2}O){sub 2}]{sup 26-}

Energy Technology Data Exchange (ETDEWEB)

Gupta, Rakesh; Saini, Mukesh Kumar; Hussain, Firasat [Department of Chemistry, University of Delhi (India)

2014-12-15

A series of lanthanoid-substituted polyoxometalates have been synthesized by a self-assembly process in potassium chloride solution by the reaction of dilacunary [P{sub 2}W{sub 19}O{sub 69}(H{sub 2}O)]{sup 14-} with mid- and late-lanthanoid Ln(NO{sub 3}){sub 3}.nH{sub 2}O salts leading to the formation of the tetrameric tungstophosphates [(Ln{sub 2}PW{sub 10}O{sub 38}){sub 4}(W{sub 3}O{sub 8})(OH){sub 4}(H{sub 2}O){sub 2}]{sup 26-} [Ln = Y{sup 3+} (1), Sm{sup 3+} (2), Eu{sup 3+} (3), Gd{sup 3+} (4), Tb{sup 3+} (5), Dy{sup 3+} (6), Ho{sup 3+} (7), Er{sup 3+} (8), Tm{sup 3+} (9), Yb{sup 3+} (10)]. The polyanions were isolated as potassium or mixed-alkali salts. Most of the compounds were characterized by single-crystal X-ray diffraction and various analytical techniques, such as FTIR, UV/Vis, {sup 31}P NMR and photoluminescence spectroscopy, magnetism, as well as thermogravimetric analysis. The FTIR spectra suggest that all the compounds are isomorphous. The crystal structures of these complexes consist of four A-[α-PW{sub 10}O{sub 36}]{sup 7-} units, each incorporating two Ln{sup III} ions to create four Keggin-like anions that further assemble with three additional tungstate units to form a tetramer species with C{sub 2} symmetry. The photoluminescent properties of 3a and 6a were investigated following photoexcitation at room temperature. The magnetic properties of 3a, 4a, 5a and 6a were investigated at room temperature, the complexes exhibiting paramagnetic behaviour. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Structural characterization of M(IV)1-xLn(III)xO2-x/2 (M = Ce, Th) mixed-oxides prepared from oxalate precursors. Multi-parametric study of dissolution and microstructural evolution

International Nuclear Information System (INIS)

Horlait, D.

2011-01-01

In the framework of Gen IV program development, several physico-chemical properties of some foreseen fuels, including the chemical durability, have to be evaluated. In this aim, a study was undertaken on M(IV) 1-x Ln(III) x O 2 (M=Ce,Th) model compounds prepared from oxalate precursors. The fluorite-type structure of CeO 2 and ThO 2 remains stable up to x ≅ 0.4, the substitution of M(IV) by Ln(III) occurring simultaneously to the formation of oxygen vacancies. For higher x values, a cubic superstructure is formed as a result of oxygen vacancies ordering. The normalized dissolution rates of such solids were found to be strongly enhanced by the Ln(III) fraction. On the contrary, the nature of the M(IV) and Ln(III) elements did not modify significantly the normalized dissolution rates. The effect of temperature and acid concentration suggested the existence of surface-controlling dissolution reactions. Simultaneously, the microstructural evolution of both powdered and sintered samples revealed some important changes in the reactive surface during dissolution tests. ESEM images allowed observing the existence of preferential dissolution sites located at grains boundaries and around crystalline defects, leading to the formation of corrosion pits. In addition, the formation of gelatinous phases, acting as diffusion barriers (thus slowing down the dissolution process) was also evidenced. (author) [fr

16-8-2 weld metal design data for 316L(N) steel

Energy Technology Data Exchange (ETDEWEB)

Tavassoli, A.-A.F. [Commissariat a l' Energie Atomique, CEA/Saclay, 91191 Gif sur Yvette (France)], E-mail: tavassoli@cea.fr

2008-12-15

ITER materials properties documentation is extended to weld metals used for welding Type 316L(N) steel, i.e. the structural material retained for manufacturing ITER major components, such as the vacuum vessel. The data presented here are mainly for the Type 16-8-2 and complete those already reported for the low temperature (Type 316L) and the high temperature (Type 19-12-2) filler metals. The weld metal properties data for Type 16-8-2 filler metal and its joints are collected, sorted and analysed according to the French design and construction rules for nuclear components (RCC-MR). Particular attention is paid to the type of weld metal (e.g. wire for TIG, covered electrode for manual arc, flux wire for automatic welding), as well as, to the weld geometry and welding position. Design allowables are derived from validated data for each category of weld and compared with those of the base metal. In most cases, the analyses performed are extended beyond the conventional analyses required for codes to cover specific needs of ITER. These include effects of exposures to high temperature cycles during component fabrication, e.g. HIPing and low dose neutron irradiation at low and medium temperatures. The ITER Materials Properties Handbook (MPH) is, here, enriched with files for physical and mechanical properties of Type 16-8-2 weld metal. These files, combined with the codification and inspection files, are part of the documentation required for ITER licensing needs. They show that all three weld-metals satisfy the code requirements, provided compositions and types of welds used correspond to those specified in RCC-MR.

Controllable synthesis of Ln3+ (Ln = Tb, Eu) doped zinc phosphate nano-/micro-structured materials: phase, morphology and luminescence properties

Science.gov (United States)

Yue, Dan; Lu, Wei; Li, Chunyang; Zhang, Xinlei; Liu, Chunxia; Wang, Zhenling

2014-01-01

Ln3+ (Ln = Tb, Eu) doped zinc phosphate tetrahydrate (ZPT:Ln3+) and ammonium zinc phosphate (AZP:Ln3+) nano-/micro-structured materials were synthesized in aqueous solution without the addition of any structure-directing agent. The phase structures, morphologies and luminescence properties of the as-synthesized samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and lifetime. These investigations indicate that different phosphate sources MnH(3-n)PO4 (M = NH4+ or Na+, n = 1, 2, 3) can lead to the altering of morphology from nanosheet to microflower, but have no significant effect on the phase structure of the samples. The microlump, nanosheet, and microflower (constructed by the primary microlumps or nanosheets) of orthorhombic ZPT:Ln3+ could be selectively prepared by adjusting the pH value from 3.5 to 7.0. A mixture of orthorhombic ZPT:Ln3+ and monoclinic AZP:Ln3+ with a microflower morphology was obtained when the pH value was adjusted to 8.0. Monoclinic AZP:Ln3+ microplate, microcube and nanoparticle morphologies were obtained at pH values of 8.5, 9.0 and 11.0 respectively. The phase transformation and growth mechanism of the diverse morphologies were proposed, and ZPT:Ln3+ (Ln3+ = Eu or Tb) samples exhibit red or green emission under the excitation of UV light.Ln3+ (Ln = Tb, Eu) doped zinc phosphate tetrahydrate (ZPT:Ln3+) and ammonium zinc phosphate (AZP:Ln3+) nano-/micro-structured materials were synthesized in aqueous solution without the addition of any structure-directing agent. The phase structures, morphologies and luminescence properties of the as-synthesized samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and lifetime. These

Research on damage evolution and damage model of 316LN steel during forging

Energy Technology Data Exchange (ETDEWEB)

Duan, X.W., E-mail: dxwmike1998@sina.com; Liu, J.S.

2013-12-20

The tensile tests and unloading tensile experiments of 316LN steel were conducted. The damage evolution processes were investigated by optical microscope. The fracture was studied using a Scanning Electron Microscope (SEM) and optical microscope, of which, the chemical compositions were analyzed by Energy Dispersive Spectrometer (EDS). The results show that voids nucleate by decohesion of Al{sub 2}O{sub 3} inclusions–matrix interface and mainly along the grain boundary, especially, at triangular grain boundary junctions. The tensile processes were simulated by Deform2D under different deformation conditions. The critical damage values were obtained. The model between the critical damage value, temperature and strain rate was established by regression analysis. A combination of numerical simulation and upsetting experiments was applied for verifying the accuracy and reliability of critical damage value. These damage values can be used to predict the initiation of voids during 316LN steel hot forging. So, they have important instructional effects on designing forging technology of 316LN steel.

Some crystal chemistry of (Ln,Ce)2CuO4-δ superconductors

International Nuclear Information System (INIS)

Goodman, P.; Keating, A.; Myhra, S.; White, T.J.

1989-01-01

Compounds of the form (Ln, Sr, Ce) 2 CuO 4-δ (Ln = rare earth element) crystallise as the Nd 2 CuO 4 structure type, K 2 NiF 4 structure type or perfectly and imperfectly ordered intergrowths of these parent structures. These structurally similar phases exhibit superconductivity in which the charge carriers are holes (in Sr-doped material) or electrons (in Ce doped material). In this study, X-ray Photoelectron Spectroscopy (XPS) and High Resolution Electron Microscopy (HREM) were used to investigate the charge balancing mechanisms operating in each superconducting regime and the structural changes accompanying compositional variation. It was found that under slightly reducing conditions charge coupled cation substitutions predominate, whilst at low pO 2 ( -5 atm) perfectly ordered oxygen superlattices form. The structural and electronic changes which accompany deoxygenation were observed in situ during XPS and HREM observations. 29 refs., 8 figs., 3 tabs

Color tunable emission in Ce3+ and Tb3+ co-doped Ba2Ln(BO3)2Cl (Ln=Gd and Y) phosphors for white light-emitting diodes.

Science.gov (United States)

Zhang, Niumiao; Guo, Chongfeng; Jing, Heng; Jeong, Jung Hyun

2013-12-01

Ce(3+) and Tb(3+) co-doped Ba2Ln(BO3)2Cl (Ln=Y and Gd) green emitting phosphors were prepared by solid state reaction in reductive atmosphere. The emission and excitation spectra as well as luminescence decays were investigated, showing the occurrence of efficient energy transfer from Ce(3+) to Tb(3+) in this system. The phosphors exhibit both a blue emission from Ce(3+) and a green emission from Tb(3+) under near ultraviolet light excitation with 325-375 nm wavelength. Emission colors of phosphors could be tuned from deep blue through cyan to green by adjusting the Tb(3+) concentrations. The energy transfer efficiency and emission intensity of Ba2Y(BO3)2Cl:Ce(3+), Tb(3+) precede those of Ba2Gd(BO3)2Cl:Ce(3+), Tb(3+), and the sample Ba2Y(BO3)2Cl:0.03Ce(3+), 0.10Tb(3+) is the best candidate for n-UV LEDs. Copyright © 2013 Elsevier B.V. All rights reserved.

High-pressure investigations of lanthanoid oxoarsenates. I. Single crystals of scheelite-type Ln[AsO{sub 4}] phases with Ln = La-Nd from monazite-type precursors

Energy Technology Data Exchange (ETDEWEB)

Metzger, Sebastian J.; Ledderboge, Florian; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

2016-08-01

Transparent single crystals of the scheelite-type Ln[AsO{sub 4}] phases with Ln = La-Nd are obtained by the pressure-induced monazite-to-scheelite type phase transition in a Walker-type module under high-pressure and high-temperature conditions of 11 GPa at 1100-1300 C. Coinciding with this transition, there is an increase in density and a reduction in molar volume of about 4.5 % for the scheelite-type phases (tetragonal, I4{sub 1}/a) for La[AsO{sub 4}] (a = 516.92(4), c = 1186.1(9) pm), Ce[AsO{sub 4}] (a = 514.60(1), c = 1175.44(2) pm), Pr[AsO{sub 4}] (a = 512.63(4), c = 1168.25(9) pm), and Nd[AsO{sub 4}] (a = 510.46(4), c = 1160.32(11) pm) as compared to the well-known monazite-type phases (monoclinic, P2{sub 1}/n). Surprisingly enough, the scheelite-type oxoarsenates(V) exhibit a lower coordination number for the Ln{sup 3+} cations (CN = 8 versus CN = 8 + 1), whereas the isolated tetrahedral [AsO{sub 4}]{sup 3-} anions (d(As-O) = 168.9-169.3 pm for the scheelites as compared to d(As-O) = 167.1-169.9 pm for the monazites) remain almost unchanged. So the densification must occur because of the loss of two edge-connections of the involved [LnO{sub 8+1}]{sup 15-} polyhedra with the [AsO{sub 4}]{sup 3-} tetrahedra in the monazite- resulting in exclusively vertex connected [LnO{sub 8}]{sup 13-} and [AsO{sub 4}]{sup 3-} units in the scheelite-type structure.

Effect of substrate temperature on structural and optical properties of nitrogen doped SnO2 thin film

International Nuclear Information System (INIS)

Thakur, Anup; Kumar, Varinder; Kang, Se Jun; Lee, Ik-Jae; Gautam, Sanjeev; Chae, K. H.; Shin, Hyun Joon

2014-01-01

Nitrogen doped SnO 2 thin films (thickness ∼ 250 nm) were deposited at different substrate temperature by radio frequency (rf) sputtering method. Crystal structure, morphology and optical properties of these films were investigated by x-ray diffraction (XRD), atomic force microscopy (AFM) and UV-VIS-NIR spectrophotometer, respectively. XRD measurement suggests that the film deposited at room temperature was amorphous in nature and films deposited at higher temperature were crystalline in nature. The film deposited at RT and 200 °C have transparency more than 90% in visible region but the film deposited at 400 °C has lesser transparency. Red shift was observed in the absorption edge may be due to decrease in ionicity due to the formation of the Sn-N bond

Effect of liquid nitrogen storage time on the survival and ...

African Journals Online (AJOL)

Investigations were undertaken on the effect of liquid nitrogen (LN) storage time on survival and regeneration of somatic embryos of cocoa (Theobroma cacao l.). Somatic embryos from different cocoa genotypes (AMAZ 3-2, AMAZ 10-1, AMAZ 12, SIAL 93, and IMC 14) at 15.45% moisture content were cryopreserved in LN ...

Welding stainless steels for structures operating at liquid helium temperature

International Nuclear Information System (INIS)

Witherell, C.E.

1980-01-01

Superconducting magnets for fusion energy reactors require massive monolithic stainless steel weldments which must operate at extremely low temperatures under stresses approaching 100 ksi (700 MPa). A three-year study was conducted to determine the feasibility of producing heavy-section welds having usable levels of strength and toughness at 4.2 0 K for fabrication of these structures in Type 304LN plate. Seven welding processes were evaluated. Test weldments in full-thickness plate were made under severe restraint to simulate that of actual structures. Type 316L filler metal was used for most welds. Welds deposited under some conditions and which solidify as primary austenite have exhibited intergranular embrittlement at 4.2 0 K. This is believed to be associated with grain boundary metal carbides or carbonitrides precipitated during reheating of already deposited beads by subsequent passes. Weld deposits which solidify as primary delta ferrite appear immune. Through use of fully austenitic filler metals of low nitrogen content under controlled shielded metal arc welding conditions, and through use of filler metals solidifying as primary delta ferrite where only minimum residuals remain to room temperature, welds of Type 316L composition have been made with 4.2K yield strength matching that of Type 304LN plate and acceptable levels of soundness, ductility and toughness

Excitation of cavitation bubbles in low-temperature liquid nitrogen

Science.gov (United States)

Sasaki, Koichi; Harada, Shingo

2017-06-01

We excited a cavitation bubble by irradiating a Nd:YAG laser pulse onto a titanium target that was installed in liquid nitrogen at a temperature below the boiling point. To our knowledge, this is the first experiment in which a cavitation bubble has been successfully excited in liquid nitrogen. We compared the cavitation bubble in liquid nitrogen with that in water on the basis of an equation reported by Florschuetz and Chao [J. Heat Transfer 87, 209 (1965)].

Testing of a Spray-bar Thermodynamic Vent System in Liquid Nitrogen

Science.gov (United States)

Flachbart, R. H.; Hastings, L. J.; Hedayat, A.; Nelson, S. L.; Tucker, S. P.

2005-01-01

To support development of a microgravity pressure control capability for liquid oxygen, thermodynamic vent system (TVS) testing was conducted at Marshall Space Flight Center (MSFC) using liquid nitrogen (LN2) as a LOX simulant. The spray bar TVS hardware used was originally designed by the Boeing Company for testing in liquid hydrogen (LH2). With this concept, a small portion of the tank fluid is passed through a Joule-Thomson (J-T) device, and then through a longitudinal spray bar mixed-heat exchanger in order to cool the bulk fluid. To accommodate the larger mass flow rates associated with LN2, the TVS hardware was modified by replacing the recirculation pump with an LN2 compatible pump and replacing the J-T valve. The primary advantage of the spray-bar configuration is that tank pressure control can be achieved independent of liquid and vapor location, enhancing the applicability of ground test data to microgravity conditions. Performance testing revealed that the spray-bar TVS was effective in controlling tank pressure within a 6.89 kPa band for fill levels of 90%, 50%, and 25%. Tests were also conducted with gaseous helium (GHe) in the ullage. The TVS operated nominally with GHe in the ullage, with performance similar to the tests with gaseous nitrogen (GN2). Testing demonstrated that the spray-bar TVS design was flexible enough for use in two different propellants with minimal hardware modifications.

Effect of lanthanide contraction on the mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien): Syntheses and characterizations of lanthanide complexes with a tetraelenidoantimonate ligand

International Nuclear Information System (INIS)

Zhao Jing; Liang Jingjing; Pan Yingli; Zhang Yong; Jia Dingxian

2011-01-01

Mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) (Ln=lanthanide, en=ethylenediamine, dien=diethylenetriamine, trien=triethylenetetramine) were investigated under solvothermal conditions, and novel mixed-coordinated lanthanide(III) complexes [Ln(en) 2 (dien)(η 2 -SbSe 4 )] (Ln=Ce(1a), Nd(1b)), [Ln(en) 2 (dien)(SbSe 4 )] (Ln=Sm(2a), Gd(2b), Dy(2c)), [Ln(en)(trien)(μ-η 1 ,η 2 -SbSe 4 )] ∞ (Ln=Ce(3a), Nd(3b)) and [Sm(en)(trien)(η 2 -SbSe 4 )] (4a) were prepared. Two structural types of lanthanide selenidoantimonates were obtained across the lanthanide series in both en+dien and en+trien systems. The tetrahedral anion [SbSe 4 ] 3- acts as a monodentate ligand mono-SbSe 4 , a bidentate chelating ligand η 2 -SbSe 4 or a tridentate bridging ligand μ-η 1 ,η 2 -SbSe 4 to the lanthanide(III) center depending on the Ln 3+ ions and the mixed ethylene polyamines, indicating the effect of lanthanide contraction on the structures of the lanthanide(III) selenidoantimonates. The lanthanide selenidoantimonates exhibit semiconducting properties with E g between 2.08 and 2.51 eV. - Graphical Abstract: Two structural types of lanthanide(III) selenidoantimonates are formed in both en-dien and en-trien mixed polyamines across lanthanide series, indicating the lanthanide contraction effect on the structures of the lanthanide(III) selenidoantimonates. Highlights: → Two structural types of lanthanide selenidoantimonates are prepared across the lanthanide series in both Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) systems. → The [SbSe 4 ] 3- anion acts as a mono-SbSe 4 , a η 2 -SbSe 4 or a μ-η 1 ,η 2 -SbSe 4 ligand to the Ln 3+ ions. → The soft base ligand [SbSe 4 ] 3- can be controlled to coordinate to the Ln 3+ ions with en+dien and en+trien as co-ligands.

Frações dos compostos nitrogenados associados à parede celular em forragens tropicais Fractions of cell wall nitrogenous compounds in tropical forages

Directory of Open Access Journals (Sweden)

L.T. Henriques

2007-02-01

Full Text Available The total and undegradable fractions of nitrogenous compounds associated to cell wall organic matrix in some tropical forages were evaluated. Samples of corn silage, elephantgrass silage and sugarcane were used. Neutral detergent insoluble nitrogenous compounds were divided in three different fractions associated with: hemicellulose (HN, cellulose (CN, and lignin (LN. The size of the different fractions varied among feeds. A portion of acid detergent insoluble nitrogen, which is the sum of CN and LN, was potentially degradable in the rumen. A portion of HN was not degradable in the rumen. The heterogeneous dimensions of degradable portion of all nitrogenous compounds among feeds can compromise the estimates of cell wall undegradable nitrogen by simple chemical approaches in tropical forages. The LN overestimated the lignin contents and the correction for those compounds on lignin has been suggested.

Hydrothermal synthesis and photoluminescent properties of hierarchical GdPO4·H2O:Ln3+ (Ln3+ = Eu3+, Ce3+, Tb3+) flower-like clusters

Science.gov (United States)

Amurisana, Bao.; Zhiqiang, Song.; Haschaolu, O.; Yi, Chen; Tegus, O.

2018-02-01

3D hierarchical GdPO4·H2O:Ln3+ (Ln3+ = Eu3+, Ce3+, Tb3+) flower clusters were successfully prepared on glass slide substrate by a simple, economical hydrothermal process with the assistance of disodium ethylenediaminetetraacetic acid (Na2H2L, where L4- = (CH2COO)2N(CH2)2N(CH2COO)24-). In this process, Na2H2L was used as both a chelating agent and a structure-director. The hierarchical flower clusters have an average diameter of 7-12 μm and are composed of well-aligned microrods. The influence of the molar ratio of Na2H2L/Gd3+ and reaction time on the morphology was systematically studied. A possible crystal growth and formation mechanism of hierarchical flower clusters is proposed based on the evolution of morphology as a function of reaction time. The self-assembled GdPO4·H2O:Ln3+ superstructures exhibit strong orange-red (Eu3+, 5D0 → 7F1), green (Tb3+, 5D4 → 7F5) and near ultraviolet emissions (Ce3+, 5d → 7F5/2) under ultraviolet excitation, respectively. This study may provide a new channel for building hierarchically superstructued oxide micro/nanomaterials with optical and new properties.

The effect of gamma irradiation on thermoelectric power and thermal conductivity of Ln0.01Sn0.99Se (Ln-Pr,Tb,Er) single crystals

International Nuclear Information System (INIS)

Guseynov, D.I.; Murguzov, M.I.; Ismaylov, Sh.S.; Mamedova, R.F.

2013-01-01

The present paper contains research results on the effect of gamma irradiation on thermal electromotive force and thermal conductivity of Ln 0 .01Sn 0 .99Se (Ln-Pr,Tb,Er) crystals. It is studied some electrical properties of the samples obtained before and after irradiation in a wide temperature range (80-420 K). As a source it was used an isotope 60Co with photon energies 1.25 MeV, the radiation dose was 65 Mrad

Co-doped sodium chloride crystals exposed to different irradiation temperature

Energy Technology Data Exchange (ETDEWEB)

Ortiz-Morales, A. [Unidad Profesional Interdisciplinaria de Ingenieria y Tecnologias Avanzadas, IPN, Av. Instituto Politecnico Nacional 2580, Col. La Laguna Ticoman, 07340 Mexico D.F., Mexico and Unidad de Irradiacion y Segurid (Mexico); Cruz-Zaragoza, E.; Furetta, C. [Unidad de Irradiacion y Seguridad Radiologica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F (Mexico); Kitis, G. [Nuclear Physics Laboratory, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Flores J, C.; Hernandez A, J.; Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP. 20-364, 01000 Mexico D.F (Mexico)

2013-07-03

Monocrystals of NaCl:XCl{sub 2}:MnCl{sub 2}(X = Ca,Cd) at four different concentrations have been analyzed. The crystals were exposed to different irradiation temperature, such as at room temperature (RT), solid water (SW), dry ice (DI) and liquid nitrogen (LN). The samples were irradiated with photon from {sup 60}Co irradiators. The co-doped sodium chloride crystals show a complex structure of glow curves that can be related to different distribution of traps. The linearity response was analyzed with the F(D) index. The F(D) value was less than unity indicating a sub-linear response was obtained from the TL response on the function of the dose. The glow curves were deconvoluted by using the CGCD program based on the first, second and general order kinetics.

Rethinking Sensitized Luminescence in Lanthanide Coordination Polymers and MOFs: Band Sensitization and Water Enhanced Eu Luminescence in [Ln(C15H9O5)3(H2O)3]n (Ln = Eu, Tb).

Science.gov (United States)

Einkauf, Jeffrey D; Kelley, Tanya T; Chan, Benny C; de Lill, Daniel T

2016-08-15

A coordination polymer [Ln(C15H9O9)3(H2O)3]n (1-Ln = Eu(III), Tb(III)) assembled from benzophenonedicarboxylate was synthesized and characterized. The organic component is shown to sensitize lanthanide-based emission in both compounds, with quantum yields of 36% (Eu) and 6% (Tb). Luminescence of lanthanide coordination polymers is currently described from a molecular approach. This methodology fails to explain the luminescence of this system. It was found that the band structure of the organic component rather than the molecular triplet state was able to explain the observed luminescence. Deuterated (Ln(C15H9O9)3(D2O)3) and dehydrated (Ln(C15H9O9)3) analogues were also studied. When bound H2O was replaced by D2O, lifetime and emission increased as expected. Upon dehydration, lifetimes increased again, but emission of 1-Eu unexpectedly decreased. This reduction is reasoned through an unprecedented enhancement effect of the compound's luminescence by the OH/OD oscillators in the organic-to-Eu(III) energy transfer process.

Preparation and use of nitrogen (2) oxide of special purity for production of oxygen and nitrogen isotopes

International Nuclear Information System (INIS)

Polevoj, A.S.

1989-01-01

Problems related with production of oxygen and nitrogen isotopes by means of low-temperature rectification of nitrogen (2) oxide are analyzed. Special attention, in particular, is payed to the techniques of synthesis and high purification of initial NO, utilization of waste flows formed during isotope separation. Ways to affect the initial isotope composition of nitrogen oxide and the rate of its homogeneous-isotope exchange, which provide for possibility of simultaneous production of oxygen and nitrogen isotopes by means of NO rectification, are considered. Description of a new technique for high purification of nitrogen oxide, prepared at decomposition of nitric acid by sulfurous anhydride, suggested by the author is presented

Low temperature tensile deformation and acoustic emission signal characteristics of AISI 304LN stainless steel

Energy Technology Data Exchange (ETDEWEB)

Barat, K.; Bar, H.N. [Material Science and Technology Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mandal, D. [Material Processing and Technology Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Roy, H., E-mail: himadri9504@gmail.com [NDT and Metallurgy Group, CSIR-Central Mechanical Engineering Research Institute, Durgapur 713209 (India); Sivaprasad, S.; Tarafder, S. [Material Science and Technology Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)

2014-03-01

This investigation examines low temperature tensile deformation behavior of AISI 304LN stainless steel along with synergistic analysis of acoustic emission signals. The tensile tests are done at a range of temperatures starting from 283 K till 223 K. The fracture surfaces of the broken specimens are investigated using scanning electron microscope. The amount of deformation induced martensite is measured using a feritscope. The obtained results reveal that with decrease in test temperature, both strength and ductility increase. The increase in strength and ductility with decreasing temperature is explained in terms of void morphologies and formation of deformation induced martensite. The rapid increment in strength and ductility at 223 K is associated with the burst of martensitic transformation at that temperature; which has been clarified from acoustic emission signals. An additional initiative has been taken to model the evolution of martensite formation from the observed cumulative emission counts using a non linear logarithmic functional form. The fitted curves from the recorded acoustic emission cumulative count data are found to be better correlated compared to earlier obtained results. However, at 223 K normal non-linear logarithmic fit is not found suitable due to presence of burst type signals at intervals, therefore; piecewise logarithmic function to model acoustic emission bursts is proposed.

Dynamic Recrystallization and Hot Workability of 316LN Stainless Steel

Directory of Open Access Journals (Sweden)

Chaoyang Sun

2016-07-01

Full Text Available To identify the optimal deformation parameters for 316LN austenitic stainless steel, it is necessary to study the macroscopic deformation and the microstructural evolution behavior simultaneously in order to ascertain the relationship between the two. Isothermal uniaxial compression tests of 316LN were conducted over the temperature range of 950–1150 °C and for the strain rate range of 0.001–10 s−1 using a Gleeble-1500 thermal-mechanical simulator. The microstructural evolution during deformation processes was investigated by studying the constitutive law and dynamic recrystallization behaviors. Dynamic recrystallization volume fraction was introduced to reveal the power dissipation during the microstructural evolution. Processing maps were developed based on the effects of various temperatures, strain rates, and strains, which suggests that power dissipation efficiency increases gradually with increasing temperature and decreasing stain rate. Optimum regimes for the hot deformation of 316LN stainless steel were revealed on conventional hot processing maps and verified effectively through the examination of the microstructure. In addition, the regimes for defects of the product were also interpreted on the conventional hot processing maps. The developed power dissipation efficiency maps allow optimized processing routes to be selected, thus enabling industry producers to effectively control forming variables to enhance practical production process efficiency.

Commissioning of the Liquid Nitrogen Thermo-Siphon System for NASA-JSC Chamber A

Science.gov (United States)

Homan, J.; Montz, M.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Garcia, S.; Garza, J.

2013-01-01

NASA s Space Environment Simulation Laboratory s (SESL) Chamber A, located at the Johnson Space Center in Houston Texas has recently implemented major enhancements of its cryogenic and vacuum systems. The new liquid nitrogen (LN) thermo-siphon system was successfully commissioned in August of 2012. Chamber A, which has 20 K helium cryo-panels (or shrouds ) which are shielded by 80 K nitrogen shrouds, is capable of simulating a deep space environment necessary to perform ground testing of NASA s James Webb Space Telescope (JWST). Chamber A s previous system used forced flow LN cooling with centrifugal pumps, requiring 220,000 liters of LN to cool-down and consuming 180,000 liters per day of LN in steady operation. The LN system did not have the reliability required to meet the long duration test of the JWST, and the cost estimate provided in the initial approach to NASA-JSC by the subcontractor for refurbishment of the system to meet the reliability goals was prohibitive. At NASA-JSC s request, the JLab Cryogenics Group provided alternative options in 2007, including a thermo-siphon, or natural flow system. This system, eliminated the need for pumps and used one tenth of the original control valves, relief valves, and burst disks. After the thermo-siphon approach was selected, JLab provided technical assistance in the process design, mechanical design, component specification development and commissioning oversight, while the installation and commissioning operations of the system was overseen by the Jacobs Technology/ESC group at JSC. The preliminary commissioning data indicate lower shroud temperatures, 68,000 liters to cool-down and less than 91,000 liters per day consumed in steady operation. All of the performance capabilities have exceeded the design goals. This paper will outline the comparison between the original system and the predicted results of the selected design option, and the commissioning results of thermo-siphon system.

The single crystal structure determination of Ln{sub 6}MnSb{sub 15} (Ln=La, Ce), Ln{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), and Ln{sub 6}ZnSb{sub 15} (Ln=La-Pr)

Energy Technology Data Exchange (ETDEWEB)

Benavides, Katherine A.; McCandless, Gregory T.; Chan, Julia Y. [Texas Univ., Dallas, Richardson, TX (United States). Dept. of Chemistry and Biochemistry

2017-09-01

Single crystals of Ln{sub 6}MnSb{sub 15} (Ln=La, Ce), Ln{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), and Ln{sub 6}ZnSb{sub 15} (Ln=La-Pr) have been successfully grown and the compounds adopt the orthorhombic Ln{sub 6}MnSb{sub 15} structure type (space group Immm), with a∝4.3 Aa, b∝15 Aa, and c∝19 Aa. This structure is comprised of antimony nets and antimony ribbons which exhibit positional disorder at connecting points between antimony substructures, in addition to two partially occupied transition metal sites. The unit cell volumes of the La analogs displayed a systematic decrease upon Zn substitution. However, for the Ce{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} and Pr{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), the volumes deviate from linearity as observed in the parent compounds.

Transport critical current measurement apparatus using liquid nitrogen cooled high-T(c) superconducting magnet with variable temperature insert.

Science.gov (United States)

Nishijima, G; Kitaguchi, H; Tshuchiya, Y; Nishimura, T; Kato, T

2013-01-01

We have developed an apparatus to investigate transport critical current (I(c)) as a function of magnetic field and temperature using only liquid nitrogen. The apparatus consists of a (Bi,Pb)(2)Sr(2)Ca(2)Cu(3)O(10) (Bi-2223) superconducting magnet, an outer dewar, and a variable temperature insert (VTI). The magnet, which is operated in depressurized liquid nitrogen, generates magnetic field up to 1.26 T. The sample is also immersed in liquid nitrogen. The pressure in the VTI is controlled from 0.02 to 0.3 MPa, which corresponds to temperature ranging from 66 to 88 K. We have confirmed the long-term stable operation of the Bi-2223 magnet at 1 T. The temperature stability of the sample at high transport current was also demonstrated. The apparatus provides easy-operating I(c) measurement environment for a high-T(c) superconductor up to 500 A in magnetic fields up to 1 T and in temperatures ranging from 66 to 88 K.

Host composition dependent tunable multicolor emission in the single-phase Ba2(Ln(1-z)Tb(z))(BO3)2Cl:Eu phosphors.

Science.gov (United States)

Xia, Zhiguo; Zhuang, Jiaqing; Meijerink, Andries; Jing, Xiping

2013-05-14

A new strategy based on the host composition design has been adopted to obtain efficient color-tunable emission from Ba2Ln(0.97-z)Tb(z)(BO3)2Cl:0.03Eu (Ln = Y, Gd and Lu, z = 0-0.97) phosphors. This study reveals that the single-phase Ba2Ln(1-z)Tb(z)(BO3)2Cl compounds can be applied to use allowed Eu(2+) absorption transitions to sensitize Eu(3+) emission via the energy transfer Eu(2+) → (Tb(3+))n → Eu(3+). The powder X-ray diffraction (XRD) and Rietveld refinement analysis shows single-phase Ba2Ln(1-z)Tb(z)(BO3)2Cl. As-prepared Ba2Ln(0.97-z)Tb(z)(BO3)2Cl:0.03Eu phosphors show intense green, yellow, orange and red emission under 377 nm near ultraviolet (n-UV) excitation due to a variation in the relative intensities of the Eu(2+), Tb(3+) and Eu(3+) emission depending on the Tb content (z) in the host composition, allowing color tuning. The variation in emission color is explained by energy transfer and has been investigated by photoluminescence and lifetime measurements and is further characterized by the Commission Internationale de l'éclairage (CIE) chromaticity indexes. The quantum efficiencies of the phosphors are high, up to 74%, and show good thermal stabilities up to 150 °C. This investigation demonstrates the possibility to sensitize Eu(3+) line emission by Eu(2+)via energy migration over Tb(3+) resulting in efficient color tunable phosphors which are promising for use in solid-state white light-emitting diodes (w-LEDs).

Recovery time of high temperature superconducting tapes exposed in liquid nitrogen

International Nuclear Information System (INIS)

Sheng, Jie; Zeng, Weina; Yao, Zhihao; Zhao, Anfeng; Hu, Daoyu; Hong, Zhiyong

2016-01-01

Highlights: • A novel method based on a sequence of AC pulses is presented. • Liquid nitrogen temperature is used as criterion to judge whether the sample has recovered. • Recovery time of some tape doesn't increase with the amplitude of fault current. • This phenomenon is caused by boiling heat transfer process of liquid nitrogen. • This phenomenon can be used in optimizing both the limiting rate and reclosing system. - Abstract: The recovery time is a crucial parameter to high temperature superconducting tapes, especially in power applications. The cooperation between the reclosing device and the superconducting facilities mostly relies on the recovery time of the superconducting tapes. In this paper, a novel method is presented to measure the recovery time of several different superconducting samples. In this method criterion used to judge whether the sample has recovered is the liquid nitrogen temperature, instead of the critical temperature. An interesting phenomenon is observed during the testing of superconducting samples exposed in the liquid nitrogen. Theoretical explanations of this phenomenon are presented from the aspect of heat transfer. Optimization strategy of recovery characteristics based on this phenomenon is also briefly discussed.

Effect of nitrogen concentration on temperature dependent mechanical properties of vanadium

International Nuclear Information System (INIS)

Carlson, O.N.; Rehbein, D.K.

1979-01-01

The critical resolved shear stress and strain rate sensitivity of vanadium were determined for vanadium-nitrogen alloys over the temperature range of 77K to 400K for concentrations of 1 to 500 wt ppm nitrogen. The concentration dependence of the hardening rate agrees quite well with either the Fleischer or Labusch strengthening model but the combined temperature and concentration dependence follows more closely the form predicted by Ono and Sommer. The strain rate sensitivity exhibits a peak at 140K which decreases with increasing nitrogen content but above 250K there is a reversal in this effect. (orig.) [de

Thermochemistry of rare earth doped uranium oxides LnxU1-xO2-0.5x+y (Ln = La, Y, Nd)

Science.gov (United States)

Zhang, Lei; Navrotsky, Alexandra

2015-10-01

Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10-50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO1.5, UO2 and UO3 in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of LnxU1-xO2-0.5x+y is similar to that of UO2 to UO3 for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U5+, U6+, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements.

Influence of lead oxide addition on LnTiTaO 6 (Ln = Ce, Pr and Nd)

Indian Academy of Sciences (India)

The effect of PbO addition on the structural, processing and microwave dielectric properties of LnTiTaO6 (Ln = Ce, Pr and Nd) ceramics are reported. Conventional solid state ceramic route was used for the preparation of samples. Phase pure LnTiTaO6 (Ln = Ce, Pr and Nd) ceramics are prepared at a calcination ...

Magnetic properties and crystal field effects in TlLnX2 compounds (X=S, Se, Te)

International Nuclear Information System (INIS)

Duczmal, M.; Pawlak, L.

1997-01-01

Ternary thallium lanthanide chalcogenides TlLnX 2 (X=S, Se or Te) crystallize in the α-NaFeO 2 type of structure (R anti 3m). Each kind of the metal ions, surrounded by the distorted chalcogenide octahedra, forms separate layers. The TlX 6 octahedra are strongly elongated and the LnX 6 octahedra slightly shrunk along the threefold axis. The deformations of the coordination polyhedra and the cell volumes change regularly with the lanthanide ionic radii. The difference between the experimental and the calculated M-X distances increases on going from sulphides to tellurides, as a result of the growing covalent character of the bonds. The crystal field parameters were estimated from the high field magnetization (0-14 T) assuming trigonal distortion of the octahedral symmetry of LnX 6 polyhedra. The second-order crystal field parameters were found to correlate with the deformation of the lanthanide ions' environments. No magnetic transition was observed down to 4.2 K. (orig.)

In vitro evaluation of encapsulated primary rat hepatocytes pre- and post-cryopreservation at -80°C and in liquid nitrogen.

Science.gov (United States)

Durkut, Serap; Elçin, A Eser; Elçin, Y Murat

2015-02-01

Encapsulation techniques have the potential to protect hepatocytes from cryoinjury. In this study, we comparatively evaluated the viability and metabolic function of primary rat hepatocytes encapsulated in calcium alginate microbeads, in chitosan tripolyphosphate beads, and in three-layered alginate-chitosan-alginate (ACA) microcapsules, before and after cryopreservation at -80°C and in liquid nitrogen (LN2) for 1 and 3 months. Findings demonstrated that LN2 was atop of -80°C in regard to preservation of viability (> 90%) and hepatic functions. LN2-cryopreserved hepatocytes encapsulated in ACA microcapsules retained metabolic function post-thawing, with > 90% of the albumin, total protein and urea syntheses activities, and > 80% of oxidative function.

Equivalence of chemical and external pressures in RCoLnO

Energy Technology Data Exchange (ETDEWEB)

Prando, Giacomo; Ortix, Carmine; Kataev, Vladislav [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW), Dresden (Germany); Profeta, Gianni [SPIN-CNR e Dipartimento di Fisica, Universita dell' Aquila (Italy); Sanna, Samuele [Dipartimento di Fisica, Universita di Pavia (Italy); Khasanov, Rustem [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen (Switzerland); Pal, Anand; Awana, Veer [National Physical Laboratory (CSIR), New Delhi (India); Buechner, Bernd [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW), Dresden (Germany); Institut fuer Festkoerperphysik, Technische Universitaet Dresden (Germany); De Renzi, Roberto [Dipartimento di Fisica, Universita di Parma e CNISM (Italy)

2015-07-01

We report on the local magnetic properties of the series of ferromagnetic (FM) materials RCoLnO (R = La, Pr, Nd, Sm; Ln = As, P) as investigated by means of muon spin spectroscopy under pressure P and electron spin resonance (ESR). The effect of P is shown to be quantitatively equivalent to the chemical lattice shrinkage triggered by the different ionic radii of R ions. This is verified for both experimental-dependent quantities (i.e., magnetic field at the muon site) and for intrinsically material-dependent properties (i.e., FM critical temperature T{sub C}). Results of ESR in a wide range of temperature and magnetic field clearly display that magnetism is of localized nature, despite the overall metallic behaviour of these materials.

Ultrafast atomic layer-by-layer oxygen vacancy-exchange diffusion in double-perovskite LnBaCo2O5.5+δ thin films.

Science.gov (United States)

Bao, Shanyong; Ma, Chunrui; Chen, Garry; Xu, Xing; Enriquez, Erik; Chen, Chonglin; Zhang, Yamei; Bettis, Jerry L; Whangbo, Myung-Hwan; Dong, Chuang; Zhang, Qingyu

2014-04-22

Surface exchange and oxygen vacancy diffusion dynamics were studied in double-perovskites LnBaCo2O5.5+δ (LnBCO) single-crystalline thin films (Ln = Er, Pr; -0.5 atoms in the LnBCO thin films is taking the layer by layer oxygen-vacancy-exchange mechanism. The first principles density functional theory calculations indicate that hydrogen atoms are present in LnBCO as bound to oxygen forming O-H bonds. This unprecedented oscillation phenomenon provides the first direct experimental evidence of the layer by layer oxygen vacancy exchange diffusion mechanism.

Studies on the sugars development of irradiated potatoes receiving different nitrogen levels during growth and stored at different temperatures

International Nuclear Information System (INIS)

Badshah, N.; Iritani, W.M.; Rom, C.R.; Patterson, M.E.

1990-01-01

Tubers of Russet Burbank potatoes from 0, 181.8 and 363.6 kg/ha nitrogen were irradiated with 0, 0.05, 0.1 and 0.2 kGy of gamma rays (Co 60 source) and stored for three months at temperatures of 10 and 15.5°C. Changes in reducing sugars and sucrose contents were significantly influenced by nitrogen and irradiation levels while storage temperatures had no significant effect. Nitrogen and irradiation significantly decreased reducing and non-reducing sugars while temperature had no significant effect. Reducing sugars decreased with increasing levels of nitrogen and irradiation. Tubers from zero fertilizer regime developed 1.5% reducing sugars. Irradiation at 0.2 kGy dosage decreased reducing sugars from 1.7 to 0.9%. The breakdown of non-reducing sugars increased with increasing nitrogen levels but decreased with irradiation. Tubers from the maximum nitrogen plot had a 36% decrease of non-reducing sugars. Irradiation at 0.1 kGy dosage had the least change (4.9% decrease) of non-reducing sugars. (author)

Photoluminescence properties of lanthanide-organic frameworks (LnOFs) with thiophene-2,5-dicarboxylate and acetate

Energy Technology Data Exchange (ETDEWEB)

Han, Jing; Wei, Qing; Xie, Gang; Chen, Sanping [Key Lab. of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest Univ., Xi' an, Shaanxi (China); Zhang, Sheng [Key Lab. of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest Univ., Xi' an, Shaanxi (China); College of Chemistry and Chemical Engineering, Baoji Univ. of Arts and Science, Baoji, Shaanxi (China)

2017-07-17

S-heterocyclic dicarboxylic acid, thiophene-2,5-dicarboxylic acid (H{sub 2}TDC), was employed to construct a series of lanthanide-organic frameworks (LnOFs) with coligand acetate, formulated as [Ln(TDC)(OAc)(H{sub 2}O)]{sub n} [Ln = Eu (1), Tb (2), Gd (3), Dy (4), Sm (5)] under hydrothermal conditions. Structure analysis reveals that 1-5 have dinuclear 3D metal organic frameworks (MOFs), in which TDC{sup 2-} and OAc{sup -} display (κ{sup 1}-κ{sup 1})-(κ{sup 1}-κ{sup 1})-μ{sub 4} and (κ{sup 2}-κ{sup 1})-μ{sub 2} coordination fashions, respectively. The dehydrated products of all compounds show high thermal stability above 410 C. As for 1, 2, 4, and 5, the photoluminescence analyses exhibit characteristic luminescence emission bands of the corresponding lanthanide ions in the visible region. In particular, compound 2 displays bright green luminescence in the solid state with {sup 5}D{sub 4} lifetime of 0.510 ms and relative high overall quantum yield of 16 %, based on an ideal energy gap between the lowest triplet state energy level of H{sub 2}TDC ligand and the {sup 5}D{sub 4} state energy level of Tb{sup 3+}. The energy transfer mechanisms in compounds 1 and 2 were also discussed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Determination of excitation temperature and vibrational temperature of the N2(C 3Πu, ν') state in Ne-N2 RF discharges

International Nuclear Information System (INIS)

Rehman, N U; Naveed, M A; Zakaullah, M; Khan, F U

2008-01-01

Optical emission spectroscopy is used to investigate the effect of neon mixing on the excitation and vibrational temperatures of the second positive system in nitrogen plasma generated by a 13.56 MHz RF generator. The excitation temperature is determined from Ne I line intensities, using Boltzmann's plot. The overpopulation of the levels of the N 2 (C 3 Π u , ν') states with neon mixing are monitored by measuring the emission intensities of the second positive system of nitrogen molecules. The vibrational temperature is calculated for the sequence Δν = -2, with the assumption that it follows Boltzmann's distribution. But due to overpopulation of levels, e.g. 1, 4, a linearization process was employed for such distributions allowing us to calculate the vibrational temperature of the N 2 (C 3 Π u , ν') state. It is found that the excitation temperature as well as the vibrational temperature of the second positive system can be raised significantly by mixing neon with nitrogen plasma. It is also found that the vibrational temperature increases with power and pressure up to 0.5 mbar.

Stress corrosion cracking of austenitic stainless steels in high temperature water and alternative stainless steel

International Nuclear Information System (INIS)

Yonezawa, T.

2015-01-01

In order to clarify the effect of SFE on SCC resistance of austenitic stainless steels and to develop the alternative material of Type 316LN stainless steel for BWR application, the effect of chemical composition and heat treatment on SFE value and SCCGR in oxygenated high temperature water were studied. The correlation factors between SFE values for 54 heats of materials and their chemical compositions for nickel, molybdenum, chromium, manganese, nitrogen, silicon and carbon were obtained. From these correlation factors, original formulae for SFE values calculation of austenitic stainless steels in the SHTWC, SHTFC and AGG conditions were established. The maximum crack length, average crack length and cracked area of the IGSCC for 33 heats were evaluated as IGSCC resistance in oxygenated high temperature water. The IGSCC resistance of strain hardened nonsensitized austenitic stainless steels in oxygenated high temperature water increases with increasing of nickel contents and SFE values. From this study, it is suggested that the SFE value is a key parameter for the IGSCC resistance of non-sensitized strain hardened austenitic stainless steels. As an alternative material of Type 316LN stainless steel, increased SFE value material, which is high nickel, high chromium, low silicon and low nitrogen material, is recommendable. (author)

Welding stainless steels for structures operating at liquid helium temperature

Energy Technology Data Exchange (ETDEWEB)

Witherell, C.E.

1980-04-18

Superconducting magnets for fusion energy reactors require massive monolithic stainless steel weldments which must operate at extremely low temperatures under stresses approaching 100 ksi (700 MPa). A three-year study was conducted to determine the feasibility of producing heavy-section welds having usable levels of strength and toughness at 4.2/sup 0/K for fabrication of these structures in Type 304LN plate. Seven welding processes were evaluated. Test weldments in full-thickness plate were made under severe restraint to simulate that of actual structures. Type 316L filler metal was used for most welds. Welds deposited under some conditions and which solidify as primary austenite have exhibited intergranular embrittlement at 4.2/sup 0/K. This is believed to be associated with grain boundary metal carbides or carbonitrides precipitated during reheating of already deposited beads by subsequent passes. Weld deposits which solidify as primary delta ferrite appear immune. Through use of fully austenitic filler metals of low nitrogen content under controlled shielded metal arc welding conditions, and through use of filler metals solidifying as primary delta ferrite where only minimum residuals remain to room temperature, welds of Type 316L composition have been made with 4.2K yield strength matching that of Type 304LN plate and acceptable levels of soundness, ductility and toughness.

A Study on Thermal Desorption of Deuterium in D-loaded SS316LN for ITER Tritium Removal System

Energy Technology Data Exchange (ETDEWEB)

Park, Myungchul; Kim, Heemoon; Ahn, Sangbok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Jaeyong; Lee, Sanghwa; LanAhn, Nguyen Thi [Hanyang University, Seoul (Korea, Republic of)

2016-10-15

Because Type B radwaste includes tritium on its inside, especially at vicinity of surface, tritium removal from the radwaste is a matter of concern in terms of the radwaste processes. Tritium behavior in materials is related with temperature. Considering a diffusion process, it is expected that tritium removal efficiency is enhanced with increasing baking temperature. However, there is a limitation about temperature due to facility capacity and economic aspect. Therefore, it is necessary to investigate the effect of temperature on the desorption behavior of Tritium in ITER materials. TDS analysis was performed in SS316LN loaded at 120, 240 and 350 °C. D2 concentration and the desorption peak temperature increased with increasing loading temperature. Using peak shift method with three ramp rates of 0.166, 0.332, and 0.5 °C/sec, trap activation energy of D in SS316LN loaded at 350 °C was 56 kJ/mol.

The pressure of hot QCD up to $g^{6}$ ln(1/g)

CERN Document Server

Kajantie, Keijou; Rummukainen, K; Schröder, Y

2003-01-01

The free energy density, or pressure, of QCD has at high temperatures an expansion in the coupling constant g, known so far up to order g^5. We compute here the last contribution which can be determined perturbatively, g^6 ln(1/g), by summing together results for the 4-loop vacuum energy densities of two different three-dimensional effective field theories. We also demonstrate that the inclusion of the new perturbative g^6 ln(1/g) terms, together with the so far unknown perturbative and non-perturbative g^6 terms, could potentially extend the applicability of the resummed coupling constant series down to surprisingly low temperatures.

Temperature dependence of nitrogen solubility in iron base multicomponent melts

International Nuclear Information System (INIS)

Sokolov, V.M.; Koval'chuk, L.A.

1986-01-01

Method for calculating temperature dependence of nitrogen solubility in iron base multicomponent melts is suggested. Application areas of existing methods were determined and advantages of the new method for calculating nitrogen solubility in multicomponent-doped iron melts (Fe-Ni-Cr-Mo, Fe-Ni-Cr-Mn, Fe-Mo-V) at 1773-2073 K are shown

Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

Directory of Open Access Journals (Sweden)

Liang Jiang

2017-12-01

Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.

Syntheses, crystal structures and properties of series of 4d–4f ln(III)–Ag(I) heterometallic coordination polymers

Energy Technology Data Exchange (ETDEWEB)

Ran, Xing-Rui [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Ning [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Xie, Wei-Ping; Xiong, Yan-Ju; Cheng, Qian [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Long, Yi [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Yue, Shan-Tang, E-mail: yuesht@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Guangzhou Key Laboratory of Materials for Energy Conversion and Storage, Guangzhou (China); Liu, Ying-Liang [College of Science, South China Agricultural University, Guangzhou 510642 (China)

2015-05-15

By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, ([Ln{sup III}Ag{sup I}(na)(ina)(ox)]·2(H{sub 2}O)){sub n} [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail. - Graphical abstract: Series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction which are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. - Highlights: • Complexes 1–8 are first built by three kinds of organic ligands based on nicotinic acid and isonicotinic acid. • PCPs 1–8 are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. • The total solvent-accessible volume of PCP 2 comprises 11.6% of the crystal volume after dislodging the free water molecules. • Complexes 2 and 4 exhibit characteristic lanthanide-centered luminescence, while compounds 3 and 5 show antiferromagnetic behaviors.

Magnetic properties of the layered oxypnictides (LnOMnAs (Ln = La, Ce, Pr, Nd

Directory of Open Access Journals (Sweden)

Morosawa Y.

2014-07-01

Full Text Available We have investigated the rare earth elements dependence on the magnetism to understand the contribution to physical properties of the 4f electrons of (LnOMnAs (Pn = La, Ce, Pr, Nd. (CeOMnAs, (PrOMnAs and (NdOMnAs shows the antiferromagnetic behaviors at low temperature. (CeOMnAs and (NdOMnAs have the magnetic anomalies around 34 K and 24 K, respectively. So, it is speculated that the anomalies depend on the Mn -Mn distance directly

Thermal and flow considerations for the 80 K shield of the SSC magnet cryostats

International Nuclear Information System (INIS)

Abramovich, S.; Yuecel, A.; Demko, J.; Thirumaleshwar, M.

1994-01-01

The nominal temperatures in the SSC magnets range between 4.2 K in the superconducting coils and 300 K on the cryostat outer wall. To minimize the 4 K heat load, one thermal shield cooled by liquid and vapor nitrogen flows at 84 K, and another cooled by helium flow at 20 K are incorporated in the cryostat. Tubes attached to the shields serve as conduits for the cryogens. The liquid nitrogen tube in the cryostat is used for shield refrigeration and also for liquid distribution around the SSC rings. The second nitrogen line is used to return the vapor to the helium refrigerators for helium precooling. The nominal LN2 flow from a 4.3 km long cryogenic string (4 sections) to the surface is 64 g/s. The total liquid nitrogen consumption of approximately 5000 g/s will be supplied at one, two or more locations on the surface. The total heat load of the 80 K shield is estimated as 3.2 W/m: about 50% is composed of infrared radiation; the remaining 50% is by heat conduction through supports, vacuum barriers and other thermal connections between the shield and the 300 K outer wall. The required LN2 flow rate depends on the distribution and circulation schemes. The LN2 temperature will in turn vary depending on the flow rate and on the recooling method used. For example, with a massflow of 400 g/s of LN2 the temperature rises from 82 K to 86 K between two compact recoolers 1 km apart. This temperature is higher than desired. The temperature can be reduced by increasing the flow rate of the liquid or by using the continuous recooling scheme. This paper discusses some thermal problems caused by certain mechanical designs of the 80 K shield and the possible improvement by using continuous recooling. The authors present results of the 80 K shield temperature distribution analysis, the 20 K shield heat load augmentation resulting from the increased 80 K shield temperatures, the continuous nitrogen recooling scheme and some flow timing related analysis

Effect of reaction temperature on structure and fluorescence properties of nitrogen-doped carbon dots

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yi [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Chemistry and Chemical Engineering, Lyuliang University, Lyuliang 033001 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Yaling [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Feng, Xiaoting [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, Feng [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Yongzhen, E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Xuguang, E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

2016-11-30

Highlights: • Nitrogen-doped carbon dots (NCDs) from ammonia solution and citric acid were synthesized at different temperatures. • Quantum yield (QY) of NCDs depends largely on the amount of fluorescent polymer chains (FPC), more FPC gives higher QY. • The law of QY of NCDs first increase and then decrease with the reaction temperature increased is found and explained. • Nitrogen doping plays significant role in getting increased UV–vis absorption and QY. - Abstract: To investigate the effect of reaction temperature and nitrogen doping on the structure and fluorescence properties of carbon dots (CDs), six kinds of nitrogen-doped CDs (NCDs) were synthesized at reaction temperatures of 120, 140, 160, 180, 200 and 220 °C, separately, by using citric acid as carbon source and ammonia solution as nitrogen source. Nitrogen-free CDs (N-free CDs-180) was also prepared at 180 °C by using citric acid as the only carbon source for comparison. Results show that reaction temperature has obvious effect on carbonization degree, quantum yield (QY), ultraviolet-visible (UV–vis) absorption and photoluminescence (PL) spectra but less effect on functional groups, nitrogen doping degree and fluorescence lifetime of NCDs. Compared with N-free CDs-180, NCDs-180 possesses enchanced QY and longer fluorescence lifetime. Doping nitrogen has obvious effect on UV–vis absorption and PL spectra but less effect on particles sizes and carbonization degree. The formation mechanism of NCDs is explored: QY of NCDs depends largely on the number of fluorescent polymer chains (FPC), the competition between FPC formation on the surface of NCDs and carbon core growth leads to the change in number of FPC, and consequently to the NCDs with highest QY at appropriate hydrothermal temperature.

Effect of nitrogen concentration and temperature on the critical resolved shear stress and strain rate sensitivity of vanadium

International Nuclear Information System (INIS)

Rehbein, D.K.

1980-08-01

The critical resolved shear stress and strain rate sensitivity were measured over the temperature range from 77 to 400 0 K for vanadium-nitrogen alloys containing from 0.0004 to 0.184 atom percent nitrogen. These properties were found to be strongly dependent on both the nitrogen concentration and temperature. The following observations were seen in this investigation: the overall behavior of the alloys for the temperature and concentration range studied follows a form similar to that predicted; the concentration dependence of the critical resolved shear stress after subtracting the hardening due to the pure vanadium lattice obeys Labusch's c/sup 2/3/ relationship above 200 0 K and Fleischer's c/sup 1/2/ relationship below 200 0 K; the theoretical predictions of Fleischer's model for the temperature dependence of the critical resolved shear stress are in marked disagreement with the behavior found; and the strain rate sensitivity, par. delta tau/par. deltaln γ, exhibits a peak at approximately 100 0 K that decreases in height as the nitrogen concentration increases. A similar peak has been observed in niobium by other investigators but the effect of concentration on the peak height is quite different

NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes† †Electronic supplementary information (ESI) available: LIFDI-MS spectra and additional NMR spectra. See DOI: 10.1039/c4sc03103b

Science.gov (United States)

Beele, Björn B.; Geist, Andreas; Müllich, Udo; Kaden, Peter; Panak, Petra J.

2015-01-01

C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15N labeling and characterized by NMR and LIFDI-MS methods. 15N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal–ligand bonding in Am(C5-BPP)3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP)3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species. PMID:29560242

Novel ultra-cryo milling and co-grinding technique in liquid nitrogen to produce dissolution-enhanced nanoparticles for poorly water-soluble drugs.

Science.gov (United States)

Sugimoto, Shohei; Niwa, Toshiyuki; Nakanishi, Yasuo; Danjo, Kazumi

2012-01-01

A novel ultra-cryo milling micronization technique for pharmaceutical powders using liquid nitrogen (LN2 milling) was used to grind phenytoin, a poorly water-soluble drug, to improve its dissolution rate. LN2 milling produced particles that were much finer and more uniform in size and shape than particles produced by jet milling. However, the dissolution rate of LN2-milled phenytoin was the same as that of unground phenytoin due to agglomeration of the submicron particles. To overcome this, phenytoin was co-ground with polyvinylpyrrolidone (PVP). The dissolution rate of co-ground phenytoin was much higher than that of original phenytoin, single-ground phenytoin, a physical mixture of phenytoin and PVP, or jet-milled phenytoin. X-Ray diffraction showed that the crystalline state of mixtures co-ground by LN2 milling remained unchanged. The equivalent improvement in dissolution, whether phenytoin was co-ground or separately ground and then mixed with PVP, suggested that even when co-ground, the grinding of PVP and phenytoin occurs essentially independently. Mixing original PVP with ground phenytoin provided a slight improvement in dissolution, indicating that the particle size of PVP is important for improving dissolution. When mixed with ground phenytoin, PVP ground by LN2 milling aided the wettability and dispersion of phenytoin, enhancing utilization of the large surface area of ground phenytoin. Co-grinding phenytoin with other excipients such as Eudragit L100, hypromellose, hypromellose acetate-succinate, microcrystalline cellulose, hydroxypropylcellulose and carboxymethyl cellulose also improved the dissolution profile, indicating an ultra-cryo milling and co-grinding technique in liquid nitrogen has a broad applicability of the dissolution enhancement of phenytoin.

Lanthanide (III) complexes of 2-(N-salicylideneamino)-4-phenylthiazole

International Nuclear Information System (INIS)

Sasidharan, G.N.; Mohanan, K.; Lakshmi Prabha, A.N.

2002-01-01

Lanthanide(III) complexes of 2-(N-salicylideneamino)-4- phenylthiazole (HSAT) have been synthesised and characterised by elemental, analytical, thermogravimetric, molar conductance, UV- visible, IR and NMR spectral data. The ligand coordinates to the lanthanide(III) ion in a tridentate fashion without deprotonation, giving complexes of the type [Ln(HSAT) 2 (NO 3 ) 3 ] and [Ln(HSAT) 2 (H 2 0) 3 Cl 3 ]. The spectral data reveal that the ligand is bonded to the lanthanide ion through azomethine nitrogen, ring nitrogen and phenolic oxygen without deprotonation. The nitrate group acts in a bidentate fashion. The ligand and the metal complexes exhibit antibacterial and antifungal activities. (author)

How important are internal temperature gradients in french straws during freezing of bovine sperm in nitrogen vapor?

Science.gov (United States)

Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

2013-01-01

The subject of present work was to predict internal temperature gradients developed during freezing of bovine sperm diluted in extender, packaged in 0.5 ml French plastic straws and suspended in static liquid nitrogen vapor at -100 degree C. For this purpose, a mathematical heat transfer model previously developed to predict freezing times (phase change was considered) of semen/extender packaged in straw was extended to predict internal temperature gradients during the cooling/freezing process. Results showed maximum temperature differences between the centre and the periphery of semen/extender "liquid" column was 1.5 degree C for an external heat transfer coefficient, h = 15 W per (m(2) K), and only 0.5 degree C for h = 5 W per (m(2) K). It is concluded that if a thermocouple wire were inserted in a 0.5 ml plastic straw to monitor the freezing process in nitrogen vapor, its radial position would have little importance since expected internal gradients may be safely neglected. This finding facilitates the interpretation of freezing rates in 0.5 ml plastic straws immersed in nitrogen vapor over liquid nitrogen, a widely used method for cryopreservation of bovine spermatozoa.

Observation of Vacancies, Faults, and Superstructures in Ln5Mo2O12 (Ln = La, Y, and Lu) Compounds with Direct Mo-Mo Bonding.

Science.gov (United States)

Colabello, Diane M; Sobalvarro, Elizabeth M; Sheckelton, John P; Neuefeind, Joerg C; McQueen, Tyrel M; Khalifah, Peter G

2017-11-06

Among oxide compounds with direct metal-metal bonding, the Y 5 Mo 2 O 12 (A 5 B 2 O 12 ) structural family of compounds has a particularly intriguing low-dimensional structure due to the presence of bioctahedral B 2 O 10 dimers arranged in one-dimensional edge-sharing chains along the direction of the metal-metal bonds. Furthermore, these compounds can have a local magnetic moment due to the noninteger oxidation state (+4.5) of the transition metal, in contrast to the conspicuous lack of a local moment that is commonly observed when oxide compounds with direct metal-metal bonding have integer oxidation states resulting from the lifting of orbital degeneracy typically induced by the metal-metal bonding. Although a monoclinic C2/m structure has been previously proposed for Ln 5 Mo 2 O 12 (Ln = La-Lu and Y) members of this family based on prior single crystal diffraction data, it is found that this structural model misses many important structural features. On the basis of synchrotron powder diffraction data, it is shown that the C2/m monoclinic unit cell represents a superstructure relative to a previously unrecognized orthorhombic Immm subcell and that the superstructure derives from the ordering of interchangeable Mo 2 O 10 and LaO 6 building blocks. The superstructure for this reason is typically highly faulted, as evidenced by the increased breadth of superstructure diffraction peaks associated with a coherence length of 1-2 nm in the c* direction. Finally, it is shown that oxygen vacancies can occur when Ln = La, producing an oxygen deficient stoichiometry of La 5 Mo 2 O 11.55 and an approximately 10-fold reduction in the number of unpaired electrons due to the reduction of the average Mo valence from +4.5 to +4.05, a result confirmed by magnetic susceptibility measurements. This represents the first observation of oxygen vacancies in this family of compounds and provides an important means of continuously tuning the magnetic interactions within the one

New intermetallic compounds Ln(Ag, AL)4 (Ln-Y, Gd, Tb, Dy) and their structure

International Nuclear Information System (INIS)

Kuz'ma, Yu.B.; Stel'makhovich, B.M.

1990-01-01

By the methods of X-ray analysis crystal structure of compounds Ln(Ag,Al) 4 , where Ln-Y, Gd, Tb, Dy, posessing rhombic structure, is determined. The intermetallics have been prepared for the first time. Ways of atom distribution and their coordinates in DyAg 0.55 Al 3.45 structure (a=0.4296(1), b=04179(1), c=0.9995(3), R=0.093) are specified. Other compounds are formed in case of LnAgAl 3 compositions. Interatomic distances in Dy(Ag,Al) 4 structure are considered. A supposition is made on the formation in Ln-Ag-Al systems of a greater number of intermetallic compounds

Analytical solution and numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe

Science.gov (United States)

Cai, Haibing; Xu, Liuxun; Yang, Yugui; Li, Longqi

2018-05-01

Artificial liquid nitrogen freezing technology is widely used in urban underground engineering due to its technical advantages, such as simple freezing system, high freezing speed, low freezing temperature, high strength of frozen soil, and absence of pollution. However, technical difficulties such as undefined range of liquid nitrogen freezing and thickness of frozen wall gradually emerge during the application process. Thus, the analytical solution of the freezing-temperature field of a single pipe is established considering the freezing temperature of soil and the constant temperature of freezing pipe wall. This solution is then applied in a liquid nitrogen freezing project. Calculation results show that the radius of freezing front of liquid nitrogen is proportional to the square root of freezing time. The radius of the freezing front also decreases with decreased the freezing temperature, and the temperature gradient of soil decreases with increased distance from the freezing pipe. The radius of cooling zone in the unfrozen area is approximately four times the radius of the freezing front. Meanwhile, the numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe is conducted using the Abaqus finite-element program. Results show that the numerical simulation of soil temperature distribution law well agrees with the analytical solution, further verifies the reliability of the established analytical solution of the liquid nitrogen freezing-temperature field of a single pipe.

Hydrothermal synthesis, structure, and optical properties of two nanosized Ln{sub 26} rate at CO{sub 3} (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yu; Huang, Lian; Miao, Hao; Wan, Hong Xiang; Mei, Hua; Liu, Ying [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University (China); Xu, Yan [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University (China); State Key Laboratory of Coordination Chemistry, Nanjing Tech University (China)

2015-02-16

Two Ln{sub 26} rate at CO{sub 3} (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs) formulated as [Dy{sub 26}Cu{sub 3}(Nic){sub 24}(CH{sub 3}COO){sub 8}(CO{sub 3}){sub 11}(OH){sub 26}(H{sub 2}O){sub 14}]Cl . 3 H{sub 2}O (1; HNic=nicotinic acid) and [Tb{sub 26}NaAg{sub 3}(Nic){sub 27}(CH{sub 3}COO){sub 6}(CO{sub 3}){sub 11}(OH){sub 26}Cl(H{sub 2}O){sub 15}] . 7.5 H{sub 2}O (2) have been successfully synthesized by hydrothermal methods and characterized by IR, thermogravimetric analysis (TGA), elemental analysis, and single X-ray diffraction. Compound 1 crystallizes in the monoclinic space group Cc with a=35.775(12) Aa, b=33.346(11) Aa, c=24.424(8) Aa, β=93.993(5) , V=29065(16) Aa{sup 3}, whereas 2 crystallizes in the triclinic space group P anti 1 with a=20.4929(19) Aa, b=24.671(2) Aa, c=29.727(3) Aa, α=81.9990(10) , β=88.0830(10) , γ=89.9940(10) , V=14875(2) Aa{sup 3}. Structural analysis indicates the framework of 1 is a 3D perovskite-like structure constructed out of CO{sub 3} rate at Dy{sub 26} building units and Cu{sup +} centers by means of nicotinic acid ligand bridging. In 2, however, nanosized CO{sub 3} rate at Tb{sub 26} units and [Ag{sub 3}Cl]{sup 2+} centers are connected by Nic{sup -} bridges to give rise to a 2D structure. It is worth mentioning that this kind of 4d-4f cluster-based MOF is quite rare as most of the reported analogous compounds are 3d-4f ones. Additionally, the solid-state emission spectra of pure compound 2 at room temperature suggest an efficient energy transfer from the ligand Nic{sup -} to Tb{sup 3+} ions, which we called the ''antenna effect''. Compound 2 shows a good two-photon absorption (TPA) with a TPA coefficient of 0.06947 cm GM{sup -1} (1 GM = 10{sup -50} cm{sup 4} s photon{sup -1}), which indicates that compound 2 might be a good choice for third-order nonlinear optical materials. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Host-sensitized luminescence properties in CaNb2O6:Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) phosphors with abundant colors.

Science.gov (United States)

Li, Kai; Liu, Xiaoming; Zhang, Yang; Li, Xuejiao; Lian, Hongzhou; Lin, Jun

2015-01-05

A series of Ln(3+) (Ln(3+) = Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+)) ion doped CaNb2O6 (CNO) phosphors have been prepared via the conventional high-temperature solid-state reaction route. The X-ray diffraction (XRD) and structure refinement, diffuse reflection, photoluminescence (PL), and fluorescent decay curves were used to characterize the as-prepared samples. Under UV radiation, the CNO host present a broad emission band from about 355 to 605 nm centered around 460 nm originating from the NbO6 octahedral groups, which has spectral overlaps with the excitation of f-f transitions of Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) samples. They show both host emission and respective emission lines derived from the characteristic f-f transitions of activators, which present different emission colors owing to the energy transfer from the NbO6 group in the host to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) with increasing activator concentrations. The decreases of decay lifetimes of host emissions in CNO:Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+) demonstrate the energy transfer from the hosts to Eu(3+)/Tb(3+)/Dy(3+)/Sm(3+). The energy transfer mechanisms in CNO:Eu(3+)/Tb(3+)/Dy(3+) phosphors have been determined to be a resonant type via dipole-dipole mechanisms. For CNO:Sm(3+), the metal-metal charge transfer transition (MMCT) might contribute to the different variations of decay lifetimes and emission intensity from CNO:Eu(3+)/Tb(3+)/Dy(3+) samples. The best quantum efficiency is 71.2% for CNO:0.01/0.02Dy(3+). The PL properties of as-prepared materials indicate the promising application in UV-pumped white-emitting lighting diodes field.

Fabrication of 2-3 YBa2Cu3O7-x/polymer composite with Tc above liquid nitrogen temperature

International Nuclear Information System (INIS)

Wilson, C.M.; Safari, A.

1990-01-01

This paper reports on high T c superconducting oxide woven networks fabricated and used to form YBa 2 Cu 3 O 7-x /polymer composites showing a superconducting resistive transition above liquid nitrogen temperature. The ceramic network was produced by soaking biaxially woven carbon fabric in a solution containing the stoichiometric proportions of Y, Ba, and Cu. Decomposition of the infiltrated carbon fabric and reaction of the remaining oxides resulted in a ceramic replica of the original fabric. The fired networks had a strand diameter ∼100 μm and were embedded in a polymer matrix to produce 2--3 superconducting/polymer composites with a superconducting transition of ∼89 K. Linear shrinkage of the networks was constrained during firing, although the radial shrinkage of the superconducting strands occurred freely. XRD of the networks indicated the presence of BaCO 3 , CuO, and BaCuO 2 as impurity phases

Uranyl and/or rare-earth mellitates in extended organic-inorganic networks: A unique case of hetero-metallic cation-cation interaction with U-VI=O-Ln(III) bonding (Ln = Ce, Nd)

International Nuclear Information System (INIS)

Volkringer, Christophe; Henry, Natacha; Grandjean, Stephane; Loiseau, Thierry

2012-01-01

A series of uranyl and lanthanide (trivalent Ce, Nd) mellitates (mel) has been hydrothermally synthesized in aqueous solvent. Mixtures of these 4f and 5f elements also revealed the formation of a rare case of lanthanide-uranyl coordination polymers. Their structures, determined by XRD single-crystal analysis, exhibit three distinct architectures. The pure lanthanide mellitate Ln 2 (H 2 O) 6 (mel) possesses a 3D framework built up from the connection of isolated LnO 6 (H 2 O) 3 polyhedra (tri-capped trigonal prism) through the mellitate ligand. The structure of the uranyl mellitate (UO 2 ) 3 (H 2 O) 6 - (mel).11.5H 2 O is lamellar and consists of 8-fold coordinated uranium atoms linked to each other through the organic ligand giving rise to the formation of a 2D 3 6 net. The third structural type, (UO 2 ) 2 Ln(OH)(H 2 O) 3 (mel).2.5H 2 O, involves direct oxygen bondings between the lanthanide and uranyl centers, with the isolation of a hetero-metallic dinuclear motif. The 9-fold coordinated Ln cation, LnO 5 (OH)(H 2 O) 3 , is linked to the 7-fold coordinated uranyl (UO 2 )O-4(OH) (pentagonal bipyramid) via one μ 2 -hydroxo group and one μ 2 -oxo group. The latter is shared between the uranyl bonding (U=O = 1.777(4)1.779(6) angstrom) and a long Ln-O bonding (Ce-O = 2.822(4) angstrom; Nd-O = 2.792(6) angstrom). This unusual linkage is a unique illustration of the so-called cation cation interaction associating 4f and 5f metals. The dinuclear motif is then further connected through the mellitate ligand, and this generates organic inorganic layers that are linked to each other via discrete uranyl (UO 2 )O 4 units (square bipyramid), which ensure the three-dimensional cohesion of the structure. The mixed U-Ln carboxylate is thermally decomposed from 260 to 280 degrees C and then transformed into the basic uranium oxide (U 3 O 8 ) together with U-Ln oxide with the fluorite structural type ('(Ln,U)O 2 '). At 1400 degrees C, only fluorite type '(Ln,U)O 2 ' is formed with

On the radiative corrections α2lnα to the positronium decay rate

International Nuclear Information System (INIS)

Khriplovich, I.B.; Elkhovskij, A.S.

1990-01-01

The radiative corrections ∼α 2 ln α to the positronium decay rate are calculated in the Breit approximation which is shown to be quite adequate for the problem. For orthopositronium the result coincides with the previous one, for parapositronium it differs from the old results. 9 refs

New Technique for Cryogenically Cooling Small Test Articles

Science.gov (United States)

Rodriquez, Karen M.; Henderson, Donald J.

2011-01-01

Convective heat removal techniques to rapidly cool small test articles to Earth-Moon L2 temperatures of 77 K were accomplished through the use of liquid nitrogen (LN2). By maintaining a selected pressure range on the saturation curve, test articles were cooled below the LN2 boiling point at ambient pressure in less than 30 min. Difficulties in achieving test pressures while maintaining the temperature tolerance necessitated a modification to the original system to include a closed loop conductive cold plate and cryogenic shroud

Simple Lanthanide Amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 as Highly Efficient Catalysts for the Nitroaldol Reaction

Institute of Scientific and Technical Information of China (English)

LIU,Yu-yu; WANG,Shao-Wu; ZHANG,Li-Jun; WU,Yun-Jun; LI,Qing-Hai; YANG,Gao-Sheng; XIE,Mei-Hua

2008-01-01

This contribution is to report the application of simple lanthanide amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 exhib-iting a high activity toward catalyzing Henry reaction of aromatic aldehydes with nitroalkanes to give β-nitroalcohols or β-nitroolefins with a very good chemoselectivity by controlling the reaction temperatures and by selecting aromatic aldehydes. It was found that this catalytic system was compatible with a wide range of substrates of aldehydes.

Effect of A-TIG Welding Process on the Weld Attributes of Type 304LN and 316LN Stainless Steels

Science.gov (United States)

Vasudevan, M.

2017-03-01

The specific activated flux has been developed for enhancing the penetration performance of TIG welding process for autogenous welding of type 304LN and 316LN stainless steels through systematic study. Initially single-component fluxes were used to study their effect on depth of penetration and tensile properties. Then multi-component activated flux was developed which was found to produce a significant increase in penetration of 10-12 mm in single-pass TIG welding of type 304LN and 316LN stainless steels. The significant improvement in penetration achieved using the activated flux developed in the present work has been attributed to the constriction of the arc and as well as reversal of Marangoni flow in the molten weld pool. The use of activated flux has been found to overcome the variable weld penetration observed in 316LN stainless steel with TIG welds compared to that of the welds produced by conventional TIG welding on the contrary the transverse strength properties of the 304LN and 316LN stainless steel welds produced by A-TIG welding exceeded the minimum specified strength values of the base metals. Improvement in toughness values were observed in 316LN stainless steel produced by A-TIG welding due to refinement in the weld microstructure in the region close to the weld center. Thus, activated flux developed in the present work has greater potential for use during the TIG welding of structural components made of type 304LN and 316LN stainless steels.

Monodisperse and hollow structured Y{sub 2}O{sub 3}:Ln{sup 3+} (Ln = Eu, Dy, Er, Tm) nanospheres: A facile synthesis and multicolor-tunable luminescence properties

Energy Technology Data Exchange (ETDEWEB)

Li, Ruiqing; Zi, Wenwen; Li, Linlin; Liu, Lu; Zhang, Junjun [College of Chemistry, Jilin University, Changchun 130026 (China); Zou, Lianchun, E-mail: zoulianchun@126.com [Teaching Center of Basic Courses, Jilin University, Changchun 130062 (China); Gan, Shucai, E-mail: gansc@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130026 (China)

2014-12-25

Highlights: • We reported a simple route to synthesize the Y{sub 2}O{sub 3} HNSs. • A possible formation mechanism of the Y{sub 2}O{sub 3} HNSs was proposed. • The Ln-doped Y{sub 2}O{sub 3} HNSs exhibit characteristic emission with different colors. • White-light-emitting phosphor Y{sub 2}O{sub 3}:Tm{sup 3+}, Dy{sup 3+} was also successfully synthesized. - Abstract: A novel, fast and simple method was developed to synthesize the undoped and lanthanide-doped yttrium oxide hollow nanospheres (Y{sub 2}O{sub 3}⋅HNSs) with multicolored downconversion emission under mild conditions by employing poly (acrylic acid sodium salt) microspheres (PAAS MSs) as active templates followed by a subsequent calcination process. The structure, morphology, formation process, and fluorescent properties are well investigated using various techniques. The results show that the samples can be well indexed to the pure cubic phase of Y{sub 2}O{sub 3}. The possible formation mechanism of the PAAS MSs, PAA-Y precursor, and Y{sub 2}O{sub 3} HNSs are proposed and discussed in detail. Upon ultraviolet excitation, the obtained Y{sub 2}O{sub 3}:Ln{sup 3+} (Ln = Eu, Dy, Er, Tm) HNSs exhibit strong red, yellow–green, blue, yellow emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor Y{sub 2}O{sub 3}:Tm{sup 3+}, Dy{sup 3+} was also successfully fabricated through optimizing the molar ratio among Tm{sup 3+} and Dy{sup 3+} in the Y{sub 2}O{sub 3} host. This material may find potential applications in field-emission display devices and white ultraviolet light-emitting diodes (UV LEDs). Furthermore, this synthesis route may be of great significance in the preparation of other hollow spherical materials.

DIMENSI METRIK GRAPH LOBSTER Ln (q;r

Directory of Open Access Journals (Sweden)

PANDE GDE DONY GUMILAR

2013-05-01

Full Text Available The metric dimension of connected graph G is the cardinality of minimum resolving set in graph G. In this research, we study how to find the metric dimension of lobster graph Ln (q;r. Lobster graph Ln (q;r is a regular lobster graph with vertices backbone on the main path, every backbone vertex is connected to q hand vertices and every hand vertex is connected to r finger vertices, with n, q, r element of N. We obtain the metric dimension of lobster graph L2 (1;1 is 1, the metric dimension of lobster graph L2 (1;1 for n > 2 is 2.

Pool boiling from rotating and stationary spheres in liquid nitrogen

Science.gov (United States)

Cuan, Winston M.; Schwartz, Sidney H.

1988-01-01

Results are presented for a preliminary experiment involving saturated pool boiling at 1 atm from rotating 2 and 3 in. diameter spheres which were immersed in liquid nitrogen (LN2). Additional results are presented for a stationary, 2 inch diameter sphere, quenched in LN2, which were obtained utilizing a more versatile and complete experimental apparatus that will eventually be used for additional rotating sphere experiments. The speed for the rotational tests was varied from 0 to 10,000 rpm. The stationary experiments parametrically varied pressure and subcooling levels from 0 to 600 psig and from 0 to 50 F, respectively. During the rotational tests, a high speed photographic analysis was undertaken to measure the thickness of the vapor film surrounding the sphere. The average Nusselt number over the cooling period was plotted against the rotational Reynolds number. Stationary sphere results included local boiling heat transfer coefficients at different latitudinal locations, for various pressure and subcooling levels.

Determination of Debye temperatures and Lamb-Mössbauer factors for LnFeO3 orthoferrite perovskites (Ln  =  La, Nd, Sm, Eu, Gd)

Science.gov (United States)

Scrimshire, A.; Lobera, A.; Bell, A. M. T.; Jones, A. H.; Sterianou, I.; Forder, S. D.; Bingham, P. A.

2018-03-01

Lanthanide orthoferrites have wide-ranging industrial uses including solar, catalytic and electronic applications. Here a series of lanthanide orthoferrite perovskites, LnFeO3 (Ln  =  La Nd; Sm; Eu; Gd), prepared through a standard stoichiometric wet ball milling route using oxide precursors, has been studied. Characterisation through x-ray diffraction and x-ray fluorescence confirmed the synthesis of phase-pure or near-pure LnFeO3 compounds. 57Fe Mössbauer spectroscopy was performed over a temperature range of 10 K-293 K to observe hyperfine structure and to enable calculation of the recoil-free fraction and Debye temperature (θ D) of each orthoferrite. Debye temperatures (Ln  =  La 474 K Nd 459 K Sm 457 K Eu 452 K Gd 473 K) and recoil-free fractions (Ln  =  La 0.827; Nd 0.817; Sm 0.816; Eu 0.812; Gd 0.826) were approximated through minimising the difference in the temperature dependent experimental centre shift and theoretical isomer shift, by allowing the Debye temperature and isomer shift values to vary. This method of minimising the difference between theoretical and actual values yields Debye temperatures consistent with results from other studies determined through thermal analysis methods. This displays the ability of variable-temperature Mössbauer spectroscopy to approximate Debye temperatures and recoil-free fractions, whilst observing temperature induced transitions over the temperature range observed. X-ray diffraction and Rietveld refinement show an inverse relationship between FeO6 octahedral volume and approximated Debye temperatures. Raman spectroscopy show an increase in the band positions attributed to soft modes of Ag symmetry, Ag(3) and Ag(5) from La to GdFeO3 corresponding to octahedral rotations and tilts in the [0 1 0] and [1 0 1] planes respectively.

Characteristics of poly- and mono-crystalline BeO and SiO{sub 2} as thermal and cold neutron filters

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Habib, N. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Bashter, I.I. [Physics Department, Faculty of Science, Zagazig University (Egypt); Morcos, H.N.; El-Mesiry, M.S. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Mansy, M.S., E-mail: drmohamedmansy88@hotmail.com [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt)

2015-09-01

Highlights: • Neutron filtering features of BeO and SiO{sub 2} poly- and mono-crystals. • Calculations of the cold and thermal neutron cross sections and transmission with the code “HEXA-FILTERS”. • Optimal mosaic spread, thicknesses and cutting planes for BeO and SiO{sub 2} mono-crystals. - Abstract: A simple model along with a computer code “HEXA-FILTERS” is used to carry out the calculation of the total cross-sections of BeO and SiO{sub 2} having poly or mono-crystalline form as a function of neutron wavelength at room (R.T.) and liquid nitrogen (L.N.) temperatures. An overall agreement is indicated between the calculated neutron cross-sections and experimental data. Calculation shows that 25 cm thick of polycrystalline BeO cooled at liquid nitrogen temperature was found to be a good filter for neutron wavelengths longer than 0.46 nm. While, 50 cm of SiO{sub 2}, with much less transmission, for neutrons with wavelengths longer than 0.85 nm. It was also found that 10 cm of BeO and 15 cm SiO{sub 2} thick mono-crystals cut along their (0 0 2) plane, with 0.5° FWHM on mosaic spread and cooled at L.N., are a good thermal neutron filter, with high effect-to-noise ratio.

Optimizing human semen cryopreservation by reducing test vial volume and repetitive test vial sampling

DEFF Research Database (Denmark)

Jensen, Christian F S; Ohl, Dana A; Parker, Walter R

2015-01-01

OBJECTIVE: To investigate optimal test vial (TV) volume, utility and reliability of TVs, intermediate temperature exposure (-88°C to -93°C) before cryostorage, cryostorage in nitrogen vapor (VN2) and liquid nitrogen (LN2), and long-term stability of VN2 cryostorage of human semen. DESIGN......: Prospective clinical laboratory study. SETTING: University assisted reproductive technology (ART) laboratory. PATIENT(S): A total of 594 patients undergoing semen analysis and cryopreservation. INTERVENTION(S): Semen analysis, cryopreservation with different intermediate steps and in different volumes (50......-1,000 μL), and long-term storage in LN2 or VN2. MAIN OUTCOME MEASURE(S): Optimal TV volume, prediction of cryosurvival (CS) in ART procedure vials (ARTVs) with pre-freeze semen parameters and TV CS, post-thaw motility after two- or three-step semen cryopreservation and cryostorage in VN2 and LN2. RESULT...

Structural and magnetocaloric properties of (Mn,Fe){sub 2}(P,Si) materials with added nitrogen

Energy Technology Data Exchange (ETDEWEB)

Thang, N.V., E-mail: v.t.nguyen-1@tudelft.nl; Miao, X.F., E-mail: X.F.Miao@tudelft.nl; Dijk, N.H. van, E-mail: N.H.vanDijk@tudelft.nl; Brück, E., E-mail: E.H.Bruck@tudelft.nl

2016-06-15

Amongst magnetic materials that exhibit a giant magnetocaloric effect near room temperature, the (Mn,Fe){sub 2}(P,Si) system is one of the most promising candidates for magnetic refrigeration. Although the (Mn,Fe){sub 2}(P,Si) materials hold many advantages, controlling the magnetic entropy change ΔS{sub m}, the adiabatic temperature change ΔT{sub ad}, the thermal hysteresis and the mechanical stability across the ferromagnetic transition requires a delicate tuning of the composition. This work investigates the addition of nitrogen, as an interstitial or substitutional element, as a new parameter to tune the properties of (Mn,Fe){sub 2}(P,Si) materials. We found that the nitrogen addition results in a decrease of the Curie temperature, consistent with the observed increase in the c/a ratio. The introduction of nitrogen in (Mn,Fe){sub 2}(P,Si) materials also results in a strong enhancement of the mechanical stability. - Highlights: • N-doped materials were synthesized by high-energy ball milling and solid-state reactions. • Nitrogen atoms enter the structure both as substitutional and as interstitial element in (Mn,Fe){sub 2}(P,Si) materials. • Nitrogen addition leads to a decrease in the Curie temperature, while improving the mechanical stability and preserving the magnetocaloric properties. • The origin of the increase in the thermal hysteresis by increasing the N content has been investigated by analyzing the XRD data.

Adaptations of hepatic amino acid uptake and net utilisation contributes to nitrogen economy or waste in lambs fed nitrogen- or energy-deficient diets.

Science.gov (United States)

Kraft, G; Ortigues-Marty, I; Durand, D; Rémond, D; Jardé, T; Bequette, B; Savary-Auzeloux, I

2011-04-01

We investigated the effect of relative changes in dietary nitrogen (N) and energy supply and the subsequent variations in net portal appearance (NPA) of nitrogenous and energy nutrients on the net amino acid (AA) uptake by the liver and net N supply to the peripheral tissues. Six lambs were catheterised across the splanchnic tissues and received, in a replicated Latin square, one of three dietary treatments. The diets were formulated to either match the requirements of N and energy (C), or supply only 0.8 of the N requirement (LN) or 0.8 of the energy requirement (LE). Net fluxes of AA and urea-N were measured across the portal-drained viscera, and estimation of arterial hepatic flow allowed the estimation of hepatic fluxes. Catheters were implanted into the portal and hepatic veins as well as in the abdominal aorta for the measurement of AA fluxes. Animals fed the LN diet showed more efficient N retention (0.59 of digested N) than did the C and LE diet (0.50 and 0.33, respectively; P < 0.001). The NPA of total AA-N for the LN diet was only 0.60 of the value measured for the control (C) diet (P < 0.01). Despite this, the total estimated AA-N net splanchnic fluxes were not significantly different across the three diets (3.3, 1.9 and 2.6 g total AA-N/day for C, LN and LE, respectively, P = 0.52). Thus, different metabolic regulations must have taken place across the liver between the three experimental diets. A combination of decreased net uptake of total AA-N by the liver of animals in the LN diet (0.61 of the C diet; P = 0.002) and reduced urinary urea-N production (0.52 of the C diet; P = 0.001) spared AA from catabolism in the LN diet relative to the other two diets. For the LE diet, the urinary urea-N output was 1.3 times the value of the C diet (P = 0.01). This may relate to an increased catabolism of AA by the muscle and/or, to a lesser extent, to an increased utilisation of AA for gluconeogenesis in the liver. These effects may explain the reduced whole body

Ordered oxygen deficient '112'perovskites, LnBaCo2 O5⋅ 50 ...

Indian Academy of Sciences (India)

... Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 32; Issue 3. Ordered oxygen deficient '112' perovskites, LnBaCo2O5.50+: complex magnetism and transport properties. B Raveau Md Motin Seikh V Pralong V Caignaert. Volume 32 Issue 3 June 2009 pp 305-312 ...

Low-temperature (75 °C) solid-state reaction enhanced by less-crystallized nanoporous PbI2 films for efficient CH3NH3PbI3 perovskite solar cells

International Nuclear Information System (INIS)

Zheng, Huifeng; Liu, Yangqiao; Sun, Jing

2017-01-01

Highlights: • Efficient perovskite solar cells were prepared with solid-state reaction at 75 °C. • Ln-PbI 2 is superior to c-PbI 2 when applied in low-temperature solid-state reaction. • A higher champion PCE was obtained at 75 °C (13.8%) than that of 140 °C (11.8%). • Non-radiative defects increase significantly when annealed at high temperature. - Abstract: Organohalide perovskite films are usually prepared with the solid-state reaction at a high temperature ≥100 °C, which causes the increase of non-radiative defects and decomposition of perovskite films. Here, we demonstrate it’s feasible to prepare high-quality perovskite films with the solid-state reaction method even at a temperature of 75 °C, when enhanced by less-crystallized nanoporous PbI 2 (ln-PbI 2 ) films. The replacement of compact PbI 2 (c-PbI 2 ) by ln-PbI 2 , results in a significant improvement of crystallinity of perovskite films, besides the elimination of remnant PbI 2 . As a result, ln-PbI 2 based perovskite solar cells display much higher power conversion efficiency (PCE) and better stability. Moreover, annealing duration was found to be critical for high PCE and was optimized as 60 min. Finally, with the optimal process, the champion device displayed a PCE of 13.8% and the average PCE reached 10.1% with a satisfactory deviation. Furthermore, we found annealing at high temperature (140 °C) led to a lower PCE compared with that annealed at 75 °C, because non-radiative defects increased significantly during high-temperature annealing. This work may open up a promising avenue for preparing high-quality perovskite films with the low-temperature solid-state reaction method, which is desirable for real application.