Perpendicular exchange coupling effects in ferrimagnetic TbFeCo/GdFeCo hard/soft structures

Science.gov (United States)

Wang, Ke; Wang, Yahong; Ling, Fujin; Xu, Zhan

2018-04-01

Bilayers consisting of magnetically hard TbFeCo and soft GdFeCo alloy were fabricated. Exchange-spring and sharp switching in a step-by-step fashion were observed in the TbFeCo/GdFeCo hard/soft bilayers with increasing GdFeCo thickness. A perpendicular exchange bias field of several hundred Oersteds is observed from the shift of minor loops pinned by TbFeCo layer. The perpendicular exchange energy is derived to be in the range of 0.18-0.30 erg/cm2. The exchange energy is shown to increase with the thickness of GdFeCo layer in the bilayers, which can be attributed to the enhanced perpendicular anisotropy of GdFeCo layer in our experimental range.

The equilibrium diagram and some properties of alloys Gd5Sb3-Tb5Sb3 system

International Nuclear Information System (INIS)

Azizov, Yu.S.; Abulkhaev, V.D.; Ganiev, I.N.

2001-01-01

The purpose of present work is investigation equilibrium diagram of Gd 5 Sb 3 -Tb 5 Sb 3 system in total range of concentrations. Equilibrium diagram of Gd 5 Sb 3 -Tb 5 Sb 3 system investigated by methods of difference-thermal, roentgen-phase and metallographic analyses. For the first time on the base of difference-thermal, roentgen-phase and metallographic analyses was formed the equilibrium diagram of Gd 5 Sb 3 -Tb 5 Sb 3 system. Was determined the cristal-chemical parameters of solid solutions with general formula Gd x Tb 5 - x Sb 3

Neutron diffraction studies on GdB{sub 6} and TbB{sub 6} powders

Energy Technology Data Exchange (ETDEWEB)

Luca, S.E.; Amara, M.; Galera, R.M.; Givord, F.; Granovsky, S.; Isnard, O.; Beneu, B

2004-07-15

We report here the first powder neutron diffraction study of GdB{sub 6} and TbB{sub 6}. GdB{sub 6} and TbB{sub 6} order antiferromagnetically at 15 and 21 K, respectively. In both compounds the transition at T{sub N} is of the first order. Moreover GdB{sub 6} presents a second spontaneous magnetic transition at T{sup *}=8 K. The present study shows that, in both compounds, the magnetic propagation vectors belong to the <((1)/(4)) ((1)/(4)) ((1)/(2))> star and that the direction of the magnetic moment is perpendicular to the ((1)/(2)) component of the wave-vector in GdB{sub 6}, while in TbB{sub 6} the moment is parallel to it. The deduced low-temperature values of the magnetic moments agree with those of the respective rare-earth trivalent ions.

The development of new phosphors of Tb3+/Eu3+ co-doped Gd3Al5O12 with tunable emission

Science.gov (United States)

Teng, Xin; Wang, Wenzhi; Cao, Zhentao; Li, Jinkai; Duan, Guangbin; Liu, Zongming

2017-07-01

The gadolinium aluminum garnets Gd3Al5O12 (GdAG) activated with Tb3+/Eu3+ were successfully prepared via co-precipitation method at 1500 °C in this work. The crystal structure stabilization, elements analysis, microphotograph, PL/PLE spectra, decay behavior and quantum efficiency were discussed in detail. The metastable GdAG compounds been effectively stabilized by doping with smaller 10 at.% Tb3+, which then allows the development of new phosphors of (Gd0.9-xTb0.1Eux)3Al5O12 (GdAG:Tb3+/Eu3+, x = 0-0.03) for opto-functionality explorations. The PLE/PL spectra displays that the strongest PLE peak was located at ∼276 nm, which overlaps the 8S7/2 → 6IJ transition of Gd3+. Under 276 nm excitation, the phosphors exhibited both Tb3+ and Eu3+ emissions at 548 nm (green, 5D4 → 7F5 transition of Tb3+) and 592 nm (orange-red, 5D0 → 7F1 transition of Eu3+), respectively. The emission intensities of Tb3+ and Eu3+ remarkably varied with the Eu3+ incorporation. As a consequence, the emission color can be readily tuned from approximately green to orange-red. Fluorescence decay analysis found that the lifetime for the Tb3+ emission rapidly decreased conforming to the Tb3+ → Eu3+ energy transfer, and the energy transfer efficiency was calculated. Owing to the Gd3+ → Eu3+ and Gd3+ → Tb3+ energy transfer, the emission intensities of Tb3+ and Eu3+ in (Gd0.9-xTb0.1Eux)AG phosphor were higher than (Y0.87Tb0.1Eu0.03)AG and (Lu0.87Tb0.1Eu0.03)AG system. The (Gd0.9-xTb0.1Eux)AG garnet phosphors developed in this work may serve as a new type of phosphor which hopefully meets the requirements of various lighting and optical display applications.

Sol-gel syntheses, luminescence, and energy transfer properties of α-GdB5O9:Ce(3+)/Tb(3+) phosphors.

Science.gov (United States)

Sun, Xiaorui; Gao, Wenliang; Yang, Tao; Cong, Rihong

2015-02-07

Sol-gel method was applied to prepare homogenous and highly crystalline phosphors with the formulas α-GdB5O9:xTb(3+) (0 ≤ x ≤ 1), α-Gd1-xCexB5O9 (0 ≤ x ≤ 0.40), α-GdB5O9:xCe(3+), 0.30Tb(3+) (0 ≤ x ≤ 0.15) and α-GdB5O9:0.20Ce(3+), xTb(3+) (0 ≤ x ≤ 0.10). The success of the syntheses was proved by the linear shrinkage or expansion of the cell volumes against the substitution contents. In α-GdB5O9:xTb(3+), an efficient energy transfer from Gd(3+) to Tb(3+) was observed and there was no luminescence quenching. The exceptionally high efficiency of the f-f excitations of Tb(3+) implies that these phosphors may be good green-emitting UV-LED phosphors. For α-Gd1-xCexB5O9, Ce(3+) absorbs the majority of the energy and transfers it to Gd(3+). Therefore, the co-doping of Ce(3+) and Tb(3+) leads to a significant enhancement in the green emission of Tb(3+). Our current results together with the study on α-GdB5O9:xEu(3+) in the literature indicate that α-GdB5O9 is a good phosphor host with advantages including controllable preparation, diverse cationic doping, the absence of concentration quenching, and effective energy transfer.

Luminescence, Energy Transfer and Tunable Color of Ce3+- and Tb3+-Activated Na3Gd(BO3)2 Phosphors

Science.gov (United States)

Zhang, Xinguo; Pan, Jialiang; Mo, Fuwang

2017-07-01

A series of blue Na3Gd(BO3)2:Ce3+ and blue-to-green color-tunable Na3Gd (BO3)2:Ce3+,Tb3+ phosphors were synthesized by the solid-state method. The luminescence, concentration quenching and energy transfer (ET) process of Na3Gd(BO3)2:Ce3+,Tb3+ were investigated. Both Ce3+ and Tb3+ occupy the Gd3+ site in the Na3Gd(BO3)2 host. Na3Gd(BO3)2:Ce3+ exhibits strong ultraviolet absorption and broadband blue emission. The Ce3+ sensitization effect on Tb3+ has been verified by the variation of PL/PLE spectra, the Ce3+ decay lifetimes and the energy transfer efficiency of Na3Gd(BO3)2:Ce3+,Tb3+ phosphors. The maximum Ce3+-Tb3+ ET efficiency has been calculated to be 95%. The emitting color of the obtained phosphors can be modulated from blue (0.179, 0.204) through bluish-green (0.271, 0.391) to green (0.349, 0.551) by properly changing the ratio of Ce3+/Tb3+.

Interlayer exchange coupling in Er|Tb superlattices mediated by short range incommensurate Er order

International Nuclear Information System (INIS)

Pfuhl, E; Brueckel, T; Voigt, J; Mattauch, S; Korolkov, D

2010-01-01

We study the magnetic correlations in Er|Tb superlattices by means of off-specular scattering of polarized neutrons. We show here the co-existence of inhomogeneous magnetic states: i) ferromagnetic order of moments within the Tb layers below 230 K (FM), correlation length of about 10 bilayer, ii) an incommensurate modulated magnetic order, restricted to single Er layers and iii) antiferromagnetic coupling of ferromagnetic layers below 70K (AFC). Polarised off-specular neutron scattering under grazing incidence reveals that i) magnetic fluctuations appear when the sample is cooled below 70 K, ii) these fluctuations lead to AFC, when the sample is cooled to 10 K, which iii) persists, when the sample is subsequently heated up to 45 K, while the order is not present during the cooling cycle. Also the short range incommensurate order changes accordingly, implying that the magnetic order in the Er layers mediates the interlayer coupling between ferromagnetic Tb layers.

Energy transfer and tunable multicolor emission and paramagnetic properties of GdF3:Dy(3+),Tb(3+),Eu(3+) phosphors.

Science.gov (United States)

Guan, Hongxia; Sheng, Ye; Xu, Chengyi; Dai, Yunzhi; Xie, Xiaoming; Zou, Haifeng

2016-07-20

A series of Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped GdF3 phosphors were synthesized by a glutamic acid assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectroscopy. The results show that the synthesized samples are all pure GdF3. The obtained samples have a peanut-like morphology with a diameter of about 270 nm and a length of about 600 nm. Under UV excitation, GdF3:Dy(3+), GdF3:Tb(3+) and GdF3:Eu(3+) samples exhibit strong blue, green and red emissions, respectively. By adjusting their relative doping concentrations in the GdF3 host, the different color hues of green and red light are obtained by co-doped Dy(3+), Tb(3+) and Tb(3+), Eu(3+) ions in the GdF3 host, respectively. Besides, there exist two energy transfer pairs in the GdF3 host: (1) Dy(3+) → Tb(3+) and (2) Tb(3+) → Eu(3+). More significantly, in the Dy(3+), Tb(3+), and Eu(3+) tri-doped GdF3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of Eu(3+). In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K) and low temperature (2 K). It is obvious that multifunctional Dy(3+), Tb(3+), Eu(3+) tri-doped GdF3 materials including tunable multicolors and intrinsic paramagnetic properties may have potential applications in the field of full-color displays.

The N=82 gap in /sup 146/Gd from beta -decay studies of Tb isotopes

CERN Document Server

Styczen, J; Kleinheinz, P; Piiparinen, M

1981-01-01

The beta -decay study of 23 s /sup 146/Tb suggests a ( pi h/sub 11/2/ nu d/sup -1//sub 3/2/) 5/sup -/ configuration for this activity. In its decay the authors have identified a pi h/sub 11/2/ to nu h/sub 9/2 / GT decay branch which populates neutron particle-hole states in /sup 146/Gd. Hence the N=82 single particle energy gap is less than 4 MeV. Neutron one-particle two-hole and two-particle one-hole states in /sup 145/Gd and /sup 147/Gd were identified in the beta -decays of 29 s /sup 145/Tb and 1.6 h /sup 147/Tb. (11 refs).

Experimental and theoretical study of pure and doped crystals: Gd2O2S, Gd2O2S:Eu3+ and Gd2O2S:Tb3+

Science.gov (United States)

Wang, Fei; Chen, Xiumin; Liu, Dachun; Yang, Bin; Dai, Yongnian

2012-08-01

Quantum chemistry and experimental method were used to study on pure and doped Gd2O2S crystals in this paper. The band structure and DOS diagrams of pure and doped Gd2O2S crystals which calculated by using DFT (Density Functional Theory) method were illustrated to explain the luminescent properties of impurities in crystals. The calculations of the crystal structure were finished by using the program of CASTEP (Cambridge Sequential Total Energy Package). The samples showed the characteristic emissions of Tb3+ ions with 5D4-7FJ transitions and Eu3+ ions with 5D0-7FJ transitions which emit pure green luminescence and red luminescence respectively. The experimental excitation spectra of Tb3+ and Eu3+ doped Gd2O2S are in agreement of the DOS diagrams over the explored energy range, which has allowed a better understanding of different luminescence mechanisms of Tb3+ and Eu3+ in Gd2O2S crystals.

Electrical characteristics of hybrid detector based Gd2O2S:Tb-Selenium for digital radiation imaging

International Nuclear Information System (INIS)

Kang, Sang-Sik; Park, Ji-Koon; Choi, Jang-Yong; Cha, Byung-Yul; Cho, Sung-Ho; Nam, Sang-Hee

2005-01-01

Fine Gd 2 O 2 S:Tb powders were synthesized by using a solution-combustion method for a high-resolution digital X-ray imaging detector. The PL spectrum showed that the phosphor was fully crystallized and that the Tb 3+ ions substituted well for the Gd 3+ sites. To investigate the X-ray response of the phosphor, a uniform Gd 2 O 2 S:Tb film was grown using a screen-printing method. The X-ray sensitivities of the 100 μm-Gd 2 O 2 S:Tb/30 μm -Se and 200 μm -Se detector were 470 and 420 pC/cm 2 /mR, respectively, at an electric field of 10 V/μm. The results of the study suggest that the hybrid detector has a significant potential in the application of digital radiography and fluoroscopy systems

Photoluminescence and thermoluminescence properties of Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor

Energy Technology Data Exchange (ETDEWEB)

Gupta, Palvi; Bedyal, A.K. [School of Physics, Shri Mata Vaishno Devi University, Katra, 182320 Jammu and Kashmir (India); Kumar, Vinay, E-mail: vinaykdhiman@yahoo.com [School of Physics, Shri Mata Vaishno Devi University, Katra, 182320 Jammu and Kashmir (India); Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300 (South Africa); Khajuria, Y. [School of Physics, Shri Mata Vaishno Devi University, Katra, 182320 Jammu and Kashmir (India); Lochab, S.P. [Inter University Accelerator Centre, Anura Asaf Ali Marg, P. O. Box 10502, New Delhi 110067 (India); Pitale, S.S. [Crystal Technology Laboratory,TPD, Bhabha Atomic Research Centre Trombay, Mumbai 400085 (India); Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300 (South Africa); Ntwaeaborwa, O.M.; Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300 (South Africa)

2014-12-15

Energy level diagram of Tb{sup 3+} ion in the K{sub 3}Gd(PO{sub 4}){sub 2} host lattice. - Highlights: • First time, a detailed TL and PL study on undoped and Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor. • Combustion method was employed to synthesize the Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor. • Mechanism of excitation and emission in undoped and Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor was given. - Abstract: Tb{sup 3+} doped nanoparticulate K{sub 3}Gd(PO{sub 4}){sub 2} phosphor was prepared by combustion method using urea as a fuel. The structure, optical and luminescent properties of the phosphor were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and thermoluminescence (TL) spectroscopy. In undoped K{sub 3}Gd(PO{sub 4}){sub 2}, the excitation and emission peaks at 273 nm and 323 nm belongs to the {sup 8}S{sub 7/2} → {sup 6}I{sub J(J=7/2)} and {sup 6}P{sub J(J=7/2)} → {sup 8} S{sub 7/2} transitions of Gd{sup 3+} while green emission was observed in the Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2}. TL study was carried out after exposing the samples to γ-radiations (0.1–5 kGy) in the K{sub 3}Gd(PO{sub 4}){sub 2}:Tb{sup 3+} (1.5 mol%). The calculated kinetic parameters were compared with different methods. The band gap of the phosphor was estimated as 5.80 eV. The green shade of the Tb{sup 3+} ion with the CIE coordinates (x, y) as (0.29, 0.54) was in good agreement with the well known green phosphors.

Synthesis and photoluminescence properties of GdBO3:Ln3+ (Ln = Eu, Tb) nanofibers by electrospinning

International Nuclear Information System (INIS)

Shen, Hongzhi; Feng, Shuo; Wang, Ying; Gu, Yipeng; Zhou, Jing; Yang, Hang; Feng, Guanlin; Li, Liang; Wang, Wenquan; Liu, Xiaoyang; Xu, Dapeng

2013-01-01

Highlights: ► GdBO 3 :Ln 3+ nanofibers were synthesized successfully by electrospinning. ► The samples have the average diameter of 150 nm and the flexible morphology. ► The GdBO 3 : Eu 3+ nanofibers have the stronger orange emission. ► The luminescence properties are different from the reported bulk material. ► We describe the energy transform process of GdBO 3 :Ln 3+ system. - Abstract: GdBO 3 :Ln 3+ (Ln = Eu, Tb) nanofibers were synthesized using electrospinning combined with heat treatment. The synthesized nanofibers were characterized by X-ray diffraction, Raman spectroscopy, field emission-scanning electron microscopy, thermogravimetric and differential thermal analyses, and photoluminescence. The experimental results show that the flexible synthesized nanofibers have an average diameter of approximately 150 nm. The nanofibers consist of crystalline grains with diameters of about 40 nm and have a vaterite-type structure of GdBO 3 . The GdBO 3 :Eu 3+ nanofibers exhibit strong orange and weak red emissions with a low ratio of red to orange emission intensities, which is different from those of the reported bulk materials and nanoparticles. The luminescence properties of the synthesized GdBO 3 :Tb 3+ nanofibers are essentially consistent with those of the synthesized GdBO 3 :Tb 3+ powders by solid-state reaction.

Development of Tb{sup 3+} activated gadolinium aluminate garnet (Gd{sub 3}Al{sub 5}O{sub 12}) as highly efficient green-emitting phosphors

Energy Technology Data Exchange (ETDEWEB)

Teng, Xin; Li, Jinkai, E-mail: mse_lijk@ujn.edu.cn; Duan, Guangbin; Liu, Zongming, E-mail: ost_liuzm@ujn.edu.cn

2016-11-15

The powder processing of (Gd{sub 1-x}Tb{sub x}){sub 3}Al{sub 5}O{sub 12} (GdAG:Tb{sup 3+}) solid solutions was achieved through precursor synthesized via carbonate precipitation, followed by calcination at 1500 °C. The performance of the GdAG:Tb{sup 3+} phosphors were characterized by the combined techniques of XRD, FE-SEM, HR-TEM, PLE/PL, and fluorescence decay analyses. Lower Tb{sup 3+} doping can stabilize the crystal structure of GdAG garnet against its thermal decomposition. The GdAG:Tb{sup 3+} phosphors with good dispersion and fairly uniform particle morphology exhibit a series of {sup 5}D{sub 4}–{sup 7}F{sub J} transitions of Tb{sup 3+} with strongest green emission at ~544 nm ({sup 5}D{sub 4}–{sup 7}F{sub 5} transitions of Tb{sup 3+}) under UV excitation at ~277 nm (4f{sup 8}−4f{sup 7}5d{sup 1} transition of Tb{sup 3+}). The later is overlapping with {sup 8}S{sub 7/2}–{sup 6}I{sub J} intra f–f transition of Gd{sup 3+} indirectly suggesting the existence of energy transfer from Gd{sup 3+} to Tb{sup 3+}. With the Gd{sup 3+}–Tb{sup 3+} energy transfer, higher Tb{sup 3+} emission and quantum efficiency than the well-known YAG:Tb{sup 3+} and LuAG:Tb{sup 3+} were obtained in the present work. The effects of Tb{sup 3+} content on luminescent property of the phosphor, especially PLE/PL properties, fluorescence lifetime and quantum efficient, were thoroughly investigated, which were also compared to those of Tb{sup 3+}-activated YAG and LuAG compounds. The CIE chromaticity coordinates and quenching concentration of GdAG:Tb{sup 3+} were determined to be (~0.37, ~0.56) and ~10 at%, respectively. Keeping the optimum Tb{sup 3+} content at ~10 at%, the (Gd{sub 0.9}Tb{sub 0.1})AG phosphor possesses high internal and external quantum efficiencies of ~88.7% and ~73.6% under ~277 nm excitation, respectively. Owing to its improved luminescent property and high theoretical density, the phosphors of (Gd{sub 1-x}Tb{sub x})AG garnet developed in the present work are

Luminescent properties of (Y,Gd)BO3:Bi3+,RE3+ (RE=Eu, Tb) phosphor under VUV/UV excitation

International Nuclear Information System (INIS)

Zeng Xiaoqing; Im, Seoung-Jae; Jang, Sang-Hun; Kim, Young-Mo; Park, Hyoung-Bin; Son, Seung-Hyun; Hatanaka, Hidekazu; Kim, Gi-Young; Kim, Seul-Gi

2006-01-01

Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors were prepared and their luminescent properties under vacuum ultraviolet (VUV)/UV excitation were investigated. Strong red emission for (Y,Gd)BO 3 :Bi 3+ ,Eu 3+ and strong green emission for (Y,Gd)BO 3 :Bi 3+ ,Tb 3+ are observed under VUV excitation from 147 to 200 nm with a much broader excitation region than that of single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 phosphor. Strong emissions are also observed under UV excitation around 265 nm where as nearly no luminescence is observed for single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 . The luminescence enhancement of Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors is due to energy transfer from Bi 3+ ion to Eu 3+ or Tb 3+ ion not only in the VUV region but also in the UV region. Besides, host sensitization competition between Bi 3+ and Eu 3+ or Tb 3+ is also observed. The investigated phosphors may be preferable for devices with a VUV light 147-200 nm as an excitation source such as PDP or mercury-free fluorescent lamp

Supporting clinical management of the difficult-to-treat TB cases: the ERS-WHO TB Consilium

Directory of Open Access Journals (Sweden)

Lia D’Ambrosio

2015-03-01

The primary objective of the ERS/WHO TB Consilium is to provide clinical consultation for drug-resistant TB and other difficult-to-treat TB cases, including co-infection with HIV and paediatric cases. Through technical guidance to clinicians managing complex TB cases, the main contribution and outcome of the initiative will be a public health response aimed at achieving correct treatment of affected patients and preventing further development of drug resistance. The Consilum's secondary objective is to ensure monitoring and evaluation of clinical practices on the ground (diagnosis, treatment and prevention.

Theoretical investigations on magnetocaloric effect in Er{sub 1−y}Tb{sub y}Al{sub 2} series

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, P.O., E-mail: paula.ribeiro@gmail.com [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Alho, B.P.; Alvarenga, T.S.T.; Nóbrega, E.P.; Sousa, V.S.R. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, SP (Brazil); Caldas, A. [Sociedade Unificada de Ensino Superior e Cultura, SUESC, 20211-351 Rio de Janeiro, RJ (Brazil); Oliveira, N.A. de; Ranke, P.J. von [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil)

2015-04-01

We report on the magnetic and magnetocaloric effect calculations in rare earth Er{sub 1−y}Tb{sub y}Al{sub 2} compounds (y=0.00, 0.25, 0.5, 0.75 and 1.00). Our model Hamiltonian has contributions of the crystalline electrical field anisotropy in both Er and Tb magnetic sublattices, disorder in exchange interactions among Er–Er, Tb–Tb and Er–Tb magnetic ions and the Zeeman effect. The magnetization, the isothermal entropy change (ΔS{sub T}) and the adiabatic temperature change (ΔT{sub ad}) dependence on temperature were simulated and, compared with the experimental data available. - Highlights: • Modeling Er{sub (1−y)}Tb{sub y}Al{sub 2} intermetallic compounds. • Magnetic entropy changes in Er{sub (1−y)}Tb{sub y}Al{sub 2}. • Adiabatic temperature changes in Er{sub 0.75}Tb{sub 0.25}Al{sub 2} and Er{sub 0.65}Tb{sub 0.35}Al{sub 2} compounds.

Hydrothermal synthesis and luminescent properties of LnPO4:Tb,Bi (Ln=La,Gd) phosphors under UV/VUV excitation

International Nuclear Information System (INIS)

Wang Yuhua; Wu Chunfang; Wei Jie

2007-01-01

Monoclinic LnPO 4 :Tb,Bi (Ln=La,Gd) phosphors were prepared by hydrothermal reaction and their luminescent properties under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation were investigated. LaPO 4 :Tb,Bi phosphor and GdPO 4 :Tb phosphor showed the strongest emission intensity under 254 and 147 nm excitation, respectively, because of the different energy transfer models. In UV region, Bi 3+ absorbed most energy then transferred to Tb 3+ , but in VUV region it was the host which absorbed most energy and transferred to Tb 3+

Surfactant mediated hydrothermal synthesis, characterization and luminescent properties of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell nanorods

Energy Technology Data Exchange (ETDEWEB)

Khajuria, Heena; Ladol, Jigmet; Khajuria, Sonika; Shah, Mohd Syed; Sheikh, H.N., E-mail: hnsheikh@rediffmail.com

2016-08-15

Highlights: • Core shell nanorods were synthesised by surfactant assisted hydrothermal method. • Morphology of core shell nanorods resembles those of core nanorods indicating coating of shell on cores. • More uniform and non-aggregated core shell nanorods were prepared in presence of surfactants. • Surfactant assisted prepared core shell nanorods show intense emission as compared to uncoated core nanorods. - Abstract: Core shell GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} nanorods were synthesized via hydrothermal route in the presence of different surfactants [cetyltrimethyl ammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS)]. The nanorods were characterized by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL) studies. The X-ray diffraction results indicate good crystallinity and effective doping in core and core shell nanorods. SEM and TEM micrographs show that all of the as prepared gadolinium phosphate products have rod like shape. The compositional analysis of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core was done by EDS. The emission intensity of the GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell increased significantly with respect to those of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core nanorods. The effect of surfactant on the uniformity, thickness and luminescence of the core shell nanorods was investigated.

Theoretical investigations on the magnetocaloric and barocaloric effects in Tb{sub y}Gd{sub (1−y)}Al{sub 2} series

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, P.O.; Alho, B.P.; Alvarenga, T.S.T.; Nóbrega, E.P. [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Carvalho, A.Magnus G. [Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo – UNIFESP, 12231-280 São José dos Campos, SP (Brazil); Instituto Nacional de Metrologia, Qualidade e Tecnologia – INMETRO, 25250-020 Duque de Caxias, RJ (Brazil); Sousa, V.S.R. de; Caldas, A.; Oliveira, N.A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Ranke, P.J. von, E-mail: von.ranke@uol.com.br [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil)

2013-06-25

Highlights: ► Anisotropic magnetocaloric effect in in Tb{sub 0.4}Gd{sub 0.6}Al{sub 2}. ► Prediction of barocaloric effect in Tb{sub 0.4}Gd{sub 0.6}Al{sub 2}. ►An optimal hybrid magnetocaloric material using Tb{sub y}Gd{sub (1-y)}Al{sub 2} compounds. -- Abstract: We report the calculations on the magnetocaloric and barocaloric effects in ferromagnetic series Tb{sub y}Gd{sub (1−y)}Al{sub 2}. Our model includes the crystalline electrical field interaction, exchange interactions among Tb–Tb, Gd–Gd and Tb–Gd magnetic ions and the Zeeman effect for an anisotropic system. The lattice and electronic entropies were included in adiabatic processes. The magnetocaloric effect calculated for magnetic field changes along the easy magnetic direction 〈1 1 1〉 is in good agreement with the experimental data. Calculation along the hard magnetization direction 〈0 0 1〉 predicts anomalous magnetocaloric effect, which was ascribed to the spin reorientation processes. From the available experimental data of Curie temperature dependence on pressure, the exchange model parameters were scaled and the barocaloric effect was calculated.

Brillouin scattering on TbAsO4 and GdVO4

International Nuclear Information System (INIS)

Wehrle, H.

1975-01-01

Using a two-pass interferometer the set of elastic constants in TbAsO 4 was determined. On the basis of these constants the Debye temperature was evaluated for T→0. The crystallographic phase transition could not be demonstrated in either case (TbAsO 4 and TmAsO 4 ) because of small Brillouin-line intensity in the low-temperature region. The frequency shifts of the Brillouin lines detected in the case of GdVO 4 show an increase of 5% for the temperature change from room temperature to helium temperature. Assuming this dependence for TbAsO 4 , too, the Debye temperature is changed by 5%. (HPOE) [de

Eu{sup 3+}/Tb{sup 3+} doped cubic BaGdF{sub 5} multifunctional nanophosphors: Multicolor tunable luminescence, energy transfer and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Li, Honglan; Liu, Guixia, E-mail: liuguixia22@163.com; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

2017-06-15

A series of BaGdF{sub 5}:Eu{sup 3+}/Tb{sup 3+} orange-green-yellow-white emitting nanophosphors (NPs) were successfully synthesized via hydrothermal method without assistance of any surfactant, catalyst, or template. The nanocrystals are in sphere-like morphology with an average size of approximately 46 nm. The quenching concentrations of Eu{sup 3+} and Tb{sup 3+} single doped BaGdF{sub 5} phosphors are 5.5% and 15%, respectively. The tunable color tone can be obtained in Eu{sup 3+} and Tb{sup 3+} co-doped BaGdF{sub 5} phosphors, the strong orange-white and green-yellow emissions can be seen in BaGdF{sub 5}:5.5%Eu{sup 3+}, y%Tb{sup 3+} and BaGdF{sub 5}:3.5%Tb{sup 3+}, x%Eu{sup 3+} phosphors, especially. More significantly, we realize the more standard white emission with a CIE chromaticity diagram point at (0.317, 0.321) and a lower correlated color temperature of 6979 K in the BaGdF{sub 5}: 5.5%Eu{sup 3+}, 4.5%Tb{sup 3+} sample. In addition, the energy transfer phenomenon from Tb{sup 3+} to Eu{sup 3+} ions is clearly observed in Tb{sup 3+}, Eu{sup 3+} co-doped BaGdF{sub 5} phosphors and the energy transfer efficiency can reach a maximum of 75%. Moreover, the as-prepared samples exhibit paramagnetic properties at room temperature. This type of multifunctional multicolor emitting nanophosphor has promising applications in the fields of full-color displays, biomedical science, MRI, and so on. - Graphical abstract: The cubic phase BaGdF{sub 5}:Eu{sup 3+}/Tb{sup 3+} sphere-like nanophosphors were prepared. Energy transfer mechanism, color-tunable emissions and magnetic properties of BaGdF{sub 5}:Eu{sup 3+}/Tb{sup 3+} have been studied, which could have promising applications in the fields of full-color displays, MRI and biomedical science, and so on.

Magnetic properties of the filled skutterudite-type structure compounds GdRu4P12 and TbRu4P12 synthesized under high pressure

OpenAIRE

Sekine, C; Uchiumi, T; Shirotani, I; Matsuhira, kazuyuki; Sakakibara, T; Goto, T; Yagi, T

2000-01-01

We have succeeded in synthesizing filled skutterudite-type structure compounds GdRu4P12 and TbRu4P12 under high pressure. The magnetic properties of GdRu4P12 and TbRu4P12 have been studied by means of electrical resistivity, magnetic susceptibility, and magnetization measurements. Magnetic experiments suggest that the Gd and Tb ions in the compounds have trivalent state. The compound GdRu4P12 displays features that suggest the occurrence of antiferromagnetic ordering below TN=22 K. In TbRu4P1...

X-ray excited photoluminescence near the giant resonance in solid-solution Gd(1-x)Tb(x)OCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd(1-x)Tb(x)F3.

Science.gov (United States)

Waetzig, Gregory R; Horrocks, Gregory A; Jude, Joshua W; Zuin, Lucia; Banerjee, Sarbajit

2016-01-14

Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb(3+) centers upon excitation in proximity to the giant resonance of the host Gd(3+) ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb(3+) centers upon X-ray excitation near the giant resonance of the host Gd(3+) ions.

Laser-plasma source parameters for Kr, Gd, and Tb ions at 6.6 nm

Energy Technology Data Exchange (ETDEWEB)

Masnavi, Majid; Szilagyi, John; Parchamy, Homaira; Richardson, Martin C. [The Townes Laser Institute, College of Optics and Photonics, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816 (United States)

2013-04-22

There is increasing interest in extreme-ultraviolet (EUV) laser-based lamps for sub-10-nm lithography operating in the region of 6.6 nm. A collisional-radiative model is developed as a post-processor of a hydrodynamic code to investigate emission from resonance lines in Kr, Gd, and Tb ions under conditions typical for mass-limited EUV sources. The analysis reveals that maximum conversion efficiencies of Kr occur at 5 Multiplication-Sign 10{sup 10}W/cm{sup 2}, while for Gd and Tb it was Asymptotically-Equal-To 0.9%/2{pi}sr for laser intensities of (2-5) Multiplication-Sign 10{sup 12}W/cm{sup 2}.

Blue and green emitting Ce3+ and Tb3+ codoped Gd2O3 nanophosphors

International Nuclear Information System (INIS)

Loitongbam, Romeo Singh; Singh, W. Rameshwor

2013-01-01

Tb 3+ doped Gd 2 O 3 nanoparticles of 4-10 nm in size were synthesized from nitrate precursors by urea hydrolysis method in ethylene glycol medium at low temperature of 140 ℃. Characteristic Tb 3+ ion green emission corresponding to 5 D 4 ’! 7 F J was observed to be very strong, which further increases with heat treatment temperature. Characteristic blue color emission of Ce 3+ ion transitions for 5 d’! 2 F 7/2 and 2 F 5/2 (at 422 nm and 485 nm respectively) was found to be very strong in as-synthesized Ce 0.06 Tb 0.14 Gd 0.8 O 3 nanoparticles. However, its luminescence intensity decreases with increase in heating temperature or increase in the particle size/crystallinity, whereas there was a weak emission peak of Tb 3+ ion at 545 nm. The polycrystalline nature of as-prepared sample change to highly crystalline state when heated at elevated temperature (900 ℃). (author)

A template-free solvothermal synthesis and photoluminescence properties of multicolor Gd2O2S:xTb3+, yEu3+ hollow spheres

Science.gov (United States)

Sang, Xiaotong; Xu, Guangxi; Lian, Jingbao; Wu, Nianchu; Zhang, Xue; He, Jiao

2018-06-01

The multicolor Gd2O2S:xTb3+, yEu3+ hollow spheres were successfully synthesized via a template-free solvothermal route without the use of surfactant from commercially available Ln (NO3)3·6H2O (Ln = Gd, Tb and Eu), absolute ethanol, ethanediamine and sublimed sulfur as the starting materials. The phase, structure, particle morphology and photoluminescence (PL) properties of the as-obtained products were investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectra. The influence of synthetic time on phase, structure and morphology was systematically investigated and discussed. The possible formation mechanism depending on synthetic time t for the Gd2O2S phase has been presented. These results demonstrate that the Gd2O2S hollow spheres could be obtained under optimal condition, namely solvothermal temperature T = 220 °C and synthetic time t = 16 h. The as-obtained Gd2O2S sample possesses hollow sphere structure, which has a typical size of about 2.5 μm in diameter and about 0.5 μm in shell thickness. PL spectroscopy reveals that the strongest emission peak for the Gd2O2S:xTb3+ and the Gd2O2S:yEu3+ samples is located at 545 nm and 628 nm, corresponding to 5D4→7F5 transitions of Tb3+ ions and 5D0→7F2 transitions of Eu3+ ions, respectively. The quenching concentration of Tb3+ ions and Eu3+ ions is 7%. In the case of Tb3+ and Eu3+ co-doped samples, when the concentration of Tb3+ or Eu3+ ions is 7%, the optimum concentration of Eu3+ or Tb3+ ions is determined to be 1%. Under 254 nm ultraviolet (UV) light excitation, the Gd2O2S:7%Tb3+, the Gd2O2S:7%Tb3+,1%Eu3+ and the Gd2O2S:7%Eu3+ samples give green, yellow and red light emissions, respectively. And the corresponding CIE coordinates vary from (0.3513, 0.5615), (0.4120, 0.4588) to (0.5868, 0.3023), which is also well consistent with their luminous photographs.

The normal and inverse magnetocaloric effect in RCu2 (R=Tb, Dy, Ho, Er) compounds

International Nuclear Information System (INIS)

Zheng, X.Q.; Xu, Z.Y.; Zhang, B.; Hu, F.X.; Shen, B.G.

2017-01-01

Orthorhombic polycrystalline RCu 2 (R=Tb, Dy, Ho and Er) compounds were synthesized and the magnetic properties and magnetocaloric effect (MCE) were investigated in detail. All of the RCu 2 compounds are antiferromagnetic (AFM) ordered. As temperature increases, RCu 2 compounds undergo an AFM to AFM transition at T t and an AFM to paramagnetic (PM) transition at T N . Besides of the normal MCE around T N , large inverse MCE around T t was found in TbCu 2 compound. Under a field change of 0–7 T, the maximal value of inverse MCE is even larger than the value of normal MCE around T N for TbCu 2 compound. Considering of the normal and inverse MCE, TbCu 2 shows the largest refrigerant capacity among the RCu 2 (R=Tb, Dy, Ho and Er) compounds indicating its potential applications in low temperature multistage refrigeration. - Highlights: • Large inverse magnetocaloric effect is observed in TbCu 2 compound. • The AFM to AFM transition is observed in RCu 2 (R=Tb, Dy, Ho, Er) compounds. • The MCE performance of TbCu 2 compound is evaluated in a more comprehensively way.

Synthesis, structure and photoluminescence of novel lanthanide (Tb(III), Gd(III)) complexes with 6-diphenylamine carbonyl 2-pyridine carboxylate

International Nuclear Information System (INIS)

An Baoli; Gong Menglian; Cheah, Kok-Wai; Wong, Wai-Kwok; Zhang Jiming

2004-01-01

A novel organic ligand, 6-diphenylamine carbonyl 2-pyridine carboxylic acid (HDPAP), and the corresponding lanthanide complexes, tris(6-diphenylamine carbonyl 2-pyridine carboxylato) terbium(III) (Tb-DPAP) and tris(6-diphenylamine carbonyl 2-pyridine carboxylato) gadolinium(III) (Gd-DPAP) have been designed and synthesized. The crystal structure and photoluminescence of Tb-DPAP and Gd-DPAP have been studied. The results showed that the lanthanide complexes have electroneutral structures, and the solid terbium complex emits characteristic green fluorescence of Tb(III) ions at room temperature while the gadolinium complex emits the DPAP ligand phosphorescence. The lowest triplet level of DPAP ligand was calculated from the phosphorescence spectrum of Gd-DPAP in N,N-dimethyl formamide (DMF) dilute solution determined at 77 K, and the energy transfer mechanisms in the lanthanide complexes were discussed. The lifetimes of the 5 D 4 levels of Tb 3+ ions in the terbium complex were examined using time-resolved spectroscopy, and the values are 0.0153±0.0001 ms for solid Tb(DPAP) 3 ·11.5H 2 O and 0.074±0.007 ms for 2.5x10 -5 mol/l Tb-DPAP ethanol solution

RNi{sub 8}Si{sub 3} (R=Gd,Tb): Novel ternary ordered derivatives of the BaCd{sub 11} type

Energy Technology Data Exchange (ETDEWEB)

Pani, M., E-mail: marcella@chimica.unige.it [Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova (Italy); Institute SPIN-CNR, Corso Perrone 24, 16152 Genova (Italy); Morozkin, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow, GSP-2 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Provino, A.; Manfrinetti, P. [Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova (Italy); Institute SPIN-CNR, Corso Perrone 24, 16152 Genova (Italy); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

2016-01-15

The title compounds have been synthesized and characterized both from the structural and magnetic point of view. Both crystallize in a new monoclinic structure strictly related to the tetragonal BaCd{sub 11} type. The structure was solved by means of X-ray single-crystal techniques for GdNi{sub 8}Si{sub 3} and confirmed for TbNi{sub 8}Si{sub 3} on powder data; the corresponding lattice parameters (obtained from Guinier powder patterns) are a=6.3259(2), b=13.7245(5), c=7.4949(3) Å, β=113.522(3)°, V{sub cell}=596.64(3) Å{sup 3} and a=6.3200(2), b=13.6987(4), c=7.4923(2) Å, β=113.494(2)°, V{sub cell}=594.88(2) Å{sup 3}. The symmetry relationship between the tI48-I4{sub 1}/amd BaCd{sub 11} aristotype and the new ordered mS48-C2/c GdNi{sub 8}Si{sub 3} derivative is described via the Bärnighausen formalism within the group theory. The large Gd–Gd (Tb–Tb) distances, mediated via Ni–Si network, likely lead to weak magnetic interactions. Low-field magnetization vs temperature measurements indicate weak and field-sensitive antiferromagnetic ground state, with ordering temperatures of 3 K in GdNi{sub 8}Si{sub 3} and about 2–3 K in TbNi{sub 8}Si{sub 3}. On the other hand, the isothermal field-dependent magnetization data show the presence of competing interactions in both compounds, with a field-induced ferromagnetic behavior for GdNi{sub 8}Si{sub 3} and a ferrimagnetic-like behavior in TbNi{sub 8}Si{sub 3} at the ordering temperature T{sub C/N} of about (or slightly higher than) 3K. The magnetocaloric effect, quantified in terms of isothermal magnetic entropy change ΔS{sub m}, has the maximum values of –19.8 J(kg K){sup −1} (at 4 K for 140 kOe field change) and −12.1 J(kg K){sup −1} (at 12 K for 140 kOe field change) in GdNi{sub 8}Si{sub 3} and TbNi{sub 8}Si{sub 3}, respectively. - Graphical abstract: GdNi{sub 8}Si{sub 3} and TbNi{sub 8}Si{sub 3} compounds are isostructural, and crystallize in a new monoclinic type strictly related to the tetragonal

Curious resistivity behaviour of vacuum evaporated Er, Dy and Gd films

International Nuclear Information System (INIS)

Saxena, U.; Kaul, V.K.; Bist, B.M.; Srivastava, O.N.

1976-01-01

The thickness dependence of electrical resistivity of Er, Dy and Gd thin films at room temperature has been studied. The electrical resistivity of these films does not show the usual behaviour expected on the basis of the size affected conduction i.e. Fuchs Sondheimer theory, which always leads to an increase in the resistivity with decreasing film thickness. Instead, the observed resistivity behaviour is characterised mainly by (i) a decrease in resistivity with decreasing film thickness (between 1600-1000 deg A) for Er films and below about 500 deg A for Gd and Dy films), (ii) a thickness independent resistivity behaviour for Er films from 1000-600 deg A, (iii) increase in resistivity of Er films in the thickness region 600-200 deg A, (iv) the resistivity values in certain thickness regions, which are even less than the corresponding bulk value. Analysis reveals that those curious rho-t characteristics arise due to three effects namely, the increase resistivity due to surface scattering the suppression of resistivity due to thickness dependence of structural phase and spin disorder scattering. All the effects are dominant in thickness regions, different in different metals giving rise to the observed characteristics. (author)

Rare Earth Chalcogels NaLnSnS4 (Ln = Y, Gd, Tb) for Selective Adsorption of Volatile Hydrocarbons and Gases

KAUST Repository

Edhaim, Fatimah

2017-06-28

The synthesis and characterization of the rare earth chalcogenide aerogels NaYSnS4, NaGdSnS4, and NaTbSnS4 is reported. Rare earth metal ions like Y3+, Gd3+, and Tb3+ react with the chalcogenide clusters [SnS4]4– in aqueous formamide solution forming extended polymeric networks by gelation. Aerogels obtained after supercritical drying have BET surface areas of 649 m2·g–1 (NaYSnS4), 479 m2·g–1 (NaGdSnS4), and 354 m2·g–1 (NaTbSnS4). Electron microscopy and physisorption studies reveal that the new materials have pores in the macro (above 50 nm) and meso (2–50 nm) regions. These aerogels show higher adsorption of toluene vapor over cyclohexane vapor and CO2 over CH4 or H2. The notable adsorption capacity for toluene (NaYSnS4: 1108 mg·g–1; NaGdSnS4: 921 mg·g–1; and NaTbSnS4: 645 mg·g–1) and high selectivity for gases (CO2/H2: 172 and CO2/CH4: 50 for NaYSnS4, CO2/H2: 155 and CO2/CH4: 37 for NaGdSnS4, and CO2/H2: 75 and CO2/CH4: 28 for NaTbSnS4) indicate potential future use of chalcogels in adsorption-based gas or hydrocarbon separation processes.

Polarized spectroscopic properties of Er3+:Gd2SiO5 crystal and evaluation of Er3+:Yb3+:Gd2SiO5 crystal as a 1.55 μm laser medium

International Nuclear Information System (INIS)

Wang, H.; Huang, J.H.; Gong, X.H.; Chen, Y.J.; Lin, Y.F.; Luo, Z.D.; Huang, Y.D.

2016-01-01

An Er 3+ -doped Gd 2 SiO 5 single crystal with high optical quality has been grown by the Czochralski method. Polarized absorption and fluorescence spectra and fluorescence lifetime of the crystal were measured at room temperature. Intensity parameters, spontaneous emission probabilities, fluorescence branching ratios, and radiative lifetimes were estimated on the basis of the Judd–Ofelt theory. Besides, potentiality of 1.55 μm laser emission in an Er 3+ –Yb 3+ co-doped Gd 2 SiO 5 crystal was evaluated.

Host-Sensitized and Tunable Luminescence of GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) Nanocrystalline Phosphors with Abundant Color.

Science.gov (United States)

Liu, Xiaoming; Chen, Chen; Li, Shuailong; Dai, Yuhua; Guo, Huiqin; Tang, Xinghua; Xie, Yu; Yan, Liushui

2016-10-17

Up to now, GdNbO 4 has always been regarded as an essentially inert material in the visible region with excitation of UV light and electron beams. Nevertheless, here we demonstrate a new recreating blue emission of GdNbO 4 nanocrystalline phosphors with a quantum efficiency of 41.6% and host sensitized luminescence in GdNbO 4 :Ln 3+ (Ln 3+ = Eu 3+ /Tb 3+ /Tm 3+ ) nanocrystalline phosphors with abundant color in response to UV light and electron beams. The GdNbO 4 and GdNbO 4 :Ln 3+ (Ln 3+ = Eu 3+ /Tb 3+ /Tm 3+ ) nanocrystalline phosphors were synthesized by a Pechini-type sol-gel process. With excitation of UV light and low-voltage electron beams, the obtained GdNbO 4 nanocrystalline phosphor presents a strong blue luminescence from 280 to 650 nm centered around 440 nm, and the GdNbO 4 :Ln 3+ nanocrystalline phosphors show both host emission and respective emission lines derived from the characterize f-f transitions of the doping Eu 3+ , Tb 3+ , and Tm 3+ ions. The luminescence color of GdNbO 4 :Ln 3+ nanocrystalline phosphors can be tuned from blue to green, red, blue-green, orange, pinkish, white, etc. by varying the doping species, concentration, and relative ratio of the codoping rare earth ions in GdNbO 4 host lattice. A single-phase white-light-emission has been realized in Eu 3+ /Tb 3+ /Tm 3+ triply doped GdNbO 4 nanocrystalline phosphors. The luminescence properties and mechanisms of GdNbO 4 and GdNbO 4 :Ln 3+ (Ln 3+ = Eu 3+ /Tb 3+ /Tm 3+ ) are updated.

Kinetics of electrophilic exchange of lanthanide(3) and copper(2) ions in aqueous solutions of ethylenediaminetetraacetates. [Rare earths: La,Pr,Nd,Eu,Gd,Tb,Er,Yb

Energy Technology Data Exchange (ETDEWEB)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I.; Spitsyn, V.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

1984-05-01

Electrophilic exchange in the MA/sup -/ - Cu/sup 2 +/ (M/sup 3 +/=La/sup 3 +/, PUPSILON/sup 3 +/, Nd/sup 3 +/, Eu/sup 3 +/, Gd/sup 3 +/, Tb/sup 3 +/, Er/sup 3 +/, Yb/sup 3 +/, A/sup 4 -/=ethylenediaminetetraacetate) systems is studied. Copper is chosen as a constituent cation, because the stability of the CuA/sup 2 +/- complex is higher than that of the MA/sup -/ complex, besides the CuA/sup 2 -/, is characterized by a high extinction coefficient E/sub 280/=3200. Electrophilic exchange in the systems is shown to be realized through the acid dissociation mechanism and through the association mechanism. Consideration of the acid dissociation mechanism assumes that the exchange is limited by a break in the metal-oxygen bond in the intermediate protonated complex. In case of the association mechanism it is limited by a break in the metal-nitrogen bond in the intermediate binuclear complex. Rate constants of the limiting stage are calculated. Dependences of the rate constants of exchange on the stability of the complexes, the order number of the element, acidity of medium, Cu/sup 2 +/ concentration are given. Differences are shown to exist between the exchange mechanisms in the studied: systems for the REE of cerium and yttrium subgroups.

Superdeformed bands in /sup 150/Gd and /sup 151/Tb: Evidence for the influence of high-N intruder states at large deformations

Energy Technology Data Exchange (ETDEWEB)

Fallon, P.; Alderson, A.; Bentley, M.A.; Bruce, A.M.; Forsyth, P.D.; Howe, D.; Roberts, J.W.; Sharpey-Schafer, J.F.; Twin, P.J.; Beck, F.A.

1989-02-16

Rotational bands, characteristic of a superdeformed prolate shape (epsilon approx. = 0.6) and extending to above spin 60 Planck constant, have been observed in both /sup 150/Gd and /sup 151/Tb. The magnitudes of the moments of inertia I/sup (2)/ were found to vary with frequency and the variation greatly exceeded that seen in /sup 148,149/Gd and /sup 151,152/Dy. The differences in the I/sup (2)/'s are attributed to the occupation of particular high-N orbitals. Moreover, contrary to the previous examples the bands in both /sup 150/Gd and /sup 151/Tb de-excited at a much higher rotational frequency of Planck constant..omega.. approx. = 0.4 MeV and this may indicate that the pair gap extends to higher frequencies in /sup 150/Gd and /sup 151/Tb.

Study of the influence of the codopant over the photoluminescent properties of PAA doped with Eu3+, Gd3+, and Tb3+

International Nuclear Information System (INIS)

Flores, M.; Arroyo, R.

2003-01-01

The results are presented obtained about the synthesis of acrylic poly acid characterization (PAA) doped with Eu 3+ , Gd 3+ and Tb 3+ . They got ready materials with even of these ions and it was studied the influence of the co dopant in the processes of emission of Eu 3+ (λ em = 618 nm), Gd 3+ (λ em = 624 nm) and Tb 3+ (λ em = 546 nm), as well as their effect in the phosphorescence (λ em = 450 nm) of the polymeric matrix. It was found that the intensity of the emission of Eu 3+ diminishes substantially due to the presence of the ions Gd 3+ , contrary to what happens when the co dopant is Tb 3+ , which causes an increase. In the one case of the emission of Tb 3+ , this it increases with the presence of Gd 3+ but it diminishes when Eu 3+ is present. These results are consequence of the homogeneous distribution of those dopants and of the phenomena of energy transfer that happen in the materials synthesized. (Author)

A study of luminescence from Eu"3"+, Ce"3"+, Tb"3"+ and Ce"3"+/Tb"3"+ in new potassium gadolinium phosphate K_3Gd_5(PO_4)_6

International Nuclear Information System (INIS)

Meng, Fangui; Zhang, Hongzhi; Chen, Cuili; Kim, Sun Il; Seo, Hyo Jin; Zhang, Xinmin

2016-01-01

New potassium gadolinium phosphate [K_3Gd_5(PO_4)_6] doped with Eu"3"+, Ce"3"+, Tb"3"+ and co-doped with Ce"3"+ and Tb"3"+ phosphors were prepared by high temperature solid state synthesis. Phase purity of the powders was checked by X-ray powder diffraction. Luminescence and excitation spectra of samples were reported. In particular, the interaction mechanism between Eu"3"+ ions was investigated in terms of the Inokuti–Hirayama model; it was found that the interactions between Eu"3"+ can be assigned to dipole–dipole interaction. K_3Gd_5(PO_4)_6:Eu"3"+ could act as a candidate for solid state lighting due to its strong absorption band in the near-UV region (350–400 nm). The energy transfer from Ce"3"+ to Tb"3"+ was confirmed and the mechanism was studied using Dexter's theory; it is concluded that electric dipole–dipole interaction predominates in the energy transfer process from Ce"3"+ to Tb"3"+ in the K_3Gd_5(PO_4)_6 host. The energy transfer efficiency and critical distance were also investigated. - Highlights: • Optical properties of K_3Gd_5(PO_4)_6:RE"3"+ are investigated for the first time. • The interaction mechanism between Eu"3"+ ions is attributed to dipole–dipole type. • K_3Eu_5(PO_4)_6 is a candidate phosphor for application to solid state lighting. • There exists an efficient energy transfer from Ce"3"+ to Tb"3"+ (η is up to 95%). • The mechanism of energy transfer process is electric dipole–dipole interaction.

Multifunctional hydroxyapatite/Na(Y/Gd)F4:Yb3+,Er3+ composite fibers for drug delivery and dual modal imaging.

Science.gov (United States)

Liu, Min; Liu, Hui; Sun, Shufen; Li, Xuejiao; Zhou, Yanmin; Hou, Zhiyao; Lin, Jun

2014-02-04

Porous hydroxyapatite (HAp) composite fibers functionalized with up-conversion (UC) luminescent and magnetic Na(Y/Gd)F4:Yb(3+),Er(3+) nanocrystals (NCs) have been fabricated via electrospinning. After transferring hydrophobic oleic acid-capped Na(Y/Gd)F4:Yb(3+),Er(3+) NCs into aqueous solution, these water-dispersible NCs were dispersed into precursor electrospun solution containing CTAB. Na(Y/Gd)F4:Yb(3+),Er(3+)@HAp composite fibers were fabricated by the high temperature treatment of the electrospun Na(Y/Gd)F4:Yb(3+),Er(3+) NCs decorated precursor fibers. The biocompatibility test on MC 3T3-E1 cells using MTT assay shows that the HAp composite fibers have negligible cytotoxity, which reveals the HAp composite fibers could be a drug carrier for drug delivery. Because the contrast brightening is enhanced at increased concentrations of Gd(3+), the HAp composite fibers can serve as T1 magnetic resonance imaging contrast agents. In addition, the composites uptaken by MC 3T3-E1 cells present the UC luminescent emission of Er(3+) under the excitation of a 980 nm near-infrared laser. The above findings reveal Na(Y/Gd)F4:Yb(3+),Er(3+)@HAp composite fibers have potential applications in drug storage/release and magnetic resonance/UC luminescence imaging.

Radioluminescence studies of colloidal oleate-capped β-Na(Gd,Lu)F4:Ln3+ nanoparticles (Ln = Ce, Eu, Tb).

Science.gov (United States)

Cooper, Daniel R; Capobianco, John A; Seuntjens, Jan

2018-04-26

We report on the synthesis, characterization, and radioluminescence quantification of several new varieties of nanoparticles with the general composition β-NaLnF4, incorporating known luminescent activator/sensitizer pairs. Using Monte Carlo modeling to complement luminescence measurements, we have calculated the radioluminescence yields and intrinsic conversion efficiencies of colloidally-dispersed nanoparticles by comparison to an organic liquid scintillator. While five of the compositions had low to modest radioluminescence yields relative to bulk materials, colloidal β-Na(Lu0.65Gd0.2Tb0.15)F4 displayed a strong output of 39 460 photons per MeV absorbed, comparable to some of the best non-hygroscopic bulk crystal scintillators and X-ray phosphors such as Gd2O2S:Tb. Measurements of β-Na(Lu0.65Gd0.2Tb0.15)F4 powder samples revealed persistent luminescence as well as stable charge trapping, warranting further investigation.

Optical and magneto-optical characterization of TbFeCo and GdFeCo thin films for high-density recording

International Nuclear Information System (INIS)

Hendren, W R; Atkinson, R; Pollard, R J; Salter, I W; Wright, C D; Clegg, W W; Jenkins, D F L

2003-01-01

Thin, optically semi-infinite films of amorphous TbFeCo and GdFeCo, suitable for magneto-optical recording, have been deposited by DC magnetron sputtering onto glass. Ellipsometric techniques have been used to determine the complex refractive index and complex magneto-optical parameter of the films in the wavelength range 400-900 nm, thus characterizing the materials. A review of the literature is presented and shows that the results for the TbFeCo films compare favourably with published results obtained from measurements conducted in situ, with the films protected with ZnS barrier layers. It is found that GdFeCo and TbFeCo are optically very similar, but magneto-optically the materials are quite different

Optical and magneto-optical characterization of TbFeCo and GdFeCo thin films for high-density recording

Energy Technology Data Exchange (ETDEWEB)

Hendren, W R [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Atkinson, R [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Pollard, R J [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Salter, I W [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Wright, C D [School of Engineering and Computer Science, University of Exeter, Exeter EX4 4QF (United Kingdom); Clegg, W W [CRIST, University of Plymouth, Plymouth PL4 8AA (United Kingdom); Jenkins, D F L [CRIST, University of Plymouth, Plymouth PL4 8AA (United Kingdom)

2003-03-12

Thin, optically semi-infinite films of amorphous TbFeCo and GdFeCo, suitable for magneto-optical recording, have been deposited by DC magnetron sputtering onto glass. Ellipsometric techniques have been used to determine the complex refractive index and complex magneto-optical parameter of the films in the wavelength range 400-900 nm, thus characterizing the materials. A review of the literature is presented and shows that the results for the TbFeCo films compare favourably with published results obtained from measurements conducted in situ, with the films protected with ZnS barrier layers. It is found that GdFeCo and TbFeCo are optically very similar, but magneto-optically the materials are quite different.

Study of the influence of the codopant over the photoluminescent properties of PAA doped with Eu{sup 3+}, Gd{sup 3+}, and Tb{sup 3+}; Estudio de la influencia del codopante sobre las propiedades fotoluminiscentes de PAA dopado con Eu{sup 3+}, Gd{sup 3+} y Tb{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Flores, M.; Arroyo, R. [Departamento de Fisica, UAM-I, A.P. 55-534, 09820 Mexico D.F. (Mexico)

2003-07-01

The results are presented obtained about the synthesis of acrylic poly acid characterization (PAA) doped with Eu{sup 3+}, Gd{sup 3+} and Tb{sup 3+}. They got ready materials with even of these ions and it was studied the influence of the co dopant in the processes of emission of Eu{sup 3+} ({lambda}{sub em} = 618 nm), Gd{sup 3+} ({lambda}{sub em} = 624 nm) and Tb{sup 3+} ({lambda}{sub em} = 546 nm), as well as their effect in the phosphorescence ({lambda}{sub em} = 450 nm) of the polymeric matrix. It was found that the intensity of the emission of Eu{sup 3+} diminishes substantially due to the presence of the ions Gd{sup 3+}, contrary to what happens when the co dopant is Tb{sup 3+} , which causes an increase. In the one case of the emission of Tb{sup 3+}, this it increases with the presence of Gd{sup 3+} but it diminishes when Eu{sup 3+} is present. These results are consequence of the homogeneous distribution of those dopants and of the phenomena of energy transfer that happen in the materials synthesized. (Author)

Reversal of the sign of giant magnetoresistance upon boron filling in RPd{sub 3} compounds (R=Tb,Er)

Energy Technology Data Exchange (ETDEWEB)

Pandey, Abhishek [S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata-700098 (India); Mazumdar, Chandan; Ranganathan, R, E-mail: abhishek.phy@gmail.co, E-mail: chandan.mazumar@saha.ac.i, E-mail: r.ranganathan@saha.ac.i [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata-700064 (India)

2010-01-01

We report the study of magnetic and transport properties of binary intermetallic compounds RPd{sub 3} (R: Tb and Er) and boron-filled perovskite compounds RPd{sub 3}B. Our results suggest that the magnetic and transport behavior of boron-filled compositions is substantially different compared to that of undoped compounds. For example, TbPd{sub 3} and ErPd{sub 3} exhibit negative magnetoresistance, while boron-filled TbPd{sub 3}B and ErPd{sub 3}B shows positive magnetoresistance. In addition, our results also suggest that there exists a strong correlation between magnetic and electrical-transport behavior of these systems.

Effect of rapid quenching on the magnetism and magnetocaloric effect of equiatomic rare earth intermetallic compounds RNi (R = Gd, Tb and Ho)

Energy Technology Data Exchange (ETDEWEB)

Rajivgandhi, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Arout Chelvane, J. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Quezado, S.; Malik, S.K. [Departamento de F’ısica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59072-970 (Brazil); Nirmala, R., E-mail: nirmala@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India)

2017-07-01

Highlights: • Melt-spinning yields microcrystalline RNi (R = Gd, Tb and Ho) samples with texture. • The texture-induced anisotropy affects magnetic and magnetocaloric properties. • Melt-spinning helps one engineer magnetocaloric effect in rare-earth compounds. - Abstract: Magnetocaloric effect (MCE) in RNi (where R = Gd, Tb and Ho) compounds has been studied in their arc-melted and melt-spun forms. The compound GdNi has the orthorhombic CrB-type structure (Space group Cmcm, No. 63) and the compound HoNi has the orthorhombic FeB-type structure (Space group Pnma, No. 62) at room temperature regardless of their synthesis condition. However, arc-melted TbNi orders in a monoclinic structure (Space group P2{sub 1}/m, No. 11) and when it is rapidly quenched to a melt-spun form, it crystallizes in an orthorhombic structure (Space group Pnma, No. 62). The arc-melted GdNi, TbNi and HoNi compounds order ferromagnetically at ∼69 K, ∼67 K and ∼36 K (T{sub C}) respectively. While the melt-spun GdNi shows about 6 K increase in T{sub C}, the ordering temperature of TbNi remains nearly the same in both arc-melted and melt-spun forms. In contrast, a reduction in T{sub C} by about 8 K is observed in melt-spun HoNi, when compared to its arc-melted counterpart. Isothermal magnetic entropy change, ∆S{sub m}, calculated from the field dependent magnetization data indicates an enhanced relative cooling power (RCP) for melt-spun GdNi for field changes of 20 kOe and 50 kOe. A lowered RCP value is observed in melt-spun TbNi and HoNi. These changes could have resulted from the competing shape anisotropy and the granular microstructure induced by the melt-spinning process. Tailoring the MCE of rare earth intermetallic compounds by suitably controlled synthesis techniques is certainly one of the directions to go forward in the search of giant magnetocaloric materials.

Rare earth chalcogels NaLnSnS{sub 4} (Ln = Y, Gd, Tb) for selective adsorption of volatile hydrocarbons and gases

Energy Technology Data Exchange (ETDEWEB)

Edhaim, Fatimah; Rothenberger, Alexander [Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

2017-08-16

The synthesis and characterization of the rare earth chalcogenide aerogels NaYSnS{sub 4}, NaGdSnS{sub 4}, and NaTbSnS{sub 4} is reported. Rare earth metal ions like Y{sup 3+}, Gd{sup 3+}, and Tb{sup 3+} react with the chalcogenide clusters [SnS{sub 4}]{sup 4-} in aqueous formamide solution forming extended polymeric networks by gelation. Aerogels obtained after supercritical drying have BET surface areas of 649 m{sup 2}.g{sup -1} (NaYSnS{sub 4}), 479 m{sup 2}.g{sup -1} (NaGdSnS{sub 4}), and 354 m{sup 2}.g{sup -1} (NaTbSnS{sub 4}). Electron microscopy and physisorption studies reveal that the new materials have pores in the macro (above 50 nm) and meso (2-50 nm) regions. These aerogels show higher adsorption of toluene vapor over cyclohexane vapor and CO{sub 2} over CH{sub 4} or H{sub 2}. The notable adsorption capacity for toluene (NaYSnS{sub 4}: 1108 mg.g{sup -1}; NaGdSnS{sub 4}: 921 mg.g{sup -1}; and NaTbSnS4: 645 mg.g{sup -1}) and high selectivity for gases (CO{sub 2}/H{sub 2}: 172 and CO{sub 2}/CH{sub 4}: 50 for NaYSnS{sub 4}, CO{sub 2}/H{sub 2}: 155 and CO{sub 2}/CH{sub 4}: 37 for NaGdSnS{sub 4}, and CO{sub 2}/H{sub 2}: 75 and CO{sub 2}/CH{sub 4}: 28 for NaTbSnS{sub 4}) indicate potential future use of chalcogels in adsorption-based gas or hydrocarbon separation processes. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Spectral properties of Er{sup 3+}-doped CaGdAlO{sub 4} crystal for laser application around 1.55 μm

Energy Technology Data Exchange (ETDEWEB)

Huang, J.H.; Gong, X.H.; Chen, Y.J.; Lin, Y.F; Luo, Z.D.; Huang, Y.D., E-mail: huyd@fjirsm.ac.cn

2014-02-05

Highlights: • Detailed spectral properties of the Er:CaGdAlO{sub 4} crystal have been investigated. • Multi-phonon relaxation rate of Er{sup 3+} ions in the Er:CaGdAlO{sub 4} crystal is estimated. • The quantum efficiency of the {sup 4}I{sub 13/2} level in the Er:CaGdAlO{sub 4} crystal is near 100%. -- Abstract: Room-temperature polarized spectral properties of the Er:CaGdAlO{sub 4} crystal are reported. The Judd–Ofelt theory was applied to analyze the polarized absorption spectra and then calculate the spontaneous emission probabilities, radiative lifetimes, and branch ratios. Room-temperature fluorescence lifetimes of the {sup 4}I{sub 13/2}, {sup 4}I{sub 11/2}, {sup 4}F{sub 9/2}, and {sup 4}S{sub 3/2} multiplets for Er{sup 3+} ions were measured. Stimulated emission cross-sections of the {sup 4}I{sub 13/2} → {sup 4}I{sub 15/2} transition obtained by the Fuchtbauer–Ladenberg formula and the reciprocity method were compared. The results show that the Er:CaGdAlO{sub 4} crystal may be a potential gain medium for a low-threshold 1.55 μm laser.

Modifying the size and uniformity of upconversion Yb/Er:NaGdF4 nanocrystals through alkaline-earth doping.

Science.gov (United States)

Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng

2013-11-21

NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times.

High-speed magnetization reversal near the compensation temperature of amorphous GdTbFe

International Nuclear Information System (INIS)

Aeschlimann, M.; Vaterlaus, A.; Lutz, M.; Stampanoni, M.; Meier, F.; Siegmann, H.C.; Klahn, S.; Hansen, P.

1991-01-01

Using spin-polarized photoemission with a pulsed laser as light source, it is shown that the time for a thermally induced magnetization reversal depends critically on the temperature of the sample. For amorphous GdTbFe the time is shorter (longer) than the duration of the 16 ns laser pulses if the initial temperature is below (above) the compensation temperature

Neutron diffraction and magnetization studies of Tb0.5Er0.5 single crystal in an external magnetic field

International Nuclear Information System (INIS)

Kosugi, T.; Yamamoto, N.

1999-01-01

Complete text of publication follows. The rare earth Tb 0.5 Er 0.5 alloy exhibits a tilted helix at low temperatures [1]. However, the magnetic structures of Tb 0.5 Er 0.5 and the magnetization processes of the tilted helix are not clear. Neutron diffraction experiments in external magnetic fields and magnetization measurements of Tb 0.5 Er 0.5 single crystal have been performed. At zero magnetic field, the Tb 0.5 Er 0.5 alloy exhibited a normal helix below 170 K, a bunching normal helix below about 28 K, and finally a bunching tilted helix below about 25 K. Below about 60 K, the helical pitch 30 deg showed a lock-in feature. The magnetization measurements at low temperatures showed a four-step magnetic transition. The results are presented as a magnetic field-temperature (H-T) phase diagram. (author) [1] H. Fujii et al., J. Phys. Soc. Jpn. 50 (1981) 2939

Morphotropic phase boundary and magnetoelastic behaviour in ferromagnetic Tb{sub 1−x}Gd{sub x}Fe{sub 2} system

Energy Technology Data Exchange (ETDEWEB)

Adil, Murtaza; Yang, Sen, E-mail: yang.sen@mail.xjtu.edu.cn; Mi, Meng; Zhou, Chao, E-mail: zhouch1982@gmail.com; Wang, Jieqiong; Zhang, Rui; Liao, Xiaoqi; Wang, Yu; Ren, Xiaobing; Song, Xiaoping, E-mail: xpsong@mail.xjtu.edu.cn [School of Sciences, Frontier Institute of Science and Technology, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ren, Yang [X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2015-03-30

Morphotropic phase boundary (MPB), separating two ferroic phases of different crystal symmetries, has been studied extensively for its extraordinary enhancement of piezoelectricity in ferroelectrics. Based on the same mechanism, we have designed a magnetic MPB in the pseudobinary ferromagnetic system of Tb{sub 1−x}Gd{sub x}Fe{sub 2} and the corresponding crystal structure, magnetic properties, and magnetostriction are explored. With the synchrotron x-ray diffractometry, the structure symmetry of TbFe{sub 2}-rich compositions is detected to be rhombohedral (R) and that of GdFe{sub 2}-rich compositions is tetragonal (T) below T{sub c}. With the change of concentration, the value of magnetostriction of the samples changes monotonously, while the MPB composition Tb{sub 0.1}Gd{sub 0.9}Fe{sub 2}, which corresponds to the coexistence of R and T phases, exhibits the maximum magnetization among all available compositions and superposition of magnetostriction behaviour of R and T phases. Our result of MPB phenomena in ferromagnets may provide an effective route to design functional magnetic materials with exotic properties.

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.

Optical thermometry based on green upconversion emission in Er3+/Yb3+ codoped BaGdF5 glass ceramics

Science.gov (United States)

Wu, Ting; Zhao, Shilong; Lei, Ruoshan; Huang, Lihui; Xu, Shiqing

2018-02-01

Er3+/Yb3+ codoped BaGdF5 glass ceramics have been prepared and used to develop a portable all-fiber temperature sensor based on fluorescence intensity ratio technique. XRD and TEM results affirm the generation of BaGdF5 nanocrystals in the borosilicate glass. Eu3+ ions are used as spectral probe to investigate external environment around rare earth (RE) ions. Intense green upconversion emissions from Er3+ ions are detected in the BaGdF5 glass ceramics and their intensity are enhanced about three orders of magnitude after heat treatment, which is attributed to the enrichment of RE ions in the BaGdF5 phase. Based on green upconversion emission from Er3+ ions, the temperature sensing property of the portable all-fiber temperature sensor is studied. The maximum absolute sensitivity is 15.5 × 10-4 K-1 at 567 K and the relative sensitivity is 1.28% K-1 at 298 K, respectively.

Magnetic properties of CaCu{sub 5}-type RNi{sub 3}TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds

Energy Technology Data Exchange (ETDEWEB)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Knotko, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Yao, Jinlei [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Yuan, Fang; Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

2015-12-15

Magnetic properties and magnetocaloric effect of CaCu{sub 5}-type RNi{sub 3}TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds have been investigated. Magnetic measurements of RNi{sub 3}TSi display the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’. In contrast to GdNi{sub 3}{Mn, Fe, Co}Si, TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi{sub 4}Si (~0.5 kOe) to TbNi{sub 3}CoSi (4 kOe), TbNi{sub 3}MnSi (13 kOe) and TbNi{sub 3}FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi{sub 3}CuSi exhibits a negligible coercive field. - Graphical abstract: Magnetic measurements of RNi{sub 3}TSi show the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of 'RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi'. In contrast to GdNi{sub 3}{Mn, Fe, Co}Si, TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi{sub 4}Si (~0.5 kOe) to TbNi{sub 3}CoSi (4 kOe), TbNi{sub 3}MnSi (13 kOe) and TbNi{sub 3}FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi{sub 3}CuSi exhibits a negligible coercive field. - Highlights: • CaCu{sub 5}-type RNi{sub 3}TSi show ferromagnetic ordering (R=Gd, Tb, T=Mn–Co, Cu). • Curie point increases in ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’ row. • MCE decreases in ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’ row. • TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. • The coercive field of TbNi{sub 3}MnSi and TbNi{sub 3}FeSi reach 13 kOe and 16 kOe at 5 K.

'Gigantic' increase of AFMR frequencies induced by nonmagnetic impurity ions in orthoferrites RFe1-xAlxO3 (R=Gd,Tb)

International Nuclear Information System (INIS)

Mukhin, A.A.; Parsegov, I.Yu.

1996-01-01

We observed a 'gigantic' increase (up to three times) of the AFMR frequencies ν 1,2 with decreasing temperature in GdFe 0.9 Al 0.1 O 3 and TbFe 0.925 Al 0.075 O 3 in contrast to pure GdFeO 3 and TbFeO 3 . The effects observed are explained by the appearance of an additional exchange field H mv ∼20 -36 kOe on rare-earth ions due to decompensation of the surrounding antiferromagnetically ordered Fe ions near nonmagnetic impurity ions. (orig.)

Folic acid-conjugated GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2} Nanoprobe for folate receptor-targeted optical and magnetic resonance bi-modal imaging

Energy Technology Data Exchange (ETDEWEB)

Xu, Xianzhu [Jiangxi Normal University, College of Life Science, Jiangxi Provincial Key Laboratory of Protection and Utilization of Subtropical Plant Resources of Jiangxi Province (China); Zhang, Xiaoying; Wu, Yanli, E-mail: Wanny118@126.com [Jiangxi Science and Technology Normal University, Jiangxi Key Laboratory of Organic Chemistry (China)

2016-11-15

Both fluorescent and magnetic nanoprobes have great potential applications for diagnostics and therapy. In the present work, a folic acid-conjugated and silica-modified GdPO{sub 4}:Tb{sup 3+} (GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA) dual nanoprobe was strategically designed and synthesized for the targeted dual-modality optical and magnetic resonance (MR) imaging via a facile aqueous method. Their structural, optical, and magnetic properties were determined using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet-visible spectra (UV-Vis), photoluminescence (PL), and superconducting quantum interference device (SQUID). These results indicated that GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA were uniform monodisperse core-shell structured nanorods (NRs) with an average length of ~200 nm and an average width of ~25 nm. The paramagnetic property of the synthesized GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA NRs was confirmed with its linear hysteresis plot (M-H). In addition, the NRs displayed an obvious T{sub 1}-weighted effect and thus it could potentially serve as a T{sub 1}-positive contrast agent. The NRs emitted green lights due to the {sup 5}D{sub 4} → {sup 7}F{sub 5} transition of the Tb{sup 3+}. The in vitro assays with NCI-H460 lung cancer cells and human embryonic kidney cell line 293T cells indicated that the GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA nanoprobe could specifically bind the cells bearing folate receptors (FR). The MTT assay of the NRs revealed that its cytotoxicity was very low. Further in vivo MRI experiments distinctively depict enhanced anatomical features in a xenograft tumor. These results suggest that the GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA NPs have excellent imaging and cell-targeting abilities for the folate receptor-targeted dual-modality optical and MR imaging and can be potentially used as the nanoprobe for bioimaging.

Polarized spectroscopic properties of Er{sup 3+}:Gd{sub 2}SiO{sub 5} crystal and evaluation of Er{sup 3+}:Yb{sup 3+}:Gd{sub 2}SiO{sub 5} crystal as a 1.55 μm laser medium

Energy Technology Data Exchange (ETDEWEB)

Wang, H. [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Huang, J.H.; Gong, X.H.; Chen, Y.J.; Lin, Y.F.; Luo, Z.D. [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang, Y.D., E-mail: huyd@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2016-10-01

An Er{sup 3+}-doped Gd{sub 2}SiO{sub 5} single crystal with high optical quality has been grown by the Czochralski method. Polarized absorption and fluorescence spectra and fluorescence lifetime of the crystal were measured at room temperature. Intensity parameters, spontaneous emission probabilities, fluorescence branching ratios, and radiative lifetimes were estimated on the basis of the Judd–Ofelt theory. Besides, potentiality of 1.55 μm laser emission in an Er{sup 3+}–Yb{sup 3+} co-doped Gd{sub 2}SiO{sub 5} crystal was evaluated.

Luminescence and energy transfer of Tb3+-doped BaO-Gd2O3-Al2O3-B2O3-SiO2 glasses.

Science.gov (United States)

Zuo, Chenggang; Huang, Jinze; Liu, Shaoyou; Xiao, Anguo; Shen, Youming; Zhang, Xiangyang; Zhou, Zhihua; Zhu, Ligang

2017-12-05

Transparent Tb 3+ -doped BaO-Gd 2 O 3 -Al 2 O 3 -B 2 O 3 -SiO 2 glasses with the greater than 4g/cm 3 were prepared by high temperature melting method and its luminescent properties have been investigated by measured UV-vis transmission, excitation, emission and luminescence decay spectra. The transmission spectrum shows there are three weak absorption bands locate at about 312, 378 and 484nm in the glasses and it has good transmittance in the visible spectrum region. Intense green emission can be observed under UV excitation. The effective energy transfer from Gd 3+ ion to Tb 3+ ion could occur and sensitize the luminescence of Tb 3+ ion. The green emission intensity of Tb 3+ ion could change with the increasing SiO 2 /B 2 O 3 ratio in the borosilicate glass matrix. With the increasing concentration of Tb 3+ ion, 5 D 4 → 7 F J transitions could be enhanced through the cross relaxation between the two nearby Tb 3+ ions. Luminescence decay time of 2.12ms from 546nm emission is obtained. The results indicate that Tb 3+ -doped BaO-Gd 2 O 3 -Al 2 O 3 -B 2 O 3 -SiO 2 glasses would be potential scintillating material for applications in X-ray imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of Er3+/Yb3+ concentration ratio on the down-conversion and up-conversion luminescence and lifetime in GdVO4:Er3+/Yb3+ microcrystals

Directory of Open Access Journals (Sweden)

Gavrilović T.V.

2015-01-01

Full Text Available In this paper, we studied the effects of Er3+/Yb3+ concentration ratio on structural, morphological and luminescence properties of GdVO4:Er3+/Yb3+ green phosphors prepared by a high-temperature solid state method. The samples with different concentrations (between 0.5 to 2 mol% of dopant Er3+ emitting ions and different concentrations (between 5 to 20 mol% of sensitizer ions (Yb3+ were studied. The phosphors were characterized by the X-ray diffraction (XRD, scanning electron microscopy (SEM and photoluminescence spectroscopy. For all samples, XRD diffraction patterns confirmed a formation of a pure GdVO4 phase, while the SEM showed that the materials are comprised of chunks of deformed particles with an average diameter ranging from approximately 2 μm to 8 μm. Both, down-conversion and up-conversion emission spectra of GdVO4:Er3+/Yb3+ samples, under near UV and IR excitations, exhibit two strong emission bands in the green spectral region at 525 nm and 552 nm wavelengths corresponding to 2H11/2 →4I15/2 and 4S3/2 → 4I15/2 electronic transitions of Er3+ ions. The intensity of the green emission was changed by changing the Er3+/Yb3+ concentration ratio. This dual-mode luminescence makes these materials ideal as green phosphors for a wide variety of applications in the fields of bioanalysis and biomedical. [Projekat Ministarstva nauke Republike Srbije, br. 45020 i br. 172056

Evaluating x-ray detectors for radiographic applications: A comparison of nSCdS:Ag with Gd sub 2 O sub 2 S:Tb and Y sub 2 O sub 2 S:Tb screens

CERN Document Server

Kandarakis, I; Panayiotakis, G S; Nomicos, C D

1997-01-01

ZnSCdS:Ag was evaluated as a radiographic image receptor and was compared with Gd sub 2 O sub 2 S:Tb and Y sub 2 O sub 2 S:Tb phosphors often used in radiography. The valuation of a radiographic receptor was modelled as a three-step process: i) determination of light output intensity as related to the input radiation dose, (ii) determination of visible light characteristics with respect to radiographic optical detectors, and (iii) determination of image information transfer efficiency. The light intensity emitted per unit of x-ray exposure rate was measured and theoretically calculated for laboratory prepared screens with coating thicknesses from 20 to 220 mg cm sup - sup 2 and tube voltages rom 50 to 250 kVp. ZnSCdS:Ag light intensity was higher than that of d sub 2 O sub 2 S:Tb or Y sub 2 O sub 2 S:Tb for tube voltages less than 70 and 80 kVp respectively. ZnSCdS:Ag displayed the highest x-ray to light conversion efficiency (0.207) and had optical properties close to those of Gd sub 2 O sub 2 S:Tb nd Y sub ...

Thermochemical properties of lanthanoid-iron-perovskite at high temperatures. [La, Nd, Sm, Eu, Gd, Tb, Dy

Energy Technology Data Exchange (ETDEWEB)

Katsura, T; Kitayama, K; Sugihara, T [Tokyo Inst. of Tech. (Japan). Faculty of Science; Kimizuka, N

1975-06-01

The standard Gibbs energy of formation of C/sup -/FeO/sub 3/(C/sup -/=La, Nd, Sm, Eu, Gd, Tb, and Dy) from metallic iron, C/sub 2//sup -/O/sub 3/, and oxygen has been determined at temperatures from 1473 to 1673 K. Based on the free-energy data, the heat of reaction and the entropy change resulting from the reaction have been calculated. The values of the heat of reaction of LaFeO/sub 3/, NdFeO/sub 3/, SmFeO/sub 3/, EuFeO/sub 3/, and GdFeO/sub 3/ (the first group) were identical, - 107 kcal/mol, at the present temperature interval. However, the values of the heat of reaction of TbFeO/sub 3/ and DyFeO/sub 3/ (the second group) decreased with an increase in the temperature. The entropy change of each reaction in the first group was constant, independent of the temperature, and each value decreased in the sequence from LaFeO/sub 3/ to GdFeO/sub 3/. The entropy change of the second group decreased with an increase in the temperature. The change of the standard Gibbs energy was intimately related to the ionic radii of C/sup -/-ions, and the relationship between the Gibbs energy and the tolerance factor has been clarified.

The risk assessment of Gd_2O_3:Yb"3"+/Er"3"+ nanocomposites as dual-modal nanoprobes for magnetic and fluorescence imaging

International Nuclear Information System (INIS)

Huang, Long; Tian, Xiumei; Liu, Jun; Zheng, Cunjing; Xie, Fukang; Li, Li

2017-01-01

Our group has synthesized Gd_2O_3:Yb"3"+/Er"3"+ nanocomposites as magnetic/fluorescence imaging successfully in the previous study, which exhibit good uniformity and monodispersibility with a mean size of 7.4 nm. However, their systematic risk assessment remains unknown. In this article, the in vitro biocompatibility of the Gd_2O_3:Yb"3"+/Er"3"+ was assessed on the basis of cell viability and apoptosis. In vivo immunotoxicity was evaluated by monitoring the product of reactive oxygen species (ROS), clusters of differentiation (CD) markers, and superoxide dismutase (SOD) in Balb/c mice. No significant differences were found in cell viability, apoptosis, and immunotoxicity between our Gd_2O_3:Yb"3"+/Er"3"+ and gadodiamide which are used commonly in clinical. Few nanoprobes were localized in the phagosomes of the liver, heart, lung, spleen, kidney, brain, and tumor under the transmission electron microscopy (TEM) images. In addition, our products reveal good T_1-weighted contrast enhancement of xenografted murine tumor. Therefore, the above results may contribute to the effective application of Gd_2O_3:Yb"3"+/Er"3"+ as molecular imaging contrast agents and dual-modal nanoprobes for cancer detection.

Pressure-enhanced light emission and its structural origin in Er:GdVO ₄

Energy Technology Data Exchange (ETDEWEB)

Hong, Fang; Yue, Binbin; Cheng, Zhenxiang; Shen, Hui; Yang, Ke; Hong, Xinguo; Chen, Bin; Mao, Ho-Kwang

2017-01-09

Rare earth phosphors have been widely studied because of their sharp emission lines and excellent optical performance. However, photoluminescence (PL) tuning by crystal field in Er3+ embedded phosphors has always been a challenge. Here, we demonstrate that pressure can help to enhance the red and green light emission simultaneously in Er:GdVO4. Synchrotron X-ray diffraction investigations revealed that a structural phase transition was responsible for the enhancement. Our work brightens the future prospects for applications of Er3+-based PL materials in various fields, such as high power lasers and (bio) medical imaging.

Multifunctional BaYbF5: Gd/Er upconversion nanoparticles for in vivo tri-modal upconversion optical, X-ray computed tomography and magnetic resonance imaging.

Science.gov (United States)

Li, Xiaolong; Yi, Zhigao; Xue, Zhenluan; Zeng, Songjun; Liu, Hongrong

2017-06-01

Development of high-quality upconversion nanoparticles (UCNPs) with combination of the merits of multiple molecular imaging techniques, such as, upconversion luminescence (UCL) imaging, X-ray computed tomography (CT), and magnetic resonance (MR) imaging, could significantly improve the accuracy of biological diagnosis. In this work, multifunctional BaYbF 5 : Gd/Er (50:2mol%) UCNPs were synthesized via a solvothermal method using oleic acid (OA) as surface ligands (denoted as OA-UCNPs). The OA-UCNPs were further treated by diluted HCl to form ligand-free UCNPs (LF-UCNPs) for later bioimaging applications. The cytotoxicity assay in HeLa cells shows low cell toxicity of these LF-UCNPs. Owing to the efficient UCL of BaYbF 5 : Gd/Er, the LF-UCNPs were successfully used as luminescent bioprobe in UCL bioimaging. And, X-ray CT imaging reveals that BaYbF 5 : Gd/Er UCNPs can act as potential contrast agents for detection of the liver and spleen in the live mice owing to the high-Z elements (e.g., Ba, Yb, and Gd) in host matrix. Moreover, with the addition of Gd, the as-designed UCNPs exhibit additional positive contrast enhancement in T 1 -weighted MR imaging. These findings demonstrate that BaYbF 5 : Gd/Er UCNPs are potential candidates for tri-modal imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

A study of luminescence from Eu{sup 3+}, Ce{sup 3+}, Tb{sup 3+} and Ce{sup 3+}/Tb{sup 3+} in new potassium gadolinium phosphate K{sub 3}Gd{sub 5}(PO{sub 4}){sub 6}

Energy Technology Data Exchange (ETDEWEB)

Meng, Fangui; Zhang, Hongzhi [School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Chen, Cuili; Kim, Sun Il [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Zhang, Xinmin, E-mail: xmzhuga@163.com [School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China)

2016-06-25

New potassium gadolinium phosphate [K{sub 3}Gd{sub 5}(PO{sub 4}){sub 6}] doped with Eu{sup 3+}, Ce{sup 3+}, Tb{sup 3+} and co-doped with Ce{sup 3+} and Tb{sup 3+} phosphors were prepared by high temperature solid state synthesis. Phase purity of the powders was checked by X-ray powder diffraction. Luminescence and excitation spectra of samples were reported. In particular, the interaction mechanism between Eu{sup 3+} ions was investigated in terms of the Inokuti–Hirayama model; it was found that the interactions between Eu{sup 3+} can be assigned to dipole–dipole interaction. K{sub 3}Gd{sub 5}(PO{sub 4}){sub 6}:Eu{sup 3+} could act as a candidate for solid state lighting due to its strong absorption band in the near-UV region (350–400 nm). The energy transfer from Ce{sup 3+} to Tb{sup 3+} was confirmed and the mechanism was studied using Dexter's theory; it is concluded that electric dipole–dipole interaction predominates in the energy transfer process from Ce{sup 3+} to Tb{sup 3+} in the K{sub 3}Gd{sub 5}(PO{sub 4}){sub 6} host. The energy transfer efficiency and critical distance were also investigated. - Highlights: • Optical properties of K{sub 3}Gd{sub 5}(PO{sub 4}){sub 6}:RE{sup 3+} are investigated for the first time. • The interaction mechanism between Eu{sup 3+} ions is attributed to dipole–dipole type. • K{sub 3}Eu{sub 5}(PO{sub 4}){sub 6} is a candidate phosphor for application to solid state lighting. • There exists an efficient energy transfer from Ce{sup 3+} to Tb{sup 3+} (η is up to 95%). • The mechanism of energy transfer process is electric dipole–dipole interaction.

EPR experiments in LiTbF4, LiHoF4, and LiErF4 at submillimeter frequencies

DEFF Research Database (Denmark)

Magariño, J.; Tuchendler, J.; Beauvillain, P.

1980-01-01

Electron-paramagnetic-resonance experiments in LiTbF4, LiHoF4, and LiErF4 have been performed at frequencies between 70 and 600 GHz, in magnetic fields up to 60 kG and in the temperature range 1.4......Electron-paramagnetic-resonance experiments in LiTbF4, LiHoF4, and LiErF4 have been performed at frequencies between 70 and 600 GHz, in magnetic fields up to 60 kG and in the temperature range 1.4...

Tune color of single-phase LiGd(MoO4)2-X(WO4)X: Sm3+, Tb3+ via adjusting the proportion of matrix and energy transfer to create white-light phosphor

Science.gov (United States)

Wu, Hongyue; Yang, Junfeng; Wang, Xiaoxue; Gan, Shucai; Li, Linlin

2018-03-01

A series of LiGd(MO4)2: Sm3+, Tb3+ (M = Mo, W) phosphors was prepared by a conventional solid state reaction method. Powder X-Ray diffraction (XRD) analysis reveals that the compounds are of the same structure type. Their luminescent properties have been studied. The optimal doping concentrations are 8% for Sm3+ and 18% for Tb3+ in the LiGd(MoO4)2 host. Sm3+ and Tb3+ have different sensitivity to the Mo/W ratio. For LiGd(MoO4)2-X(WO4)X: Sm3+ (X = 0, 0.4, 0.8, 1.2, 1.6, 2.0), the strongest emission intensity is 1.766 times than that of the weakest, while 171 times for LiGd(MoO4)2-X(WO4)X: Tb3+. The experimental results show that Mo/W ratio strong influences on the properties of LiGd(MoO4)2-X(WO4)X: Tb3+. With the increasing of WO42- groups concentration, the shape of characteristic excitation peaks of Tb3+ is almost the same and the excitation intensity gradually increase. Moreover, the energy transfer from Tb3+ to Sm3+ has been realized in the co-doped phosphors. The experimental analysis and theoretical calculations reveal that the quadrupole-quadrupole interaction is the dominant mechanism for the Tb3+→Sm3+ energy transfer. Therefore, luminous intensity can be adjusted by different sensitivities to matrix composition and energy transfer from Tb3+→Sm3+. By this tuning color method, white-light-emitting phosphor has been prepared. The excitation wavelength is 378 nm, and this indicates that the white-light-emitting phosphor could be pumped by near-UV light.

Theoretical investigations on magnetic entropy change in amorphous and crystalline systems: Applications to RAg (R=Tb, Dy, Ho) and GdCuAl

Energy Technology Data Exchange (ETDEWEB)

Ranke, P.J. von, E-mail: von.ranke@uol.com.br [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Nóbrega, E.P. [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Caldas, A. [Sociedade Unificada de Ensino Superior e Cultura, SUESC, 20211-351 Rio de Janeiro, RJ (Brazil); Alho, B.P. [Instituto de Aplicação Fernando Rodrigues da Silveira, Universidade do Estado do Rio de Janeiro, Rua Santa Alexandrina, 288, 20260-232 RJ (Brazil); Ribeiro, P.O.; Alvarenga, T.S.T.; Lopes, P.H.O.; Sousa, V.S.R. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, SP (Brazil); Oliveira, N.A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil)

2014-11-15

We report theoretical investigations on the magnetic entropy changes in amorphous systems through two different assumptions. In the first assumption, the HPZ-anisotropic model is considered to deal with the random direction of magnetic moments, where the amorphous RAg (R=Tb, Dy and Ho) were used as prototypes systems. In the second assumption, the amorphisation is parameterized through the exchange interaction distribution and GdCuAl, in amorphous and crystalline structures, were considered as prototypes systems. Comparisons between the magnetic entropy changes under amorphisation and under the usual magnetic field variation were performed. The model reveals the dependence of refrigerant capacity on the amorphisation parameter, and an optimum amorphisation parameter was calculated. - Highlights: • Theoretical investigation on RAg (R=Tb, Dy and Ho) and GdCuAl amorphous alloys. • Magnetic entropy changes in GdCuAl in both amorphous and crystalline structures. • The refrigerant capacity was compared in both amorphous and crystalline phases.

Strong enhancement of the upconversion emission in ZrO{sub 2}: Yb{sup 3+}, Er{sup 3+}, Gd{sup 3+} nanocubes synthesized with Na{sub 2}S

Energy Technology Data Exchange (ETDEWEB)

Urbina-Frías, Alejandra; López-Luke, Tzarara; Oliva, Jorge [Centro de Investigaciones en Óptica, A.P. 1-948, León, Guanajuato 37150 (Mexico); Salas, Pedro [Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, A.P. 1-1010, Querétaro 76000 (Mexico); Torres-Castro, Alejandro [Universidad Autónoma de Nuevo León, A.P. 126-F, Monterrey, NeNuevo Leon 66450 (Mexico); De la Rosa, Elder, E-mail: elder@cio.mx [Centro de Investigaciones en Óptica, A.P. 1-948, León, Guanajuato 37150 (Mexico)

2016-04-15

In this work, the structural, morphological and luminescent characterization of ZrO{sub 2}:Yb{sup 3+},Er{sup 3+}, Gd{sup 3+} nanocrystals prepared with Na{sub 2}S by precipitation method is reported. The XRD spectra showed a mixture of tetragonal (88%) and monoclinic phases (12%) in samples fabricated with and without Na{sub 2}S. The tetragonal phase (100%) was stabilized by the introduction of the Gd{sup 3+}. According to TEM images, samples showed a cubic morphology with an average size of 150 nm, when both, Na{sub 2}S and Gd{sup 3+} were added. Red (678 nm), green (545 nm) and ultraviolet (275, 285 nm) emissions were obtained as a result of the upconversion process due to the energy transfer between Yb{sup 3+}–Er{sup 3+}–Gd{sup 3+} ions, under 970 nm of excitation. The integrated red band showed an increment of 40% and 125%, for samples prepared with Na{sub 2}S and combined with Gd{sup 3+}, respectively, compared to the ZrO{sub 2}:Yb{sup 3+}–Er{sup 3+} sample. Such increments are explained in terms of the surface pasivation by using Na{sub 2}S during the synthesis process and the role of Gd{sup 3+} as a reservoir of energy from Er{sup 3+}. - Highlights: • ZrO{sub 2}:Yb,Er nanoparticles were synthesized by a precipitation method. • ZrO{sub 2}:Yb,Er nanoparticles were prepared with Na{sub 2}S and sensitized with Gd{sup 3+}. • An increment of 40% in luminescence occurred in samples prepared with Na{sub 2}S. • An increment of 125% were obtained by the synergistic effect between Na{sub 2}S and Gd3{sup +}.

Electronic and Spectral Properties of RRhSn (R = Gd, Tb) Intermetallic Compounds

Science.gov (United States)

Knyazev, Yu. V.; Lukoyanov, A. V.; Kuz'min, Yu. I.; Gupta, S.; Suresh, K. G.

2018-02-01

The investigations of electronic structure and optical properties of GdRhSn and TbRhSn were carried out. The calculations of band spectrum, taking into account the spin polarization, were performed in a local electron density approximation with a correction for strong correlation effects in 4f shell of rare earth metal (LSDA + U method). The optical studies were done by ellipsometry in a wide range of wavelengths, and the set of spectral and electronic characteristics was determined. It was shown that optical absorption in a region of interband transitions has a satisfactory explanation within a scope of calculations of density of electronic states carried out.

Magnetism in RRhGe (R = Tb, Dy, Er, Tm): An experimental and theoretical study

Energy Technology Data Exchange (ETDEWEB)

Gupta, Sachin [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Lukoyanov, A.V. [Institute of Metal Physics, Russian Academy of Sciences, Ural Branch, Yekaterinburg 620137 (Russian Federation); Ural Federal University, Yekaterinburg 620002 (Russian Federation)

2015-08-15

Highlights: • RRhGe (R = Tb, Dy, Er, Tm) compounds show low temperature antiferromagnetic ordering. • All compounds show field induced metamagnetic transitions. • Some of these compounds show large magnetocaloric effect and magnetoresistance. • Change of sign in MR take place on temperature variation. - Abstract: RRhGe (R = Tb, Dy, Er, Tm) compounds have been studied by different experimental probes and theoretical ab initio calculations. These compounds show very interesting magnetic and transport properties. All the compounds are antiferromagnetic with some of them showing spin-reorientation transition at low temperatures. The magnetocaloric effect estimated from magnetization data shows high values in all these compounds. Magnetoresistance is negative near the ordering temperatures and positive at low temperatures. The electronic structure calculations accounting for electronic correlations in the 4f rare-earth shell reveal the closeness of the antiferromagnetic ground state and other types of magnetic orderings in the rare-earth sublattice. These calculations are also in agreement with the experimental results.

Predictions of thermomagnetic properties of Laves phase compounds: TbAl2, GdAl2 and SmAl2 performed with ATOMIC MATTERS MFA computation system

Science.gov (United States)

Michalski, Rafał; Zygadło, Jakub

2018-04-01

Recent calculations of properties of TbAl2 GdAl2 and SmAl2 single crystals, performed with our new computation system called ATOMIC MATTERS MFA are presented. We applied localized electron approach to describe the thermal evolution of Fine Electronic Structure of Tb3+, Gd3+ and Sm3+ ions over a wide temperature range and estimate Magnetocaloric Effect (MCE). Thermomagnetic properties of TbAl2, GdAl2 and SmAl2 were calculated based on the fine electronic structure of the 4f8, 4f7 and 4f5 electronic configuration of the Tb3+ and Gd3+ and Sm3+ ions, respectively. Our calculations yielded: magnetic moment value and direction; single-crystalline magnetization curves in zero field and in external magnetic field applied in various directions m(T,Bext); the 4f-electronic components of specific heat c4f(T,Bext); and temperature dependence of the magnetic entropy and isothermal entropy change with external magnetic field - ΔS(T,Bext). The cubic universal CEF parameters values used for all CEF calculations was taken from literature and recalculated for universal cubic parameters set for the RAl2 series: A4 = +7.164 Ka04 and A6 = -1.038 Ka06. Magnetic properties were found to be anisotropic due to cubic Laves phase C15 crystal structure symmetry. These studies reveal the importance of multipolar charge interactions when describing thermomagnetic properties of real 4f electronic systems and the effectiveness of an applied self-consistent molecular field in calculations for magnetic phase transition simulation.

Isothiocyanato complexes of Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl)benzimidazole

Energy Technology Data Exchange (ETDEWEB)

Mishra, A; Singh, V K

1982-01-01

Six-coordinated complexes of the type (Ln(PyBzH)/sub 2/NCS.H/sub 2/O) (NCS)/sub 2/.nH/sub 2/O/mC/sub 2/H/sub 5/OH (Ln = Gd(III), Tb(III), Dy(III) and Ho(III), n=1-2; m=1) have been prepared from Ln(NCS)/sub 6//sup 3 -/. The room temperature magnetic moment values confirm the terpositive state of the lanthanide ions. Infrared spectra suggest the N-coordination of thiocyanate group. Electronic spectral studies of Tb(III), Dy(III) and Ho(III) complexes have been made in terms of LSJ term energies. 13 refs.

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.

Multifunctional BaYbF{sub 5}: Gd/Er upconversion nanoparticles for in vivo tri-modal upconversion optical, X-ray computed tomography and magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Li, Xiaolong; Yi, Zhigao; Xue, Zhenluan; Zeng, Songjun, E-mail: songjunz@hunnu.edu.cn; Liu, Hongrong, E-mail: hrliu@hunnu.edu.cn

2017-06-01

Development of high-quality upconversion nanoparticles (UCNPs) with combination of the merits of multiple molecular imaging techniques, such as, upconversion luminescence (UCL) imaging, X-ray computed tomography (CT), and magnetic resonance (MR) imaging, could significantly improve the accuracy of biological diagnosis. In this work, multifunctional BaYbF{sub 5}: Gd/Er (50:2 mol%) UCNPs were synthesized via a solvothermal method using oleic acid (OA) as surface ligands (denoted as OA-UCNPs). The OA-UCNPs were further treated by diluted HCl to form ligand-free UCNPs (LF-UCNPs) for later bioimaging applications. The cytotoxicity assay in HeLa cells shows low cell toxicity of these LF-UCNPs. Owing to the efficient UCL of BaYbF{sub 5}: Gd/Er, the LF-UCNPs were successfully used as luminescent bioprobe in UCL bioimaging. And, X-ray CT imaging reveals that BaYbF{sub 5}: Gd/Er UCNPs can act as potential contrast agents for detection of the liver and spleen in the live mice owing to the high-Z elements (e.g., Ba, Yb, and Gd) in host matrix. Moreover, with the addition of Gd, the as-designed UCNPs exhibit additional positive contrast enhancement in T{sub 1}-weighted MR imaging. These findings demonstrate that BaYbF{sub 5}: Gd/Er UCNPs are potential candidates for tri-modal imaging. - Graphical abstract: Multifunctional BaYbF{sub 5}: Gd/Er upconversion nanoparticles with efficient upconversion emission, high absorption coefficient, predominant paramagnetic behavior, and low biological toxicity were demonstrated for tri-modality in vivo UCL, CT and MR imaging. Display Omitted - Highlights: • The multifunctional UCNPs with high monodispersity were synthesized. • The UCNPs present large r{sub 1} value and binary CT contrast agents. • These UCNPs were demonstrated as optimal probes for tri-modal bioimaging.

Peculiarities of component interaction in {Gd, Er}-V-Sn Ternary systems at 870 K and crystal structure of RV6Sn6 stannides

International Nuclear Information System (INIS)

Romaka, L.; Stadnyk, Yu.; Romaka, V.V.; Demchenko, P.; Stadnyshyn, M.; Konyk, M.

2011-01-01

Highlights: → {Gd, Er}-V-Sn ternary systems at 870 K are characterized by formation of stannides with general compositions RV 6 Sn 6 . → Isostructural RV 6 Sn 6 compounds were also found with Y, Dy, Ho, Tm, and Lu. → The crystal structure of RV 6 Sn 6 compounds was determined by powder diffraction method. → Structural analysis showed that RV 6 Sn 6 compounds (R = Gd, Dy-Tm, Lu) are disordered; YV 6 Sn 6 is characterized by structure ordering. - Abstract: The phase equilibria in the Gd-V-Sn and Er-V-Sn ternary systems were studied at 870 K by means of X-ray and metallographic analyses in the whole concentration range. Both Gd-V-Sn and Er-V-Sn systems are characterized by formation of one ternary compound at investigated temperature, with stoichiometry RV 6 Sn 6 (SmMn 6 Sn 6 -type, space group P6/mmm, a = 0.55322(3) nm, c = 0.91949(7) nm for Gd, a = 0.55191(2) nm, c = 0.91869(8) nm for Er). Solubility of the third component in the binary compounds was not observed. Compounds with the SmMn 6 Sn 6 -type were also found with Dy, Ho, Tm, and Lu, while YV 6 Sn 6 compound crystallizes in HfFe 6 Ge 6 structure type. All investigated compounds are the first ternary stannides with rare earth elements and vanadium.

Hyperfine interaction studies of the perovskite oxides of the type RCrO3 (R = Gd, Tb e Dy)

International Nuclear Information System (INIS)

Silva, Renilson Adriano da

2009-01-01

ABO 3 perovskite oxides have ideal cubic structure, however, some distortions in this type of structure may induce changes from cubic to orthorhombic or rhombroedric symmetry. The larger atoms A are located at the center of a cube, the B atoms are on 8 vertices and oxygen atoms occupy 12 positions in the middle of each side of the cube. Distortions in this structure may lead to new magnetic and electrical properties, with great scientific and technological interest. In this work RCrO 3 (R = Gd, Tb, Dγ) compounds (also known as orthocromites) were studied. The samples were produced by means of sol-gel chemical procedure and analyzed by X-Ray Diffraction. The results showed a single phase with Pbnm space group. The perturbed gamma-gamma angular correlation (PAC) measurements were carried out using 181 Hf( 181 Ta) and 111 In( 111 Cd) nuclear probes, which substitute 'A' and 'B' positions respectively. The probe nuclei were introduced in the samples during the chemical procedures for preparation. One of the objectives of this work's was to study the hyperfine magnetic field and its variation as a function of temperature, crystallographic structure as well as the antiferromagnetic transition temperature (T N ). The PAC Measurements were carried out in the temperature range of 20 to 300 K for R = Gd, Tb and 20 to 800 K in the case of R = Dγ from. Electric field gradient was also measured as a function of temperature. It was possible to observe the expected transition as well as the alignment of Cr spins, as found in literature. The Neel temperatures (TN) for investigated samples are ∼170 K, ∼164 K and ∼148 K for GdCrO 3 , TbCrO 3 and DyCrO 3 respectively. (author)

Transport properties in amorphous U/sub x/-T1/sub -//sub x/ films (T = Fe, Ni, Gd, Tb, and Yb) (invited)

International Nuclear Information System (INIS)

Freitas, P.P.; Plaskett, T.S.; Moreira, J.M.; Amaral, V.S.

1988-01-01

We describe the competing magnetic, localization, and phonon effects on the transport properties of amorphous magnetic U/sub x/T/sub 1-//sub x/ films, with T = Fe, Ni, Gd, Tb, and Yb. Amorphous U/sub x/Fe/sub 1-//sub x/ films change from collinear to random ferromagnetism as x increases, and the temperature dependence of the resistivity denotes the competing effects of spin-flip and non-spin-flip exchange scattering processes. The resistivity has a minimum at T/sub f/ rising sharply below this temperature. The sign of the magnetic resistivity and the magnetoresistance indicates >0, while the anisotropic magnetoresistance indicates a local exchange gap. Amorphous U/sub x/Gd/sub 1-//sub x/ and a-U/sub x/Tb/sub 1-//sub x/ are, respectively, spin glasses and random anisotropy dominated systems. The resistivity increases smoothly through T/sub f/ and has a slight upturn at low temperatures that we associate with weak localization. The magnetoresistance is negative in both systems and the anisotropic magnetoresistance is null, although the applied field induces anisotropic behavior in the Tb containing films (asperomagnets). All samples show quadratic and positive field dependence of magnetoresistance well inside the paramagnetic regime, and a linear regime below T/sub f/. At low temperatures and in the a-U/sub x/Gd/sub 1-//sub x/ films, negative (H)/sup 1/2/ and H 2 regimes occur and are associated with weak localization processes dominated by the inelastic mean free path

Fabrication and characterization of Gd2O2SO4:Tb3+ phosphors by sol-gel method

Science.gov (United States)

Aritman, I.; Yildirim, S.; Kisa, A.; Guleryuz, L. F.; Yurddaskal, M.; Dikici, T.; Celik, E.

2017-02-01

The objective of the innovative approaches of the scintillation materials to be used in the digital portal imaging systems in the radiotherapy applications is to research the GOS material production that has been activated with the rare earth elements (RE), to produce the scintillation detectors that have a rapid imaging process with a lesser radiation and higher image quality from these materials and to apply the radiographic imaging systems. The GOS: Tb3+ showed high emission peak and high x-ray absorption properties which have been determined for application to mammography and dental radiography. In this study, Gd2O2SO4:Tb3+ phosphors were fabricated by the sol-gel method that is a unique technique and not previously applied. Besides, the structural characterization of GOS: Tb3+ has been investigated. The strongest emission peak located at 549 nm under 312 nm UV light excitation was appeared on the GOS: Tb3+ phosphor particles. The characterization processing optimized by using FTIR, DTA-TG, XRD, XPS, SEM and the luminescence spectroscopy.

Synthesis and photoluminescence characteristics of (Y,Gd)BO3:RE (RE = Eu(3+), Ce(3+), Dy(3+) and Tb(3+)) phosphors for blue chip and near-UV white LEDs.

Science.gov (United States)

Rangari, V V; Singh, V; Dhoble, S J

2016-03-01

A series of Eu(3+)-, Ce(3+)-, Dy(3+)- and Tb(3+)-doped (Y,Gd)BO3 phosphors was synthesized by a solid-state diffusion method. X-Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu(3+), Ce(3+), Dy(3+) and Tb(3+) are effectively excited with near UV-light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu(3+)-, Ce(3+)- and Tb(3+)/Dy(3+)-doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60Gd0.38BO3:Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu(2+) phosphor. The phosphor (Y,Gd)BO3 doped with Eu(3+), Dy(3+) and Tb(3+) showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near-UV white light-emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.

Optical and magneto-optical properties of single crystals of RFe{sub 2} (R = Gd, Tb, Ho, and Lu) and GdCo{sub 2} intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Lee, S.J.

1999-02-12

The author has studied the diagonal and off-diagonal optical conductivity of RFe{sub 2}(R = Gd, Tb, Ho, Lu) and GdCo{sub 2} single crystals grown by the flux method. Using spectroscopic ellipsometry the author has measured the dielectric function from 1.5 to 5.5 eV. The magneto-optical Kerr spectrometer at temperatures between 7 and 295 K and applied magnetic fields between 0.5 to 1.6 T. The apparatus and calibration method are described in detail. Using magneto-optical data and optical constants he derives the experimental value of the off-diagonal conductivity components. Theoretical calculations of optical conductivities and magneto-optical parameters were performed using the tight binding-linear muffin tin orbitals method within the local spin density approximation. He applied this TB-LMTO method to LuFe{sub 2}. The theoretical results obtained agree well with the experimental data. The oxidation effects on the diagonal part of the optical conductivity were considered using a three-phase model. The oxidation effects on the magneto-optical parameters were also considered by treating the oxide layer as a nonmagnetic thin transparent layer. These corrections change not only the magnitude but also the shape of the optical conductivity and the magneto-optical parameters.

Magnetic ordering of Hf{sub 3}Ni{sub 2}Si{sub 3}-type {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and {Tb, Ho}{sub 3}Ni{sub 2}Ge{sub 3} compounds

Energy Technology Data Exchange (ETDEWEB)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow, GSP-1, 119991 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil); Mozharivskyj, Y. [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Isnard, O. [CNRS, Institut. Néel, 25 rue des Martyrs BP166 x, F-38042 Grenoble (France); Université Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France)

2017-02-15

The magnetic ordering of Hf{sub 3}Ni{sub 2}Si{sub 3}-type {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and {Tb, Ho}{sub 3}Ni{sub 2}Ge{sub 3} compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3} exhibit field sensitive complex antiferromagnetic orderings with T{sub N}=51 K, T{sub m}=10 K for Sm{sub 3}Co{sub 2}Ge{sub 3}, T{sub N}=34 K, T{sub m}=13 K for Tb{sub 3}Co{sub 2}Ge{sub 3}, T{sub N}=7 K for Er{sub 3}Co{sub 2}Ge{sub 3} and T{sub N}=11 K for Ho{sub 3}Ni{sub 2}Ge{sub 3}. At 2 K and above the critical field of ~5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm{sub 3}Co{sub 2}Ge{sub 3}, Tb{sub 3}Co{sub 2}Ge{sub 3}, Er{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3}, respectively, saturation magnetizations per rare-earth atom are 6.5 μ{sub B} for Tb{sub 3}Co{sub 2}Ge{sub 3}, 7.0 μ{sub B} for Er{sub 3}Co{sub 2}Ge{sub 3} and 8.0 μ{sub B} for Ho{sub 3}Ni{sub 2}Ge{sub 3} in the field of 140 kOe, whereas magnetization of Sm{sub 3}Co{sub 2}Ge{sub 3} has an antiferromagnetic behaviour. The isothermal magnetic entropy change, ΔS{sub m}, indicates a field-induced ferromagnetic ordering in Sm{sub 3}Co{sub 2}Ge{sub 3}, Tb{sub 3}Co{sub 2}Ge3, Er{sub 3}Co{sub 2}Ge{sub 3} and Ho{sub 3}Ni{sub 2}Ge{sub 3} with a maximal ΔS{sub m} value of −10.9 J/kg K for Ho{sub 3}Ni{sub 2}Ge{sub 3} at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below T{sub N}=33 K and down to T{sub m}{sup ND}=15 K Tb{sub 3}Ni{sub 2}Ge{sub 3} shows an ac-antiferromagnetic ordering with the C2′/c magnetic space group, a K{sub 0}=[0, 0, 0] propagation vector and a a{sub Tb3Ni2Ge3}×b{sub Tb3Ni2Ge3}×c{sub Tb3Ni2Ge3} magnetic unit cell. Below T{sub m}{sup ND}=15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2′/c magnetic space group of the K{sub 0} vector and a sine-modulated a

Enhancement of CdSiO3: Tb3+ green long-lasting phosphors by co-doping with Re3+ (Re3+=Gd3+, Y3+, La3+) ions

International Nuclear Information System (INIS)

Zeng, Wei; Wang, Yuhua; Han, Shaochun; Chen, Wenbo; Li, Gen

2014-01-01

CdSiO 3 : Tb 3+ , Re 3+ long-lasting phosphors were synthesized by the conventional high temperature solid-state method. A green-light phosphorescence phenomenon, which was associated with the 5 D 4 → 7 F J (J=6, 5, 4, 3) transitions of the Tb 3+ ion, was observed. Introduction of Re 3+ (Re 3+ =Gd 3+ , Y 3+ , La 3+ ) ions, which deepens the depth (E t ) or/and increases the density (n 0 ) of traps, greatly improved the afterglow properties of CdSiO 3 : Tb 3+ . Possible mechanism of CdSiO 3 : Tb 3+ , Re 3+ was discussed in this work. - Highlights: • CdSiO 3 : Tb 3+ , Re 3+ samples enrich the color of long-lasting afterglow phosphors in CdSiO 3 host. • Both the afterglow intensity and the lasting time are greatly enhanced for the co-doped samples, especially for Cd 0.96 SiO 3 : Tb 0.03 3+ , La 0.01 3+ . • Introduction of Re 3+ (Re 3+ =Gd 3+ , Y 3+ , La 3+ ) ions, which deepens the depth (E t ) or increase density(n 0 ) of traps, greatly improved the afterglow properties of CdSiO 3 : Tb 3+

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method.

Science.gov (United States)

Gavrilović, Tamara V; Jovanović, Dragana J; Lojpur, Vesna; Dramićanin, Miroslav D

2014-02-27

Synthesis of Eu(3+)- and Er(3+)/Yb(3+)-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu(3+)-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er(3+)/Yb(3+)-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from (2)H11/2 → (2)I15/2 and (4)S3/2 → (4)I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K(-1), which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

Science.gov (United States)

Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

2014-02-01

Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 --> 2I15/2 and 4S3/2 --> 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K-1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

Crystalline structure of the manganites solid solution RE(Me,MnO₃, (RE=Gd,Er; Me=Ni,Co

Directory of Open Access Journals (Sweden)

Peña, O.

2009-08-01

Full Text Available The structural properties of the manganites solid solution RE(Me,MnO₃, RE=Er,Gd, have been studied by X-ray diffraction and electric measurements. Powders were prepared by solid state reaction between the component oxides. Incorporation of Ni²⁺ or Co²⁺ on the lattice in the Mn sites leads to changes in the parameters and symmetry of the perovskite or hexagonal compounds GdMnO₃ and ErMnO₃ respectively. The phase transitions depend on the amount of substituted Jahn-Teller Mn³⁺ cations, and, therefore, of the cooperative Jahn-Teller interaction weakness. Solid solutions based on GdMnO₃ perovskite compound change from O’-type to O-type orthorhombic perovskite symmetry when the Mn³⁺ cation amount decreases, because of the progressive substitution for Ni, Co. This transition occurs for lower amount of Ni²⁺ than for Co²⁺ cation. The Er-based solid solutions showed a different behaviour. For Ni²⁺ and Co²⁺ incorporation there are changes from hexagonal ErMnO₃-type lattice to perovskite-type symmetry, for 20 at% and 30 at% respectively of substituting cations. The resultant perovskites crystallised directly in the O-type orthorhombic perovskite structure. The steric influence seems to play a secondary role, such as it can be deduced of the small variation of the Goldschmidt tolerance factor, t, for perovskite structure.

Las propiedades estructurales de las soluciones sólidas RE(Me,MnO₃, RE=Gd,Er, Me=Ni,Co, han sido estudiadas por difracción de rayos X, (DRX y medidas eléctricas. Las fases se sintetizaron por reacción en estado sólido entre los óxidos componentes. La incorporación de los cationes Ni²⁺ y Co^2+,3+ en la red en lugar de Mn lleva a cambios en los parámetros de red y en la simetría de la perovskita, GdMnO₃ o del compuesto hexagonal Er

The risk assessment of Gd{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} nanocomposites as dual-modal nanoprobes for magnetic and fluorescence imaging

Energy Technology Data Exchange (ETDEWEB)

Huang, Long [Sun Yat-sen University, Department of Histology and Embryology, Zhongshan School of Medicine (China); Tian, Xiumei [Guangzhou Medical University, Department of Biomedical Engineering (China); Liu, Jun [Guangdong Ocean University, School of Electronics and Information Technology (China); Zheng, Cunjing; Xie, Fukang, E-mail: frankxie2000@yahoo.com [Sun Yat-sen University, Department of Histology and Embryology, Zhongshan School of Medicine (China); Li, Li, E-mail: li2@mail.sysu.edu.cn [Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Imaging Diagnosis and Interventional Center (China)

2017-02-15

Our group has synthesized Gd{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} nanocomposites as magnetic/fluorescence imaging successfully in the previous study, which exhibit good uniformity and monodispersibility with a mean size of 7.4 nm. However, their systematic risk assessment remains unknown. In this article, the in vitro biocompatibility of the Gd{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} was assessed on the basis of cell viability and apoptosis. In vivo immunotoxicity was evaluated by monitoring the product of reactive oxygen species (ROS), clusters of differentiation (CD) markers, and superoxide dismutase (SOD) in Balb/c mice. No significant differences were found in cell viability, apoptosis, and immunotoxicity between our Gd{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} and gadodiamide which are used commonly in clinical. Few nanoprobes were localized in the phagosomes of the liver, heart, lung, spleen, kidney, brain, and tumor under the transmission electron microscopy (TEM) images. In addition, our products reveal good T{sub 1}-weighted contrast enhancement of xenografted murine tumor. Therefore, the above results may contribute to the effective application of Gd{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} as molecular imaging contrast agents and dual-modal nanoprobes for cancer detection.

Preparation and studies of Eu3+ and Tb3+ co-doped Gd2O3 and Y2O3 sol-gel scintillating films

International Nuclear Information System (INIS)

Morales Ramirez, A. de J; Garcia Murillo, A.; Carrillo Romo, F. de J; Ramirez Salgado, J.; Le Luyer, C.; Chadeyron, G.; Boyer, D.; Moreno Palmerin, J.

2009-01-01

Eu 3+ (2.5 at.%) and Tb 3+ (0.005-0.01 at.%) co-doped gadolinium and yttrium oxide (Gd 2 O 3 and Y 2 O 3 ) powders and films have been prepared using the sol-gel process. High density and optical quality thin films were prepared with the dip-coating technique. Gadolinium (III) 2,4-pentadionate and yttrium (III) 2,4-pentadionate were used as precursors, and europium and terbium in their nitrate forms were used as doping agents. Chemical and structural analyses (infrared spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy) were conducted on both sol-gel precursor powders and dip-coated films. The morphology of thin films heat-treated at 700 o C was studied by means of atomic force microscopy. It was shown that the highly dense and very smooth films had a root mean roughness (RMS) of 2 nm ± 0.2 (A = 0.0075 Tb 3+ ) and 24 nm ± 3.0 (B = 0.01 Tb 3+ ). After treatment at 700 o C, the crystallized films were in the cubic phase and presented a polycrystalline structure made up of randomly oriented crystallites with grain sizes varying from 20 to 60 nm. The X-ray induced emission spectra of Eu 3+ - and Tb 3+ -doped Gd 2 O 3 and Y 2 O 3 powders showed that Tb 3+ contents of 0.005, 0.0075 and 0.01 at.% affected their optical properties. Lower Tb 3+ concentrations (down to 0.005 at.%) in both systems enhanced the light yield.

Nuclear magnetic resonance study of (Y[sub 1-x]R[sub x])[sub 2]Co[sub 14]B compounds (R=Gd, Tb)

Energy Technology Data Exchange (ETDEWEB)

Myojin, T. (Takamatsu National Coll. of Technology, Takamatsu (Japan)); Hayashi, M. (Takamatsu Coll. (Japan)); Ohno, T. (Faculty of Engineering, Tokushima Univ. (Japan)); Imaeda, Y. (Faculty of Engineering, Tokushima Bunri Univ., Shido (Japan)); Ushida, T. (Faculty of Engineering, Tokushima Bunri Univ., Shido (Japan)); Tsujimura, A. (Faculty of Engineering, Tokushima Bunri Univ., Shido (Japan)); Hihara, T. (Faculty of Integrated Arts and Sciences, Hiroshima Univ. (Japan))

1993-03-15

Influence of the Gd spin on the Co hyperfine field has been studied by [sup 59] Co nuclear magnetic resonance (NMR) in (Y[sub 1-x]Gd[sub x])[sub 2]Co[sub 14]B compounds. It is shown that the hyperfine coupling constants from the Gd spin for 8j[sub 1] and 8j[sub 2] sites are negative while those for 16k[sub 1] and 16k[sub 2] sites are positive. The dependence of the spin orientation temperature on the non-magnetic Y concentration in (Y[sub 1-x]Tb[sub x])[sub 2]Co[sub 14]B is also investigated by magnetization and [sup 59]Co NMR measurements. A spin phase diagram for this compound is proposed. (orig.)

Thermoelectric properties, crystal and electronic structure of semiconducting RECuSe2 (RE = Pr, Sm, Gd, Dy and Er)

International Nuclear Information System (INIS)

Esmaeili, Mehdi; Tseng, Yu-Chih; Mozharivskyj, Yurij

2014-01-01

Highlights: • Crystal and electronic structure of monoclinic and trigonal RECuSe 2 phases. • Thermoelectric properties of the RECuSe 2 phases. • Temperature stability of the RECuSe 2 phases. - Abstract: The ternary RECuSe 2 phases have been prepared and structurally characterized. They adopt either a monoclinic structure (P2 1 /c, z = 4) for lighter rare earths (RE = Pr, Sm and Gd) or Cu-disordered trigonal structure for heavier rare-earths (P3 ¯ m1, z = 1, RE = Dy and Er). The resistivity and Seebeck coefficient measurements on GdCuSe 2 , DyCuSe 2 and ErCuSe 2 indicate that the studied phases are p-type semiconductors with relatively small activation energies (0.045–0.11 eV). However, their electrical resistivities are too high (0.45–220 Ω cm at room temperature) to make them competitive thermoelectric materials. Electronic structure calculations indicate presence of a band gap in the RECuSe 2 phases

A study on the photographic characteristics related to the morphology of phosphor layers in the ca wo4 and gd2o2s : Tb screen

International Nuclear Information System (INIS)

Lee, In Ja; Huh, Joon

1993-01-01

Recently, various screen film system have been introduced in diagnostic radiology. There are two kinds of screen film system : blue emitting Ca WO 4 screen has been largely used in these days. However, it tends to be changed to use green emitting Gd 2 O 2 S : Tb screen. In this study, photographic characteristics of Ca WO 4 , and Gd 2 O 2 S : Tb screen were investigated with luminescence, spectroscopy. The morphology of Ca WO 4 , and Gd 2 O 2 S : Tb were also observed by using scanning electron microscope. The result obtained were as follows: 1. There was small difference in the thickness of phosphor layers for the front and back screen of blue emitting system, but little difference in those of green emitting system. 2. There was no difference in the size of phosphor particles between the front and back screen for each screen. However, the particle size was different for the various kinds of screens. 3. The shape of phosphor particle was round with many faces for all the screens. 4. In the exposure of X - ray with the same intensity, luminescent intensity of a green emitting system was 6∼7 times larger than that of a blue emitting system. 5. The thickness of phosphor layers does not affect on the sensitivity of the screens exposed by X - ray

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

Reaction kinetics of H{sub 2}, O{sub 2}, and H{sub 2}O with rare earths (Y, La, Ce, Pr, Nd, Gd, Tb, Dy, and Er) at 298 K

Energy Technology Data Exchange (ETDEWEB)

Enomoto, M.; Ohata, Y. [Course of Applied Science, Graduate School of Engineering, Tokai University, 4-1-1 Kita-Kaname, Hiratsuka, Kanagawa 259-1292 (Japan); Uchida, H., E-mail: huchida@keyaki.cc.u-tokai.ac.jp [Course of Applied Science, Graduate School of Engineering, Tokai University, 4-1-1 Kita-Kaname, Hiratsuka, Kanagawa 259-1292 (Japan)

2013-12-15

Highlights: ► H{sub 2} molecules react with a clean surface of each RE sample at the highest reactivity even at 298 K. ► The H{sub 2} reactivity becomes reduced by the formation of dihydrides of each RE sample. ► The RE with a clean surface adsorb O{sub 2} more than one monolayer of O{sub 2} even at 298 K. ► The quantitative reactivity of the H atoms dissociated from H{sub 2}O was calculated. -- Abstract: High reactivity of rare earths (RE) with H{sub 2}, O{sub 2} and H{sub 2}O is well known even at room temperature. The formation of stable surface oxides/hydroxides on the surface is the one of serious problems in the production and use of materials containing RE. We have investigated the quantitative reactivities of H{sub 2}, O{sub 2}, and H{sub 2}O with the surface of Y, La, Ce, Pr, Nd, Gd, Tb, Dy, and Er under ultra high vacuum condition. The H{sub 2}, O{sub 2} and H{sub 2}O gases exhibited the highest reactivity on the clean surface of the RE at 298 K. This means that all gas molecules impinging the surface dissociate and chemisorbed. The O atoms dissociated from O{sub 2} adsorb to for oxides layers of the metals. The H atoms dissociated from H{sub 2} diffuse into the metals to form hydrides which were found to decrease the H{sub 2} reactivity. The H atoms dissociated form H{sub 2}O diffuse into the metals or form hydroxides of the metals. With increasing coverage of each gas molecules, the reactivity of each gas was decreased by several orders of magnitude.

In-band pumping of expitaxially grown Er:(Gd,Lu)2O3 waveguides for active integrated optical devices

NARCIS (Netherlands)

Kahn, A.; Kühn, H.; Heinrich, S.; Gün, T.; Tellkamp, F.; Petermann, K.; Bradley, J.; Ay, F.; Worhoff, Kerstin; Pollnau, Markus; Kuzminykh, Y.; Luo, Y.; Hoffmann, P.; Huber, G.

Monocrystalline lattice matched Er(0.6%):(Gd, Lu)2O3 films with thicknesses up to 3 �?�m and nearly atomically flat surfaces have been deposited on Y2O3 substrates by Pulsed Laser Deposition (PLD). The epitaxial growth has been verified in-situ by Reflection High Energy Electron Diffraction (RHEED).

Ultrasmall, water dispersible, TWEEN80 modified Yb:Er:NaGd(WO4)2 nanoparticles with record upconversion ratiometric thermal sensitivity and their internalization by mesenchymal stem cells

Science.gov (United States)

Cascales, Concepción; Paíno, Carlos L.; Bazán, Eulalia; Zaldo, Carlos

2017-05-01

This work presents the synthesis by coprecipitation of diamond shaped Yb:Er:NaGd(WO4)2 crystalline nanoparticles (NPs) with diagonal dimensions in the 5-7 nm × 10-12 nm range which have been modified with TWEEN80 for their dispersion in water, and their interaction with mesenchymal stem cells (MSCs) proposed as cellular NP vehicles. These NPs belong to a large family of tetragonal Yb:Er:NaT(XO4)2 (T = Y, La, Gd, Lu; X = Mo, W) compounds with green (2H11/2 + 4S3/2 → 4I15/2) Er-related upconversion (UC) efficiency comparable to that of Yb:Er:β-NaYF4 reference compound, but with a ratiometric thermal sensitivity (S) 2.5-3.5 times larger than that of the fluoride. At the temperature range of interest for biomedical applications (˜293-317 K/20-44 °C) S = 108-118 × 10-4 K-1 for 20 at%Yb:5 at%Er:NaGd(WO4)2 NPs, being the largest values so far reported using the 2H11/2/4S3/2 Er intensity ratiometric method. Cultured MSCs, incubated with these water NP emulsions, internalize and accumulate the NPs enclosed in endosomes/lysosomes. Incubations with up to 10 μg of NPs per ml of culture medium maintain cellular metabolism at 72 h. A thermal assisted excitation path is discussed as responsible for the UC behavior of Yb:Er:NaT(XO4)2 compounds.

Spectral management and morphology evolution of β-NaGdF4:Yb3+,Er3+ by tuning the concentration of citric acid

Science.gov (United States)

Yao, Lu; Xu, Dekang; Lin, Hao; Yang, Shenghong; Zhang, Yueli

2018-05-01

β-NaGdF4:Yb3+,Er3+ upconversion (UC) particles were prepared by a facile hydrothermal process with assistance of citric acid (CA). The morphologies of β-NaGdF4 UC particles were controlled by changing the doses of CA in precursor. With an increase CA concentration in precursor, increase sizes of crystals were observed, resulting in the increasing of luminescence intensity. The energy transfer ET mechanism was analyzed in detail.

Subsolidus Phase Relations of the CaO-REOx-CuO Systems (RE = Eu, Tb, Dy, Ho, Er, Lu and Sc) at 900 °C in Air

DEFF Research Database (Denmark)

Grivel, Jean-Claude

2016-01-01

The subsolidus phase relations of the CaO-REOx-CuO systems (RE = Eu, Tb, Dy, Ho, Er, Lu and Sc) were investigated in air at 900 °C. The pseudo-ternary sections with RE = Tb, Dy, Ho, Er and Lu have a similar structure. They have in common with the RE = Eu system a solid solution of Ca0.833−xRExCuO2......+y composition but the system with RE = Eu differs by the presence of an Eu2CuO4 phase instead of RE2Cu2O5 for RE = Tb, Dy, Ho, Er and Lu. In contrast, the CaO-ScO1.5-CuO section does not contain a Ca0.833−xScxCuO2+y solid solution and is dominated by the CaSc2O4 phase, which has no equivalent...... in the other systems at 900 °C in air....

Thermal decomposition of RE(C2H5CO2)3·H2O (RE = Dy, Tb, Gd, Eu and Sm)

DEFF Research Database (Denmark)

Grivel, Jean-Claude

2014-01-01

The thermal decomposition of Dy(III), Tb(III), Gd(III), Eu(III), and Sm(III) propionate monohydrates was studied in argon by means of simultaneous differential thermal analysis and thermogravimetry, infrared-spectroscopy, X-ray diffraction, and optical microscopy. After dehydration, which takes......, an intermediate stage involving a RE2O(C2H5CO2)4 composition was evidenced in the case of the Eu- and Sm-propionates. For all compounds, further decomposition of RE2O2CO3 into the corresponding sesquioxides (RE2O3) is accompanied by the release of CO2. The thermal decomposition of Dy- and Tb-propionates occurs...

Slow magnetic relaxation and single-molecule toroidal behaviour in a family of heptanuclear {Cr"I"I"ILn"I"I"I_6} (Ln=Tb, Ho, Er) complexes

Energy Technology Data Exchange (ETDEWEB)

Vignesh, Kuduva R. [IITB-Monash Research Academy, IIT Bombay, Powai, Mumbai (India); Langley, Stuart K. [School of Science and the Environment, Division of Chemistry, Manchester Metropolitan University, Manchester (United Kingdom); Swain, Abinash; Rajaraman, Gopalan [Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai (India); Moubaraki, Boujemaa; Murray, Keith S. [School of Chemistry, Monash University, Clayton, VIC (Australia); Damjanovic, Marko; Wernsdorfer, Wolfgang [Institute Neel, CNRS, Universite Grenoble Alpes, Grenoble (France); Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany)

2018-01-15

The synthesis, magnetic properties, and theoretical studies of three heterometallic {Cr"I"I"ILn"I"I"I_6} (Ln=Tb, Ho, Er) complexes, each containing a metal topology consisting of two Ln{sub 3} triangles connected via a Cr{sup III} linker, are reported. The {CrTb_6} and {CrEr_6} analogues display slow relaxation of magnetization in a 3000 Oe static magnetic field. Single-crystal measurements reveal opening up of the hysteresis loop for {CrTb_6} and {CrHo_6} molecules at low temperatures. Ab initio calculations predict toroidal magnetic moments in the two Ln{sub 3} triangles, which are found to couple, stabilizing a con-rotating ferrotoroidal ground state in Tb and Ho examples and extend the possibility of observing toroidal behaviour in non Dy{sup III} complexes for the first time. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

CeNi{sub 3}-type rare earth compounds: crystal structure of R{sub 3}Co{sub 7}Al{sub 2} (R=Y, Gd–Tm) and magnetic properties of {Gd–Er}{sub 3}Co{sub 7}Al{sub 2}, {Tb, Dy}{sub 3}Ni{sub 8}Si and Dy{sub 3}Co{sub 7.68}Si{sub 1.32}

Energy Technology Data Exchange (ETDEWEB)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-1, Moscow 119991 (Russian Federation); Yapaskurt, V.O. [Department of Petrology, Geological Faculty Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600 036 (India); Quezado, S.; Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

2017-03-15

The crystal structure of new CeNi{sub 3}-type {Y, Gd–Tm}{sub 3}Co{sub 7}Al{sub 2} (P63/mmc. N 194, hP24) compounds has been established using powder X-ray diffraction studies. The magnetism of Tb{sub 3}Ni{sub 8}Si and Dy{sub 3}Ni{sub 8}Si is dominated by rare earth sublattice and the magnetic properties of R{sub 3}Co{sub 7}Al{sub 2} (R =Gd–Er) and Dy{sub 3}Co{sub 7.68}Si{sub 1.32} are determined by both rare earth and cobalt sublattices. Magnetization data indicate ferromagnetic ordering of {Tb, Dy}{sub 3}Ni{sub 8}Si at 32 K and 21 K, respectively. Gd{sub 3}Co{sub 7}Al{sub 2} and Tb{sub 3}Co{sub 7}Al{sub 2} exhibit ferromagnetic ordering at 309 K and 209 K, respectively, whereas Dy{sub 3}Co{sub 7}Al{sub 2}, Ho{sub 3}Co{sub 7}Al{sub 2}, Er{sub 3}Co{sub 7}Al{sub 2} and Dy{sub 3}Co{sub 7.68}Si{sub 1.32} show a field dependent ferromagnetic-like ordering at 166 K, 124 K, 84 K and 226 K, respectively followed by a low temperature transition at 34 K for Dy{sub 3}Co{sub 7}Al{sub 2}, 18 K for Ho{sub 3}Co{sub 7}Al{sub 2}, 56 K for Er{sub 3}Co{sub 7}Al{sub 2}, 155 K and 42 K for Dy{sub 3}Co{sub 7.68}Si{sub 1.32}. Among these compounds, Dy{sub 3}Ni{sub 8}Si shows largest magnetocaloric effect (isothermal magnetic entropy change) of −11.6 J/kg·K at 18 K in field change of 50 kOe, whereas Tb{sub 3}Co{sub 7}Al{sub 2}, Dy{sub 3}Co{sub 7}Al{sub 2} and Dy{sub 3}Co{sub 7.68}Si{sub 1.32} exhibit best permanent magnet properties in the temperature range of 2–5 K with remanent magnetization of 11.95 μ{sub B}/fu, 12.86 μ{sub B}/fu and 14.4 μ{sub B}/fu, respectively and coercive field of 3.0 kOe, 1.9 kOe and 4.4 kOe, respectively. - Highlights: • {Y, Gd–Tm}{sub 3}Co{sub 7}Al{sub 2} compounds crystallize in the CeNi{sub 3}-type structure. • {Gd-Er}{sub 3}Co{sub 7}Al{sub 2} show ferrimagnetic ordering at 309 K, 209 K, 166 K, 124 K and 84 K. • Dy{sub 3}Co{sub 7.68}Si{sub 1.32} exhibits magnetic transitions at 226 K, 155 K and 42 K. • {Tb-Er}{sub 3}Co{sub 7}Al{sub 2

Peculiarities of component interaction in {l_brace}Gd, Er{r_brace}-V-Sn Ternary systems at 870 K and crystal structure of RV{sub 6}Sn{sub 6} stannides

Energy Technology Data Exchange (ETDEWEB)

Romaka, L., E-mail: romakal@franko.lviv.ua [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine); Stadnyk, Yu. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine); Romaka, V.V. [Department of Materials Engineering and Applied Physics, Lviv Polytechnic National University, Ustyyanovycha Str. 5, 79013 Lviv (Ukraine); Demchenko, P.; Stadnyshyn, M.; Konyk, M. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine)

2011-09-08

Highlights: > {l_brace}Gd, Er{r_brace}-V-Sn ternary systems at 870 K are characterized by formation of stannides with general compositions RV{sub 6}Sn{sub 6}. > Isostructural RV{sub 6}Sn{sub 6} compounds were also found with Y, Dy, Ho, Tm, and Lu. > The crystal structure of RV{sub 6}Sn{sub 6} compounds was determined by powder diffraction method. > Structural analysis showed that RV{sub 6}Sn{sub 6} compounds (R = Gd, Dy-Tm, Lu) are disordered; YV{sub 6}Sn{sub 6} is characterized by structure ordering. - Abstract: The phase equilibria in the Gd-V-Sn and Er-V-Sn ternary systems were studied at 870 K by means of X-ray and metallographic analyses in the whole concentration range. Both Gd-V-Sn and Er-V-Sn systems are characterized by formation of one ternary compound at investigated temperature, with stoichiometry RV{sub 6}Sn{sub 6} (SmMn{sub 6}Sn{sub 6}-type, space group P6/mmm, a = 0.55322(3) nm, c = 0.91949(7) nm for Gd, a = 0.55191(2) nm, c = 0.91869(8) nm for Er). Solubility of the third component in the binary compounds was not observed. Compounds with the SmMn{sub 6}Sn{sub 6}-type were also found with Dy, Ho, Tm, and Lu, while YV{sub 6}Sn{sub 6} compound crystallizes in HfFe{sub 6}Ge{sub 6} structure type. All investigated compounds are the first ternary stannides with rare earth elements and vanadium.

Thermoelectric properties, crystal and electronic structure of semiconducting RECuSe{sub 2} (RE = Pr, Sm, Gd, Dy and Er)

Energy Technology Data Exchange (ETDEWEB)

Esmaeili, Mehdi [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Tseng, Yu-Chih [CANMET Materials, Natural Resources Canada, 183 Longwood Road South, Hamilton, Ontario L8P 0A5 (Canada); Mozharivskyj, Yurij, E-mail: mozhar@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada)

2014-10-15

Highlights: • Crystal and electronic structure of monoclinic and trigonal RECuSe{sub 2} phases. • Thermoelectric properties of the RECuSe{sub 2} phases. • Temperature stability of the RECuSe{sub 2} phases. - Abstract: The ternary RECuSe{sub 2} phases have been prepared and structurally characterized. They adopt either a monoclinic structure (P2{sub 1}/c, z = 4) for lighter rare earths (RE = Pr, Sm and Gd) or Cu-disordered trigonal structure for heavier rare-earths (P3{sup ¯}m1, z = 1, RE = Dy and Er). The resistivity and Seebeck coefficient measurements on GdCuSe{sub 2}, DyCuSe{sub 2} and ErCuSe{sub 2} indicate that the studied phases are p-type semiconductors with relatively small activation energies (0.045–0.11 eV). However, their electrical resistivities are too high (0.45–220 Ω cm at room temperature) to make them competitive thermoelectric materials. Electronic structure calculations indicate presence of a band gap in the RECuSe{sub 2} phases.

Judd–Ofelt analysis and transition probabilities of Er{sup 3+} doped KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Martínez de Mendívil, Jon, E-mail: jon.martinez@uam.es [Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Lifante, Ginés [Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Pujol, Maria Cinta; Aguiló, Magdalena; Díaz, Francesc [Física i Cristalografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili, Tarragona (Spain); Cantelar, Eugenio [Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

2015-09-15

In this work the transition probabilities, radiative lifetimes and branching ratios of Er{sup 3+} ions in KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals have been determined. With this aim, Er{sup 3+} doped KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals have been grown by means of the high temperature Top-Seeded Solution Growth. A spectroscopic analysis of Er{sup 3+} ions in this crystal has been performed following anisotropic Judd–Ofelt analysis to obtain basic spectroscopic properties. A quantum efficiency over 97% has been determined for the {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition, indicating that this material is adequate for the development of lasers and amplifiers working in the third telecommunication window. - Highlights: • Er{sub 0.01}:KY{sub 1−x−y}Gd{sub x}Lu{sub y}(WO{sub 4}){sub 2} crystals have been grown. • Anisotropic Judd Ofelt analysis has been carried out. • Optical transition probabilities and branching ratios have been calculated. • Radiative and non-radiative lifetimes have been obtained.

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

Energy Technology Data Exchange (ETDEWEB)

Mishra, A; Singh, M P; Singh, V K

1982-05-01

The nitrato-complexes, (Y(PyBzH)/sub 2/(NO/sub 3/)/sub 2/)NO/sub 3/.H/sub 2/O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole) are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm/sup -1/cm/sup 2/mol/sup -1/) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the positive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C/sub 2/v) and uncoordinated (D/sub 3/h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms.

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

International Nuclear Information System (INIS)

Mishra, A.; Singh, M.P.; Singh, V.K.

1982-01-01

The nitrato-complexes, [Y(PyBzH) 2 (NO 3 ) 2 ]NO 3 .H 2 O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole] are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm -1 cm 2 mol -1 ) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the terpositive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C 2 v) and uncoordinated (D 3 h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms. (author)

Hard X-ray MCD in GdNi/sub 5/ and TbNi/sub 5/ single crystals

CERN Document Server

Galera, R M

1999-01-01

XMCD experiments have been performed at the R L/sub 2,3/ and Ni K- edges on magnetically saturated single crystals of GdNi/sub 5/ and Tb Ni/sub 5/ ferromagnetic compounds. The spectra present huge and well structured dichroic $9 signals at both the R L/sub 2,3/ and the Ni K- edges. Structures from the quadrupolar (2p to 4f) transitions are clearly observed at the R L/sub 2,3/-edges. Though Ni is not magnetic, large intensities, up to 0.4, are measured at the $9 Ni K- edge. The Ni K-edge XMCD shows a three-peak structure which intensities dependent on the rare earth. (7 refs).

Luminescent and laser properties of Yb Er:GdCa4O(BO3)3: a new crystal for eye-safe 1.5-μm lasers

Science.gov (United States)

Denker, B.; Galagan, B.; Ivleva, L.; Osiko, V.; Sverchkov, S.; Voronina, I.; Hellstrom, J. E.; Karlsson, G.; Laurell, F.

2004-09-01

We present for the first time 1.5-μm laser emission in Yb Er:GdCa4O(BO3)3 (GdCOB). The crystals were grown by the Czochralski method from platinum crucibles. Spectroscopic and laser tests of the crystals are described. A continuous-wave output power of 80 mW was achieved in a monolithic microchip cavity under laser-diode pumping.

Structure, magnetism, and transport of single-crystalline R NiSi3 (R = Y, Gd-Tm, Lu)

Science.gov (United States)

Arantes, Fabiana R.; Aristizábal-Giraldo, Deisy; Masunaga, Sueli H.; Costa, Fanny N.; Ferreira, Fabio F.; Takabatake, Toshiro; Mendonça-Ferreira, Leticie; Ribeiro, Raquel A.; Avila, Marcos A.

2018-04-01

We report on the physical properties of the intermetallic series R NiSi3 (R =Y , Gd-Tm, Lu). High quality single crystals with platelike morphology were grown using the Sn flux method. X-ray powder diffraction data show that this series crystallizes in the orthorhombic space group Cmmm, and Laue patterns indicate that the b axis remains perpendicular to the plane of the plates. Magnetization measurements show anisotropic antiferromagnetic ground states for R = Gd-Tm with Néel temperatures ranging from TN=2.6 K (TmNiSi3) up to 32.2 K (TbNiSi3), as well as metamagnetic transitions that in some cases appear together with hysteresis (TbNiSi3,DyNiSi3, and HoNiSi3). The easy axis changes from a axis to b axis on going from R = Gd-Ho to R = Er-Tm. All transitions from antiferromagnetic to paramagnetic states are clearly marked by sharp peaks in specific heat as well as in the derivative of resistivity measurements, which show metallic temperature dependence for all compounds and residual values in the range of 1 μ Ω cm . DyNiSi3 has two close phase transitions, while HoNiSi3 presents distinct critical temperatures for applied fields in the a or c directions (10.4 and 6.3 K, respectively), pointing to possible component-specific ordering of the local magnetic moments.

Measurement of the K X-ray absorption jump factors and jump ratios of Gd, Dy, Ho and Er by attenuation of a Compton peak

International Nuclear Information System (INIS)

Budak, G.; Polat, R.

2004-01-01

The X-ray absorption jump factor and jump ratio of Gd, Dy, Ho and Er were measured with a Si(Li) detector by attenuation, with Gd, Dy, Ho and Er foil, a Compton peak produced by the scattering of the 59.5 keV Am-241 Gamma rays. Al was chosen as secondary exciter. The experimental absorption jump factors and jump ratios are compared with the theoretical estimates of WinXcom (Radiat. Phys. Chem. 60 (2001) 23), McMaster (Compilation of X-ray cross sections UCRL-50174, 1969; Sec. II. Rev. I), Broll (X-ray Spectrom 15 (1986) 271), Hubbel and Seltzer (NISTIR (1995) 5632) and Budak (Radiat. Meas. accepted for publication). The present results constitute the first measurement for this combination of energy and elements, and good agreement is obtained between experiment and theory

X-ray excited photoluminescence near the giant resonance in solid-solution Gd1-xTbxOCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd1-xTbxF3

Science.gov (United States)

Waetzig, Gregory R.; Horrocks, Gregory A.; Jude, Joshua W.; Zuin, Lucia; Banerjee, Sarbajit

2015-12-01

Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb3+ centers upon excitation in proximity to the giant resonance of the host Gd3+ ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb3+ centers upon X-ray excitation near the giant resonance of the host Gd3+ ions.Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb3+ centers upon excitation in proximity to the giant resonance of the host Gd3+ ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism

Study of a new magnetic dipole mode in the heavy deformed nuclei 154Sm, 156Gd, 158Gd, 164Dy, 168Er, and 174Yb by high-resolution electron spectroscopy

International Nuclear Information System (INIS)

Bohle, D.

1985-01-01

By inelastic electron scattering with high energy resolution a new magnetic dipole mode in heavy, deformed nuclei could be detected. For this the nuclei 154 Sm, 156 Gd, 158 Gd, 164 Dy, 168 Er, and 174 Yb were studied at the Darmstadt electron linear accelerator (DALINAC) at small momentum transfer q ≤ 0.6 fm -1 and low excitation energies. A collective magnetic dipole excitation could be discovered in all nuclei at an excitation energy of E x ≅ 66 δA -1/3 MeV whereby δ means the mass deformation. The transition strength extends in the mean to B(M1)↑ ≅ 1.3 μ N 2 . A systematic study of the nucleus 156 Gd yielded hints to a strong fragmentation of the magnetic dipole strength. A comparison of electron scattering, proton scattering, and nuclear resonance fluorescence experiments shows that the new mode is a pure orbital mode. (orig./HSI) [de

A facile synthesis approach and impact of shell formation on morphological structure and luminescent properties of aqueous dispersible NaGdF{sub 4}:Yb/Er upconversion nanorods

Energy Technology Data Exchange (ETDEWEB)

Ansari, Anees A., E-mail: aneesaansari@gmail.com [King Saud University, King Abdullah Institute for Nanotechnology (Saudi Arabia); Yadav, Ranvijay; Rai, S. B. [Banaras Hindu University, Department of Physics (India)

2016-12-15

A general facile synthesis approach was used for fabrication of highly emissive aqueous dispersible hexagonal phase upconversion luminescent NaGdF{sub 4}:Yb/Er nanorods (core NRs) through metal complex decomposition process. An inert NaGdF{sub 4} and porous silica layers were grafted surrounding the surface of each and every NRs to enhance their luminescence efficiency and colloidal dispersibility in aqueous environment. Optical properties in terms of band gap energy of core, core/shell, and silica-coated core/shell/SiO{sub 2} nanorods were observed to investigate the influence of surface coating, which was gradually decreased after surface coating because of increase crystalline size after growth of inert and silica shells. The inert shell formation before silica surface grafting, upconversion luminescence intensity was greatly improved by about 20 times, owing to the effective surface passivation of the seed core and, therefore, protection of Er{sup 3+} ion in the core from the nonradiative decay caused by surface defects. Moreover, after silica coating, core/shell nanorods shows strong upconversion luminescence property similar to the hexagonal upconversion core NRs. It is expected that these NaGdF{sub 4}:Yb/Er@NaGdF{sub 4}@SiO{sub 2} (core/shell/SiO{sub 2}) NRs including highly upconversion emissive and aqueous dispersible properties make them an ideal materials for various photonic-based potential applications such as in upconversion luminescent bioimaging, magnetic resonance imaging, and photodynamic therapy.

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

OpenAIRE

Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

2014-01-01

Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each ...

Induction of apoptosis through ER stress and TP53 in MCF-7 cells by the nanoparticle [Gd@C82(OH)22]n: A systems biology study.

Science.gov (United States)

Wang, Lin; Meng, Jie; Cao, Weipeng; Li, Qizhai; Qiu, Yuqing; Sun, Baoyun; Li, Lei M

2014-06-01

The nanoparticle gadolinium endohedral metallofullerenol [Gd@C82(OH)22]n is a new candidate for cancer treatment with low toxicity. However, its anti-cancer mechanisms remain mostly unknown. In this study, we took a systems biology view of the gene expression profiles of human breast cancer cells (MCF-7) and human umbilical vein endothelial cells (ECV304) treated with and without [Gd@C82(OH)22]n, respectively, measured by the Agilent Gene Chip G4112F. To properly analyze these data, we modified a suit of statistical methods we developed. For the first time we applied the sub-sub normalization to Agilent two-color microarrays. Instead of a simple linear regression, we proposed to use a one-knot SPLINE model in the sub-sub normalization to account for nonlinear spatial effects. The parameters estimated by least trimmed squares- and S-estimators show similar normalization results. We made several kinds of inferences by integrating the expression profiles with the bioinformatic knowledge in KEGG pathways, Gene Ontology, JASPAR, and TRANSFAC. In the transcriptional inference, we proposed the BASE2.0 method to infer a transcription factor's up-regulation and down-regulation activities separately. Overall, [Gd@C82(OH)22]n induces more differentiation in MCF-7 cells than in ECV304 cells, particularly in the reduction of protein processing such as protein glucosylation, folding, targeting, exporting, and transporting. Among the KEGG pathways, the ErbB signaling pathway is up-regulated, whereas protein processing in endoplasmic reticulum (ER) is down-regulated. CHOP, a key pro-apoptotic gene downstream of the ER stress pathway, increases to nine folds in MCF-7 cells after treatment. These findings indicate that ER stress may be one important factor that induces apoptosis in MCF-7 cells after [Gd@C82(OH)22]n treatment. The expression profiles of genes associated with ER stress and apoptosis are statistically consistent with other profiles reported in the literature, such as

The low-energy β(-) and electron emitter (161)Tb as an alternative to (177)Lu for targeted radionuclide therapy.

Science.gov (United States)

Lehenberger, Silvia; Barkhausen, Christoph; Cohrs, Susan; Fischer, Eliane; Grünberg, Jürgen; Hohn, Alexander; Köster, Ulli; Schibli, Roger; Türler, Andreas; Zhernosekov, Konstantin

2011-08-01

The low-energy β(-) emitter (161)Tb is very similar to (177)Lu with respect to half-life, beta energy and chemical properties. However, (161)Tb also emits a significant amount of conversion and Auger electrons. Greater therapeutic effect can therefore be expected in comparison to (177)Lu. It also emits low-energy photons that are useful for gamma camera imaging. The (160)Gd(n,γ)(161)Gd→(161)Tb production route was used to produce (161)Tb by neutron irradiation of massive (160)Gd targets (up to 40 mg) in nuclear reactors. A semiautomated procedure based on cation exchange chromatography was developed and applied to isolate no carrier added (n.c.a.) (161)Tb from the bulk of the (160)Gd target and from its stable decay product (161)Dy. (161)Tb was used for radiolabeling DOTA-Tyr3-octreotate; the radiolabeling profile was compared to the commercially available n.c.a. (177)Lu. A (161)Tb Derenzo phantom was imaged using a small-animal single-photon emission computed tomography camera. Up to 15 GBq of (161)Tb was produced by long-term irradiation of Gd targets. Using a cation exchange resin, we obtained 80%-90% of the available (161)Tb with high specific activity, radionuclide and chemical purity and in quantities sufficient for therapeutic applications. The (161)Tb obtained was of the quality required to prepare (161)Tb-DOTA-Tyr3-octreotate. We were able to produce (161)Tb in n.c.a. form by irradiating highly enriched (160)Gd targets; it can be obtained in the quantity and quality required for the preparation of (161)Tb-labeled therapeutic agents. Copyright © 2011 Elsevier Inc. All rights reserved.

A ₂ TiO ₅ (A = Dy, Gd, Er, Yb) at High Pressure

Energy Technology Data Exchange (ETDEWEB)

Park, Sulgiye [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Rittman, Dylan R. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Tracy, Cameron L. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Chapman, Karena W. [X-ray Science Division, Advanced Photon; Zhang, Fuxiang [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States; Park, Changyong [HPCAT, Carnegie Institution of Washington, Argonne, Illinois 60439, United States; Tkachev, Sergey N. [Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States; O’Quinn, Eric [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Shamblin, Jacob [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Lang, Maik [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Mao, Wendy L. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Stanford; amp, Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States; Ewing, Rodney C. [Department of Geological Science, Stanford University, Stanford, California 94305, United States

2018-02-07

The structural evolution of lanthanide A2TiO5 (A = Dy, Gd, Yb, and Er) at high pressure is investigated using synchrotron X-ray diffraction. The effects of A-site cation size and of the initial structure are systematically examined by varying the composition of the isostructural lanthanide titanates, and the structure of dysprosium titanate polymorphs (orthorhombic, hexagonal and cubic), respectively. All samples undergo irreversible high pressure phase transformations, but with different onset pressures depending on the initial structure. While individual phase exhibits different phase transformation histories, all samples commonly experience a sluggish transformation to a defect cotunnite-like (Pnma) phase for a certain pressure range. Orthorhombic Dy2TiO5 and Gd2TiO5 form P21am at pressures below 9 GPa and Pnma above 13 GPa. Pyrochlore-type Dy2TiO5 and Er2TiO5 as well as defect-fluorite-type Yb2TiO5 form Pnma at ~ 21 GPa, followed by Im-3m. Hexagonal Dy2TiO5 forms Pnma directly, although a small amount of remnants of hexagonal Dy2TiO5 is observed even at the highest pressure (~ 55 GPa) reached, indicating a kinetic limitations in the hexagonal Dy2TiO5 phase transformations at high pressure. Decompression of these materials leads to different metastable phases. Most interestingly, a high pressure cubic X-type phase (Im-3m) is confirmed using highresolution transmission electron microscopy on recovered pyrochlore-type Er2TiO5. The kinetic constraints on this metastable phase yield a mixture of both the X-type phase and amorphous domains upon pressure release. This is the first observation of an X-type phase for an A2BO5 composition at high pressure.

Investigation of local magnetism in RZn (R = Ce, Gd, Tb, Dy) and GdCu intermetallic compounds using perturbed angular correlation gamma-gamma spectroscopy; Investigacao do magnetismo local em compostos intermetalicos do tipo RZn (R = Ce, Gd, Tb, Dy) e GdCu pela espectroscopia de correlacao angular gama-gama perturbada

Energy Technology Data Exchange (ETDEWEB)

Santos, Brianna Bosch dos

2010-07-01

This work presents, from a microscopic point of view, a systematic study of the local magnetism in RZn (R = Ce, Gd, Tb, Dy) and GdCu intermetallic compounds through measurements of hyperfine interactions using the Perturbed Angular Correlation Gamma- Gamma Spectroscopy technique with {sup 111}In {yields} {sup 111}Cd and {sup 140}La {yields} {sup 140}Ce as probe nuclei. As the magnetism in these compounds originates from the 4f electrons of the rare-earth elements it is interesting to observe in a systematic study of RZn compounds the behavior of the magnetic hyperfine field with the variation of the number of 4f electrons in the R element. The use of probe nuclei {sup 140}La {yields} {sup 140}Ce is interesting because Ce{sup +3} ion posses one 4f electron which may contribute to the total hyperfine field, and the results showed anomalous behavior. The results for {sup 111}Cd probe showed that the temperature dependence of the magnetic hyperfine field follows the Brillouin function, and the magnetic hyperfine field decreases linearly with increase of the atomic number of rare earth when plotted as a function of the rare-earth J spin projection, showing that the main contribution to the magnetic hyperfine field in RZn compounds comes from the polarization of the conduction electrons. The results for the electric field gradient measured with {sup 111}Cd for all compounds showed a strong decrease with the atomic number of the rare-earth element. We have therefore assumed that the major contribution to the electric field gradient originates from the 4f electrons of the rare-earths. The measurements of the electric field gradient for GdCu with {sup 111}Cd, after temperature decreases and increases again showed that two different structures, CsCl-type cubic and FeB-type orthorhombic structures co-exist. Finally, it is the first time that measurements of hyperfine parameters have been carried out with theses two probe nuclei in the studied RZn. (author)

Analysis of green luminescent Tb3+:Ca4GdO(BO3)3 powder phosphor

International Nuclear Information System (INIS)

Vengala Rao, B.; Rambabu, U.; Buddhudu, S.

2007-01-01

This paper reports on the emission analysis of a green luminescent Tb 3+ :Ca 4 GdO(BO 3 ) 3 powder phosphor based on the measurements of excitation, emission and lifetimes. Besides this, we have also observed an intense green emission from this powder phosphor under an UV source. The emission transitions of ( 5 D 4 →7 F 3,4,5,6 ) with λ exci =257 nm have been measured. Particularly, the green emission transition ( 5 D 4 →7 F 5 ) at 553 nm has been found to be more prominent and intense. Such green strong emission displaying powder phosphor will find applications in the development of coated screens in certain electronic systems. Apart from the emission analysis of this phosphor, XRD, SEM and FTIR studies have also been carried out in order to understand the structural details of it

Preparation and studies of Eu{sup 3+} and Tb{sup 3+} co-doped Gd{sub 2}O{sub 3} and Y{sub 2}O{sub 3} sol-gel scintillating films

Energy Technology Data Exchange (ETDEWEB)

Morales Ramirez, A. de J, E-mail: amoralesra@ipn.m [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA) Unidad Altamira Instituto Politecnico Nacional Km. 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Depto. de Ingenieria Metalurgica, ESIQIE-Instituto Politecnico Nacional UPALM C.P. 07738, Mexico D.F. (Mexico); Garcia Murillo, A.; Carrillo Romo, F. de J [Depto. de Ingenieria Metalurgica, ESIQIE-Instituto Politecnico Nacional UPALM C.P. 07738, Mexico D.F. (Mexico); Ramirez Salgado, J. [Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas No. 152, CP 07730, Mexico D.F. (Mexico); Le Luyer, C. [LPCML, CNRS-UMR 5620/Universite Claude Bernard Lyon 1/69622 Villeurbanne Cedex (France); Chadeyron, G.; Boyer, D. [Laboratoire des Materiaux Inorganiques, CNRS-UMR 6002, Universite Blaise Pascal, 24 Ave des Landais F 63177 Aubiere Cedex (France); Moreno Palmerin, J. [Depto. de Ingenieria Metalurgica, ESIQIE-Instituto Politecnico Nacional UPALM C.P. 07738, Mexico D.F. (Mexico)

2009-10-30

Eu{sup 3+} (2.5 at.%) and Tb{sup 3+} (0.005-0.01 at.%) co-doped gadolinium and yttrium oxide (Gd{sub 2}O{sub 3} and Y{sub 2}O{sub 3}) powders and films have been prepared using the sol-gel process. High density and optical quality thin films were prepared with the dip-coating technique. Gadolinium (III) 2,4-pentadionate and yttrium (III) 2,4-pentadionate were used as precursors, and europium and terbium in their nitrate forms were used as doping agents. Chemical and structural analyses (infrared spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy) were conducted on both sol-gel precursor powders and dip-coated films. The morphology of thin films heat-treated at 700 {sup o}C was studied by means of atomic force microscopy. It was shown that the highly dense and very smooth films had a root mean roughness (RMS) of 2 nm {+-} 0.2 (A = 0.0075 Tb{sup 3+}) and 24 nm {+-} 3.0 (B = 0.01 Tb{sup 3+}). After treatment at 700 {sup o}C, the crystallized films were in the cubic phase and presented a polycrystalline structure made up of randomly oriented crystallites with grain sizes varying from 20 to 60 nm. The X-ray induced emission spectra of Eu{sup 3+}- and Tb{sup 3+}-doped Gd{sub 2}O{sub 3} and Y{sub 2}O{sub 3} powders showed that Tb{sup 3+} contents of 0.005, 0.0075 and 0.01 at.% affected their optical properties. Lower Tb{sup 3+} concentrations (down to 0.005 at.%) in both systems enhanced the light yield.

Optical emission, vibrational feature, and shear-thinning aspect of Tb3+-doped Gd2O3 nanoparticle-based novel ferrofluids irradiated by gamma photons

Science.gov (United States)

Paul, Nibedita; Hazarika, Samiran; Saha, Abhijit; Mohanta, Dambarudhar

2013-10-01

The present work reports on the spectroscopic and rheological properties of un-exposed and gamma (γ-) irradiated rare earth (RE) oxide nanoparticle-based ferrofluids (FFs). The FFs were produced by dispersing surfactant coated terbium (Tb3+)-doped gadolinium oxide (Gd2O3) nanoparticles in the ethanol medium and later on they were subjected to energetic γ-irradiation (1.25 MeV) at select doses (97 Gy and 2.635 kGy). The synthesized RE oxide nanoparticles were of ˜7 nm size and having a cubic crystal structure, as predicted from transmission electron microscopy and x-ray diffraction studies. Fourier transformed infra-red (FT-IR) spectra showed an adequate blue shift of the Gd-O vibrational stretching mode from a wavenumber value of ˜558 cm-1, for the un-irradiated sample to a value of ˜540 cm-1 corresponding to the irradiated sample (2.635 kGy). In contrast, photoluminescence spectra have revealed modification of defect states along with Tb3+ assisted radiative transitions. The rheology measurements have illustrated unusual shear thinning behavior of the FFs, with an apparently improved power index (s) value from 0.34 to 0.50, obtained for increasing γ-dose cases. The variation of the decay parameter with irradiation dose, as predicted from the nature of apparent viscosity curves, is attributed to the defect formation, role of impurity ions (Tb3+), and weakening of inter nanoparticle bonding. The unusual properties of the novel RE oxide based FFs may find scope in sealing and shielding elements in the radiation environment including accelerator and other related zones.

Photoluminescence and cathodoluminescence properties of Sr{sub 2}Gd{sub 8}Si{sub 6}O{sub 26}:RE{sup 3+}(RE{sup 3+}=Tb{sup 3+}or Sm{sup 3+}) phosphors

Energy Technology Data Exchange (ETDEWEB)

Hussain, Sk. Khaja [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Rao, Gattupalli Manikya [Department of Physics, College of Science and Technology, Andhra University, Visakhapatanam, Andhra Pradesh 53003 (India); Raju, G. Seeta Rama; Krishna Bharat, L. [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Subba Rao, P.S.V., E-mail: raopsvs@rediffmail.com [Department of Physics, College of Science and Technology, Andhra University, Visakhapatanam, Andhra Pradesh 53003 (India); Yu, Jae Su, E-mail: jsyu@khu.ac.kr [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

2016-10-15

Trivalent terbium (Tb{sup 3+}) or samarium (Sm{sup 3+}) ions individually activated green and orange emitting Sr{sub 2}Gd{sub 8}Si{sub 6}O{sub 26} (SGSO) phosphors were synthesized by a citrate sol–gel method. The X-ray diffraction patterns of SGSO:Tb{sup 3+} and SGSO:Sm{sup 3+} phosphors exhibited the characteristic diffraction peaks of oxyapatite in a hexagonal lattice structure. The photoluminescence (PL) properties at ultraviolet (UV) or near-UV excitation wavelengths were measured for Tb{sup 3+} or Sm{sup 3+} ions doped SGSO phosphors as a function of its respective concentration. The PL spectra of SGSO:Tb{sup 3+} phosphors revealed the characteristic emission peaks of both Gd{sup 3+} and Tb{sup 3+} ions which are associated with 4f–4f transitions under 274 nm of excitation wavelength. When the concentration of Tb{sup 3+} ions increased over 0.05 mol (5 mol%), the emission intensities of {sup 5}D{sub 3} transitions decreased due to the well-known cross-relaxation process. However, based on the intensities of {sup 5}D{sub 4} transitions, the optimum concentration of Tb{sup 3+} ions was found to be 0.05 mol. Under 404 nm of excitation wavelength, the SGSO:Sm{sup 3+} phosphors exhibited the characteristic orange emission at 600 nm due to the {sup 4}G{sub 5/2}→{sup 6}H{sub 7/2} electronic transition. The optimum concentration of SGSO:Sm{sup 3+} phosphors was found to be 0.02 mol. The decay curves of the optimized SGSO:Tb{sup 3+} and SGSO:Sm{sup 3+} phosphors were well fitted to single exponential functions and their lifetimes were calculated. Furthermore, the optimized phosphor samples showed good thermal stability. Likewise, cathodoluminescence properties were also studied for the optimized samples as a function of filament current and accelerating voltage. The Commission International de I-Eclairage chromaticity coordinates were calculated for the SGSO:Tb{sup 3+} and SGSO:Sm{sup 3+} phosphors.

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.

Platinum triangles in the Pt/Al framework of the intermetallic REPt6Al3 (RE = Ce-Nd, Sm, Gd, Tb) series

International Nuclear Information System (INIS)

Eustermann, Fabian; Stegemann, Frank; Renner, Konstantin; Janka, Oliver

2017-01-01

The compounds of the REPt 6 Al 3 series (RE = Ce-Nd, Sm, Gd, Tb) were obtained by reaction of the elements via arc-melting. They were characterized by powder and single-crystal X-ray diffraction (NdPt 6 Al 3 : wR = 0.0432, 759 F 2 values, 33 variables) as well as by magnetic susceptibility measurements. The isostructural compounds crystallize with a new structure type in the trigonal crystal system with space group R anti 3c, twelve formula units in the unit cell, and lattice parameters of a = 752-755 and c = 3882-3945 pm. The crystal structure can be described by different slabs stacked along [001]. One layer features Pt 3 triangles, centering the cavities of a flat honeycomb RE layer that are arranged in a..ABCA ' B ' C ' .. sequence. The other layer consists of condensed hexagonal [Pt 6 Al 6 ] prisms, centered by Pt atoms, separating the before mentioned slabs. Magnetic measurements revealed that all rare-earth atoms are in the trivalent oxidation state, however, due to the low lanthanoide content magnetic ordering phenomena were observed only at low temperatures [SmPt 6 Al 3 : T C = 5.0(1) K; GdPt 6 Al 3 : T C = 7.3(1) K; TbPt 6 Al 3 : T N = 3.6(1) K]. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Bulk glass ceramics containing Yb{sup 3+}/Er{sup 3+}: β-NaGdF{sub 4} nanocrystals: Phase-separation-controlled crystallization, optical spectroscopy and upconverted temperature sensing behavior

Energy Technology Data Exchange (ETDEWEB)

Chen, Daqin, E-mail: dqchen@fjirsm.ac.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wan, Zhongyi; Zhou, Yan [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Huang, Ping, E-mail: phuang@fjirsm.ac.cn [Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Zhong, Jiasong; Ding, Mingye [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Xiang, Weidong; Liang, Xiaojuan [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Ji, Zhenguo, E-mail: jizg@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

2015-07-25

Highlights: • Hexagonal NaGdF{sub 4} nanocrystals embedded bulk glass ceramics were fabricated. • The incorporation of Ln{sup 3+} dopants into the β-NaGdF{sub 4} lattice was demonstrated. • Upconversion luminescence was highly intensified after glass crystallization. • Such glass ceramics had possible application in the optical temperature sensors. - Abstract: Lanthanide doped hexagonal β-NaGdF{sub 4} nanocrystals embedded transparent bulk glass ceramics were successfully fabricated via a phase-separation-controlled crystallization route. Elemental mapping in the scanning transmission electron microscope and optical spectroscopy analysis demonstrated the partition of the active centers into the β-NaGdF{sub 4} crystalline lattice. As a result, upconversion luminescence of the glass ceramic co-doped with Yb{sup 3+} and Er{sup 3+} is about 60 times as high as that of the precursor glass, attributing to the modification of Yb{sup 3+}/Er{sup 3+} surrounding from phase-separated amorphous nanoparticle to β-NaGdF{sub 4} crystalline lattice with low phonon energy and high crystallinity after crystallization. Furthermore, the temperature-dependent green upconversion emissions assigned to {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2} (520 nm) and {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} (540 nm) transitions were investigated, and the corresponding fluorescence intensity ratio of these two thermally coupled emitting-states greatly enhanced with increase of temperature. Using such fabricated glass ceramic as an optical thermometric medium, the maximum sensitivity reached as high as 0.0037 K{sup −1} at 580 K. It is expected that the investigated Er{sup 3+}/Yb{sup 3+} codoped glass ceramic might be a very promising candidate for accurate optical temperature sensors.

A single crystal study of RE{sub 14}Co{sub 3}In{sub 3} (RE = Y, Tb, Dy, Ho, Er)

Energy Technology Data Exchange (ETDEWEB)

Zaremba, V.I.; Kalychak, Y.M.; Dzevenko, M.V. [Inorganic Chemistry Dept., Ivan Franko National Univ. of Lviv (Ukraine); Rodewald, U.Ch.; Heying, B.; Poettgen, R. [Inst. fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Univ. Muenster (Germany)

2006-01-01

The rare earth-cobalt-indides RE{sub 14}Co{sub 3}In{sub 3} (RE = Y, Tb, Dy, Ho, Er) were prepared in polycrystalline form from the elements by arc-melting. Small single crystals were grown through a special annealing sequence. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu{sub 14}Co{sub 2}In{sub 3} (Gd{sub 14}Co{sub 3}In{sub 2.7}) type, P4{sub 2}/nmc, Z = 4, a = 959.0(1), c = 2319.1(5) pm, wR2 = 0.055, 2289 F{sup 2} values, 65 variables for Y{sub 13.90}Co{sub 2.99}In{sub 3.02}, a = 953.8(1), c = 2315.8(5) pm, wR2 = 0.108, 2357 F{sup 2} values, 65 variables for Tb{sub 13.92}Co{sub 3.01}In{sub 2.92}, a = 949.24(3), c = 2296.5(1) pm, wR2 = 0.129, 2518 F{sup 2} values, 65 variables for Dy{sub 13.90}Co{sub 2.97}In{sub 2.95}, a = 946.3(1), c = 2289.0(5) pm, wR2 = 0.099, 2297 F{sup 2} values, 64 variables for Ho{sub 14}Co{sub 2.80}In{sub 2.89}, and a = 941.0(1), c = 2274.2(5) pm, wR2 = 0.140, 2450 F{sup 2} values, 65 variables for Er{sub 13.83}Co{sub 2.88}In{sub 3.10}. All RE{sub 14}Co{sub 3}In{sub 3} indides show a small degree of In/Co mixing (between 7 and 16% Co) on the 4c In1 site and defects on the 8g Co1 positions (between 84 and 95% Co). Except for the holmium compound, the RE{sub 14}Co{sub 3}In{sub 3} intermetallics also reveal RE/In mixing on the 4c RE1 sites, leading to the refined compositions. The seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE{sub 14}Co{sub 3}In{sub 3} structures consist of a complex intergrowth of rare earth based polyhedra. Both cobalt sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell with an In2-In2 distance of 300 pm (for Ho{sub 14}Co{sub 2.80}In{sub 2.89}). The crystal chemistry of the RE{sub 14}Co{sub 3}In{sub 3} indides is discussed. (orig.)

Thermal, Spectral and Laser Properties of Er3+:Yb3+:GdMgB₅O10: A New Crystal for 1.5 μm Lasers.

Science.gov (United States)

Huang, Yisheng; Yuan, Feifei; Sun, Shijia; Lin, Zhoubin; Zhang, Lizhen

2017-12-25

A novel laser crystal of Er 3+ :Yb 3+ :GdMgB₅O 10 with dimension of 26 × 16 × 12 mm³ was grown successfully from K₂Mo₃O 10 flux by the top seeded solution growth method. The thermal diffusivity and specific heat capacity were measured to calculate the thermal conductivity of the crystal. The absorption and fluorescence properties of the crystal at room temperature were investigated in detail. The Judd-Ofelt method was used to analyze the polarized absorption spectra. The emission cross-section of the ⁴I 13/2 →⁴I 15/2 transition was calculated by the Füchtbauer-Ladenburg formula and the relevant gain cross-sections were estimated. Continuous-wave laser output of 140 mW at 1569 nm with the slope efficiency of 17.8% was demonstrated in a plano-concave resonator. The results reveal that Er 3+ :Yb 3+ :GdMgB₅O 10 crystal is a promising material for 1.5 μm lasers.

Influence of core size on the upconversion luminescence properties of spherical Gd2O3:Yb3+/Er3+@SiO2 particles with core-shell structures

International Nuclear Information System (INIS)

Zheng, Kezhi; Liu, Zhenyu; Liu, Ye; Song, Weiye; Qin, Weiping

2013-01-01

Spherical SiO 2 particles with different sizes (30, 80, 120, and 180 nm) have been coated with Gd 2 O 3 :Yb 3+ /Er 3+ layers by a heterogeneous precipitation method, leading to the formation of core-shell structural Gd 2 O 3 :Yb 3+ /Er 3+ @SiO 2 particles. The samples were characterized by using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, upconversion (UC) emission spectra, and fluorescent dynamical analysis. The obtained core-shell particles have perfect spherical shape with narrow size distribution. Under the excitation of 980 nm diode laser, the core-shell samples showed size-dependent upconversion luminescence (UCL) properties. The inner SiO 2 cores in core-shell samples were proved to have limited effect on the total UCL intensities of Er 3+ ions. The UCL intensities of core-shell particles were demonstrated much higher than the values obtained in pure Gd 2 O 3 :Yb 3+ /Er 3+ with the same phosphor volume. The dependence of the specific area of a UCL shell on the size of its inner SiO 2 particle was calculated and analyzed for the first time. It was confirmed that the surface effect came from the outer surfaces of emitting shells is dominant in influencing the UCL property in the core-shell samples. Three-photon UC processes for the green emissions were observed in the samples with small sizes of SiO 2 cores. The results of dynamical analysis illustrated that more nonradiative relaxation occurred in the core-shell samples with smaller SiO 2 core sizes

Magnetism of cyano-bridged Ln3+-M3+ complexes. Part II: one-dimensional complexes (Ln3+ = Eu, Tb, Dy, Ho, Er, Tm; M3+ = Fe or Co) with bpy as blocking ligand.

Science.gov (United States)

Figuerola, Albert; Ribas, Joan; Casanova, David; Maestro, Miguel; Alvarez, Santiago; Diaz, Carmen

2005-10-03

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to 13 one-dimensional complexes: trans-[M(CN)4(mu-CN)2Ln(H2O)4(bpy)]n.4nH2O.1.5nbpy (Ln = Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Lu3+; M = Fe3+, Co3+). The structures for [EuFe]n (1), [TbFe]n (2), [DyFe]n (3), [HoFe]n (4), [ErFe]n (5), [TmFe]n (6), [LuFe]n (7), [EuCo]n (8), [TbCo]n (9), [DyCo]n (10), [HoCo]n (11), [ErCo]n (12), and [TmCo]n (13) have been solved: they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular architecture created by the interplay of coordinative, hydrogen bonding, and pi-pi interactions. A stereochemical study of the eight-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. The Ln3+-Fe3+ interaction is antiferromagnetic in [DyFe]n and [TbFe]n. For [EuFe]n, [HoFe]n, [ErFe]n, and [TmFe]n, there is no sign of any significant interaction. The magnetic behavior of [DyFe]n suggests the onset of weak long-range ferromagnetic ordering at 2.5 K.

Induction of ER stress in macrophages of tuberculosis granulomas.

Directory of Open Access Journals (Sweden)

Tracie A Seimon

2010-09-01

Full Text Available The endoplasmic reticulum (ER stress pathway known as the Unfolded Protein Response (UPR is an adaptive survival pathway that protects cells from the buildup of misfolded proteins, but under certain circumstances it can lead to apoptosis. ER stress has been causally associated with macrophage apoptosis in advanced atherosclerosis of mice and humans. Because atherosclerosis shares certain features with tuberculosis (TB with regard to lesional macrophage accumulation, foam cell formation, and apoptosis, we investigated if the ER stress pathway is activated during TB infection.Here we show that ER stress markers such as C/EBP homologous protein (CHOP; also known as GADD153, phosphorylated inositol-requiring enzyme 1 alpha (Ire1α and eukaryotic initiation factor 2 alpha (eIF2α, and activating transcription factor 3 (ATF3 are expressed in macrophage-rich areas of granulomas in lungs of mice infected with virulent Mycobacterium tuberculosis (Mtb. These areas were also positive for numerous apoptotic cells as assayed by TUNEL. Microarray analysis of human caseous TB granulomas isolated by laser capture microdissection reveal that 73% of genes involved in the UPR are upregulated at the mRNA transcript level. The expression of two ER stress markers, ATF3 and CHOP, were also increased in macrophages of human TB granulomas when assayed by immunohistochemistry. CHOP has been causally associated with ER stress-induced macrophage apoptosis. We found that apoptosis was more abundant in granulomas as compared to non-granulomatous tissue isolated from patients with pulmonary TB, and apoptosis correlated with CHOP expression in areas surrounding the centralized areas of caseation.In summary, ER stress is induced in macrophages of TB granulomas in areas where apoptotic cells accumulate in mice and humans. Although macrophage apoptosis is generally thought to be beneficial in initially protecting the host from Mtb infection, death of infected macrophages in

Study of X-ray L2 absorption edges of Gd, Dy, Ho and Er in metals and compounds

International Nuclear Information System (INIS)

Agarwal, B.K.; Agarwal, B.R.K.

1978-01-01

The positions and shapes of L2 X-ray absorption edges of Gd, Dy, Ho and Er have been studied in metals and in oxides and chlorides, using a forty centimetre bent mica crystal spectrograph. It has been found that the L2 edge shifts towards the high energy side in the compounds and that the chemical shift ΔE depends on the degree of covalency involved. The white line structure at the edge has been analysed in terms of transitions of L2 shell electron to optical nd (n >= 5) states. (author)

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.

Investigation of chemical bond characteristics, thermal expansion coefficients and bulk moduli of alpha-R2MoO6 and R2Mo2O7 (R = rare earths) by using a dielectric chemical bond method.

Science.gov (United States)

Li, Huaiyong; Zhang, Siyuan; Zhou, Shihong; Cao, Xueqiang

2009-09-01

Theoretical researches are performed on the alpha-R2MoO6 (R = Y, Gd, Tb Dy, Ho, Er, Tm and Yb) and pyrochlore-type R2Mo2O7 (R = Y, Nd, Sm, Gd, Tb and Dy) rare earth molybdates by using chemical bond theory of dielectric description. The chemical bonding characteristics and their relationship with thermal expansion property and compressibility are explored. The calculated values of linear thermal expansion coefficient (LTEC) and bulk modulus agree well with the available experimental values. The calculations reveal that the LTECs and the bulk moduli do have linear relationship with the ionic radii of the lanthanides: the LTEC decreases from 6.80 to 6.62 10(-6)/K and the bulk modulus increases from 141 to 154 GPa when R goes in the order Gd, Tb Dy, Ho, Er, Tm, and Yb in the alpha-R2MoO6 series; while in the R2Mo2O7 series, the LTEC ranges from 6.80 to 6.61 10(-6)/K and the bulk modulus ranges from 147 to 163 GPa when R varies in the order Nd, Sm, Gd, Tb and Dy. Copyright 2008 Wiley Periodicals, Inc.

Crystal fields of dilute Tb, Dy, Ho, or Er in Lu obtained by magnetization measurements

International Nuclear Information System (INIS)

Touborg, P.; Hog, J.

1975-01-01

Magnetization measurements are reported on single crystals of dilute Tb, Dy, Ho, or Er in Lu. These measurements were performed in the temperature range 1.5--100 K and field range 0--6 T and include measurements of initial susceptibility, isothermal and isofield magnetization, and basal-plane anisotropy. The results show features similar to the corresponding Y-R alloys, where R is a rare earth. Crystal-field and molecular-field parameters could be unabiguously deduced from the experimental data. The effects of crystal-field level broadening were investigated and demonstrated for Ho. Comparison of the Y-R and Lu-R results makes possible an estimate of the crystal-field parameters in the pure-rare-earth metals

Synthesis and functionalization of NaGdF4:Yb,Er@NaGdF4 core–shell nanoparticles for possible application as multimodal contrast agents

Directory of Open Access Journals (Sweden)

Dovile Baziulyte-Paulaviciene

2017-09-01

Full Text Available Upconverting nanoparticles (UCNPs are promising, new imaging probes capable of serving as multimodal contrast agents. In this study, monodisperse and ultrasmall core and core–shell UCNPs were synthesized via a thermal decomposition method. Furthermore, it was shown that the epitaxial growth of a NaGdF4 optical inert layer covering the NaGdF4:Yb,Er core effectively minimizes surface quenching due to the spatial isolation of the core from the surroundings. The mean diameter of the synthesized core and core–shell nanoparticles was ≈8 and ≈16 nm, respectively. Hydrophobic UCNPs were converted into hydrophilic ones using a nonionic surfactant Tween 80. The successful coating of the UCNPs by Tween 80 has been confirmed by Fourier transform infrared (FTIR spectroscopy. Scanning electron microscopy (SEM, powder X-ray diffraction (XRD, photoluminescence (PL spectra and magnetic resonance (MR T1 relaxation measurements were used to characterize the size, crystal structure, optical and magnetic properties of the core and core–shell nanoparticles. Moreover, Tween 80-coated core–shell nanoparticles presented enhanced optical and MR signal intensity, good colloidal stability, low cytotoxicity and nonspecific internalization into two different breast cancer cell lines, which indicates that these nanoparticles could be applied as an efficient, dual-modal contrast probe for in vivo bioimaging.

Magnetic properties of the high-Tsub(c) superconductors RBa2Cu3Osub(9-delta) (R=Gd, Dy, Er)

International Nuclear Information System (INIS)

Groot, P.A.J. de; Rainford, B.D.; McK-Paul, D.; Balakrishnan, G.; Lanchester, P.C.; Weller, M.T.; Grasmeder, J.

1987-01-01

Magnetic properties of RBa 2 Cu 3 Osub(9-delta) with R = Y, Gd, Dy, Er have been measured for 4.2 K < T < 300 K and magnetic fields up to 7 T. They exhibit a superconductive transition around 91 K, above which temperature the magnetisation can be described by a Curie-Weiss law. The magnetic and superconductive properties develop independently below the phase transition. Magnetic hysteresis is prominent at low temperatures (T < or approx. 25 K) and varies for different samples. Estimates for critical densities are given. (author)

Multi-quasiparticle excitations in 145Tb

International Nuclear Information System (INIS)

Zheng Yong; Zhou Xiaohong; Zhang Yuhu; Liu Minliang; Guo Yingxiang; Lei Xiangguo; Kusakari, H.; Sugawara, M.

2004-01-01

High-spin states in 145 Tb have been populated using the 118 Sn( 32 S, 1p4n) reaction at a beam energy of 165 MeV. The level scheme of 145 Tb has been established for the first time. The level scheme shows characteristics of spherical or slightly oblate nucleus. Based on the systematic trends of the level structure in the neighboring N=80 isotones, the level structure in 145 Tb below 2 MeV excitation is well explained by coupling an h 11/2 valence proton to the even-even 144 Gd core. Above 2 MeV excitation, most of the yrast levels are interpreted with multi-quasiparticle shell-model configurations. (authors)

Ternary rhombohedral Laves phases RE_2Rh_3Ga (RE = Y, La-Nd, Sm, Gd-Er)

International Nuclear Information System (INIS)

Seidel, Stefan; Benndorf, Christopher; Heletta, Lukas; Poettgen, Rainer; Eckert, Hellmut; Sao Paulo Univ., Sao Carlos

2017-01-01

The ordered Laves phases RE_2Rh_3Ga (RE=Y, La-Nd, Sm, Gd-Er) were synthesized by arc-melting of the elements and subsequent annealing. The samples were characterized by powder X-ray diffraction (XRD). They crystallize with the rhombohedral Mg_2Ni_3Si type structure, space group R3m. Three structures were refined from single crystal X-ray diffractometer data: a=557.1(1), c=1183.1(2), wR2=0.0591, 159 F"2 values, 10 variables for Y_2Rh_3Ga, a=562.5(2), c=1194.4(2) pm, wR2=0.0519, 206 F"2 values, 11 variables for Ce_2Rh_3Ga and a=556.7(2), c=1184.1(3) pm, wR2=0.0396, 176 F"2 values, 11 variables for Tb_2Rh_3Ga. The Rh_3Ga tetrahedra are condensed via common corners and the large cavities left by the network are filled by the rare earth atoms. The RE_2Rh_3Ga Laves phases crystallize with a translationengleiche subgroup of the cubic RERh_2 Laves phases with MgCu_2 type. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y_2Rh_3Ga and La_2Rh_3Ga. Ce_2Rh_3Ga shows intermediate cerium valence while all other RE_2Rh_3Ga phases are Curie-Weiss paramagnets which order magnetically at low temperatures. The "8"9Y and "7"1Ga solid state nuclear magnetic resonance (NMR) spectra of the diamagnetic representative Y_2Rh_3Ga show well-defined single resonances in agreement with an ordered bulk phase. In comparison to the binary Laves phase YRh_2 a strongly increased "8"9Y resonance frequency is observed owing to a higher s-electron spin density at the "8"9Y nuclei as proven by density of states (DOS) calculations.

(Gd1−xErx)5Si2Ge2 compounds

Indian Academy of Sciences (India)

Gd metal (3 N) by arc melting, and then annealed at 1523 K (3 h). The phase, microstructure, Curie ... The temperature of magnetic transition decreases linearly from 281 K to 177 K with the increase of Er content from x = 0–0·2. ... Gd5Si2Ge2 serial compounds, different rare earth elements substituted for Gd in Gd5(Six ...

3D Rare earth porous coordination frameworks with formamide generated in situ syntheses: Crystal structure and down- and up-conversion luminescence

Energy Technology Data Exchange (ETDEWEB)

Ma, Xue [Department of Chemistry, Capital Normal University, Beijing 100048 (China); Tian, Jing [Department of Chemistry, Capital Normal University, Beijing 100048 (China); Experiment and Teaching Resource Management Centre, Yibin University, Yibin, 644000 (China); Yang, Hong-Y.; Zhao, Kai [Department of Chemistry, Capital Normal University, Beijing 100048 (China); Li, Xia, E-mail: xiali@mail.cnu.edu.cn [Department of Chemistry, Capital Normal University, Beijing 100048 (China)

2013-05-01

The reaction of RE(NO)₃·6H₂O and formamide yielded the coordination polymers, [RE(HCOO)₄]⁻[NH₂CHNH₂]⁺ (RE=Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Er 6, and Yb 7). They possess 3D porous frameworks with the 1D rhombic channels occupied by [NH₂CHNH₂]⁺ cations. Complexes 2 and 4 display the characteristic down-conversion emissions corresponding to ⁵D₀→⁷F_J (J=1–4) transitions of Eu(III) ion and ⁵D₄→⁷F_J (J=6–3) transitions of Tb(III) ion, respectively. Longer lifetime values of 2.128±0.002 ms (⁵D₀) for 2 and 2.132±0.002 ms (⁵D₄) for 4 have been observed. The up-conversion spectra of the Y:Yb,Er and Gd:Yb,Er codoped complexes exhibit three emission bands around 410 (⁴H_9/2→⁴I_15/2, blue), 518–570 (⁴S_3/2, ²H_11/2→⁴I_15/2, green), and 655 nm (⁴F_9/2→⁴I_15/2, red). - Graphical Abstract: The complexes [RE(HCOO)₄]⁻[NH₂CHNH₂]⁺ possess 3D porous frameworks. Eu(III) and Tb(III) complexes show characteristic emission of Ln(III) ions. The up-conversion emission of the Y:Yb,Er and Gd:Yb,Er codoped complexes was observed. Highlights: •The reaction of RE(NO)₃·6H₂O and formamide produced complexes [RE(HCOO)₄]⁻[NH₂CHNH₂]⁺. • The complexes possess 3D frameworks with the 1D channels occupied by [NH₂CHNH₂]⁺ cations. • Eu(III)/Tb(III) complexes display the characteristic down-conversion emission of Ln(III) ions. • The Y:Yb,Er and Gd:Yb,Er doped complexes exhibit the up-conversion emission.

New magnetic refrigeration materials for the liquefaction of hydrogen

International Nuclear Information System (INIS)

Gschneidner, K.A.; Takeya, H.; Moorman, J.O.; Pecharsky, V.K.; Malik, S.K.; Zimm, C.B.

1994-01-01

Five heavy lanthanide ferromagnetic intermetallic compounds were studied as potential magnetic refrigerants for the liquefaction of hydrogen gas. (Dy 0.5 Er 0.5 )Al 2 and TbNi 2 appear to be better refrigerants than GdPd for a Joule-Brayton cycle refrigerator, while (Gd 0.54 Er 0.46 )AlNi seems to be a suitable refrigerant for an Ericsson cycle refrigerator

Complexes of o-Vanillin oxime with La(III), Ce(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III), Ho(III) and Yb(III)

International Nuclear Information System (INIS)

Dhar, M.L.; Gupta, V.K.; Singh, Onkar

1988-01-01

Ten complexes of lanthanides with o-vanillin oxime have been swynthesised and characterised. The composition of the complexes as determined by elemental and thermal analyses, infrared electronic spectral and magnetic moment studies is [Ln(C 8 H 8 NO 3 ) 3 .XH 2 O], where X=2 when Ln=La, Ce, Pr, Nd, Sm and X=3 when Ln=Gd, Dy, Tb, Ho, Yb; C 8 H 8 NO 3 - represents the anion of the ligand. (author). 16 refs., 2 figs., 2 tables

Probing influence of rare earth ions (Er3+, Dy3+ and Gd3+) on structural, magnetic and optical properties of magnetite nanoparticles

Science.gov (United States)

Jain, Richa; Luthra, Vandna; Gokhale, Shubha

2018-06-01

Fe3-xRExO4 (RE = Er, Dy and Gd) nanoparticles with x varying from 0 to 0.1 were synthesized using co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and UV-Vis spectroscopy techniques. TEM images reveal round shaped particles of ∼8-14 nm diameter in case of undoped magnetite (Fe3O4) nanoparticles whereas there is evolution of rod like structures by the doping of RE ions with aspect ratio in the range of 6-16. The room temperature saturation magnetization (Ms) values show gradual increase with doping till a critical doping level which is found to depend on the ionic radius of dopant ion (x = 0.01 for Er, 0.03 for Dy and 0.04 for Gd). There is a variation in the maximum value of saturation magnetization which is directly proportional to the number of unpaired 4f electrons in the dopant element. Low temperature magnetization study, carried out at 5 K and 120 K reveal an increase in the value of Ms as well as coercivity. The direct bandgaps calculated from UV-Visible data are found to decrease with increasing number of unpaired electrons in the dopant ions.

Synthesis and luminescence properties of BaTiO3:RE (RE = Gd , Dy ...

Indian Academy of Sciences (India)

thermoluminescence (TL) properties of BaTiO3 samples doped with Gd3+, Dy3+, Tb3+ and Lu3+ were investigated. ... electron microscope using an accelerating voltage of 20 kV. .... doping of 1% mole Gd3+ ion into the BaTiO3 compound.

Blue and green emissions with high color purity from nanocrystalline Ca2Gd8Si6O26:Ln (Ln = Tm or Er) phosphors

International Nuclear Information System (INIS)

Seeta Rama Raju, G.; Park, Jin Young; Jung, Hong Chae; Pavitra, E.; Moon, Byung Kee; Jeong, Jung Hyun; Yu, Jae Su; Kim, Jung Hwan; Choi, Haeyoung

2011-01-01

Graphical abstract: Highlights: → Nanocrystalline Ca 2 Gd 8 Si 6 O 26 (CGS):Tm 3+ and CGS:Er 3+ phosphors were prepared by solvothermal reaction method. → The visible luminescence properties of phosphors were investigated by exciting with ultraviolet (UV) or near-UV light and low voltage electron beam (0.5-5 kV). → The photoluminescence spectra of CGS:Tm 3+ under 359 nm excitation and CGS:Er 3+ under 380 nm excitation showed the strong blue ( 1 D 2 → 3 F 4 at 456 nm) and green ( 4 S 3/2 → 4 I 15/2 at 550 nm) colors with the color purity 87% and 96%, respectively → The low accelerating voltage cathodoluminescence spectra of CGS:Tm 3+ and CGS:Er 3+ showed the strong blue and green emissions with the high color purity 95% and 96%, respectively. → The obtained results are hint at the promising applications to produce high quality LEDs and FED devices. - Abstract: Blue and green light emissive nanocrystalline Ca 2 Gd 8 Si 6 O 26 (CGS):Tm 3+ and CGS:Er 3+ phosphors with high color purity were prepared by solvothermal reaction method. The structural and morphological properties of these phosphors were evaluated by the powder X-ray diffraction (XRD) and scanning electron microscopy, respectively. From the XRD results, Tm 3+ :CGS and Er 3+ :CGS phosphors had the characteristic peaks of oxyapatite in the hexagonal lattice structure. The visible luminescence properties of phosphors were obtained by ultraviolet (UV) or near-UV light and low voltage electron beam (0.5-5 kV) excitation. The photoluminescence and cathodoluminescence properties were investigated by changing the variation of Tm 3+ or Er 3+ concentrations and the acceleration voltage, respectively. The CGS:Tm 3+ phosphors exhibited the blue emission due to 1 D 2 → 3 F 4 transition, while the CGS:Er 3+ phosphors showed the green emission due to 4 S 3/2 → 4 I 15/2 transition. The color purity and chromaticity coordinates of the fabricated phosphors are comparable to or better than those of standard

Platinum triangles in the Pt/Al framework of the intermetallic REPt{sub 6}Al{sub 3} (RE = Ce-Nd, Sm, Gd, Tb) series

Energy Technology Data Exchange (ETDEWEB)

Eustermann, Fabian; Stegemann, Frank; Renner, Konstantin [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Janka, Oliver [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Chemie, Carl von Ossietzky Universitaet Oldenburg (Germany)

2017-12-13

The compounds of the REPt{sub 6}Al{sub 3} series (RE = Ce-Nd, Sm, Gd, Tb) were obtained by reaction of the elements via arc-melting. They were characterized by powder and single-crystal X-ray diffraction (NdPt{sub 6}Al{sub 3}: wR = 0.0432, 759 F{sup 2} values, 33 variables) as well as by magnetic susceptibility measurements. The isostructural compounds crystallize with a new structure type in the trigonal crystal system with space group R anti 3c, twelve formula units in the unit cell, and lattice parameters of a = 752-755 and c = 3882-3945 pm. The crystal structure can be described by different slabs stacked along [001]. One layer features Pt{sub 3} triangles, centering the cavities of a flat honeycomb RE layer that are arranged in a..ABCA{sup '}B{sup '}C{sup '}.. sequence. The other layer consists of condensed hexagonal [Pt{sub 6}Al{sub 6}] prisms, centered by Pt atoms, separating the before mentioned slabs. Magnetic measurements revealed that all rare-earth atoms are in the trivalent oxidation state, however, due to the low lanthanoide content magnetic ordering phenomena were observed only at low temperatures [SmPt{sub 6}Al{sub 3}: T{sub C} = 5.0(1) K; GdPt{sub 6}Al{sub 3}: T{sub C} = 7.3(1) K; TbPt{sub 6}Al{sub 3}: T{sub N} = 3.6(1) K]. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Half Life Measurements in 155Gd

International Nuclear Information System (INIS)

Malmskog, S.G.

1966-08-01

In the literature there exists a definite difference for the half life of the 86.5 keV level in Gd depending on whether 155 Eu or 155 Tb sources have been used. Using a good energy resolution electron-electron coincidence spectrometer and a 155 Eu source, a half life of 6.48 ± 0.26 nsec was obtained for the 86.5 keV level. This is in agreement with the values previously measured with 155 Tb sources. The half life of the 105.4 keV level was measured to be 1.12 ± 0.05 nsec

First-principles calculation of structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La)

International Nuclear Information System (INIS)

Zhang, Z.L.; Xiao, H.Y.; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

2009-01-01

A first-principles method has been employed to investigate the structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La), including the formation energies of the cation antisite-pair, the anion Frenkel pair that defines anion-disorder, and the coupled cation antisite-pair/anion-Frenkel. It is proposed that the interaction may have more significant influence on the radiation resistance behavior of titanate pyrochlores, although the interactions are relatively much stronger than the interactions. It is found that the defect formation energies are not simple functions of the A-site cation radii. The formation energy of the cation antisite-pair increases continuously as the A-site cation varies from Lu to Gd, and then decreases continuously with the variation of the A-site cation from Gd to La, in excellent agreement with the radiation-resistance trend of the titanate pyrochlores. The band gaps in these pyrochlores were also measured, and the band gap widths changed continuously with cation radius.

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

Half Life Measurements in {sup 155}Gd

Energy Technology Data Exchange (ETDEWEB)

Malmskog, S G

1966-08-15

In the literature there exists a definite difference for the half life of the 86.5 keV level in Gd depending on whether {sup 155}Eu or {sup 155}Tb sources have been used. Using a good energy resolution electron-electron coincidence spectrometer and a {sup 155}Eu source, a half life of 6.48 {+-} 0.26 nsec was obtained for the 86.5 keV level. This is in agreement with the values previously measured with {sup 155}Tb sources. The half life of the 105.4 keV level was measured to be 1.12 {+-} 0.05 nsec.

The Gd-Co-Al system at 870/1070 K as a representative of the rare earth-Co-Al family and new rare-earth cobalt aluminides: Crystal structure and magnetic properties

Science.gov (United States)

Morozkin, A. V.; Garshev, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Mozharivskyj, Y.; Yuan, Fang; Yao, Jinlei; Nirmala, R.; Quezado, S.; Malik, S. K.

2018-05-01

The Gd-Co-Al system has been investigated at 870/1070 K by X-ray and elemental EDS analyses. The existence of the known compounds Gd2Co3Al9 (Y2Co3Ga9-type), Gd3Co4.5Al11.5 (Gd3Co4.6Al11) (Gd3Ru4Al12-type), Gd3Co6-7.4Al3-1.6 (CeNi3-type), GdCo1.15-0.65Al0.85-1.35 (MgZn2-type), Gd2Co2Al (Mo2NiB2-type) and Gd3Co3.5-3.25Al0.5-0.75 (W3CoB3-type) has been confirmed at 870/1070 K. Structure types have been determined for Gd2Co6Al19 (U2Co6Al19-type), Gd7Co6Al7 (Pr7Co6Al7-type), Gd6Co2-2.21Al1-0.79 (Ho6Co2Ga-type) and Gd14Co3.2Al2.8 (Gd14Co2.58Al3.42 at 970 K) (Lu14Co3In3-type). The structures of Gd6Co2Al, Gd6Co2.21Al0.79 and Gd14Co2.58Al3.42 flux-grown at 970 K have been refined from the single crystal X-ray diffraction data. Additionally, new ternary compounds Gd2Co5.7-5.3Al1.3-1.7 (Er2Co7-type) and Gd58Co20Al22 (unknown type structure) have been identified. Quasi-binary solid solutions were detected for Gd2Co17, GdCo5, Gd2Co7, GdCo3, GdCo2 and GdAl2 at 870/1070 K, while no appreciable solubility was observed for the other binary compounds in the Gd-Co-Al system. Magnetic properties of the Gd2Co3Al9, Gd3Co4.6Al11, Gd7Co6Al7, Gd6Co2.2Al0.8 and Gd14Co2.58Al3.42 compounds have been studied and are presented in this work. Gd6Co2.2Al0.8, Gd3Co4.6Al11, Gd7Co6Al7 and Gd14Co2.58Al3.42 order ferromagnetically, while Gd2Co3Al9 displays antiferromagnetic transition. Additionally, {Y, Sm, Tb - Tm}2Co6Al19 (U2Co6Al19-type), Yb2Co3Al9 (Y2Co3Ga9-type), {Y, Sm, Tm, Yb}3Co4.6Al11 (Gd3Ru4Al12-type) and Tb7Co6Al7 (Pr7Co6Al7-type) compounds have been synthesized and investigated.

Multicolor Tunable Luminescence Based on Tb3+/Eu3+ Doping through a Facile Hydrothermal Route.

Science.gov (United States)

Wang, Chao; Zhou, Ting; Jiang, Jing; Geng, Huiyuan; Ning, Zhanglei; Lai, Xin; Bi, Jian; Gao, Daojiang

2017-08-09

Ln 3+ -doped fluoride is a far efficient material for realizing multicolor emission, which plays an important part in full-color displays, biolabeling, and MRI. However, studies on the multicolor tuning properties of Ln 3+ -doped fluoride are mainly concentrated on a complicated process using three or more dopants, and the principle of energy transfer mechanism is still unclear. Herein, multicolor tunable emission is successfully obtained only by codoping with Tb 3+ and Eu 3+ ions in β-NaGdF 4 submicrocrystals via a facile hydrothermal route. Our work reveals that various emission colors can be obtained and tuned from red, orange-red, pink, and blue-green to green under single excitation energy via codoping Tb 3+ and Eu 3+ with rationally changed Eu 3+ /Tb 3+ molar ratio due to the energy transfer between Tb 3+ and Eu 3+ ions in the β-NaGdF 4 host matrix. Meanwhile, the energy transfer mechanism in β-NaGdF 4 : x Eu 3+ /y Tb 3+ (x + y = 5 mol %) submicrocrystals is investigated. Our results evidence the potential of the dopants' distribution density as an effective way for analyzing energy transfer and multicolor-controlled mechanism in other rare earth fluoride luminescence materials. Discussions on the multicolor luminescence under a certain dopant concentration based on single host and wavelength excitation are essential toward the goal of the practical applications in the field of light display systems and optoelectronic devices.

Ternary gallides RE_4Rh_9Ga_5, RE_5Rh_1_2Ga_7 and RE_7Rh_1_8Ga_1_1 (RE=Y, La-Nd, Sm, Gd, Tb). Intergrowth structures with MgCu_2 and CaCu_5 related slabs

International Nuclear Information System (INIS)

Seidel, Stefan; Rodewald, Ute C.; Poettgen, Rainer; Janka, Oliver

2017-01-01

Fourteen ternary gallides RE_4Rh_9Ga_5, RE_5Rh_1_2Ga_7 and RE_7Rh_1_8Ga_1_1 (RE=Y, La-Nd, Sm, Gd, Tb) were synthesized from the elements by arc-melting, followed by different annealing sequences either in muffle or induction furnaces. The samples were characterized through Guinier powder patterns and the crystal structures of Ce_4Rh_9Ga_5, Ce_5Rh_1_2Ga_7, Ce_7Rh_1_8Ga_1_1, Nd_5Rh_1_0_._4_4_(_4_)Ga_8_._5_6_(_4_), Nd_4Rh_9Ga_5 and Gd_4Rh_9Ga_5 were refined from single crystal X-ray diffractometer data. The new gallides are the n=2, 3 and 5 members of the RE_2_+_n Rh_3_+_3_n Ga_1_+_2_n structure series in the Parthe intergrowth concept. The slabs of these intergrowth structures derive from the cubic Laves phase MgCu_2 (Mg_2Ni_3Si as ternary variant) and CaCu_5 (CeCo_3B_2 as ternary variant). Only the Nd_5Rh_1_0_._4_4_(_4_)Ga_8_._5_6_(_4_) crystal shows Rh/Ga mixing within the Laves type slabs. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y_4Rh_9Ga_5 and Curie-Weiss paramagnetism for Gd_4Rh_9Ga_5 and Tb_4Rh_9Ga_5. Low-temperature data show ferromagnetic ordering at T_C=78.1 (Gd_4Rh_9Ga_5) and 55.8 K (Tb_4Rh_9Ga_5).

Crystal fields in Sc, Y, and the heavy-rare-earth metals Tb, Dy, Ho, Er, Tm, and Lu

International Nuclear Information System (INIS)

Touborg, P.

1977-01-01

Experimental investigations of the magnetic poperties of dilute alloys of the rare-earth solutes Tb, Dy, Ho, Er, and Tm in the nonmagnetic hosts Lu, Y, and Sc have been performed. These measurements, which include and supplement earlier published results, have been analyzed and crystal-field parameters for all these 15 alloy systems deduced. The consistency of the parameters was confirmed by a variety of magnetic measurements, including neutron spectroscopy. Crystal-field parameters have also been derived for the ions in pure magnetic rare-earth metals and their alloys using the results for the dilute alloys supplemented with paramagnetic measurements up to high temperatures on the concentrated systems. Mean values and standard deviations of the higher-order crystal-field parameters for all Y and Lu alloys are B 40 /β = 6.8 +- 0.9 K, B 60 /γ = 13.6 +- 0.7 K, and B 66 /γ = (9.7 +- 1.1) B 60 /γ. These values: with the inaccuracies somewhat increased: are expected to be representative also for the magnetic rare-earth metals. For rare-earth ions in the Sc host the values B 40 /β = 9.9 +- 1.9 K, B 60 /γ = 19.8 +- 1.5 K, and B 66 /γ = (9.4 +- 0.9) B 60 /γ were deduced. B 20 /α is a host-sensitive parameter which has the average values of -102.7, -53.4, and 29.5 K for rare-earth ions in Y, Lu, and Sc, respectively. There is also evidence that this parameter varies with the solute. B 20 /α for ions in the pure magnetic rare-earth metals and their alloys shows a linear variation with c/a ratio characteristic of each ion. The results indicate a contribution from anisotropic exchange to the high-temperature paramagnetic anisotropy of approximately 20% for Tb, Dy, Ho, and Er, and approximately 10% for Tm

Miljøundersøgelser ved Kvanefjeldet 2001

DEFF Research Database (Denmark)

Asmund, G.

jordarter' (La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu) Af de mange grundstoffer, der er undersøgt er det kun 'Sjældne jordarter', zirkonium, niobium og thorium, der viser forhøjelser i forhold til baggrundsværdier og samtidigt er stærkt forhøjede i det vand, der siver ud fra minen. Imidlertid fandtes denne...

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 of the high-Tsub(c) superconductors RBa/sub 2/Cu/sub 3/Osub(9-delta) (R=Y) (Gd, Dy, Er)

Energy Technology Data Exchange (ETDEWEB)

Groot, P.A.J. de; Rainford, B.D.; McK-Paul, D.; Balakrishnan, G.; Lanchester, P.C.; Weller, M.T.; Grasmeder, J.

1987-08-01

Magnetic properties of RBa/sub 2/Cu/sub 3/Osub(9-delta) with R = Y, Gd, Dy, Er have been measured for 4.2 K < T < 300 K and magnetic fields up to 7 T. They exhibit a superconductive transition around 91 K, above which temperature the magnetisation can be described by a Curie-Weiss law. The magnetic and superconductive properties develop independently below the phase transition. Magnetic hysteresis is prominent at low temperatures (T

Compensation scheme for online neutron detection using a Gd-covered CdZnTe sensor

Energy Technology Data Exchange (ETDEWEB)

Dumazert, Jonathan, E-mail: jonathan.dumazert@cea.fr; Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim

2017-06-11

The development of portable and personal neutron dosimeters requires compact and efficient radiation sensors. Gd-157, Gd-155 and Cd-113 nuclei present the highest cross-sections for thermal neutron capture among natural isotopes. In order to allow for the exploitation of the low and medium-energy radiative signature of the said captures, the contribution of gamma background radiation, falling into the same energy range, needs to be cancelled out. This paper introduces a thermal neutron detector based on a twin-dense semiconductor scheme. The neutron-sensitive channel takes the form of a Gd-covered CdZnTe crystal, a high density and effective atomic number detection medium. The background compensation will be carried out by means of an identical CdZnTe sensor with a Tb cover. The setting of a hypothesis test aims at discriminating the signal generated by the signature of thermal neutron captures in Gd from statistical fluctuations over the compensation of both independent channels. The measurement campaign conducted with an integrated single-channel chain and two metal Gd and Tb covers, under Cs-137 and Cf-252 irradiations, provides first quantitative results on gamma-rejection and neutron sensitivity. The described study of concept gives grounds for a portable, online-compatible device, operable in conventional to controlled environments.

Triple energy transfer and color tuning in Tb3+ and Eu3+-coactivated apatite-type gadolinium-containing phosphors

Science.gov (United States)

Guo, Ning; Liang, Qimeng; Li, Shuo; Ouyang, Ruizhuo; Lü, Wei

2017-11-01

A family of apatite-type fluorophosphate phosphors with general formula Sr3Gd(1-m-n)Na(PO4)3F:mTb3+,nEu3+ (SGN:mTb3+,nEu3+) have been synthesized via the high-temperature solid-state reaction method. Triple energy transfer processes from Gd3+ in the host to both Tb3+ and Eu3+, as well as from Tb3+ to Eu3+ have been verified by the photoluminescence spectra. Under the excitation of UV light, both green line from the transitions of Tb3+ and red line origin from the transitions of Eu3+ have been simultaneously observed in a single phase phosphor, which makes a promise for tunable color emissions from yellowish-green through yellow and ultimately to reddish-orange by simply adjusting the Eu3+ content (n) in SGN:0.20Tb3+,nEu3+ phosphors. Additionally, the energy transfer from the Tb3+ to the Eu3+ ions has been demonstrated to be a resonant type via a quadrupole-quadrupole mechanism based on the Dexter's theoretical model, and the energy transfer efficiency increases with an increase in Eu3+ concentration.

Impact of firing temperature on multi-wavelength selective Stokes and anti-Stokes luminescent behavior by Gd2O2S:Er,Yb phosphor and its application in solar energy harvesting

Science.gov (United States)

Kataria, V.; Mehta, D. S.

2018-04-01

Erbium (Er3+)-ytterbium (Yb3+) doped gadolinium oxysulphide (Gd2O2S) phosphor has been developed via a facile method of solid-state flux fusion, and offers two-fold spectrum modification with highly intense Stokes and anti-Stokes shift. The effect of the firing cycle on the photoluminescent response and morphology of Gd2O2S:Er,Yb is scrutinized, wherein the firing temperature was varied (1000 °C-1250 °C), keeping firing time and all other parameters constant. Interestingly, the nanostructures fired below 1150 °C showed nanorods of diameter ~200 nm and length ~1-2 µm, whereas firing at 1150 °C and above rendered nanospheres with small diameter, ~350 nm. Highly bright upconversion (UC) emission was achieved even under an extremely low excitation power density of 800 µW cm-2 from a 980 nm laser, and was comfortably visible to the naked eye. The incident power dependent studies disclosed increase in UC-emission intensity with increasing excitation power and a quasi-linear dependence on excitation power density. Intense characteristic UC-emission of Er3+ excited states at 525 nm, 556 nm and 668 nm were observed, and the green emission band was found to be dominant over the red band in intensity. Concurrently, downconversion (DC) emission at 556 nm and 669 nm was also exhibited under ultraviolet excitation (285 nm and 380 nm), with the red band being more powerful than the green, unlike UC-emission. Firing temperature dependent studies divulged the dependence of luminescence intensity on the firing cycle of the luminophore and formation of the respective luminescent phase. The UC-emission intensity was found to be maximum for samples fired at 1150 °C, whereas samples fired at 1000 °C showed the highest DC-emission intensity. The excitation and emission profile of single Gd2O2S:Er,Yb phosphor lying in the desired spectral region and as a dual spectral converter marks its possible application for enhanced harvesting of sunlight.

Extraordinarily large intrinsic magnetodielectric coupling of the Tb member within the Haldane spin-chain family R2BaNiO5

Science.gov (United States)

Upadhyay, Sanjay Kumar; Paulose, P. L.; Sampathkumaran, E. V.

2017-07-01

The Haldane spin-chain compound Tb2BaNiO5 has been known to order antiferromagnetically below (TN= )63 K . The present magnetic studies on the polycrystals bring out that there is another magnetic transition at a lower temperature (T2=)25 K with pronounced magnetic-field-induced metamagnetic and metaelectric behaviors. Multiferroic features are found below T2 only and not at TN. The most intriguing observation is that the observed change in dielectric constant (Δɛ') is intrinsic and largest (e.g., ˜18% at 15 K) within this Haldane spin-chain family R2BaNiO5 . Taking into account the fact that this trend (that is, the largest value of Δɛ' for the Tb case within this family) correlates well with a similar trend in TN (with the values of TN being ˜55, 58, 53, and 32 K for Gd, Dy, Ho, and Er cases), we believe that the explanation usually offered for this TN behavior in rare-earth systems is applicable for this Δɛ' behavior as well. That is, single-ion anisotropy following crystal-field splitting is responsible for the extraordinary magnetodielectric effect in this Tb case. This work provides a pathway in the field of multiferroics to promote magnetoelectric coupling.

Synthesis under ambient pressure and tri-axial magnetic orientation in REBa2Cu4O8 (RE = Y, Sm, Eu, Gd, Dy, Ho, Er)

International Nuclear Information System (INIS)

Yamaki, M.; Horii, S.; Haruta, M.; Maeda, T.; Shimoyama, J.

2011-01-01

REBa 2 Cu 4 O 8 (RE124) was synthesized by a flux method in ambient pressure for RE = Y, Sm, Eu, Gd, Dy, Ho and Er. Tri-axial orientation of RE124 was achieved in a modulated rotating magnetic field of 10 T. Orientation axes in RE124 depended on the type of RE. Magnetization axes were determined from magnetic anisotropies of Cu and RE ions. We report the rare-earth (RE)-dependent magnetization axes of REBa 2 Cu 4 O 8 , which was synthesized by a flux method under ambient pressure, using powder samples tri-axially oriented in a modulated rotating magnetic field of 10 T. By optimizing the growth temperature and cooling rate, RE124 crystals were successfully grown for RE = Y, Sm, Eu, Gd, Dy, Ho, and Er. From the X-ray diffraction measurement, the magnetically oriented directions were largely dependent on the type of RE ions of RE124. However, the tri-axial magnetic anisotropies of RE124 could be qualitatively understood in terms of the magnitude relation between the single-ion magnetic anisotropy of RE 3+ ions and the magnetic anisotropy generated by the CuO 2 plane and Cu-O chain. For the practical use of this magneto-scientific process, the control of magnetization axes and tri-axial magnetic anisotropies through crystallochemical control is indispensable.

Nuclear spectroscopy of very proton rich nuclei through HI induced reactions; the 14s high spin isomer in /sup 95/Pd

CERN Document Server

Nolte, E; Geier, R; Gui, S Z; Heim, U; Hick, H; Komninos, P; Korschinek, G; Kubik, P; Morinaga, H; Schollmeier, W

1981-01-01

/sup 40/Ca, /sup 58/Ni and /sup 60/Ni beams from the Munich tandem and the Munich heavy ion postaccelerator have been used to produce very proton rich nuclei in the N=50 N=82 regions. The residual nuclei have been studied with the help of gamma and particle spectroscopy. The level schemes of /sup 95/Rh, /sup 146/Dy and /sup 150/Er and the beta -decay schemes, /sup 95/Pd/sup m/ to /sup 95/Rh, /sup 144/Tb to /sup 144/Gd, /sup 146/Ho to /sup 146/Dy to /sup 146/Tb to /sup 146/Gd, /sup 148/Er to /sup 148/Ho to /sup 148/Dy and /sup 150/Tm to /sup 150/Er to /sup 150/Dy have been investigated. beta delayed proton emission from a J/sup pi / approximately=21/sup +/ isomeric state in /sup 95/Pd has been observed. (12 refs).

Structural Characterization and Absolute Luminescence Efficiency Evaluation of Gd2O2S High Packing Density Ceramic Screens Doped with Tb3+ and Eu3+ for further Applications in Radiology

Science.gov (United States)

Dezi, Anna; Monachesi, Elenasophie; D'Ignazio, Michela; Scalise, Lorenzo; Montalto, Luigi; Paone, Nicola; Rinaldi, Daniele; Mengucci, Paolo; Loudos, George; Bakas, Athanasios; Michail, Christos; Valais, Ioannis; Fountzoula, Christine; Fountos, George; David, Stratos

2017-11-01

Rare earth activators are impurities added in the phosphor material to enhance probability of visible photon emission during the luminescence process. The main activators employed are rare earth trivalent ions such as Ce+3, Tb+3, Pr3+ and Eu+3. In this work, four terbium-activated Gd2O2S (GOS) powder screens with different thicknesses (1049 mg/cm2, 425.41 mg/cm2, 313 mg/cm2 and 187.36 mg/cm2) and one europium-activated GOS powder screen (232.18 mg/cm2) were studied to investigate possible applications for general radiology detectors. Results presented relevant differences in crystallinity between the GOS:Tb doped screens and GOS:Eu screens in respect to the dopant agent present. The AE (Absolute efficiency) was found to rise (i) with the increase of the X-ray tube voltage with the highest peaking at 110kVp and (ii) with the decrease of the thickness among the four GOS:Tb. Comparing similar thickness values, the europium-activated powder screen showed lower AE than the corresponding terbium-activated.

Production, characterization and application of Gd2O3 and Er2O3 nanoparticles as radiosensitizers in radiotherapy beams

International Nuclear Information System (INIS)

Corrêa, Eduardo de Lima

2017-01-01

In this study Gd 2 O 3 and Er 2 O 3 nanoparticles were produced for application as radiosensitizers in radiotherapy beams. They were synthesized at the Hyperfine Interactions Laboratory, IPEN, using thermal decomposition method and characterized by X-ray diffraction, to verify crystalline structure, transmission electron microscopy, to obtain information about shape, size and size distribution, neutron activation analysis, whereby it was possible to determine samples purity and gadolinium and erbium concentration. Magnetization and perturbed γ-γ angular correlation (PAC) measurements were performed in order to study particles magnetic behavior and quadrupole interactions, respectively. Characterization results showed a bixbyite structure, 5 nm diameter post-synthesis particles with narrow size distribution. Rare-earth mass determination in each sample was important to perform normalization in magnetic susceptibility measurements, making possible the view of a high magnetization under 30 K for post-synthesis samples, what was not observed in larger particles, together with an effective magnetic moment enhancement for nanoparticles, not seen in bulk samples, and a change in the antiferromagnetic ordering temperature for Er 2 O 3 . PAC spectroscopy results show possible surface effects. The absence of a well-defined frequency in 5 nm samples indicates the amount of 111 In( 111 Cd) at particle surface is bigger than in the core, resulting in a non-evident hyperfine interaction between the probe nuclei and the host. The X-ray diffraction and PAC spectroscopy joint was vital to understand the particles structural damage caused by 60 Co irradiation. About radiosensitizer measurements a dose enhancement factor (DEF) of up to 1,67 and 1,09 for Gd 2 O 3 nanoparticles under 60 Co and 6MV irradiation, respectively, were observed. Under same conditions DEF values of up to 1,37 and 1,06 were found for Er 2 O 3 samples. Results reached in this study provide not only important

Magnetic ordering of Gd/sub x/Er/sub 1-x/Rh4B4 near the superconducting region

International Nuclear Information System (INIS)

Kohn, S.; Wang, R.H.; Smith, J.L.; Huang, C.Y.

1979-01-01

Gd/sub x/Er/sub 1-x/Rh 4 B 4 exhibits superconductivity at some critical temperature T/sub c/ followed by the onset of long-range ferromagnetic ordering at a lower temperature and a loss of superconductivity for x 2 Oe), the extrema in chi (T) and R(T) are depressed and smeared considerably with a corresponding shift in the temperature at which the extrema occur. (2) The sample is not superconducting down to 0.6 K. (3) In the presence of a dc magnetic field, a second ac chi peak appears at a slightly higher temperature. (4) The field dependence of the ac susceptibility resembles that of a spin glass. Details of the field dependence of these observations and the nature of these phenomena will be presented

UV and gamma ray induced thermoluminescence properties of cubic Gd2O3:Er3+ phosphor

Directory of Open Access Journals (Sweden)

Raunak Kumar Tamrakar

2014-10-01

Full Text Available This paper reports the thermoluminescence properties of Er3+ doped gadolinium oxide nanophosphor. The phosphor is prepared by high temperature solid state reaction method. The method is suitable for large scale production. Starting materials used for sample preparation were Gd2O3, Er2O3 (0.5–2.5 mol% and fixed concentration of boric acid using as a flux. The prepared samples were characterized by X-ray diffraction technique and the particle size calculated by Scherer's formula. The surface morphology of prepared phosphor is determined by scanning electron microscopic (SEM technique. Functional group analysis was done by Fourier transform infra-red spectroscopy (FTIR analysis. The elemental analysis of prepared sample was determined by energy dispersive X-ray analysis (EDX and the exact particle size of prepared phosphor for the different concentration of dopant (Er3+ was evaluated by transmission electron microscopy (TEM technique. The prepared phosphors for different concentration of Er3+ were examined by thermoluminescence (TL glow curve for UV and gamma irradiation. The UV 254 nm source was used for UV irradiation and Co60 source was used for gamma irradiation. The samples show well resolved broad peak covered the temperature range 50–250 °C and the peak temperature found at 126 °C for UV irradiation and higher temperature peak at 214 °C for gamma irradiation. The effect of heating rate on TL studies was presented for optimized sample. Here UV irradiated sample shows the formation of shallow trap (surface trapping and the gamma irradiated sample shows the formation of deep trapping. The estimation of trap formation was evaluated by knowledge of trapping parameters. The trapping parameters such as activation energy, order of kinetics and frequency factor were calculated by peak shape method. Here most of the peak shows second order of kinetics. The effect of gamma and UV exposure on TL studies was also examined and it shows linear

Fabrication and characterization of pixelated Gd{sub 2}O{sub 2}S:Tb scintillator screens for digital X-ray imaging applications

Energy Technology Data Exchange (ETDEWEB)

Kim, Jongyul, E-mail: kjongyul@kaist.ac.kr [Korea Advanced Institute of Science and Technology, 335 Gwahangno, Daejeon 305-701 (Korea, Republic of); Kyoung Cha, Bo; Hyung Bae, Jun; Lee, Chae-hun; Kim, Hyungtaek; Chang, Sungho; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, 335 Gwahangno, Daejeon 305-701 (Korea, Republic of); Sim, Cheulmuu; Kim, Taejoo [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Daejeon 305-353 (Korea, Republic of)

2011-05-15

X-ray imaging detectors in combination with scintillator screens have been widely used in digital X-ray imaging applications. Gd{sub 2}O{sub 2}S:Tb was used as scintillation material for pixelated scintillator screens based on silicon substrates (wafer) with a micropore array of various dimensions fabricated using the photolithography and deep reactive ion etching (DRIE) process. The relative light output and the modulation transfer function (MTF) of each fabricated scintillator screen were measured by a cooled CCD and compared with those of Lanex screens. The spatial resolution of our scintillator screens was higher but their light outputs were lower than those of Lanex screen probably due to the loss of light at the wall surfaces. Therefore further treatment of the wall surface, such as reflective coating, seems necessary to compensate the light loss.

A family of rare-earth-based single chain magnets: playing with anisotropy.

Science.gov (United States)

Bernot, Kevin; Bogani, Lapo; Caneschi, Andrea; Gatteschi, Dante; Sessoli, Roberta

2006-06-21

The first family of rare-earth-based single chain magnets is presented. Compounds of general formula [M(hfac)3(NITPhOPh)], where M = Eu, Gd, Tb, Dy, Ho, Er, or Yb, and PhOPh is the nitronyl-nitroxide radical (2,4'-benzoxo-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), have been structurally characterized and found to be isostructural. The characterization of both static and dynamic magnetic properties of the whole family is reported. Dy, Tb, and Ho compounds display slow relaxation of the magnetization, and ac susceptibility shows a thermally activated regime with energy barriers of 69, 45, and 34 K for Dy, Tb, and Ho compounds, respectively, while only a frequency-dependent susceptibility is observed for Er below 2.0 K. In Gd and Yb derivatives, antiferromagnetic interactions dominate. The pre-exponential factors differ by about 4 orders of magnitude. Finite size effects, due to naturally occurring defects, affect the static and dynamic properties of the compounds differently.

Lanthanide 4f-level location in AVO4:Ln3+ (A = La, Gd, Lu) crystals

NARCIS (Netherlands)

Krumpel, A.H.; Van der Kolk, E.; Cavalli, E.; Boutinaud, P.; Bettinelli, M.; Dorenbos, P.

2009-01-01

The spectral properties of LaVO4, GdVO4 and LuVO4 crystals doped with Ce3+, Pr3+, Eu3+ or Tb3+ have been investigated in order to determine the position of the energy levels relative to the valence and conduction bands of the hosts along the trivalent and divalent lanthanide series. Pr3+ and Tb3+

Study of hyperfine interactions in intermetallic compounds Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In; Estudo de interacoes hiperfinas em compostos intermetalicos Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In e Ho(Ni,Pd)In

Energy Technology Data Exchange (ETDEWEB)

Lapolli, Andre Luis

2006-07-01

Systematic behavior of magnetic hyperfine field (B{sub hf}) in the intermetallic compounds Gd(Ni,Pd,Cu)In Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In was studied by Perturbed Gamma-Gamma Angular Correlation spectroscopy. The measurements of B{sub hf} were carried out at the rare earth atom and in sites using the nuclear probes {sup 140}Ce and {sup 11}'1Cd respectively. The variation of hyperfine field with temperature, in most cases, follows the Brillouin function predicted from the molecular field theory. The hyperfine field values at rare earth atom sites obtained from {sup 140}Ce probe as well as at in sites obtained from {sup 111}Cd probe for each series of compounds were extrapolated to zero Kelvin B{sub hf}(T=0) from these curves. These values were compared with the values of the literature for other compounds containing the same rare earth element and all of them show a linear relationship with the ordering temperature. This indicates that the main contribution to B{sub hf} comes from the conduction electron polarization (CEP) through Fermi contact interaction and the principal mechanism of magnetic interaction in these compounds can be described by the RKKY type interaction. The values of B{sub hf}(T=0) for each family of intermetallic compounds RNiIn and RPdIn when plotted as a function of 4f spin projection of rare earth element also shows a linear relationship. Exceptions are the results for the compounds RNiIn obtained with {sup 111}Cd probe where a small deviation from linearity is observed. The results of the measurements carried out with the {sup 111}Cd probe were also analyzed to obtain the hyperfine parameters of the quadrupole interaction as a function of temperature for RPdln and GdNiIn compounds. The results show that for the compound GdPdIn there might be some Gd-In disorder at high temperature. (author)

Study of hyperfine interactions in intermetallic compounds Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In; Estudo de interacoes hiperfinas em compostos intermetalicos Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In e Ho(Ni,Pd)In

Energy Technology Data Exchange (ETDEWEB)

Lapolli, Andre Luis

2006-07-01

Systematic behavior of magnetic hyperfine field (B{sub hf}) in the intermetallic compounds Gd(Ni,Pd,Cu)In Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In was studied by Perturbed Gamma-Gamma Angular Correlation spectroscopy. The measurements of B{sub hf} were carried out at the rare earth atom and in sites using the nuclear probes {sup 140}Ce and {sup 11}'1Cd respectively. The variation of hyperfine field with temperature, in most cases, follows the Brillouin function predicted from the molecular field theory. The hyperfine field values at rare earth atom sites obtained from {sup 140}Ce probe as well as at in sites obtained from {sup 111}Cd probe for each series of compounds were extrapolated to zero Kelvin B{sub hf}(T=0) from these curves. These values were compared with the values of the literature for other compounds containing the same rare earth element and all of them show a linear relationship with the ordering temperature. This indicates that the main contribution to B{sub hf} comes from the conduction electron polarization (CEP) through Fermi contact interaction and the principal mechanism of magnetic interaction in these compounds can be described by the RKKY type interaction. The values of B{sub hf}(T=0) for each family of intermetallic compounds RNiIn and RPdIn when plotted as a function of 4f spin projection of rare earth element also shows a linear relationship. Exceptions are the results for the compounds RNiIn obtained with {sup 111}Cd probe where a small deviation from linearity is observed. The results of the measurements carried out with the {sup 111}Cd probe were also analyzed to obtain the hyperfine parameters of the quadrupole interaction as a function of temperature for RPdln and GdNiIn compounds. The results show that for the compound GdPdIn there might be some Gd-In disorder at high temperature. (author)

The correlation of the magnetic properties and the magnetocaloric effect in (Gd1-xErx)NiAl alloys

International Nuclear Information System (INIS)

Korte, B.J.; Pecharsky, V.K.; Gschneidner, K.A. Jr.

1998-01-01

A study of the magnetic properties of several (Gd 1-x Er x )NiAl alloys (where x=0, 0.30, 0.40, 0.46, 0.50, 0.55, 0.60, 0.80, and 1.00) was undertaken using both ac and dc magnetic and heat capacity measurements in an attempt to understand the table-like magnetocaloric effect previously observed in (Gd 0.54 Er 0.46 )NiAl. Results indicate the presence of both antiferromagnetic and ferromagnetic ordering processes in all alloys containing Gd. For ErNiAl, a metamagnetic transition from an antiferromagnetic ground state was observed. Within each alloy, several magnetic transitions occur over a temperature range from 10 K [in (Gd 0.20 Er 0.80 )NiAl] up to 35 K (in GdNiAl), with all but the lowest temperature transition shifting to higher temperatures with increasing Gd content. The change in magnetic entropy (ΔS mag ) induced by a change in field is observed to peak around the Nacute eel temperature for ErNiAl while gradually broadening and shifting toward the Curie temperature as the Gd content is increased. For Gd-rich alloys, a significant contribution to ΔS mag is observed at both the low and high temperature transitions, resulting in a rounded, skewed caret-like temperature profile of the magnetocaloric effect. Factors, which are believed to contribute to this effect, include the presence and temperature spacing of multiple zero-field transitions, which most likely result from competing anisotropy and exchange interactions within a frustrated hexagonal spin lattice. This leads to broad peaks in the magnetic heat capacity that span several transition temperatures, providing for a substantial ΔS mag over an extended temperature range. This characteristic is desired for application to magnetic refrigeration, where certain thermodynamic cycles (e.g., Ericsson cycle) require specific temperature profiles of the magnetocaloric effect in refrigerant materials (e.g., a constant change in magnetic entropy as a function of temperature within the region of cooling). In

Near infrared emission of TbAG:Ce{sup 3+},Yb{sup 3+} phosphor for solar cell applications

Energy Technology Data Exchange (ETDEWEB)

Meshram, N. D., E-mail: meshramnileshsd@gmail.com [Shri. Mathuradas Mohota College of Science, Sakkardara Square, Nagpur-440009 (India); Yadav, P. J., E-mail: yadav.pooja75@yahoo.in [Department of Electronics, Nagpur University campus, Nagpur-440010 (India); Pathak, A. A., E-mail: aapathak@yahoo.com [National power Training Institute, South ambazari road, Nagpur-440022 (India); Joshi, C. P., E-mail: charusheela-4253@yahoo.co.in [Ramdeobaba College of Engineering and Management, Katol road, Gittikhadan Nagpur-440012 (India); Moharil, S. V., E-mail: svmoharil@yahoo.com [Department of Physics, Nagpur University campus, Nagpur-440010 (India)

2016-05-06

Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimated to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr{sup 3+}, Gd{sup 3+},Gd{sup 3+}–Eu{sup 3+}, and Er{sup 3+}–Tb{sup 3+} had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb{sup 3+}–Yb{sup 3+}, Pr{sup 3+}–Yb{sup 3+}, and Tm{sup 3+}–Yb{sup 3+} has been reported. The Yb{sup 3+} ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb{sup 3+} is close to 100% and the energy of the only excited level of Yb{sup 3+} (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce{sup 3+}-doped Tb{sub 3}Al{sub 5}O{sub 12} (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300–500 nm due to strong ligand field and high luminescent quantum efficiency. Therefore, the

Ternary rhombohedral Laves phases RE{sub 2}Rh{sub 3}Ga (RE = Y, La-Nd, Sm, Gd-Er)

Energy Technology Data Exchange (ETDEWEB)

Seidel, Stefan; Benndorf, Christopher; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Janka, Oliver [Oldenburg Univ. (Germany). Inst. fuer Chemie; Mausolf, Bernhard [RWTH Aachen (Germany). Inst. fuer Anorganische Chemie; Haarmann, Frank [RWTH Aachen (Germany). Inst. fuer Anorganische Chemie; Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics

2017-06-01

The ordered Laves phases RE{sub 2}Rh{sub 3}Ga (RE=Y, La-Nd, Sm, Gd-Er) were synthesized by arc-melting of the elements and subsequent annealing. The samples were characterized by powder X-ray diffraction (XRD). They crystallize with the rhombohedral Mg{sub 2}Ni{sub 3}Si type structure, space group R3m. Three structures were refined from single crystal X-ray diffractometer data: a=557.1(1), c=1183.1(2), wR2=0.0591, 159 F{sup 2} values, 10 variables for Y{sub 2}Rh{sub 3}Ga, a=562.5(2), c=1194.4(2) pm, wR2=0.0519, 206 F{sup 2} values, 11 variables for Ce{sub 2}Rh{sub 3}Ga and a=556.7(2), c=1184.1(3) pm, wR2=0.0396, 176 F{sup 2} values, 11 variables for Tb{sub 2}Rh{sub 3}Ga. The Rh{sub 3}Ga tetrahedra are condensed via common corners and the large cavities left by the network are filled by the rare earth atoms. The RE{sub 2}Rh{sub 3}Ga Laves phases crystallize with a translationengleiche subgroup of the cubic RERh{sub 2} Laves phases with MgCu{sub 2} type. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y{sub 2}Rh{sub 3}Ga and La{sub 2}Rh{sub 3}Ga. Ce{sub 2}Rh{sub 3}Ga shows intermediate cerium valence while all other RE{sub 2}Rh{sub 3}Ga phases are Curie-Weiss paramagnets which order magnetically at low temperatures. The {sup 89}Y and {sup 71}Ga solid state nuclear magnetic resonance (NMR) spectra of the diamagnetic representative Y{sub 2}Rh{sub 3}Ga show well-defined single resonances in agreement with an ordered bulk phase. In comparison to the binary Laves phase YRh{sub 2} a strongly increased {sup 89}Y resonance frequency is observed owing to a higher s-electron spin density at the {sup 89}Y nuclei as proven by density of states (DOS) calculations.

Electronic and magnetic properties of R0.5A0.5MnO3 compounds (R=Gd, Dy, Ho, Er; A=Sr, Ca)

International Nuclear Information System (INIS)

Terai, T.; Sasaki, T.; Kakeshita, T.; Fukuda, T.; Saburi, T.; Kitagawa, H.; Kindo, K.; Honda, M.

2000-01-01

Electronic and magnetic properties of the perovskitelike compounds of R 0.5 A 0.5 MnO 3 (R=Gd, Dy, Ho, Er; A=Sr, Ca) have been studied by measuring lattice parameter, electrical resistivity, magnetic susceptibility, and magnetization. All the Sr-doped compounds show a transition from a paramagnetic insulator to a spin-glass-like insulator at T g , even though the manganite La 0.5 Ca 0.5 MnO 3 , with nearly the same tolerance factor t, have been shown by others, to have different transitions. On the other hand, all the Ca-doped compounds show a charge-ordering transition at T CO and show a transition from a paramagnetic insulator to a canted antiferromagnetic insulator and/or a spin-glass-like insulator at T CA below T CO . These transition temperatures decrease with decreasing t. In the compound of Gd 0.5 Ca 0.5 MnO 3 , the collapse of the charge ordering has been observed under a pulsed high magnetic field of 45 T at 4.2 K. On the other hand, in the compound of Gd 0.5 Sr 0.5 MnO 3 , the magnetization process depends on the strength of magnetic field. These electronic and magnetic properties depend not only on the tolerance factor but also the variance (second moment) of the A-site ion radii distribution

Synthesis and characterization of heterobinuclear (La-Zn, Pr-Zn, Nd-Zn, Sm-Zn, Eu-Zn, Gd-Zn, Tb-Zn, Dy-Zn) azine-bridged complexes

International Nuclear Information System (INIS)

Singh, Bachcha; Srivastav, A.K.; Singh, P.K.

1997-01-01

Zinc(II) complex of 2-acetylpyridine salicyl aldazine (Haps) of the type Zn(aps) 2 (H 2 O) 2 has been synthesised. The reaction of Zn(aps) 2 (H 2 O) 2 with lanthanide chlorides, LnCl 3 (where Ln=La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) yields azine-bridged heterobinuclear complexes of the formulae LnCl 3 Zn(aps) 2 (H 2 O) 2 . These complexes have been characterized by elemental analyses, molecular weight, conductance (solid and solution) and magnetic susceptibility measurements, mass, IR and electronic spectral data. X-ray powder diffraction data indicate the tetragonal unit lattice for Zn(aps) 2 (H 2 O) 2 and PrCl 3 Zn(aps) 2 (H 2 O) 2 . (author)

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

Magnetic properties of RNi5-xCux intermetallics

International Nuclear Information System (INIS)

Kuchin, A.G.; Ermolenko, A.S.; Kulikov, Yu.A.; Khrabrov, V.I.; Rosenfeld, E.V.; Makarova, G.M.; Lapina, T.P.; Belozerov, Ye.V.

2006-01-01

The magnetic properties have been studied for the series of RNi 5-x Cu x intermetallics with R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu; x= 5-x Cu x but GdNi 5-x Cu x . These results are explained in the frame of band magnetism, random local crystal field, and domain wall pinning theories

Electronic and ionic transport in Ce0.8PrxTb0.2-xO2-δ and evaluation of performance as oxygen permeation membranes

DEFF Research Database (Denmark)

Chatzichristodoulou, Christodoulos; Hendriksen, Peter Vang

2012-01-01

is significantly enhanced relative to that of a Ce0.9Gd0.1O1.95-δ membrane at high oxygen activities of the permeate gas (aO2 an > 10-15) due to the enhanced electronic conductivity of the Ce0.8PrxTb0.2-xO2-δ compounds. Interference between the ionic and electronic flows has a significant positive effect......The electronic conductivity of Ce0.8PrxTb0.2-xO2-δ (x = 0, 0.05, 0.10, 0.15, 0.20) was determined in the oxygen activity range aO2 ≈ 103 to aO2 ≈ 10-17 at 700- 900 °C by means of Hebb-Wagner polarisation. The electronic conductivity of all the Ce0.8PrxTb0.2-xO2-δ compositions was significantly...... enhanced as compared to that of Ce0.9Gd0.1O1.95-δ, and its value was found to increase with increasing Pr/Tb ratio. The ionic mobility of Ce0.8PrxTb0.2-xO2-δ is similar to that of Ce1- 2δGd2δO2-δ at the same oxygen vacancy concentration. The calculated oxygen flux of a Ce0.8PrxTb0.2-xO2-δ membrane...

Temperature dependence of Er{sup 3+} ionoluminescence and photoluminescence in Gd{sub 2}O{sub 3}:Bi nanopowder

Energy Technology Data Exchange (ETDEWEB)

Boruc, Zuzanna, E-mail: z.boruc@stud.elka.pw.edu.pl; Fetliński, Bartosz; Kaczkan, Marcin; Malinowski, Michał [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland); Gawlik, Grzegorz [Institute of Electronic Materials Technology, ul. Wolczynska 133, 01-919 Warsaw (Poland)

2014-06-15

Ionoluminescence (IL) and photoluminescence (PL) of trivalent erbium ions (Er{sup 3+}) in Gd{sub 2}O{sub 3} nanopowder host activated with Bi{sup 3+} ions has been studied in order to establish the link between changes in luminescent spectra and temperature of the sample material. IL measurements have been performed with H{sub 2}{sup +} 100 keV ion beam bombarding the target material for a few seconds, while PL spectra have been collected for temperatures ranging from 20 °C to 700 °C. The PL data was used as a reference in determining the temperature corresponding to IL spectra. The collected data enabled the definition of empirical formula based on the Boltzmann distribution, which allows the temperature to be determined with a maximum sensitivity of 9.7 × 10{sup −3} °C{sup −1}. The analysis of the Er{sup 3+} energy level structure in terms of tendency of the system to stay in thermal equilibrium, explained different behaviors of the line intensities. This work led to the conclusion that temperature changes during ion excitation can be easily defined with separately collected PL spectra. The final result, which is empirical formula describing dependence of fluorescence intensity ratio on temperature, raises the idea of an application of method in temperature control, during processes like ion implantation and some nuclear applications.

Theoretical and experimental spectroscopic studies of the first highly luminescent binuclear hydrocinnamate of Eu(III), Tb(III) and Gd(III) with bidentate 2,2'-bipyridine ligand

Energy Technology Data Exchange (ETDEWEB)

Marques, Lippy F.; Correa, Charlane C.; Garcia, Humberto C. [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG 36036-330 (Brazil); Martins Francisco, Thiago [Departamento de Física-ICEx, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte-MG 30123-970 (Brazil); Ribeiro, Sidney J.L. [Instituto de Química, Universidade Estadual Paulista Júlio de Mesquita Filho-UNESP, CP 355, Araraquara-SP 14801-970 (Brazil); Dutra, José Diogo L.; Freire, Ricardo O. [Pople Computational Chemistry Laboratory, Departamento de Química, Universidade Federal de Sergipe, São Cristóvão-SE 49100-000 (Brazil); Machado, Flávia C., E-mail: flavia.machado@ufjf.edu.br [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG 36036-330 (Brazil)

2014-04-15

In this paper, the synthesis of three new binuclear lanthanide (III) complexes [Ln{sub 2}(cin){sub 6}(bpy){sub 2}] (Ln=Eu (1), Tb (2), Gd (3), cin=hydrocinnamate anion; bpy=2,2'-bipyridine), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermal analysis (TGA/DTA) are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structures of 1–3 reveal that all compounds are isostructural and that each lanthanide ion is nine-coordinated by oxygen and nitrogen atoms in an overall distorted tricapped trigonal-prismatic geometry. Eu(III) complex structure was also calculated using the Sparkle model for lanthanide complexes and the intensity parameters (Ω{sub 2}, Ω{sub 4}, and Ω{sub 6}), calculated from the experimental data and from Sparkle/PM3 model. The theoretical emission quantum efficiencies obtained for Sparkle/PM3 structures are in excellent agreement with the experimental values, clearly attesting to the efficacy of the theoretical models. The theoretical procedure applied here shows that the europium binuclear compound displays a quantum yield about 65% suggesting that the system can be excellent for the development of efficient luminescent devices. Highlights: • First binuclear Ln{sup 3+}-hydrocinnamate have been synthesized and characterized. • Eu{sup 3+}, Tb{sup 3+} and Gd{sup 3+} complexes photoluminescence properties were investigated. • Theoretical approaches for Eu{sup 3+} complex luminescence has been performed. • An energy level diagram is used to establish the ligand-to-metal energy transfer. • 65% Quantum yield suggests an excellent system for luminescent devices.

Structural and optical properties of Tb-doped Na-Gd metaphosphate glasses and glass-ceramics

Czech Academy of Sciences Publication Activity Database

Moretti, F.; Vedda, A.; Nikl, Martin; Nitsch, Karel

2009-01-01

Roč. 21, č. 15 (2009), 155103/1-155103/7 ISSN 0953-8984 R&D Projects: GA AV ČR IAA200100626 Institutional research plan: CEZ:AV0Z10100521 Keywords : Na-Gd metaphosphate glass * glass -ceramics * NaGd(PO 3 ) 4 * optical properties * structural properties * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.964, year: 2009

Symmetry-Breaking Transitions in RECuAs_2-xP_x (RE=Sm, Gd, Ho, and Er)

Energy Technology Data Exchange (ETDEWEB)

Mozharivskyj, Yurij [Iowa State Univ., Ames, IA (United States)

2002-01-01

Structural changes resulting in lower symmetries can be understood in terms of electronic instabilities and Coulomb interactions. The interplay of these two interrelated factors is complicated and difficult to analyze. The RECuAs_2-xP _x phases, because of the variation in the chemical content (As/P substitution), allow, with the aid of band structures, Madelung energies and Landau theory, a partial unraveling of the forces important in the symmetry-breaking transitions in RECuAs_2-xP _x (RE = Sm, Gd, Ho and Er). Distortions of the P layers in SmCu_1.15P₂, GdCuP_2.20 and ErCuP₂ are usefully thought of as generalized Peierls distortions, i.e., they lower the electronic (and total) energy and lead to more stable structures. On the other hand, the P4/nmm → Pmmn transitions, which are observed in all studied arsenophosphide series and occur upon substitution of P for As, originate from the B1g vibrational mode and are structural adaptations to smaller P atoms. These transitions provide tighter atomic packing and better Coulomb interactions. Configurational contribution to the entropy becomes important in stabilizing the mixed occupancy in the RECuAs _2-xP _x arsenophosphides. While geometric and electronic factors favor separation of the As and P atoms over two different crystallographic sites, configurational entropy stabilizes the As/P mixing on these two sites.;Progress in the research on RECuAs_2-xP _x was dependent upon the ability of Landau theory to predict, explain and dismiss structural models and transitions. The space group Pmmn (arising from the B 1g vibrational mode) in all mixed arsenophosphides and the existence of these mixed arsenophosphides followed from the analysis of GdCuAs ₂ and GdCuP₂, using Landau theory. The impossibility of obtaining the high-symmetry structure (P4/nmm) and the low symmetry structure

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.

2017-12-01

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 their response 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 feature that influences their response on compression. The ionic radius of Sn4+ is intermediate to that of Ti4+, Zr4+, and Hf4+, but the 〈Sn-O〉 bond in stannate pyrochlore is more covalent than the 〈B-O〉 bonds in titanates, zirconate, and hafnates. In stannates, based on in situ Raman spectroscopy, pyrochlore cation and anion sublattices begin to disorder with the onset of compression, first measured at 0.3 GPa. The extent of sublattice disorder versus pressure is greater in stannates with a smaller Ln3+ cation. Stannate pyrochlores (Fd-3m) begin a sluggish transformation to an orthorhombic, cotunnite-like structure at ~28 GPa similar transitions have been observed in titanate, zirconate, and hafnate pyrochlores at varying pressures (18-40 GPa) with cation radius ratio. The extent of the phase transition versus 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 multi-scale defect-fluorite  +  weberite-type structure adopted by Nd2Sn2O7 that is characteristic of titanate, zirconate, and hafnate pyrochlores under similar conditions. Like pyrochlore titanates, zirconates, and hafnates, the bulk modulus, B 0, of stannates varies linearly and inversely with cation radius ratio from 1 1 1 GPa (Nd2Sn2O7) to 251 GPa (Er2Sn2O7). 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 the primary determining factor of B 0. Additionally, when normalized to r A

Use of the ion exchange method for the determination of stability constants of trivalent metal complexes with humic and fulvic acids II. Tb3+, Yb3+ and Gd3+ complexes in weakly alkaline conditions

International Nuclear Information System (INIS)

Dong Wenming; Li Weijuan; Tao Zuyi

2002-01-01

The conditional stability constants for tracer concentrations of Tb(III), Yb(III), and Gd(III) with three soil humic acids, three soil fulvic acids and a fulvic acid from weathered coal were determined at pH 9.0-9.1 (these values are similar to those in calcareous soils) in the presence of NaHCO 3 by using the anion exchange method. It was found that 1 : 1 and 1 : 2 complexes were simultaneously formed in the weakly alkaline conditions. The conditional stability constants of these 1 : 1 and 1 : 2 complexes were calculated from the distribution coefficients of rare earth elements at various concentrations of humate or fulvate. The stability constants indicate the very high stability of trivalent Tb 3+ , Yb 3+ and Gd 3+ complexes with humic substances in weakly alkaline conditions. The key parameters necessary for the experimental determination of the conditional stability constants of metal ions with humic substances in the presence of NaHCO 3 by using an anion exchange method were discussed. The conditional stability constants of these 1 : 1 and 1 : 2 complexes were compared in this paper. It was found that stabilities of Tb 3+ 1 : 1 and 1 : 2 complexes with humic acid are greater than the corresponding ones with fulvic acid from the same soil. In addition, the effect of the presence of Ca 2+ as a competitor on the stabilities of 1 : 1 and 1 : 2 complexes of Yb was examined and no pronounced change of stabilities of 1 : 1 complex was found, even though Ca 2+ is in a 10 3 excess to Yb 3+

The new carbodiimide Li_2Gd_2Sr(CN_2)_5 having a crystal structure related to that of Gd_2(CN_2)_3

International Nuclear Information System (INIS)

Unverfehrt, Leonid; Stroebele, Markus; Meyer, H. Juergen

2013-01-01

The new carbodiimide compounds Li_2RE_2Sr(CN_2)_5 (RE = Sm, Gd, Eu, Tb) were prepared by a straight forward solid state metathesis reaction of REF_3, SrF_2, and Li_2(CN_2) at around 600 C. The crystal structure of Li_2Gd_2Sr(CN_2)_5 was solved based on X-ray single-crystal diffraction data. Corresponding Li_2RE_2Sr(CN_2)_5 compounds were analyzed by isotypic indexing of their powder patterns. The crystal structure of Li_2Gd_2Sr(CN_2)_5 can be well related to that of Gd_2(CN_2)_3, because both structures are based on layered structures composed of close packed layers of [N=C=N]"2"- sticks, alternating with layers of metal ions. The crystal structure of Li_2Gd_2Sr(CN_2)_5 can be considered to contain an ABC layer sequence of [N = C=N]"2"- layers with the interlayer voids being occupied by (three) distinct types of cations. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

A study utility of gadolinium enhanced magnetic resonance imaging (Gd-MRI) in the preoperative diagnosis of lymph node metastasis of esophageal carcinoma

International Nuclear Information System (INIS)

Makino, Harufumi

1997-01-01

We evaluated the utility of gadolinium enhanced magnetic resonance imaging (Gd-MRI) in the diagnosis of lymph node metastasis of esophageal carcinoma. Gd-MRI was performed in 42 patients with esophageal carcinoma. The intensities of 50 lymph nodes in MR imaging were measured. No differences were observed in intensity between metastatic and non-metastatic nodes. However, intensity values did overlap. Thus, the author devised a new method allowing comparison of metastatic and non-metastatic nodes on Gd-MRI utilizing an enhancement ratio (ER). ER higher than 45% reflected metastatic nodes. (author)

Expression of OATP1B3 determines uptake of Gd-EOB-DTPA in hepatocellular carcinoma

OpenAIRE

Narita, Masato; Hatano, Etsuro; Arizono, Shigeki; Miyagawa-Hayashino, Aya; Isoda, Hiroyoshi; Kitamura, Koji; Yasuchika, Kentaro; Nitta, Takashi; Uemoto, Shinji

2009-01-01

Background: Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is an MRI contrast agent with perfusion and hepatoselective properties. The purpose of the study was to examine uptake of Gd-EOB-DTPA in the hepatobiliary phase in hepatocellular carcinoma (HCC). Methods: A retrospective analysis of 22 patients with HCC who underwent preoperative Gd-EOB-DTPA-enhanced MRI was performed. Enhancement ratios (ERs) and expression levels of the organic anion transporter (OATP) 1B3...

(Dy0.5Er0.5)Al2: A large magnetocaloric effect material for low-temperature magnetic refrigeration

International Nuclear Information System (INIS)

Gschneidner, K.A. Jr.; Takeya, H.; Moorman, J.O.; Pecharsky, V.K.

1994-01-01

The low-temprature heat capacity and ac and dc magnetic properties of (Dy 0.5 Er 0.5 )Al 2 have been studied as a function of magnetic fields up to ∼10 T. The magnetocaloric effect in (Dy 0.5 Er 0.5 )Al 2 is 30% larger than that of the prototype material, GdPd. Magnetic measurements show that there is no measurable magnetic hysteresis above ∼17 K. These results suggest that (Dy 0.5 Er 0.5 )Al 2 would be a significantly better magnetic refrigerant than GdPd

Raman and Fluorescence Spectroscopy of CeO2, Er2O3, Nd2O3, Tm2O3, Yb2O3, La2O3, and Tb4O7

Directory of Open Access Journals (Sweden)

Jianlan Cui

2015-01-01

Full Text Available To better understand and ascertain the mechanisms of flotation reagent interaction with rare earth (RE minerals, it is necessary to determine the physical and chemical properties of the constituent components. Seven rare earth oxides (CeO2, Er2O3, Nd2O3, Tm2O3, Yb2O3, La2O3, and Tb4O7 that cover the rare earth elements (REEs from light to heavy REEs have been investigated using Raman spectroscopy. Multiple laser sources (wavelengths of 325 nm, 442 nm, 514 nm, and 632.8 nm for the Raman shift ranges from 100 cm−1 to 5000 cm−1 of these excitations were used for each individual rare earth oxide. Raman shifts and fluorescence emission have been identified. Theoretical energy levels for Er, Nd, and Yb were used for the interpretation of fluorescence emission. The experimental results showed good agreement with the theoretical calculation for Er2O3 and Nd2O3. Additional fluorescence emission was observed with Yb2O3 that did not fit the reported energy level diagram. Tb4O7 was observed undergoing laser induced changes during examination.

Lanthanide-doped NaGdF4 core-shell nanoparticles for non-contact self-referencing temperature sensors.

Science.gov (United States)

Zheng, Shuhong; Chen, Weibo; Tan, Dezhi; Zhou, Jiajia; Guo, Qiangbing; Jiang, Wei; Xu, Cheng; Liu, Xiaofeng; Qiu, Jianrong

2014-06-07

We report that non-contact self-referencing temperature sensors can be realized with the use of core-shell nanostructures. These lanthanide-based nanothermometers (NaGdF4:Yb(3+)/Tm(3+)@Tb(3+)/Eu(3+)) exhibit higher sensitivity in a wide range from 125 to 300 K based on two emissions of Tb(3+) at 545 nm and Eu(3+) at 615 nm under near-infrared laser excitation.

Evaluation of optoelectronic response and Raman active modes in Tb{sup 3+} and Eu{sup 3+}-doped gadolinium oxide (Gd{sub 2}O{sub 3}) nanoparticle systems

Energy Technology Data Exchange (ETDEWEB)

Paul, Nibedita [National Institute of Technology Nagaland, Department of Physics, Dimapur, Nagaland (India); Tezpur University, Department of Physics, Tezpur, Assam (India); Mohanta, D. [Tezpur University, Department of Physics, Tezpur, Assam (India)

2016-09-15

Rare earth oxide (Tb{sup 3+}:Gd{sub 2}O{sub 3} and Eu{sup 3+}:Gd{sub 2}O{sub 3}) nanophosphors are exploited through spectroscopic and microscopic tools with special emphasis on D-F mediated radiative emission and Raman active vibrational modes. Powder X-ray diffraction measurements have revealed cubic crystal structure of the nanosystems and with an average crystallite size varying between ∝3.2 and 4.8 nm. Photoluminescence (PL) spectra of Tb{sup 3+} doped systems signify intense blue-green (∝490 nm) and green (∝544 nm) emissions mediated by {sup 5}D{sub 4} → {sup 7}F{sub 6} and {sup 5}D{sub 4} → {sup 7}F{sub 5} transitional events; respectively. In the PL responses of Eu{sup 3+} doped nanoparticle systems, we also identify magnetically-driven {sup 5}D{sub 0} → {sup 7}F{sub 1} (∝591 nm) and electrically driven {sup 5}D{sub 0} → {sup 7}F{sub 2} (∝619 nm) radiative features which seem to improve with increasing doping level. However, the magnitude of Judd-Ofelt (J-O) intensity parameters (Ω {sub 2,} {sub 4}), is significantly lowered for the high doping cases. Raman spectra of the undoped and RE doped systems exhibited several A{sub g} and F{sub g} modes in the range of Raman shift ∝100-600 cm{sup -1}. In the Raman spectra, the peaks located at ∝355 cm{sup -1} are assigned to the mixed mode of F{sub g} + A{sub g}, the line width of which was found to increase with RE doping. Moreover, owing to the enhanced defect concentration in the doped systems than its undoped counterpart, we anticipate a faster phonon relaxation and consequently, a suppression of phonon lifetime in the former case. (orig.)

NaGd(MoO4)2 nanocrystals with diverse morphologies: controlled synthesis, growth mechanism, photoluminescence and thermometric properties.

Science.gov (United States)

Li, Anming; Xu, Dekang; Lin, Hao; Yang, Shenghong; Shao, Yuanzhi; Zhang, Yueli

2016-08-10

Pure tetragonal phase, uniform and well-crystallized sodium gadolinium molybdate (NaGd(MoO4)2) nanocrystals with diverse morphologies, e.g. nanocylinders, nanocubes and square nanoplates have been selectively synthesized via oleic acid-mediated hydrothermal method. The phase, structure, morphology and composition of the as-synthesized products are studied. Contents of both sodium molybdate and oleic acid of the precursor solutions are found to affect the morphologies of the products significantly, and oleic acid plays a key role in the morphology-controlled synthesis of NaGd(MoO4)2 nanocrystals with diverse morphologies. Growth mechanism of NaGd(MoO4)2 nanocrystals is proposed based on time-dependent morphology evolution and X-ray diffraction analysis. Morphology-dependent down-shifting photoluminescence properties of NaGd(MoO4)2: Eu(3+) nanocrystals, and upconversion photoluminescence properties of NaGd(MoO4)2: Yb(3+)/Er(3+) and Yb(3+)/Tm(3+) nanoplates are investigated in detail. Charge transfer band in the down-shifting excitation spectra shows a slight blue-shift, and the luminescence intensities and lifetimes of Eu(3+) are decreased gradually with the morphology of the nanocrystals varying from nanocubes to thin square nanoplates. Upconversion energy transfer mechanisms of NaGd(MoO4)2: Yb(3+)/Er(3+), Yb(3+)/Tm(3+) nanoplates are proposed based on the energy level scheme and power dependence of upconversion emissions. Thermometric properties of NaGd(MoO4)2: Yb(3+)/Er(3+) nanoplates are investigated, and the maximum sensitivity is determined to be 0.01333 K(-1) at 285 K.

Study of hyperfine interactions in intermetallic compounds Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In

International Nuclear Information System (INIS)

Lapolli, Andre Luis

2006-01-01

Systematic behavior of magnetic hyperfine field (B hf ) in the intermetallic compounds Gd(Ni,Pd,Cu)In Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In was studied by Perturbed Gamma-Gamma Angular Correlation spectroscopy. The measurements of B hf were carried out at the rare earth atom and in sites using the nuclear probes 140 Ce and 11 '1Cd respectively. The variation of hyperfine field with temperature, in most cases, follows the Brillouin function predicted from the molecular field theory. The hyperfine field values at rare earth atom sites obtained from 140 Ce probe as well as at in sites obtained from 111 Cd probe for each series of compounds were extrapolated to zero Kelvin B hf (T=0) from these curves. These values were compared with the values of the literature for other compounds containing the same rare earth element and all of them show a linear relationship with the ordering temperature. This indicates that the main contribution to B hf comes from the conduction electron polarization (CEP) through Fermi contact interaction and the principal mechanism of magnetic interaction in these compounds can be described by the RKKY type interaction. The values of B hf (T=0) for each family of intermetallic compounds RNiIn and RPdIn when plotted as a function of 4f spin projection of rare earth element also shows a linear relationship. Exceptions are the results for the compounds RNiIn obtained with 111 Cd probe where a small deviation from linearity is observed. The results of the measurements carried out with the 111 Cd probe were also analyzed to obtain the hyperfine parameters of the quadrupole interaction as a function of temperature for RPdln and GdNiIn compounds. The results show that for the compound GdPdIn there might be some Gd-In disorder at high temperature. (author)

Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

International Nuclear Information System (INIS)

Majeed, Abdul; Khan, Muhammad Azhar; Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F.; Murtaza, Ghulam; Akhtar, Majid Niaz; Shakir, Imran; Warsi, Muhammad Farooq

2016-01-01

Rare-earth (RE=La 3+ , Nd 3+ , Gd 3+ , Tb 3+ , Dy 3+ ) doped Ba 2 NiCoRE x Fe 28−x O 46 (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7–19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500–2400 cm −1. Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3b VI ). The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Graphical abstract: Nano-sized rare-earth (RE=La 3+ , Nd 3+ , Gd 3+ , Tb 3+ , Dy 3+ ) doped Ba 2 NiCoRE x Fe 28−x O 46 (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route and the crystallite size was found in the range 7–19 nm. The enhancement in the coercivity was observed with the doping of rare-earth cations. The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Highlights: • Micro-emulsion route was used to synthesize Ba 2 NiCoRE x Fe 28−x O 46 ferrites. • The crystallite size was found in the range 7–19 nm. • The rare-earth incorporation enhanced the coercivity (664–926 Oe). �

Growth of multiferroic Gd1-xYxMnO3 single crystals by optical floating zone technique

International Nuclear Information System (INIS)

Sarguna, R.M.; Ganesamoorthy, S.; Sridharan, V.; Subramanian, N.

2014-01-01

Rare earth manganites RMnO 3 with distorted perovskite structure are excellent multiferroic materials. The discovery of magnetic spin driven ferroelectricity in orthorhombic manganites (TbMnO 3 ) has sparked a surge in research into understanding the fundamental mechanism of multiferroic behavior. These systems fall under the category of type-2 multiferroics, the change of spatially modulated magnetic moment from sinusoidal to cycloidal gives rise to electric polarization. The magnetic structure depends upon the Mn-O-Mn bond angle. GdMnO 3 shows multiferroic properties only in the presence of applied magnetic field. When a magnetic field is applied along the b-axis, GdMnO 3 enters a ferroelectric state with an electric polarisation along the c-axis. By altering the Mn-O-Mn angle it is expected that GdMnO 3 will show multiferroic property even in the absence of magnetic field like TbMnO 3 . To alter the Mn-O-Mn bond angle GdMnO 3 was substituted with Y having lower ionic radius at Gd site. The effect of Y doping at the rare-earth site in GdMnO 3 investigated on polycrystalline samples of Gd 1-x Y x MnO 3 demonstrated a magneto-electric coupling in x=0.1-0.4. Single crystals are expected to give much amplified signal in respect of ferroelectric and magnetic properties. In this work we have grown Y substituted Gd 1-x Y x MnO 3 (x = 0.2, 0.3 and 0.4) by optical floating zone technique under different gas atmosphere. Growth rate of 1-2 mm/h yielded crack free crystals. Quality of the crystals was checked using Laue diffraction. Effect of growth rate and atmosphere pressure will be presented in this talk. (author)

Proton configurations and pairing correlations at the N=80 superdeformed shell closure: Study of 145Tb

International Nuclear Information System (INIS)

Mullins, S.M.; Schmeing, N.C.; Flibotte, S.; Hackman, G.; Rodriguez, J.L.; Waddington, J.C.; Yao, L.; Andrews, H.R.; Galindo-Uribarri, A.; Janzen, V.P.; Radford, D.C.; Ward, D.; DeGraaf, J.; Drake, T.E.; Pilotte, S.; Paul, E.S.

1994-01-01

A superdeformed band has been observed in the N=80 nucleus 145 Tb which was produced with the reactions 112 Sn( 37 Cl,2p2n) and 118 Sn( 31 P,4n) at bombarding energies of 187 and 160 MeV, respectively. Since superdeformed bands also exist in the three lighter N=80 isotones 142 Sm, 143 Eu, and 144 Gd, it is now possible to understand the valence-proton configurations of these bands in a systematic way. The T (2) dynamic moment of inertia in 145 Tb shows no evidence for the N = 6 quasiproton crossing that is observed in 144 Gd. Comparison with cranked Woods-Saxon and total Routhian surface calculations suggests that the proton configuration in 145 Tb is 6 1 direct-product[404] 9/2 + 2 in which the quasiproton crossing is blocked. Furthermore, like 143 Eu and 142 Sm, there is no evidence in the T (2) for the N=6 quasineutron crossing predicted by the calculations. This may indicate that static neutron pairing correlations are quenched at the N=80 superdeformed shell closure

Crystal Chemistry and Photocatalytic Properties of RE4S4Te3 (RE = Gd, Ho, Er, Tm): Experimental and Theoretical Investigations.

Science.gov (United States)

Chi, Yang; Rong, Liang-Zhen; Suen, Nian-Tzu; Xue, Huai-Guo; Guo, Sheng-Ping

2018-04-25

Reported are the synthesis and structural characterization of a new series of ternary rare-earth mix-chalcogenides RE 4 S 4 Te 3 (RE = Gd, Ho, Er, Tm) that have been obtained from high-temperature solid state reactions. These compounds crystallize in Ho 4 S 4 Te 2.68 structure types with monoclinic C2/ m and/or orthorhombic Immm space groups. The space group variation within this series is due to the position disorder along the Te plane (Te to TeA and TeB). The structural relationship and change between these two space groups are analyzed. It is realized that these compounds are all photocatalytic active under simulated sunlight. The trend of their photocatalytic activities and photocurrent responses is well-explained by using theoretical calculation as well as dipole moment analysis.

Structural and sensing characteristics of Gd2Ti2O7, Er2TiO5 and Lu2Ti2O7 sensing membrane electrolyte–insulator–semiconductor for bio-sensing applications

International Nuclear Information System (INIS)

Pan, Tung-Ming; Liao, Pei-You; Chang, Kung-Yuan; Chi, Lifeng

2013-01-01

Highlights: ► The structural and sensing properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 and Lu 2 Ti 2 O 7 sensing films grown on Si substrates by reactive co-sputtering. ► The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity, a larger drift rate, a higher hysteresis voltage, and a larger hysteresis gap than other sensing films. ► The impedance effect of EIS sensors has been investigated using C–V method. -- Abstract: This paper describes the structural and sensing characteristics of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 sensing membranes deposited on Si substrates through reactive co-sputtering for electrolyte–insulator–semiconductor (EIS) pH sensors. In this work, the structural properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 membranes were investigated by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. The observed structural properties were then correlated with the resulting pH sensing performances. The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity (59.32 mV pH −1 ), a larger drift rate (0.55 mV h −1 ), a higher hysteresis voltage (5 mV), and a larger hysteresis gap (∼70 mV) compared to those of the other sensing films. This result is attributed to the higher surface roughness and the formation of a thicker interfacial layer at the oxide–Si interface. Furthermore, the impedance effect of EIS sensors has been investigated using capacitance–voltage (C–V) method (frequency-dependent C–V curves). From the impedance spectroscopy analysis, we find that the diameter of a semicircle of an EIS sensor becomes smaller due to a gradual decrease in the bulk resistance of the device with degree of pH value

Rare earth elements in the Pacific and Atlantic Oceans. [Pr, Tb, Ho, Tm, Lu, La, Nd, Sm, Eu, Gd, Yb, Ce

Energy Technology Data Exchange (ETDEWEB)

Baar, H J.W. de; Bacon, M P; Brewer, P G; Bruland, K W

1985-09-01

The first profiles of Pr, Tb, Ho, Tm and Lu in the Pacific Ocean, as well as profiles of La, Ce, Nd, Sm, Eu, Gd and Yb are reported. Concentrations of REE (except Ce) in the deep water are two to three times higher than those observed in the deep Atlantic Ocean. Surface water concentrations are typically lower than in the Atlantic Ocean, especially for the heavier elements Ho,Tm,Yb and Lu. Cerium is strongly depleted in the Pacific water column, but less so in the oxygen minimum zone. The distribution of the REE group is consistent with two simultaneous processes: (1) cycling similar to that of opal and calcium carbonate, and (2) adsorptive scavenging by settling particles and possibly by uptake at ocean boundaries. However, the first process can probably not be sustained by the low REE contents of shells, unless additional adsorption on surfaces is invoked. The second process, adsorptive scavenging, largely controls the oceanic distribution and typical seawater pattern of the rare earths. (author).

Judd-Ofelt analysis and temperature dependent upconversion luminescence of Er{sup 3+}/Yb{sup 3+} codoped Gd{sub 2}(MoO{sub 4}){sub 3} phosphor

Energy Technology Data Exchange (ETDEWEB)

Lu, Hongyu [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Gao, Yachen [College of Electronic Engineering, Heilongjiang University, Harbin 150080 (China); Hao, Haoyue; Shi, Guang [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Li, Dongyu [Department of Physics, Lingnan Normal University, Zhanjiang 524048 (China); Song, Yinglin [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Wang, Yuxiao, E-mail: wangyx@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Zhang, Xueru, E-mail: xrzhang@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China)

2017-06-15

Although lanthanide doped luminescent materials have been extensively investigated, a quantitative analysis of how temperature affects upconversion luminescence is still incomplete. The Gd{sub 2}(MoO{sub 4}){sub 3}:Er{sup 3+}/Yb{sup 3+} phosphor is synthetized by sol-gel method. Based on the absorption spectra of Er{sup 3+} ions, J-O intensity parameters and radiative transition probabilities are computed to estimate the optical properties. In view of ion-phonon interaction, the phonon-assisted energy transfer and multiphonon relaxation are responsible for the temperature dependent luminescence. Additionally, cross relaxation probability for {sup 4}I{sub 11/2}+{sup 4}I{sub 11/2}→{sup 4}I{sub 15/2}+{sup 4}F{sub 7/2} is determined to be 240 s{sup −1} through quantitative simulation of ion-ion interaction. These meaningful results are of vital values for the field of laser crystal and optical temperature sensing.

Synthesis and characterization of La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III) and Dy(III) complexes of 2-acetylfuran-2-thenoylhydrazone

International Nuclear Information System (INIS)

Singh, B.; Singh, Praveen K.

1998-01-01

The reaction of 2-acetylfuran-2-thenoylhydrazone(afth) with Ln(III) trichlorides yields complexes of the type [Ln(afth)Cl 2 (H 2 O)(EtOH)]Cl, [Ln(III) = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy]. The complexes have been characterized by molar conductance, magnetic susceptibility and TGA and DTA measurements, magnetic susceptibility and TGA and DTA measurements, FAB mass, infrared, proton NMR, electronic absorption and emission spectra. The terbium complex is found to be monomer from the FAB mass spectrum. The IR and NMR spectra suggest neutral tridentate behaviour of the Schiff base. A coordination number seven is proposed around the metal ions. Emission spectra suggest C 3v , symmetry around the metal ion with capped octahedron geometry for the europium complex. (author)

Enhancement of the up-conversion luminescence from NaYF{sub 4}:Yb{sup 3+},Tb{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Hölsä, Jorma, E-mail: jholsa@utu.fi [University of Turku, Department of Chemistry, FI-20014 Turku (Finland); Turku University Centre for Materials and Surfaces (MatSurf), Turku (Finland); Universidade de São Paulo, Instituto de Química, São Paulo-SP (Brazil); Laihinen, Tero [University of Turku, Department of Chemistry, FI-20014 Turku (Finland); Laamanen, Taneli; Lastusaari, Mika [University of Turku, Department of Chemistry, FI-20014 Turku (Finland); Turku University Centre for Materials and Surfaces (MatSurf), Turku (Finland); Pihlgren, Laura [University of Turku, Department of Chemistry, FI-20014 Turku (Finland); Graduate School of Materials Research (GSMR), Turku (Finland); Rodrigues, Lucas C.V. [University of Turku, Department of Chemistry, FI-20014 Turku (Finland); Universidade de São Paulo, Instituto de Química, São Paulo-SP (Brazil); Soukka, Tero [University of Turku, Department of Biochemistry, FI-20014 Turku (Finland)

2014-04-15

The synthesis conditions of the Yb{sup 3+} and Tb{sup 3+} co-doped NaYF{sub 4} were optimized by reducing the number of washings to include only ethanol. The avoidance of the loss of amorphous NaF prior to post-annealing of the as-prepared materials resulted in the enhancement of the otherwise rather weak up-conversion from Tb{sup 3+} by 1–2 orders of magnitude. At the same time, the temperature of formation of the hexagonal NaRF{sub 4} phase with high up-conversion could be lowered by 100 °C down to 350 °C. This improvement in up-conversion was concluded to result from the better stoichiometry of the material without washing with water. The deficit of Na{sup +} would result in the excess of fluoride which, although not as fatal to the luminescence as the fluoride vacancies, has serious implications to the up-conversion intensity. A further enhancement in the up-conversion luminescence was observed to be due to the Er{sup 3+} ion impurity frequently associated with high-concentration Yb{sup 3+} materials. The mechanism involving the unintentional Er{sup 3+} sensitizer and the resonance energy transfer in the Yb{sup 3+}–Er{sup 3+}–Tb{sup 3+} co-doped NaYF{sub 4} were discussed based on the energy level schemes of the Yb{sup 3+}, Er{sup 3+}, and Tb{sup 3+} ions in NaYF{sub 4}.

Luminescence and magnetic properties of novel nanoparticle-sheathed 3D Micro-Architectures of Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) for bifunctional application

Science.gov (United States)

Krishnan, Rajagopalan; Thirumalai, Jagannathan; Kathiravan, Arunkumar

2015-01-01

For the first time, we report the successful synthesis of novel nanoparticle-sheathed bipyramid-like and almond-like Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) 3D hierarchical microstructures through a simple disodium ethylenediaminetetraacetic acid (Na2EDTA) facilitated hydrothermal method. Interestingly, time-dependent experiments confirm that the assembly-disassembly process is responsible for the formation of self-aggregated 3D architectures via Ostwald ripening phenomena. The resultant products are characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and magnetic measurements. The growth and formation mechanisms of the self-assembled 3D micro structures are discussed in detail. To confirm the presence of all the elements in the microstructure, the energy loss induced by the K, L shell electron ionization is observed in order to map the Fe, Gd, Mo, O, and Eu components. The photo luminescence properties of Fe0.5R0.5(MoO4)1.5 doped with Eu3+, Tb3+, Dy3+ are investigated. The room temperature and low temperature magnetic properties suggest that the interaction between the local-fields introduced by the magnetic Fe3+ ions and the R3+ (La, Gd) ions in the dodecahedral sites determine the magnetism in Fe0.5R0.5(MoO4)1.5:Eu3+. This work provides a new approach to synthesizing the novel Fe0.5R0.5(MoO4)1.5:Ln3+ for bi-functional magnetic and luminescence applications.

Energy transfer processes in Tb(III)-dibenzoylmethanate complexes with phosphine oxide ligands

International Nuclear Information System (INIS)

Silva Junior, Francisco A.; Nascimento, Helenise A.; Pereira, Dariston K.S.; Teotonio, Ercules E.S.; Espinola, Jose Geraldo P.; Faustino, Wagner M.; Sa, Gilberto F.

2013-01-01

The Tb 3+ -β-diketonate complexes [Tb(DBM) 3 L], [Tb(DBM) 2 (NO 3 )L 2 ] and [Tb(DBM)(NO 3 ) 2 (HMPA) 2 ] (DBM = dibenzoylmethanate; L: TPPO triphenylphosphine oxide or HMPA=hexamethylphosphine oxide) were prepared and characterized by elemental analysis (CHN), complexometric titration with EDTA and Fourier transform infrared (FTIR) spectroscopy, and the photoluminescence properties evaluated. The triplet state energies of the coordinated DBM ligands were determined using time-resolved phosphorescence spectra of analogous Gd 3+ complexes. The results show that the energies increase along with the number of coordinated nitrate anions replacing the DBM ligand in the complexes. The luminescence spectra and emission lifetime measurements revealed that the ligand-to-metal energy transfer efficiency follows the same tendency. Unlike the tris-DBM complexes, bis- and mono-DBM presented high luminescence, and may act as promising candidates for preparation of the emitting layer of light converting molecular devices (LCMDs). (author)

Energy transfer processes in Tb(III)-dibenzoylmethanate complexes with phosphine oxide ligands

Energy Technology Data Exchange (ETDEWEB)

Silva Junior, Francisco A.; Nascimento, Helenise A.; Pereira, Dariston K.S.; Teotonio, Ercules E.S.; Espinola, Jose Geraldo P.; Faustino, Wagner M., E-mail: teotonioees@quimica.ufpb.br [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Departamento de Quimica; Brito, Hermi F. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Quimica. Departamento de Quimica Fundamental; Felinto, Maria Claudia F.C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), SP (Brazil); Sa, Gilberto F. [Universidade Federal de Pernambuco (UFPE/CCEN), Recife, PE (Brazil). Centro de Ciencias Exatas e da Natureza. Departamento de Quimica Fundamental

2013-04-15

The Tb{sup 3+}-{beta}-diketonate complexes [Tb(DBM){sub 3}L], [Tb(DBM){sub 2}(NO{sub 3})L{sub 2}] and [Tb(DBM)(NO{sub 3}){sub 2} (HMPA){sub 2}] (DBM = dibenzoylmethanate; L: TPPO triphenylphosphine oxide or HMPA=hexamethylphosphine oxide) were prepared and characterized by elemental analysis (CHN), complexometric titration with EDTA and Fourier transform infrared (FTIR) spectroscopy, and the photoluminescence properties evaluated. The triplet state energies of the coordinated DBM ligands were determined using time-resolved phosphorescence spectra of analogous Gd{sup 3+} complexes. The results show that the energies increase along with the number of coordinated nitrate anions replacing the DBM ligand in the complexes. The luminescence spectra and emission lifetime measurements revealed that the ligand-to-metal energy transfer efficiency follows the same tendency. Unlike the tris-DBM complexes, bis- and mono-DBM presented high luminescence, and may act as promising candidates for preparation of the emitting layer of light converting molecular devices (LCMDs). (author)

Physico-chemical characterization of terbium-161-chloride (161TbCl3) radioisotope from irradiated natural gadolinium oxide target

International Nuclear Information System (INIS)

Azmairit Aziz; Nana Suherman

2015-01-01

Currently cancer patients are increasing every year in Indonesia and become the third leading cause of death after heart disease and high blood pressure. Terbium-161 ( 161 Tb) is a low β- emitter (E β - = 0.155 MeV, T 1/2 = 6.9 d) and very similar to 177 Lu in terms of half-life, E β - energy and chemical properties.However, 161 Tb also ejects internal conversion electrons and Auger electrons which can provide a greater therapeutic effect than 177 Lu. Radioisotope of 161 Tb can be produced as a carrier-free for use in labeling of biomolecules as a targeted radiopharmaceutical for cancer therapy. 161 Tb was obtained through 160 Gd(n,γ) 161 Tb nuclear reaction by thermal neutron bombardment on 100 mg of natural gadolinium oxide target in RSG-G.A. Siwabessy at a thermal neutron flux of ~10 14 n.cm -2 .s -1 and followed by radiochemical separation of 161 Tb from Gd isotopes using extraction chromatography method. The physico-chemical characterization of 161 TbCl 3 solution was studied by determination of its radionuclide purity by means of a γ-rays spectrometry with HP-Ge detector coupled to a multichannel analyzer (MCA). Radiochemical purity was determined using paper chromatography and paper electrophoresis methods. The results showed that 161 TbCl 3 radioisotope has a pH of 2, radiochemical purity of 99.64 ± 0.34%, radionuclide purity of 99.69 ± 0.20%, specific activity and radioactive concentration at the end of irradiation (EOI) of 2.26 – 5.31 Ci/mg and 3.84 – 9.03 mCi/mL, respectively. 161 TbCl 3 solution stable for 3 weeks at room temperature with a radiochemical purity of 98.41 ± 0.42%. 161 TbCl 3 solution from irradiated natural gadolinium oxide target has the physico-chemical characteristic that meets the requirements for use as a precursor in preparation of radiopharmaceuticals. (author)

Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

Energy Technology Data Exchange (ETDEWEB)

Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of Scientific Research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

2016-06-15

Rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7–19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500–2400 cm{sup −1.} Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3b{sub VI}). The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Graphical abstract: Nano-sized rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route and the crystallite size was found in the range 7–19 nm. The enhancement in the coercivity was observed with the doping of rare-earth cations. The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Highlights: • Micro-emulsion route was used to synthesize Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} ferrites. • The crystallite size was found

Benefits of Silica Core-Shell Structures on the Temperature Sensing Properties of Er,Yb:GdVO4 Up-Conversion Nanoparticles.

Science.gov (United States)

Savchuk, Oleksandr A; Carvajal, Joan J; Cascales, C; Aguiló, M; Díaz, F

2016-03-23

We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er(3+) (1 mol %) and Yb(3+) (20 mol %) and determined their thermal sensing properties through the fluorescence intensity ratio (FIR) technique. We also analyzed how a silica coating, in a core-shell structure, affects the temperature sensing properties of this material. Spectra were recorded in the range of biological temperatures (298-343 K). The absolute sensitivity for temperature determination calculated for the core-shell nanoparticles is double the one calculated for bare nanoparticles, achieving a thermal resolution of 0.4 K. Moreover, silica-coated nanoparticles show good dispersibility in different solvents, such as water, DMSO, and methanol. Also, they show good luminescence stability without interactions with solvent molecules. Furthermore, we also observed that the silica coating shell prevents progressive heating of the nanoparticles during prolonged excitation periods with the 980 nm laser, preventing effects on their thermometric applications.

Ternary gallides RE{sub 4}Rh{sub 9}Ga{sub 5}, RE{sub 5}Rh{sub 12}Ga{sub 7} and RE{sub 7}Rh{sub 18}Ga{sub 11} (RE=Y, La-Nd, Sm, Gd, Tb). Intergrowth structures with MgCu{sub 2} and CaCu{sub 5} related slabs

Energy Technology Data Exchange (ETDEWEB)

Seidel, Stefan; Rodewald, Ute C.; Poettgen, Rainer [Univ. Muenster (Germany). Inst. fuer Anorganische und Analytische Chemie; Janka, Oliver [Univ. Oldenburg (Germany). Inst. fuer Chemie

2017-07-01

Fourteen ternary gallides RE{sub 4}Rh{sub 9}Ga{sub 5}, RE{sub 5}Rh{sub 12}Ga{sub 7} and RE{sub 7}Rh{sub 18}Ga{sub 11} (RE=Y, La-Nd, Sm, Gd, Tb) were synthesized from the elements by arc-melting, followed by different annealing sequences either in muffle or induction furnaces. The samples were characterized through Guinier powder patterns and the crystal structures of Ce{sub 4}Rh{sub 9}Ga{sub 5}, Ce{sub 5}Rh{sub 12}Ga{sub 7}, Ce{sub 7}Rh{sub 18}Ga{sub 11}, Nd{sub 5}Rh{sub 10.44(4)}Ga{sub 8.56(4)}, Nd{sub 4}Rh{sub 9}Ga{sub 5} and Gd{sub 4}Rh{sub 9}Ga{sub 5} were refined from single crystal X-ray diffractometer data. The new gallides are the n=2, 3 and 5 members of the RE{sub 2+n} Rh{sub 3+3n} Ga{sub 1+2n} structure series in the Parthe intergrowth concept. The slabs of these intergrowth structures derive from the cubic Laves phase MgCu{sub 2} (Mg{sub 2}Ni{sub 3}Si as ternary variant) and CaCu{sub 5} (CeCo{sub 3}B{sub 2} as ternary variant). Only the Nd{sub 5}Rh{sub 10.44(4)}Ga{sub 8.56(4)} crystal shows Rh/Ga mixing within the Laves type slabs. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y{sub 4}Rh{sub 9}Ga{sub 5} and Curie-Weiss paramagnetism for Gd{sub 4}Rh{sub 9}Ga{sub 5} and Tb{sub 4}Rh{sub 9}Ga{sub 5}. Low-temperature data show ferromagnetic ordering at T{sub C}=78.1 (Gd{sub 4}Rh{sub 9}Ga{sub 5}) and 55.8 K (Tb{sub 4}Rh{sub 9}Ga{sub 5}).

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)

Influence of Al-atoms on the spin fluctuation scattering in R(Co,Al)2 compounds

International Nuclear Information System (INIS)

Duc, N.H.; Hung, D.T.; Kim-Ngan, N.H.; Sechovsky, V.

1992-01-01

The resistivity and magnetisation have been measured for the R(Co 1-x Al x ) 2 compounds with R=Nd, Gd, Tb, Dy, Ho, Er and Lu. For x=0.2 the resistivity enhancement is observed below T c , however, for the compounds with R=Lu-Tb only. The results are discussed in terms of the spin fluctuation scattering and indicate that the enhancement of the spin fluctuation scattering is strongly related to the lattice parameter. (orig.)

Heat capacity of RFe{sub x}Mn{sub 12-x} (R = Gd, Tb and Dy) compounds: wiping out a cooperative 4f-4f exchange interaction by breaking the 3d-4f magnetic symmetry

Energy Technology Data Exchange (ETDEWEB)

Pique, C; Blanco, J A; Abad, E [Departamento de Fisica, Universidad de Oviedo, Campus de Viesques, E-33204 Gijon (Spain); Burriel, R; Artigas, M [Instituto de Ciencia de Materiales de Aragon (CSIC-Universidad de Zaragoza), E-50009 Zaragoza (Spain); Fernandez-RodrIguez, J [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France)], E-mail: pique@uniovi.es

2008-08-27

Using adiabatic calorimetry the heat capacity of a series of RFe{sub x}Mn{sub 12-x} (R = Gd, Tb and Dy) compounds has been measured from 3 to 350 K. The substitution of Fe for Mn in RFe{sub x}Mn{sub 12-x} influences both the magnetic interactions on the 3d sublattice and the magnetism of R (the Neel temperature doubles on going from x = 0 to 6 and the compounds become ferromagnetic for x = 8 with Curie temperatures of around 300 K). In pure TbMn{sub 12} the heat-capacity data shows a {lambda}-type anomaly associated with the independent cooperative magnetic ordering of the R sublattice ({approx}5 K), while the anomaly related to the Mn magnetic ordering ({approx}100 K) is rather smooth, as observed in other itinerant magnetic systems such as YMn{sub 12}. In contrast, the substitution of Fe for Mn leads, on the one hand, to a more localized magnetic behaviour of the 3d sublattice, and, on the other, to magnetic polarization effects between the 3d and 4f sublattices, together with the disappearance of the cooperative magnetic ordering of the R sublattice due to the breaking of the antiferromagnetic symmetry in the 3d sublattice. This is reflected in the heat-capacity curve through a smooth Schottky-like anomaly. In the case of Gd compounds the magnitude of the exchange molecular-field parameter has been deduced by fitting the magnetic contribution to the heat capacity within a simple mean-field model. From this analysis we found that this molecular field acting on the rare-earth site increases with the iron concentration, reaching values as large as 48 T for the concentration x = 6. A similar analysis of the heat capacity in the ordered phase on the Tb compounds also leads to an enhancement of the molecular field with increasing Fe content. These results allow checking the possible crystal-field parameters for these RFe{sub x}Mn{sub 12-x} compounds.

Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores

NARCIS (Netherlands)

Malkin, B. Z.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Dhalenne, G.; Zakirov, A. R.

2010-01-01

The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R2Ti2O7 (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the

Structural and electronic properties of Er-monopnictides under high pressure

International Nuclear Information System (INIS)

Pandit, Premlata; Srivastava, Vipul; Rajagopalan, M.; Sanyal, Sankar P.

2010-01-01

We present the results of theoretical calculations on the structural, magnetic and electronic properties of Er-monopnictides using self-consistent first principles tight-binding linear-muffin-tin-orbital (TB-LMTO) method within the atomic-sphere approximation (ASA). Both spin-polarized and non-spin-polarized calculations are performed to check the magnetic stability of these compounds. We find that ErN, ErP and ErAs are metallic in ferromagnetic (FM) phase in both the spin channels and stable in NaCl-type (B 1 ) structure at ambient pressure. We predict NaCl-type (B 1 ) to CsCl-type (B 2 ) structural phase transition in ErN, ErP and ErAs at pressures of 146.1, 60.2 and 53.2 GPa, respectively and remain metallic ferromagnetic at high pressure. We calculate equilibrium lattice constants (a), bulk modulus (B), magnetic moments (μ B ) and electronic properties of these compounds in B 1 and B 2 phases and compare with available experimental and theoretical results.

Ion chromatography separation of lanthanides at trace concentrations from Gd Matrix and quantification by ICP-MS

International Nuclear Information System (INIS)

Raut, V.V.; Jeyakumar, S.; Nagar, B.K.; Deb, S.B.; Saxena, M.K.; Tomar, B.S.

2014-01-01

Gadolinium compounds are mainly used as burnable poison. The presence of certain impurities is undesirable in the nuclear grade Gd compounds. Gd 2 O 3 , a most common raw material used for the preparation of nuclear grade Gd compounds. Analysis of rare earth impurities in Gd-matrices is one of the important exercises carried out to ensure the purity of Gd 2 O 3 . Determination of lanthanides at trace concentrations in lanthanide (Gd) matrix is complicated and difficult to realize. This is because the selective separation of REE's in one of the lanthanide elements is a challenging task. The present study was carried out to explore the feasibility of separating trace level lanthanides from Gd matrix by ion interaction chromatography (IIC) and to develop an analytical methodology for the determination of lanthanides by inductively coupled plasma mass spectrometry (ICP-MS). In the present investigation, the reversed phase column was dynamically modified into sulphonic acid functionalized surface by using 0.025 M n-Octane sulphonic acid (OSA). With α-HIBA eluent system, the elution order follows as Lu to La. The separations are employed with gradient elution mode. Since the sample has large excess of Gd, elution profiles with concentration gradient of HIBA were attempted. Separated fractions of Light lanthanides (LLn) and Heavy lanthanides (HLn) were collected and analyzed by ICP-MS. During MS analysis, it was observed that due to high concentration of salt (Na salt of OSA) present in the collected fractions caused difficulty in ICP-MS . Hence the experiments were carried out using another ion interacting reagent viz. 0.03 M camphor-10-sulphonic acid (CSA). Initial concentration of HIBA was kept at 0.025 M up to 15 min for the elution of HLns i.e. from Lu to Tb and it was then increased to 0.05 M to 0.3 M in 30 min. After elution of Tb, outlet of the column was switched to drain for 7 min to separate bulk Gd fraction. From 22 to 35 min effluent fraction containing Eu

Synthesis, characterization and magnetic properties of novel μ-oxamido heterodinuclear copper(II) - lanthanide(III) complexes

International Nuclear Information System (INIS)

Li, Y.T.; Miao, M.M.; Liao, D.Z.; Jiang, Z.H.; Wang, G.L.

1995-01-01

Six novel μ-oxamido heterobinuclear complexes have been prepared and identified as Cu(oxpn)Ln(L) 2 (ClO 4 ) 3 , where oxpn denotes the N, N'-bis(3-aminopropyl)oxamido dianion, L, 1,10-phenanthroline (phen) and Ln stands for La, Nd, Gd, Tb, Ho, Er. The complexes Cu(oxpn)Gd(oxpn)Gd(phen) 2 (ClO 4 ) 3 were characterized with variable temperature magnetic susceptibility (4-300 K). The exchange integral J (Cu-Gd) was found to be 2.03 cm -1 . The result is commensurate with ferromagnetic interaction between the adjacent metal ions. One plausible mechanism that can cause a ferromagnetic coupling between Gd(III) and Cu(II) is also discussed in terms of spin polarized. (author). 32 refs, 3 figs, 3 tabs

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.

Completing the series. New coordination networks of composition {sup 3}{sub ∞}[RE{sub 2}(ADC){sub 3}(H{sub 2}O){sub 6}].2H{sub 2}O with RE = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Y and ADC{sup 2-} = acetylenedicarboxylate ({sup -}O{sub 2}C-C≡C-CO{sub 2}{sup -})

Energy Technology Data Exchange (ETDEWEB)

Gramm, Verena K.; Schuy, Andrea; Ruschewitz, Uwe [Institut fuer Anorganische Chemie, Koeln Univ. (Germany); Suta, Markus; Wickleder, Claudia [Anorganische Chemie, Universitaet Siegen (Germany); Sternemann, Christian [Fakultaet Physik / DELTA, Technische Universitaet Dortmund (Germany)

2018-02-01

The crystal structures of {sup 3}{sub ∞}[RE{sub 2}(ADC){sub 3}(H{sub 2}O){sub 6}].2H{sub 2}O (RE = Pr, Nd, Sm, Eu, Tb, Dy) were solved and refined from X-ray single crystal data. They crystallize in a structure type already known for RE = La, Ce and Gd (P1, no. 2, Z = 2), which is characterized by REO{sub 9} polyhedra forming dimeric units being the nodes of a 3D framework structure linked by ADC{sup 2-} anions ({sup -}O{sub 2}C-C≡C-CO{sub 2}{sup -} = acetylenedicarboxylate). From synchrotron powder diffraction data it was shown that isostructural coordination networks are formed for RE = Ho, Er, Y, whereas for RE = Tm, Yb, Lu a new structure type crystallizing in a highly complex crystal structure with a large orthorhombic unit cell is found. All compounds are obtained by slow evaporation of an aqueous solution containing RE(OAc){sub 3}.xH{sub 2}O and acetylenedicarboxylic acid (H{sub 2}ADC). The coordination networks of composition {sup 3}{sub ∞}[RE{sub 2}(ADC){sub 3}(H{sub 2}O){sub 6}].2H{sub 2}O were thoroughly investigated by thermal analysis and for RE = Eu, Tb, a strong red and green photoluminescence was observed and investigated by means of UV/Vis spectroscopy. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

First principle studies of electronic and magnetic properties of Lanthanide-Gold (RAu) binary intermetallics

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Sardar [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Department of Chemistry, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Ahmad, Rashid, E-mail: rashmad@gmail.com [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Department of Chemistry, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Jalali-Asadabadi, S. [Department of Physics, Faculty of Sciences, University of Isfahan (UI), Hezar Gerib Avenue, Isfahan 81746-73441 (Iran, Islamic Republic of); Ali, Zahid [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Department of Physics, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Ahmad, Iftikhar [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Vice Chancellor, Abbott Abad University of Science and Technology, Abbott Abad (Pakistan)

2017-01-15

In this article we explore the electronic and magnetic properties of RAu intermetallics (R=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) for the first time. These properties are calculated by using GGA, GGA+U and hybrid density functional theory (HF) approaches. Our calculations show that HF provides superior results, consistent to the experimentally reported data. The chemical bonding between rare-earth and gold atoms within these compounds are explained on the basis of spin dependent electronic clouds in different planes, which shows predominantly ionic and metallic nature between Au and R atoms. The Cohesive energies of RAu compounds show direct relation with the melting points. Spin-dependent electronic band structure demonstrates that all these compounds are metallic in nature. The magnetic studies show that HoAu and LuAu are stable in non-magnetic structure, PrAu is stable in ferromagnetic phase and CeAu, NdAu, SmAu, GdAu, TbAu, DyAu, ErAu, TmAu, YbAu are anti-ferromagnetic materials.

Preparation and characterization of electroluminescent devices based on complexes of β-diketonates of Tb3+, Eu3+, Gd3+ ions with macrocyclic ligands and UO22+ films

International Nuclear Information System (INIS)

Gibelli, Edison Bessa

2010-01-01

Complexes containing Rare Earth ions are of great interest in the manufacture of electro luminescent devices as organic light emitting devices (OLED). These devices, using rare earth trivalent ions (TR 3+ ) as emitting centers, show high luminescence with extremely fine spectral bands due to the structure of their energy levels, long life time and high quantum efficiency. This work reports the preparation of Rare Earth β-diketonate complexes (Tb 3+ , Eu 3+ and Gd 3+ ) and (tta - thenoyltrifluoroacetonate and acac - acetylacetonate) containing a ligand macrocyclic crown ether (DB18C6 - dibenzo18coroa6) and polymer films of UO 2 2+ . The materials were characterized by complexometric titration with EDTA, CH elemental analysis, near infrared absorption spectroscopy, thermal analysis, X-ray diffraction (powder method) and luminescence spectroscopy. For manufacturing the OLED it was used the technique of deposition of thin films by physical vapor (PVD, Physical Vapor Deposition). (author)

Production, characterization and application of Gd{sub 2}O{sub 3} and Er{sub 2}O{sub 3} nanoparticles as radiosensitizers in radiotherapy beams; Produção, caracterização e aplicação de nanopartículas de Gd{sub 2}O{sub 3} e Er{sub 2}O{sub 3} como radiossensibilizadores em feixes de radioterapia

Energy Technology Data Exchange (ETDEWEB)

Corrêa, Eduardo de Lima

2017-07-01

In this study Gd{sub 2}O{sub 3} and Er{sub 2}O{sub 3} nanoparticles were produced for application as radiosensitizers in radiotherapy beams. They were synthesized at the Hyperfine Interactions Laboratory, IPEN, using thermal decomposition method and characterized by X-ray diffraction, to verify crystalline structure, transmission electron microscopy, to obtain information about shape, size and size distribution, neutron activation analysis, whereby it was possible to determine samples purity and gadolinium and erbium concentration. Magnetization and perturbed γ-γ angular correlation (PAC) measurements were performed in order to study particles magnetic behavior and quadrupole interactions, respectively. Characterization results showed a bixbyite structure, 5 nm diameter post-synthesis particles with narrow size distribution. Rare-earth mass determination in each sample was important to perform normalization in magnetic susceptibility measurements, making possible the view of a high magnetization under 30 K for post-synthesis samples, what was not observed in larger particles, together with an effective magnetic moment enhancement for nanoparticles, not seen in bulk samples, and a change in the antiferromagnetic ordering temperature for Er{sub 2}O{sub 3}. PAC spectroscopy results show possible surface effects. The absence of a well-defined frequency in 5 nm samples indicates the amount of {sup 111}In({sup 111}Cd) at particle surface is bigger than in the core, resulting in a non-evident hyperfine interaction between the probe nuclei and the host. The X-ray diffraction and PAC spectroscopy joint was vital to understand the particles structural damage caused by {sup 60}Co irradiation. About radiosensitizer measurements a dose enhancement factor (DEF) of up to 1,67 and 1,09 for Gd{sub 2}O{sub 3} nanoparticles under {sup 60}Co and 6MV irradiation, respectively, were observed. Under same conditions DEF values of up to 1,37 and 1,06 were found for Er{sub 2}O{sub 3

Magnetic resonance imaging of the pancreas in streptozotocin-induced diabetic rats: Gadofluorine P and Gd-DOTA.

Science.gov (United States)

Cho, Hye Rim; Lee, Youkyung; Doble, Philip; Bishop, David; Hare, Dominic; Kim, Young-Jae; Kim, Kwang Gi; Jung, Hye Seung; Park, Kyong Soo; Choi, Seung Hong; Moon, Woo Kyung

2015-05-21

To investigate the performance of Gadofluorine P-enhanced magnetic resonance imaging (MRI) on the diagnosis of diabetes in a streptozotocin (STZ) -induced diabetic rat model. Fischer 344 rats were treated with STZ. Rats not treated with STZ served as controls. T1-weighted MRI was performed using a 3T scanner before and after the injection of Gd-DOTA or Gadofluorine P (6 diabetic rats, 5 controls). The normalized signal intensity (SI) and the enhancement ratio (ER) of the pancreas were measured at each time point, and the values were compared between the normal and diabetic rats using the Mann-Whitney test. In addition, the values were correlated with the mean islet number. Optimal cut-off values were calculated using a positive test based on receiver operating characteristics. Intrapancreatic Gd concentration after the injection of each contrast media was measured using laser ablation-inductively coupled plasma-mass spectrometry in a separate set of rats (4 diabetic rats, 4 controls for Gadofluorine P; 2, 2 for Gd-DOTA). The normalized SI and ER of the pancreas using Gd-DOTA were not significantly different between diabetic rats and controls. With Gadofluorine P, the values were significantly higher in the diabetic rats than in the control rats 30 min after injection (P DOTA (0.967 vs 0.667, P = 0.085). An increase in normalized SI 30 min after Gadofluorine P was correlated with a decrease in the mean number of islets (r (2) = 0.510, P = 0.014). Intra-pancreatic Gd was higher in rats with Gadofluorine P injection than Gd-DOTA injection (Gadofluorine P vs Gd-DOTA, 7.37 vs 0.00, P < 0.01). A significant difference in the concentration of intrapancreatic Gd was observed between the control and diabetic animals that were sacrificed 30 min after Gadofluorine P injection (control vs diabetic, 3.25 ng/g vs 10.55 ng/g, P < 0.05) CONCLUSION: In this STZ-induced diabetes rat model, Gadofluorine P-enhanced MRI of the pancreas showed high accuracy in the diagnosis of diabetes.

Synthesis of Halide- and Solvent free metal borohydrides

DEFF Research Database (Denmark)

Grinderslev, Jakob; Møller, Kasper Trans; Jensen, Torben René

chloride or LiBH4 is present in the sample. The synthesis pathway has been shown to work for most of the already known metal borohydrides, M = Na, Ca, Sr, Ba, Y, La, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb, but also new borohydrides are formed, M = Pr, Nd and Lu. Besides new compounds, new polymorphs...

Ultraviolet photoluminescence in Gd-doped silica and phosphosilicate fibers

Directory of Open Access Journals (Sweden)

Y. Wang

2017-04-01

Full Text Available Optical fiber lasers operating in the near infrared and visible spectral regions have relied on the spectroscopic properties of rare earth ions such as Yb3+, Er3+, Tm3+, Nd3+, and Sm3+. Here, we investigate Gd3+ doping in phosphosilicate and pure silica fibers using solution doping and sol-gel techniques, respectively, for potential applications in the ultraviolet. Photoluminescence spectra for optical fiber bundles and fiber preforms were recorded and compared. Emissions at 312 nm (phosphosilicate and 314 nm (pure silica were observed when pumping to the Gd3+ 6DJ, 6IJ, and 6PJ = 5/2, 3/2 energy levels. Oxygen deficient center was observed in solution doping sample with a wide absorption band centered at around 248 nm not affecting pumping to 6IJ states.

Charge Carrier Trapping Processes in RE2O2S (RE = La, Gd, Y, and Lu)

NARCIS (Netherlands)

Luo, H.; Bos, A.J.J.; Dorenbos, P.

2017-01-01

Two different charge carrier trapping processes have been investigated in RE2O2S:Ln3+ (RE = La, Gd, Y, and Lu; Ln = Ce, Pr, and Tb) and RE2O2S:M (M = Ti4+ and Eu3+). Cerium, praseodymium and terbium act as recombination centers and hole trapping centers while host intrinsic defects provide the

Structural and electronic properties of Er-monopnictides under high pressure

Energy Technology Data Exchange (ETDEWEB)

Pandit, Premlata, E-mail: lataprem29@gmail.co [Department of Physics, Barkatullah University, Bhopal, Madhya Pradesh 462026 (India); Srivastava, Vipul [Department of Physics, Oriental Institute of Science and Technology, Thakral Nagar, Bhopal (India); Rajagopalan, M. [Crystal Growth Centre, Anna University, Chennai 600 025 (India); Sanyal, Sankar P. [Department of Physics, Barkatullah University, Bhopal, Madhya Pradesh 462026 (India)

2010-05-01

We present the results of theoretical calculations on the structural, magnetic and electronic properties of Er-monopnictides using self-consistent first principles tight-binding linear-muffin-tin-orbital (TB-LMTO) method within the atomic-sphere approximation (ASA). Both spin-polarized and non-spin-polarized calculations are performed to check the magnetic stability of these compounds. We find that ErN, ErP and ErAs are metallic in ferromagnetic (FM) phase in both the spin channels and stable in NaCl-type (B{sub 1}) structure at ambient pressure. We predict NaCl-type (B{sub 1}) to CsCl-type (B{sub 2}) structural phase transition in ErN, ErP and ErAs at pressures of 146.1, 60.2 and 53.2 GPa, respectively and remain metallic ferromagnetic at high pressure. We calculate equilibrium lattice constants (a), bulk modulus (B), magnetic moments (mu{sub B}) and electronic properties of these compounds in B{sub 1} and B{sub 2} phases and compare with available experimental and theoretical results.

Neutron scattering study on R2PdSi3 (R=Ho,Er,Tm) compounds

International Nuclear Information System (INIS)

Tang, Fei

2010-01-01

Previous studies on the family of inter-metallic rare-earth compounds R 2 PdSi 3 revealed multifaceted magnetic properties, for instance, spin-glass like behavior. Experimental observations include: Signs of a crystallographic superstructure, complicated magnetic structures both in zero field and in applied magnetic fields as well as a generic phase in applied fields for compounds in the series with the heavy rare-earths R=Gd, Tb, Dy, Ho, Er and Tm. This thesis expands the studies on the magnetic properties of R 2 PdSi 3 employing mainly neutron scattering on single crystals with the focus on the compounds with R=Ho, Er and Tm. A detailed analysis of the crystallographic superstructure using modulation wave approach and group theory is presented. The resulting structure implies the existence of two different rare-earth sites with reduced symmetry and an arrangement of the different sites according to sequences as determined by the superstructure. It is shown that the reduced symmetry of the rare-earth sites is explicitly observed in the energy spectra of inelastic neutron scattering. The results on the magnetic structures and excitations are shown and discussed in the framework of the superstructure model. Specifically the generic phase in applied fields is interpreted as a direct consequence of the crystallographic superstructure. It is rather unusual that a crystallographic superstructure is playing such a decisive, and through the field dependence also tunable role in determining the magnetic properties as observed in R 2 PdSi 3 . The mediating interactions between the crystallographic part and the magnetic part of the system are discussed. (orig.)

Preparation and spectral analysis of a new Tb3+-doped CaO-MgO-SiO2 glass ceramics

International Nuclear Information System (INIS)

Cheng Jinshu; Tian Peijing; Zheng Weihong; Xie Jun; Chen Zhenxia

2009-01-01

Tb 3+ -doped CaO-MgO-SiO 2 glass ceramics have been prepared and characterized. The structure and optical properties of the glass ceramics were studied by XRD, SEM, Raman, and fluorescence spectra. The precipitated crystalline phase in the glass ceramics was columnar CaMgSi 2 O 6 . Raman spectra showed the introduction of rare earth nearly had no influence on the sample structure. Fluorescence measurements showed that Tb 3+ ions entered into the diopside crystalline phase and induced a much stronger emission in the glass ceramics than that in the corresponding glass. With increase of Tb 3+ content and the introduction of Gd 3+ , the fluorescence intensity of the luminescent glass ceramic increased

Effect of terbium substitution on the magnetocaloric properties of Gd3Ga5O12

International Nuclear Information System (INIS)

Reshmi, C.P.; Savitha Pillai, S.; Varma, Manoj Raama; Suresh, K.G.

2011-01-01

The magnetic refrigeration is an environment friendly cooling technology based on magnetocaloric effect. The most crucial ingredient behind a magnetic refrigerator is a magnetic material which possesses large magnetocaloric effect. Certain materials when placed in a magnetic field suddenly get heats up and suddenly cooled down by the application and the removal of magnetic field due to their change in entropy. This is measured either in terms of isothermal entropy change and adiabatic temperature change observed when the applied magnetic field is varied. The refrigerators which operate below 15K have applications in liquefying helium and for the development of space based cooling system for the space crafts. The material of choice in this temperature range is rare earth gallium garnets. Rare earth garnets are complex ceramic oxides having the chemical formula A 3 B 2 C 3 O 12 have attracted attention due to their interesting magnetic properties. The magnetism in R 3 Ga 5 O 12 is due to the exchange interaction between the rare earth spins. In the proposed work we have chosen Gd 3 Ga 5 O 12 as parent material, substituted Tb systematically in the place of Gd. The structural studies were done by using Rietveld analysis of X-Ray diffraction. There is a systematic variation of volume and lattice parameter upon substitution of Tb. The magnetic characterizations were done by a vibrating sample magnetometer. The experimental magnetic moments of the materials were calculated from the M-T curve by using Curie-Weiss fit and are good agreement with the theoretical values. There is a systematic increase of magnetic moments by Tb substitution. The magnetocaloric effect is calculated by using the integrated Maxwell's relation from the magnetization data. At low magnetic fields the Tb substituted compounds show good MCE values than GGG. Tb substitution enhances the magnetocaloric effect at low magnetic fields and the ΔS M values are higher for x = 1 and 3 at 1T. Hence these

Treatment: Latent TB Infection (LTBI) and TB Disease

Science.gov (United States)

... Adverse Events TB Treatment of Persons Living with HIV TB Treatment and Pregnancy TB Treatment for Children Drug-Resistant TB Research TB Epidemiologic Studies Consortium Research Projects Publications TB Trials Consortium Study ...

Seed-mediated synthesis of NaY F4:Y b, Er/NaGdF4 nanocrystals with improved upconversion fluorescence and MR relaxivity

International Nuclear Information System (INIS)

Guo Hai; Li Zhengquan; Qian Haisheng; Hu Yong; Muhammad, Idris Niagara

2010-01-01

Rational combination of different functional lanthanide materials within a single nanocrystal presents a feasible way to develop a multifunctional nanoplatform for various biomedical applications. The conventional methods of synthesizing and integrating two kinds of material together generally involve laborious procedures, whilst codoping different functional ions inside a single lanthanide nanocrystal usually results in a decrease in both its fluorescence and its magnetic resonance relaxivity. Here, we present a seed-mediated synthetic route to prepare core-shell structured NaY F 4 :Y b, Er/NaGdF 4 nanocrystals. Epitaxial growth of a gadolinium layer on an upconversion lanthanide seed not only improves its upconversion fluorescence, but also creates a paramagnetic shell with high magnetic resonance relaxivity. The prepared nanocrystals are uniform in size, stable in water and easy for conjugation after modification, which may have the potential to serve as a versatile imaging tool for smart detection or diagnosis in future biomedical engineering.

Rhodium-rich silicides RERh{sub 6}Si{sub 4} (RE=La, Nd, Tb, Dy, Er, Yb)

Energy Technology Data Exchange (ETDEWEB)

Vosswinkel, Daniel; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

2017-07-01

Polycrystalline RERh{sub 6}Si{sub 4} (RE=La, Nd, Tb, Dy, Er, Yb) samples can be synthesized by arc-melting of the elements. Single crystals of LaRh{sub 6}Si{sub 4}, NdRh{sub 6}Si{sub 4} and YbRh{sub 6}Si{sub 4} were synthesized from the elements in bismuth fluxes (non-reactive flux medium). The structures were refined on the basis of single-crystal X-ray diffractometer data: LiCo{sub 6}P{sub 4} type, P anti 6m2, a=700.56(3), c=380.55(1) pm, wR2=0.0257, 317 F{sup 2} values, 19 variables for LaRh{sub 6}Si{sub 4}, a=698.4(5), c=377.7(2) pm, wR2=0.0578, 219 F{sup 2} values, 19 variables for NdRh{sub 6}Si{sub 4} and a=696.00(3), c=371.97(1) pm, wR2=0.0440, 309 F{sup 2} values, 19 variables for YbRh{sub 6}Si{sub 4}. The rhodium and silicon atoms build up three-dimensional, covalently bonded [Rh{sub 6}Si{sub 4}]{sup δ-} polyanionic networks with Rh-Si distances ranging from 239 to 249 pm. The rare earth atoms fill larger cavities within channels of these networks and they are coordinated by six silicon and twelve rhodium atoms in the form of hexa-capped hexagonal prisms.

Core/shell structured NaYF4:Yb3+/Er3+/Gd+3 nanorods with Au nanoparticles or shells for flexible amorphous silicon solar cells

International Nuclear Information System (INIS)

Li, Z Q; Li, X D; Liu, Q Q; Chen, X H; Sun, Z; Huang, S M; Liu, C; Ye, X J

2012-01-01

A simple approach for preparing near-infrared (NIR) to visible upconversion (UC) NaYF 4 :Yb/Er/Gd nanorods in combination with gold nanostructures has been reported. The grown UC nanomaterials with Au nanostructures have been applied to flexible amorphous silicon solar cells on the steel substrates to investigate their responses to sub-bandgap infrared irradiation. Photocurrent–voltage measurements were performed on the solar cells. It was demonstrated that UC of NIR light led to a 16-fold to 72-fold improvement of the short-circuit current under 980 nm illumination compared to a cell without upconverters. A maximum current of 1.16 mA was obtained for the cell using UC nanorods coated with Au nanoparticles under 980 nm laser illumination. This result corresponds to an external quantum efficiency of 0.14% of the solar cell. Mechanisms of erbium luminescence in the grown UC nanorods were analyzed and discussed. (paper)

Electronic and Ionic Transport in Ce0.8PrxTb0.2−xO2−δ and Evaluation of Performance as Oxygen Permeation Membranes

DEFF Research Database (Denmark)

Chatzichristodoulou, Christodoulos; Hendriksen, Peter Vang

2012-01-01

to that of Ce0.9Gd0.1O1.95−δ, and was found to increase with increasing Pr/Tb ratio. The oxide ion mobility in Ce0.8PrxTb0.2−xO2−δ is similar to that in Ce1−2δGd2δO2−δ at the same oxygen vacancy concentration. Based on the measured ionic and electronic conductivities, fluxes through thin film Ce0.8PrxTb0.2−xO2......The electronic conductivity of Ce0.8PrxTb0.2−xO2−δ (x = 0, 0.05, 0.10, 0.15, 0.20) was determined in the oxygen activity range aO2 ≈ 103 – 10−17 at 700–900°C by Hebb-Wagner polarization. The electronic conductivity of all the Ce0.8PrxTb0.2−xO2−δ compositions was significantly enhanced as compared......−δ membranes were calculated. Calculated fluxes exceed 10 Nml min−1 cm−2 under oxyfuel relevant conditions (T = 800°C, aO2,permeate side = 10−3). Hence, in terms of transport properties, these materials are promising for this application. Interference between the ionic and electronic flows has...

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

The rare earth elements like La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the heavy metals like Mg, V, Cr, Mn, Fe, Cu, Zn, U, Th were analysed by using standard analytical methods. The Post-Archean Australian Shale composition was used to normalise the rare earth elements. It was found that the sediments ...

Oxygen stabilized rare-earth iron intermetallic compounds

International Nuclear Information System (INIS)

Dariel, M.P.; Malekzadeh, M.; Pickus, M.R.

1975-10-01

A new, oxygen-stabilized intermetallic compound was identified in sintered, pre-alloyed rare-earth iron powder samples. Its composition corresponds to formula R 12 Fe 32 O 2 and its crystal structure belongs to space group Im3m. The presence of these compounds was observed, so far, in several R--Fe--O systems, with R = Gd, Tb, Dy, Ho, Er, and Y

Co-operative energy transfer in Yb3+-Er3+ co-doped SrGdxOy upconverting phosphor

Science.gov (United States)

Kumar, Ashwini; Pathak, Trilok K.; Dhoble, S. J.; . Terblans, J. J.; Swart, H. C.

2018-04-01

Upconversion nanoparticles (UCNPs) have shown considerable interest in many fields; however, low upconversion efficiency of UCNPs is still the most severe limitation of their applications. Yb3+ and Er3+ co-doped SrGd4O7/Gd2O3(SGO) upconversion (UC) phosphors were synthesized by a modified co-precipitation process. The UC properties were investigated by direct excitation with a 980 nm laser. It was observed that the as prepared materials showed relatively strong green emission, while upon the incorporation of the Er3+ ion, there was an increase in the upconversion luminescence intensity for the red component. The effect of different doping concentration of Er3+on the emission spectra and X-ray diffraction patterns of the UC materials have also been studied. The luminescence lifetimes and Commission Internationale de L'Eclairage coordinates for these as prepared samples were determined to understand the energy transfer (ET) mechanisms occurring between Yb3+ and Er3+ in the SGO host matrix. The UC luminescence intensity as a function of laser pump power was monitored and it was confirmed that the UC process in SGO:Yb3+/Er3+is a two-photon absorption process. The findings reported here are expected to provide a better approach for understanding of the ET mechanisms in the oxide based Yb3+/Er3+ co-doped UC phosphors. This study might be helpful in precisely defined applications where optical transitions are essential criterion and this can be easily achieved by smart tuning of the emission properties of Yb3+/Er3+ co-doped UC phosphors.

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

Digital health for the End TB Strategy: developing priority products and making them work.

Science.gov (United States)

Falzon, Dennis; Timimi, Hazim; Kurosinski, Pascal; Migliori, Giovanni Battista; Van Gemert, Wayne; Denkinger, Claudia; Isaacs, Chris; Story, Alistair; Garfein, Richard S; do Valle Bastos, Luis Gustavo; Yassin, Mohammed A; Rusovich, Valiantsin; Skrahina, Alena; Van Hoi, Le; Broger, Tobias; Abubakar, Ibrahim; Hayward, Andrew; Thomas, Bruce V; Temesgen, Zelalem; Quraishi, Subhi; von Delft, Dalene; Jaramillo, Ernesto; Weyer, Karin; Raviglione, Mario C

2016-07-01

In 2014, the World Health Organization (WHO) developed the End TB Strategy in response to a World Health Assembly Resolution requesting Member States to end the worldwide epidemic of tuberculosis (TB) by 2035. For the strategy's objectives to be realised, the next 20 years will need novel solutions to address the challenges posed by TB to health professionals, and to affected people and communities. Information and communication technology presents opportunities for innovative approaches to support TB efforts in patient care, surveillance, programme management and electronic learning. The effective application of digital health products at a large scale and their continued development need the engagement of TB patients and their caregivers, innovators, funders, policy-makers, advocacy groups, and affected communities.In April 2015, WHO established its Global Task Force on Digital Health for TB to advocate and support the development of digital health innovations in global efforts to improve TB care and prevention. We outline the group's approach to stewarding this process in alignment with the three pillars of the End TB Strategy. The supplementary material of this article includes target product profiles, as developed by early 2016, defining nine priority digital health concepts and products that are strategically positioned to enhance TB action at the country level. The content of this work is ©the authors or their employers. Design and branding are ©ERS 2016.

The ternary rare earth ruthenium gallides R3Ru4Ga15 (R=Y, Tb-Er) with a new structure type, a further example of a recently recognized large family of structures

International Nuclear Information System (INIS)

Schlueter, Martin; Jeitschko, Wolfgang

2003-01-01

The title compounds were prepared by reaction of the elemental components at high temperature. They crystallize with a new orthorhombic structure type which was determined from single-crystal diffractometer data of Ho 3 Ru 4 Ga 15 : Pnma, a=871.7(1) pm, b=956.4(1) pm, c=1765.9(3) pm, Z=4, R=0.040 for 1039 structure factors and 114 variable parameters. The structure may be viewed as consisting of two kinds of atomic layers, although atomic bonding within and between the layers is comparable strength, as can be judged from the near-neighbor environments, where all of the 15 atomic sites have high coordination numbers. One kind of atomic layers (A) contains all of the holmium and additional gallium atoms in the ratio Ho:Ga=3:5 with a unit mesh content of 2Ho 3 Ga 5 ; these layers are flat. The other layers (B) consist of sheets of corner- and edge-sharing condensed RuGa 6 octahedra, which are extremely compressed resulting in a hexagonal close-packed, puckered net with a Ru:Ga ratio of 2:5 and a unit mesh content of 4Ru 2 Ga 5 . These nets alternate in the sequence ABAB, ABAB, thus yielding the formula 4Ho 3 Ga 5 ·8Ru 2 Ga 5 =4Ho 3 Ru 4 Ga 15 . Similar layers are observed in the structures of Y 2 Co 3 Ga 9 , Gd 3 Ru 4 Al 12 , Er 4 Pt 9 Al 24 , CeOsGa 4 , CaCr 2 Al 10 , and the four stacking variants with the compositions TbRe 2 Al 10 , DyRe 2 Al 10 , YbFe 2 Al 10 , and LuRe 2 Al 10

The Gd14Ag51 structure type and its relation to some complex amalgam structures

International Nuclear Information System (INIS)

Tambornino, Frank; Sappl, Jonathan; Hoch, Constantin

2015-01-01

Highlights: • The Gd 14 Ag 51 structure type has been revisited on the basis of single crystal diffraction data. • Symmetry analysis from electron density and TEM shows the space group P6/m to be true. • Gd 14 Ag 51 shows good metallic behaviour. • Structure relations to alkali, alkaline-earth and rare-earth metal amalgams can be established. • Complexity values for the RE 14 Ag 51 structure family were calculated. - Abstract: A plethora of binary and ternary intermetallic compounds has been assigned to the Gd 14 Ag 51 structure type, crystallising in the hexagonal system (space group P6/m, a = 1264.30(18) pm, c = 933.58(11) pm for Gd 14 Ag 51 ). Starting in the late 1960s, much work has been invested in the structural elucidation of these crystal structures. However, reliable single crystal data are scarce, and most structure type assignments have been performed merely on the basis of powder data. We have redetermined four representatives of the binary RE 14 Ag 51 structure type (RE = Y, Ce, Gd, Tb) with modern high-precision single crystal X-ray methods. The assignment of the Gd 14 Ag 51 structure type to space group P6/m was additionally verified by careful analysis of high resolution transmission electron micrographs. We emphasise the close relation of the Gd 14 Ag 51 structure type to the structures of some recently described amalgams of similar composition focussing on disorder phenomena and structural complexity. Furthermore, we provide detailed information on synthesis as well as electrical and magnetic properties for Gd 14 Ag 51 , the parent compound of this structure family

Ternary silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and quaternary derivatives RERh{sub 4}Si{sub 2-x}Sn{sub x} (RE = Y, Nd, Sm, Gd-Lu) - structure, chemical bonding, and solid state NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Vosswinkel, Daniel; Benndorf, Christopher; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics; Matar, Samir F. [Bordeaux Univ., CNRS, ICMCB, UPR 9048, Pessac (France)

2016-11-01

The silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and silicide stannides RERh{sub 4}Si{sub 2-x}Sn{sub x}(RE = Y, Nd, Sm, Gd-Lu) were synthesized from the elements by arc-melting and subsequent annealing. The new compounds crystallize with the orthorhombic YRh{sub 4}Ge{sub 2} type structure, space group Pnma. They were characterized by X-ray powder patterns and several structures were refined from single crystal X-ray diffractometer data. The main structural motifs of this series of silicides are tricapped trigonal prisms formed by the transition metal and rare earth atoms. One of the two crystallographically independent silicon sites allows for formation of solid solutions with tin, exemplarily studied for ErRh{sub 4}Si{sub 2-x}Sn{sub x}. Electronic structure calculations reveal strong covalent Rh-Si bonding as the main stability factor. Multinuclear ({sup 29}Si, {sup 45}Sc, and {sup 89}Y) magic-angle spinning (MAS) NMR spectra of the structure representatives with diamagnetic rare-earth elements (Sc, Y, Lu) are found to be consistent with the crystallographic data and specifically confirm the selective substitution of Sn in the Si2 sites in the quaternary compounds YRh{sub 4}SiSn and LuRh{sub 4}SiSn.

Syntheses of rare-earth metal oxide nanotubes by the sol-gel method assisted with porous anodic aluminum oxide templates

International Nuclear Information System (INIS)

Kuang Qin; Lin Zhiwei; Lian Wei; Jiang Zhiyuan; Xie Zhaoxiong; Huang Rongbin; Zheng Lansun

2007-01-01

In this paper, we report a versatile synthetic method of ordered rare-earth metal (RE) oxide nanotubes. RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction (XRD) have been employed to characterize the morphology and composition of the as-prepared nanotubes. It is found that as-prepared RE oxides evolve into bamboo-like nanotubes and entirely hollow nanotubes. A new possible formation mechanism of RE oxide nanotubes in the AAO channels is proposed. These high-quantity RE oxide nanotubes are expected to have promising applications in many areas such as luminescent materials, catalysts, magnets, etc. - Graphical abstract: A versatile synthetic method for the preparation of ordered rare-earth (RE) oxide nanotubes is reported, by which RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates

Luminescent properties of Tb doped gadolinium aluminate nanophosphors for display and forensic applications

Directory of Open Access Journals (Sweden)

P.K. Jisha

2017-12-01

Full Text Available A novel green light emitting GdAlO3:Tb3+ (1–11 mol% nanophosphor has been synthesized by the solution combustion method and the final products were characterized. The energy band gap of the samples was estimated in the range of 5.13–5.88 eV from diffuse reflectance spectra. The effect of the added Tb3+ ions on the electronic structure was considered based on the absolute electronegativity. The characteristic photoluminescence emission corresponding to the transition 5D4→7Fj (j = 6, 5, 4, 3 of the Tb3+ ions was observed in the wavelength range of 500–650 nm, and assigned due to the f–f transitions upon the 378 nm excitation. The optimized nanophosphor was found suitable for applications in the latent fingerprint detection. The photometric characterization has revealed the excellent color chromaticity coordinates and the correlated color temperature levels. They are on the same level of commercial phosphors and quite useful for green WLEDs, solid state displays and forensic applications as well.

Tuberculosis care among refugees arriving in Europe: a ERS/WHO Europe Region survey of current practices.

Science.gov (United States)

Dara, Masoud; Solovic, Ivan; Sotgiu, Giovanni; D'Ambrosio, Lia; Centis, Rosella; Tran, Richard; Goletti, Delia; Duarte, Raquel; Aliberti, Stefano; de Benedictis, Fernando Maria; Bothamley, Graham; Schaberg, Tom; Abubakar, Ibrahim; Teixeira, Vitor; Ward, Brian; Gratziou, Christina; Migliori, Giovanni Battista

2016-09-01

No evidence exists on tuberculosis (TB) and latent TB infection (LTBI) management policies among refugees in European countries.A questionnaire investigating screening and management practices among refugees was sent to 38 national TB programme representatives of low and intermediate TB incidence European countries/territories of the WHO European Region.Out of 36 responding countries, 31 (86.1%) reported screening for active TB, 19 for LTBI, and eight (22.2%) reporting outcomes of LTBI treatment. Screening for TB is based on algorithms including different combinations of symptom-based questionnaires, bacteriology and chest radiography and LTBI screening on different combinations of tuberculin skin test and interferon-γ release assays. In 22 (61.1%) countries, TB and LTBI screening are performed in refugee centres. In 22 (61.1%) countries, TB services are organised in collaboration with the private sector. 27 (75%) countries answered that screening for TB is performed as per national and international guidelines, while 19 (52.7%) gave the same answer with regards to LTBI screening. Infection control measures are inadequate in several of the countries surveyed.There is need for improved coordination of TB screening in Europe to implement the End TB Strategy and achieve TB elimination. Copyright ©ERS 2016.

Implantation sites of Ce and Gd in diamond

CERN Document Server

Bharuth-Ram, K; Hofsäss, H C; Ronning, C; Dietrich, M

2002-01-01

The implantation sites of rare earth (RE) probes /sup 141/Ce (t/sub 1 /2/=32 d) and /sup 149/Gd (t/sub 1/2/=9.28 d) in diamond have been investigated using the emission channeling (EC) technique. Parent isotopes /sup 141/Cs and /sup 149/Dy were implanted into type IIa, diamond samples at an energy of 60 keV at the online isotope separator ISOLDE at CERN. /sup 141/Cs decays through the chain /sup 141/Cs-/sup 141/Ba-/sup 141/La-/sup 141/Ce-/sup 141/ Pr. EC measurements were made on the 102 keV conversion electrons emitted in the decay of /sup 141/Pr to its ground state. The decay of /sup 149 /Dy follows the chain /sup 149/Dy-/sup 149/Tb-/sup 149/Gd-/sup 149 /Eu-/sup 149/Sm. EC measurements were made on the 101 keV electrons emitted in the decay of /sup 149/Eu. Two-dimensional channeling patterns of the conversion electrons were obtained along and axial directions by raster scans with a Si surface barrier detector. Comparison of the observed patterns with simulated spectra show that in diamond 45-50% of the RE...

Powder Neutron Diffraction and Magnetic structures

International Nuclear Information System (INIS)

Vigneron, F.

1986-01-01

The determination of the magnetic structures of materials (ferromagnetic, antiferromagnetic, helimagnetic, .) can be achieved only by neutron diffraction. A general survey of the powder technique is given: 2-axis spectrometer and analysis of the magnetic data. For the REBe/sb13/ intermetallic compounds (RE = Rare Earth), commensurate and/or incommensurate magnetic structures are observed and discussed as a function of RE (Gd, Tb, Dy, Ho, Er)

Team approach to manage difficult-to-treat TB cases: Experiences in Europe and beyond

Directory of Open Access Journals (Sweden)

L. D’Ambrosio

2018-03-01

Full Text Available As recommended by the World Health Organization (WHO, optimal management of MDR-TB cases can be ensured by a multi-speciality consultation body known as ‘TB Consilium’. This body usually includes different medical specialities, competences and perspectives (e.g., clinical expertise both for adults and children; surgical, radiological and public health expertise; psychological background and nursing experience, among others, thus lowering the risk of making mistakes – or managing the patients inappropriately, in order to improve their clinical outcomes.At present, several high MDR-TB burden countries in the different WHO regions (and beyond have introduced TB Consilium-like bodies at the national or subnational level to reach consensus on the best treatment approach for their patients affected by TB.In addition, in countries/settings where a formal system of consultation does not exist, specialized staff from MDR-TB reference centres or international organizations usually spend a considerable amount of their working time responding to phone or e-mail clinical queries on how to manage M/XDR-TB cases.The aim of this manuscript is to describe the different experiences with the TB Consilia both at the international level (European Respiratory Society – ERS/WHO TB Consilium and in some of the countries where this experience operates successfully in Europe and beyond. The Consilium experiences are described around the following topics: (1 history, aims and focus; (2 management and funding; (3 technical functioning and structure; (4 results achieved.In addition a comparative analysis of the TB Consilia in the different countries has been performed. Keywords: MDR-TB, XDR-TB, Clinical management, Drug resistance, Prevention, Consilium

Synchrotron topography of grow defects in GdCa4O(BO3)3

International Nuclear Information System (INIS)

Wierzbicka, E.; Lefeld-Sosnowska, M.; Wierzchowski, W.; Wieteska, K.; Graeff, W.

2005-01-01

Gadolinium calcium oxyborane (GdCOB) is a perspective material, especially in the optoelectronics. GdCOB exhibits excellent nonlinear optical parameters and can be easily doped with Nd 3+ , Yb 3+ or Er 3+ ions. To be applied in the optoelectronics it is necessary to obtain crystals with small number of defects, which cause unwanted tensions changing optical properties of the material. The aim of the work was analysis of the defects distribution in the GdCOB and finding its dependence on the crystal growing conditions. Crystals were grown in the Institute of Electronic Materials Technology (ITME) using Czochralski method. Analyses of the crystal quality are the first studies performed using the synchrotron beam reflection topography in the white beam, monochromatic and projecting transmission topography and the Lang reflections. It has been shown, that the main observed defects are the dislocations, which occur in all crystals of different density depending on the grown parameters [pl

Magnetic structures: neutron diffraction studies

International Nuclear Information System (INIS)

Bouree-Vigneron, F.

1990-01-01

Neutron diffraction is often an unequivocal method for determining magnetic structures. Here we present some typical examples, stressing the sequence through experiments, data analysis, interpretation and modelisation. Two series of compounds are chosen: Tb Ni 2 Ge 2 and RBe 13 (R = Gd, Tb, Dy, Ho, Er). Depending on the nature of the elements, the magnetic structures produced can be commensurate, incommensurate or even show a transition between two such phases as a function of temperature. A model, taking magnetic exchange and anisotropy into account, will be presented in the case of commensurate-incommensurate magnetic transitions in RBe 13

Energy transfer phenomena and Judd-Ofelt analysis on Sm{sup 3+} ions in K{sub 2}GdF{sub 5} crystal

Energy Technology Data Exchange (ETDEWEB)

Do, Phan Van [Thuyloi University, 175 Tay Son, Dong da Dist, Hanoi (Viet Nam); Tuyen, Vu Phi, E-mail: vptuyen@gust-edu.vast.vn [Graduate University of Science and Technology - VAST, 18 Hoang quoc Viet, Hanoi (Viet Nam); DuyTan University, K7/25 QuangTrung, Danang (Viet Nam); Quang, Vu Xuan [DuyTan University, K7/25 QuangTrung, Danang (Viet Nam); Khaidukov, Nicholas M. [Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation); TrongThanh, Nguyen [Institute of Materials Science - VAST, 18 Hoang quoc Viet, Hanoi (Viet Nam); Sengthong, Bounyavong [DuyTan University, K7/25 QuangTrung, Danang (Viet Nam); Huy, Bui The, E-mail: buithehuy.nt@gmail.com [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

2016-11-15

The Raman, absorption, luminescence spectra and lifetimes curves of Sm{sup 3+}-doped K{sub 2}GdF{sub 5}were measured. Based on the Judd-Ofelt analysis, the values of radiative transition probabilities, branching ratios, integrated emission cross-sections and radiative lifetimes of excited states of Sm{sup 3+} in K{sub 2}GdF{sub 5} crystal were calculated. The migration of excitation energy between the Gd{sup 3+} ions and the trapping processes of Gd{sup 3+} excitation energy by Sm{sup 3+} and Tb{sup 3+}ions in K{sub 2}GdF{sub 5} crystal are reported. The role of the overlapping between the broad, allowed absorption bands of the RE{sup 3+} ions and the narrow absorption lines {sup 6}I{sub J} and {sup 6}P{sub J} of Gd{sup 3+} ions on the trapping rates of the RE{sup 3+} was discussed. The energy transfer between the Sm{sup 3+} ions was studied by the decay measurement, which has been fitted by Inokuti-Hirayama energy transfer model and revealed that electric dipole–quadrupole interaction is responsible for the energy transfer process in Sm{sup 3+} ions doped K{sub 2}GdF{sub 5} crystal.

Gd-Ni-Si system

International Nuclear Information System (INIS)

Bodak, O.I.; Shvets, A.F.

1983-01-01

By X-ray phase analysis method isothermal cross section of phase diagram of the Gd-Ni-Si system at 870 K is studied. The existence of nine previously known compounds (GdNisub(6.72)Sisub(6.28), GdNi 10 Si 2 , GdNi 5 Si 3 , GdNi 4 Si, GdNi 2 Si 2 , GdNiSi 3 , GdNiSi 2 , Gd 3 Ni 6 Si 2 and GdNiSi) is confirmed and three new compounds (GdNisub(0.2)Sisub(1.8), Gdsub(2)Nisub(1-0.8)Sisub(1-1.2), Gd 5 NiSi 4 ) are found. On the base of Gd 2 Si 3 compound up to 0.15 at. Ni fractions, an interstitial solid solution is formed up to 0.25 at Ni fractions dissolution continues of substitution type. The Gd-Ni-Si system is similar to the Y-Ni-Si system

Aqueous phase synthesis of upconversion nanocrystals through layer-by-layer epitaxial growth for in vivo X-ray computed tomography

KAUST Repository

Li, Feifei

2013-05-21

Lanthanide-doped core-shell upconversion nanocrystals (UCNCs) have tremendous potential for applications in many fields, especially in bio-imaging and medical therapy. As core-shell UCNCs are mostly synthesized in organic solvents, tedious organic-aqueous phase transfer processes are usually needed for their use in bio-applications. Herein, we demonstrate the first example of one-step synthesis of highly luminescent core-shell UCNCs in the "aqueous" phase under mild conditions using innocuous reagents. A microwave-assisted approach allowed for layer-by-layer epitaxial growth of a hydrophilic NaGdF4 shell on NaYF4:Yb, Er cores. During this process, surface defects of the nanocrystals could be gradually passivated by the homogeneous shell deposition, resulting in obvious enhancement in the overall upconversion emission efficiency. In addition, the up-down conversion dual-mode luminescent NaYF4:Yb, Er@NaGdF4:Ce, Ln (Eu, Tb, Sm, Dy) nanocrystals were also synthesized to further validate the successful formation of the core-shell structure. More significantly, based on their superior solubility and stability in water solution, high upconversion efficiency and Gd-doped predominant X-ray absorption, the as-prepared NaYF4:Yb, Er@NaGdF4 core-shell UCNCs exhibited high contrast in in vitro cell imaging and in vivo X-ray computed tomography (CT) imaging, demonstrating great potential as multiplexed luminescent biolabels and CT contrast agents.

Preparation and characterization of electroluminescent devices based on complexes of {beta}-diketonates of Tb{sup 3+}, Eu{sup 3+}, Gd{sup 3+} ions with macrocyclic ligands and UO{sub 2}{sup 2+} films; Preparacao e caracterizacao de dispositivos eletroluminescentes de complexos de {beta}-dicetonados de ions Tb{sup 3+}, Eu{sup 3+}, Gd{sup 3+} com ligantes macrociclicos e filmes de UO{sub 2}{sup 2+}

Energy Technology Data Exchange (ETDEWEB)

Gibelli, Edison Bessa

2010-07-01

Complexes containing Rare Earth ions are of great interest in the manufacture of electro luminescent devices as organic light emitting devices (OLED). These devices, using rare earth trivalent ions (TR{sup 3+}) as emitting centers, show high luminescence with extremely fine spectral bands due to the structure of their energy levels, long life time and high quantum efficiency. This work reports the preparation of Rare Earth {beta}-diketonate complexes (Tb{sup 3+}, Eu{sup 3+} and Gd{sup 3+}) and (tta - thenoyltrifluoroacetonate and acac - acetylacetonate) containing a ligand macrocyclic crown ether (DB18C6 - dibenzo18coroa6) and polymer films of UO{sub 2}{sup 2+}. The materials were characterized by complexometric titration with EDTA, CH elemental analysis, near infrared absorption spectroscopy, thermal analysis, X-ray diffraction (powder method) and luminescence spectroscopy. For manufacturing the OLED it was used the technique of deposition of thin films by physical vapor (PVD, Physical Vapor Deposition). (author)

Propiedades estructurales y magnéticas de aleaciones Gd0.257 -xTbxFe0.743 obtenidas por aleamiento mecánico

Directory of Open Access Journals (Sweden)

Mauricio Galvis-Patiño

2017-01-01

Full Text Available En el presente trabajo se reporta el estudio de las propiedades estructurales y magnéticas de la composición en forma de polvo de Gd0.257-xTbxFe0.743 con x=0,  0.1285,  0.257,preparados por Aleamiento Mecánico (AM en atmosfera de argón durante 72 horas mediante un molino planetario de alta energía ;la caracterización estructural se realizó por medio de Difractometría de rayos X(DRX, para la caracterización magnética se utilizó la espectroscopía Mössbauer, los ciclos de histéresis se llevaron a cabo a través de  PPMS (Physical Property Measurement System, Sistema de Medidas de Propiedades Físicas. La fase de α-Fe se presenta en los tres difractogramas mediante un pico característico cuya  intensidad disminuye al reemplazar el Tb por el Gd, presentándose la menor en x= 0 así mismo se observa un aumento de su ancho atribuible a la presencia de átomos de Gd en lugares propios del Fe. Los espectros Mössbauer (EM fueron ajustados con sextetos, dobletes, singletes y distribuciones de campo hiperfino lo que señala que el orden magnético se ve alterado al sustituir el Tb por el Gd en la composición. Las propiedades magnéticas extrínsecas de la composición en estudio, la caracterizan como materiales magnéticamente semiduros.

Gd3+-ESR and magnetic susceptibility of GdCu4Al8 and GdMn4Al8

International Nuclear Information System (INIS)

Coldea, R.; Coldea, M.; Pop, I.

1994-01-01

Gd ESR of GdCu 4 Al 8 and GdMn 4 Al 8 and magnetic susceptibility of GdCu 4 Al 8 , GdMn 4 Al 8 , and YMn 4 Al 8 were measured in the temperature range of 290K--460K and 90K--1050K, respectively. The occurrence of the Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 is strongly correlated with the critical value of d∼2.6 angstrom of the Mn-Mn distance below which the Mn moment is not stable. The experimental data for GdMn 4 Al 8 , compared with the data for the isostructural compounds GdCu 4 Al 8 and YMn 4 Al 8 , show that near the critical value of d, the existence of Mn moment depends not only on the value of d, but also on the local magnetic surroundings. It has been revealed that the magnetic character of Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 changes from an itinerant electron type to a local-moment type with increasing temperature

TB Terms

Science.gov (United States)

... sputum can also be used to do a culture. TB blood test – a test that uses a blood sample to find out if you are infected with TB bacteria. The test measures the response to TB proteins when they are mixed with a small amount of blood. Examples of these TB blood tests include QuantiFERON ® -TB ...

Synthesis and magneto-structural studies on a new family of carbonato bridged 3d-4f complexes featuring a [CoLn(CO3)] (Ln = La, Gd, Tb, Dy and Ho) core: slow magnetic relaxation displayed by the cobalt(ii)-dysprosium(iii) analogue.

Science.gov (United States)

Majee, Mithun Chandra; Towsif Abtab, Sk Md; Mondal, Dhrubajyoti; Maity, Manoranjan; Weselski, Marek; Witwicki, Maciej; Bieńko, Alina; Antkowiak, Michał; Kamieniarz, Grzegorz; Chaudhury, Muktimoy

2018-03-06

A new family of [3 + 3] hexanuclear 3d-4f complexes [(μ 3 -CO 3 ){Co II Ln III L(μ 3 -OH)(OH 2 )} 3 ]-(ClO 4 )·mC 2 H 5 OH·nH 2 O (1-5) [Ln = La (1), Gd (2), Tb (3), Dy (4), and Ho (5)] have been prepared in moderate to high yields (62-78%) following a self-assembly reaction between the ligand 6,6',6''-(nitrilotris(methylene))tris-(2-methoxy-4-methylphenol) (H 3 L), Co(OAc) 2 ·4H 2 O and the lanthanide ion precursors in the mandatory presence of tetrabutylammonium hydroxide. During the reaction, atmospheric carbon dioxide is fixed in the product molecule as a bridging carbonato ligand which connects all the three lanthanide centers of this molecular assembly through a rare η 2 :η 2 :η 2 -μ 3 mode of bridging as revealed from X-ray crystallography. The metal centers in all these compounds, except the Gd III analogue (2), are coupled in antiferromagnetic manner while the nature of coupling in the CoGd complex is ferromagnetic. DFT calculations revealed that this ferromagnetic interaction occurs most likely by the Co II -Gd III superexchange, mediated via the bridging oxygen atoms. Only the Co II -Dy III compound (4) displayed a slow relaxation of the magnetization at a very low temperature as established by AC susceptibility measurements. The data provides an estimation of the activation energy U/k B = 9.2 K and the relaxation time constant τ 0 = 1.0 × 10 -7 s.

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.

Magnetic and transport properties of amorphous ferro magnetic Gd--Au, Gd--Ni and Gd--Co alloys obtained by splat-cooling

International Nuclear Information System (INIS)

Durand, J.; Poon, S.J.

1977-06-01

We present the results of magnetization and transport measurements on the amorphous Gd 80 Au 20 , Gd 68 Ni 32 and Gd 67 Co 33 alloys over a temperature range of 1.8 to 300 0 K in fields up to 75 kOe. These ferromagnetic alloys obtained by splat-cooling have Curie temperatures T/sub c/ of 150, 125 and 175 0 K, respectively. The saturation moment per Gd atom extrapolated to 0 0 K is estimated to be 7 +- 0.1 μ/sub B/. The exchange integrals for Gd-Au and Gd-Ni are determined from the value of T/sub c/ and from the temperature dependence of the saturation magnetization. The zero-field resistivity for Gd-Ni and Gd-Co exhibits maxima around T/sub c/. We present some preliminary results of magnetoresistivity measurements with applied field parallel and perpendicular to the foil plane. The anisotropy is in-plane for Gd-Co. For the Gd-Au and Gd-Ni alloys, there is no well-defined easy axis

New lanthanide(III) complexes of chiral nonadendate macrocyclic amine derived from (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol

Energy Technology Data Exchange (ETDEWEB)

Paluch, Marta [Department of Chemistry, University of Wroclaw, 14 F. Joliot-Curie, 50-383 Wroclaw (Poland); Lisowski, Jerzy [Department of Chemistry, University of Wroclaw, 14 F. Joliot-Curie, 50-383 Wroclaw (Poland)], E-mail: jurekl@wchuwr.chem.uni.wroc.pl

2008-02-28

The series of complexes [LnH{sub 4}L(NO{sub 3}){sub 2}](NO{sub 3}){sub 2}.nH{sub 2}O (Ln = La, Ce, Pr, Nd, Gd, Tb, Ho, Er, Tm) of the positively charged protonated form of a chiral macrocyclic amine H{sub 4}L{sup +}, derived from the 3 + 3 condensation product of (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol, have been synthesized. The series of complexes Na{sub x}[LnL](X){sub y}(OH){sub x-y}.n(solv) (X = NO{sup 3-} or Cl{sup -}, and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) of the deprotonated anionic form of the ligand, L{sup 3-}, have also been synthesised. The complexes have been characterised by elemental analyses, {sup 1}H NMR and ESI MS spectra. The X-ray crystal structures of the [LaH{sub 4}L(NO{sub 3}){sub 2}](NO{sub 3}){sub 2}.5CH{sub 3}OH and [GdH{sub 4}L(NO{sub 3}){sub 2}](NO{sub 3}){sub 2}.5CH{sub 3}OH complexes have been determined. The two complexes are isostructural, and the protonated macrocycle acts as pentadentate ligand. The Ln(III) ion is bound to three phenolate oxygen atoms and two amine nitrogen atoms of the macrocyclic ligand and its coordination sphere is completed by the two axial bidendate nitrate anions.

Levels in Gd156 excited in the decay of 5.6 d Tb156

DEFF Research Database (Denmark)

Hansen, P.Gregers; Nielsen, O.B.; Sheline, R.K.

1959-01-01

The decay of 5.6 day Tb156 has been studied by means of a six gap β-ray spectrometer, scintillation spectrometers, and coincidence techniques. Conversion electron and γ-ray coincidence measurements have been used extensively for obtaining quantitative estimates of γ-ray intensities. A description...... for transitions to a rotational band are observed. These features are discussed in terms of a probable mixing of the rotational bands....

Studies of the energy transfer processes from Er3+ and Ho3+ to Nd3+, Tb3+ or Eu3+ in LiYF4 crystal and ZBLAN glass for the laser media optimization operating near 3μm region

International Nuclear Information System (INIS)

Jagosich, Fabio Henrique

2006-01-01

The energy transfer processes (ET) from the 4 I 13/2 ; 4 I 11/2 levels of Er 3+ and 5 I 6 levels of Ho 3+ ions in LiYF 4 (YLF) crystal and ZBLAN glass to Nd 3+ , Tb 3+ or Eu 3+ deactivators ions were studied. The micro parameters of these energy transfer processes were determined using the overlap integral method, and showed that Eu 3+ ion is the best deactivator of the first excited state of the Ho 3+ in YLF, and Nd 3+ is the best deactivator of the Er 3+ in YLF and ZBLAN materials. The 1.5 and 2.7μm emissions of Er 3+ and 2.1 and 2.9μm fluorescence of Ho 3+ were measured using short laser pulses excitations from a tunable OPO pumped 2w-Nd:YAG laser system. We proposed a criterion for discriminating the energy transfer processes assisted by excitation migration (diffusion or hopping) among donors. It was observed that diffusion model describes the ET process from the second excited state of the donor (Er 3+ or Ho 3+ ) independently of the C D-D /C D-A ratio, while the hopping model can describe the ET process involving the first excited state of donor. We proposed a modification of the hopping model in order to describe the experimental results for systems having C D-D /C D-A ≥ 10. Using the ET parameters, we determined that the best systems for laser action at 3μm are the Ho:Eu:YLF, Ho:Nd:YLF and Er:Nd:YLF systems. On the other hand, we found that Er 3+ doped (1.5 mol%) ZBLAN glasses, single and co-doped with Nd 3+ , Tb 3+ or Eu 3+ , do not show potential for laser action at 2.8μm. The up-conversion processes were studied in Er:YLF systems as a function of the Er 3+ concentration, and the excited state absorption (ESA) and up conversion by energy transfer (ETU) processes were discriminated using a time resolved fluorescence decays. It was observed that 980 nm is the most convenient wavelength for pumping the Er:YLF system for quasi cw laser operation at 2.8μm. The pump-probe technique was used to investigate the lifetime effects in Er:YLF system showing

Neutron scattering study on R{sub 2}PdSi{sub 3} (R=Ho,Er,Tm) compounds

Energy Technology Data Exchange (ETDEWEB)

Tang, Fei

2010-12-14

Previous studies on the family of inter-metallic rare-earth compounds R{sub 2}PdSi{sub 3} revealed multifaceted magnetic properties, for instance, spin-glass like behavior. Experimental observations include: Signs of a crystallographic superstructure, complicated magnetic structures both in zero field and in applied magnetic fields as well as a generic phase in applied fields for compounds in the series with the heavy rare-earths R=Gd, Tb, Dy, Ho, Er and Tm. This thesis expands the studies on the magnetic properties of R{sub 2}PdSi{sub 3} employing mainly neutron scattering on single crystals with the focus on the compounds with R=Ho, Er and Tm. A detailed analysis of the crystallographic superstructure using modulation wave approach and group theory is presented. The resulting structure implies the existence of two different rare-earth sites with reduced symmetry and an arrangement of the different sites according to sequences as determined by the superstructure. It is shown that the reduced symmetry of the rare-earth sites is explicitly observed in the energy spectra of inelastic neutron scattering. The results on the magnetic structures and excitations are shown and discussed in the framework of the superstructure model. Specifically the generic phase in applied fields is interpreted as a direct consequence of the crystallographic superstructure. It is rather unusual that a crystallographic superstructure is playing such a decisive, and through the field dependence also tunable role in determining the magnetic properties as observed in R{sub 2}PdSi{sub 3}. The mediating interactions between the crystallographic part and the magnetic part of the system are discussed. (orig.)

Heightened vulnerability to MDR-TB epidemics after controlling drug-susceptible TB.

Directory of Open Access Journals (Sweden)

Jason D Bishai

2010-09-01

Full Text Available Prior infection with one strain TB has been linked with diminished likelihood of re-infection by a new strain. This paper attempts to determine the role of declining prevalence of drug-susceptible TB in enabling future epidemics of MDR-TB.A computer simulation of MDR-TB epidemics was developed using an agent-based model platform programmed in NetLogo (See http://mdr.tbtools.org/. Eighty-one scenarios were created, varying levels of treatment quality, diagnostic accuracy, microbial fitness cost, and the degree of immunogenicity elicited by drug-susceptible TB. Outcome measures were the number of independent MDR-TB cases per trial and the proportion of trials resulting in MDR-TB epidemics for a 500 year period after drug therapy for TB is introduced.MDR-TB epidemics propagated more extensively after TB prevalence had fallen. At a case detection rate of 75%, improving therapeutic compliance from 50% to 75% can reduce the probability of an epidemic from 45% to 15%. Paradoxically, improving the case-detection rate from 50% to 75% when compliance with DOT is constant at 75% increases the probability of MDR-TB epidemics from 3% to 45%.The ability of MDR-TB to spread depends on the prevalence of drug-susceptible TB. Immunologic protection conferred by exposure to drug-susceptible TB can be a crucial factor that prevents MDR-TB epidemics when TB treatment is poor. Any single population that successfully reduces its burden of drug-susceptible TB will have reduced herd immunity to externally or internally introduced strains of MDR-TB and can experience heightened vulnerability to an epidemic. Since countries with good TB control may be more vulnerable, their self interest dictates greater promotion of case detection and DOTS implementation in countries with poor control to control their risk of MDR-TB.

Measurement of 160Tb and 161Tb in nuclear forensics samples

International Nuclear Information System (INIS)

Jiang, J.; Davies, A.V.; Britton, R.E.

2017-01-01

160 Tb and 161 Tb are important radionuclides to measure when analysing a Nuclear Forensics sample. An analytical method for the measurement of both 160 Tb and 161 Tb was developed in this study. Terbium was separated and purified using exchange resin and TrisKem LN Resin. The purified fraction containing 160 Tb and 161 Tb was measured by gamma spectrometry and liquid scintillation counting. The counting efficiencies of 160 Tb and 161 Tb were determined using the CIEMAT/NIST efficiency tracing method. The LSC count rate ratio, R160 Tb /R161 Tb , on the reference date was determined by sequential counting and calculated using a custom script based on their half-lives. (author)

Hydrothermal synthesis, characterization and up/down-conversion luminescence of barium rare earth fluoride nanocrystals

International Nuclear Information System (INIS)

Jia, Li-Ping; Zhang, Qiang; Yan, Bing

2014-01-01

Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF 5 (RE = Ce, Pr, Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba 2 REF 7 (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd 3+ , Eu 3+ , Tb 3+ ) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba 2 LaF 7 :Yb, Tm(Er), Ba 2 REF 7 :Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed

Luminescence Properties of Self-Aggregating TbIII-DOTA-Functionalized Calix[4]arenes

Science.gov (United States)

Mayer, Florian; Tiruvadi Krishnan, Sriram; Schühle, Daniel T.; Eliseeva, Svetlana V.; Petoud, Stéphane; Tóth, Éva; Djanashvili, Kristina

2018-01-01

Self-aggregating calix[4]arenes carrying four DOTA ligands on the upper rim for stable complexation of paramagnetic GdIII-ions have already been proposed as MRI probes. In this work, we investigate the luminescence properties of TbIII-DOTA-calix[4]arene-4OPr containing four propyl-groups and compare them with those of the analogue substituted with a phthalimide chromophore (TbIII-DOTA-calix[4]arene-3OPr-OPhth). We show that, given its four aromatic rings, the calix[4]arene core acts as an effective sensitizer of Tb-centered luminescence. Substituents on the lower rim can modulate the aggregation behavior, which in turn determines the luminescence properties of the compounds. In solid state, the quantum yield of the phthalimide derivative is almost three times as high as that of the propyl-functionalized analogue demonstrating a beneficial role of the chromophore on Tb-luminescence. In solution, however, the effect of the phthalimide group vanishes, which we attribute to the large distance between the chromophore and the lanthanide, situated on the opposite rims of the calix[4]arene. Both quantum yields and luminescence lifetimes show clear concentration dependence in solution, related to the strong impact of aggregation on the luminescence behaviour. We also evidence the variability in the values of the critical micelle concentration depending on the experimental technique. Such luminescent calix[4]arene platforms accommodating stable lanthanide complexes can be considered valuable building blocks for the design of dual MR/optical imaging probes.

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.

The Gd{sub 14}Ag{sub 51} structure type and its relation to some complex amalgam structures

Energy Technology Data Exchange (ETDEWEB)

Tambornino, Frank; Sappl, Jonathan; Hoch, Constantin, E-mail: constantin.hoch@cup.uni-muenchen.de

2015-01-05

Highlights: • The Gd{sub 14}Ag{sub 51} structure type has been revisited on the basis of single crystal diffraction data. • Symmetry analysis from electron density and TEM shows the space group P6/m to be true. • Gd{sub 14}Ag{sub 51} shows good metallic behaviour. • Structure relations to alkali, alkaline-earth and rare-earth metal amalgams can be established. • Complexity values for the RE{sub 14}Ag{sub 51} structure family were calculated. - Abstract: A plethora of binary and ternary intermetallic compounds has been assigned to the Gd{sub 14}Ag{sub 51} structure type, crystallising in the hexagonal system (space group P6/m, a = 1264.30(18) pm, c = 933.58(11) pm for Gd{sub 14}Ag{sub 51}). Starting in the late 1960s, much work has been invested in the structural elucidation of these crystal structures. However, reliable single crystal data are scarce, and most structure type assignments have been performed merely on the basis of powder data. We have redetermined four representatives of the binary RE{sub 14}Ag{sub 51} structure type (RE = Y, Ce, Gd, Tb) with modern high-precision single crystal X-ray methods. The assignment of the Gd{sub 14}Ag{sub 51} structure type to space group P6/m was additionally verified by careful analysis of high resolution transmission electron micrographs. We emphasise the close relation of the Gd{sub 14}Ag{sub 51} structure type to the structures of some recently described amalgams of similar composition focussing on disorder phenomena and structural complexity. Furthermore, we provide detailed information on synthesis as well as electrical and magnetic properties for Gd{sub 14}Ag{sub 51}, the parent compound of this structure family.

TB or not TB?: a case of isolated testicular TB with scrotal involvement.

LENUS (Irish Health Repository)

Bhargava, A

2009-06-01

Despite the genitourinary tract being the most common site affected by extrapulmonary TB, isolated testicular TB remains a rare clinical entity. In patients with co-morbidities such as hepatic impairment, treatment proves a challenge, as first-line hepatotoxic pharmaceuticals are contraindicated. Here, we report a case of isolated testicular TB with scrotal involvement, on a background of hepatic dysfunction.

em cristais de Ho:YLF e Er:YLF na região de 3m

Directory of Open Access Journals (Sweden)

Fábio Henrique Jagosich

2006-01-01

Full Text Available In this work, the deactivation energy transfer mechanisms of 4I13/2 of Er3+ and 5I7 of Ho3+ levels in crystals of LiYF4 (YLF co-doped with Nd3+, Tb3+ and Eu3+ are studied. It was determined the best combination with deactivator ions, capable to maximize the laser gain in the middle of the Ho3+ in 2.9 micrometers (mm and the Er3+ in 2.75 mm operation. The results showed that the Tb3+ and Eu3+ are the best deactivators to the Ho3+ laser operation, while for the Ho3+ laser operation, the best ion deactivator is the Nd3+. The energy transfer characterizations were carried out using the Förster-Dexter method, which consists in the determination of the interaction critic ray, to start from the integral superposition of the absorption cross section spectrum and the involved ions emission.

Find TB. Treat TB. Working together to eliminate TB.

Centers for Disease Control (CDC) Podcasts

2014-02-26

In this podcast, Dr. Sundari Mase, Medical Team Lead in the Field Services and Evaluation Branch in the Division of Tuberculosis Elimination, discusses World TB Day and the 2014 theme.  Created: 2/26/2014 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 2/26/2014.

Single-molecule magnet behavior in 2,2’-bipyrimidine-bridged dilanthanide complexes

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Wen Yu

2016-01-01

Full Text Available A series of 2,2’-bipyrimidine-bridged dinuclear lanthanide complexes with the general formula [Ln(tmhd3]2bpm (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate, bpm = 2,2’-bipyrimidine, Ln = Gd(III, 1; Tb(III, 2; Dy(III, 3; Ho(III, 4 and Er(III, 5 has been synthesized and characterized. Sublimation of [Tb(tmhd3]2bpm onto a Au(111 surface leads to the formation of a homogeneous film with hexagonal pattern, which was studied by scanning tunneling microscopy (STM. The bulk magnetic properties of all complexes have been studied comprehensively. The dynamic magnetic behavior of the Dy(III and Er(III compounds clearly exhibits single molecule magnet (SMM characteristics with an energy barrier of 97 and 25 K, respectively. Moreover, micro-SQUID measurements on single crystals confirm their SMM behavior with the presence of hysteresis loops.

Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

OpenAIRE

Edelman , Irina; Ivanova , Oxana; Ivantsov , Ruslan; Velikanov , D.; Zabluda , V.; Zubavichus , Y.; Veligzhanin , A.; Zaikovskiy , V.; Stepanov , S.; Artemenko , Alla; Curély , Jacques; Kliava , Janis

2012-01-01

International audience; A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge struct...

Chemical composition of Kiscellian silty sediment (sivica from the Trobni Dol area, Eastern Slovenia

Directory of Open Access Journals (Sweden)

Miha Mišič

2003-06-01

Full Text Available Kiscellian marine silt termed »sivica« is widely developed in Tertiary basins of Eastern Slovenia. Chemical composition is rather uniform and reflects the dominance of filosilicates (mainly illite/muscovite, chlorite and montmorillonite and carbonates. PAAS normalised REE and Y abundances are slightly depleted for La, Ce, Pr and Nd, very close to PAAS for Sm, Eu, Gd and Tb, and depleted for Y, Ho, Er, Tm, Yb and Lu.

On the formation and structural properties of hexagonal rare earth (Y, Gd, Dy, Er and Yb) disilicide thin films

Energy Technology Data Exchange (ETDEWEB)

Geenen, F.A., E-mail: Filip.Geenen@UGent.be [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium); Knaepen, W. [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium); Demeulemeester, J. [Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven (Belgium); De Keyser, K. [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium); Jordan-Sweet, J.L.; Lavoie, C. [IBM T.J. Watson Research Center, Yorktown Heights, NY (United States); Vantomme, A. [Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven (Belgium); Detavernier, C. [Department of Solid-State Sciences, Ghent University, 9000 Gent (Belgium)

2014-10-25

Highlights: • Solid-state reaction is studied of a several rare earth thin films with Si substrates. • h-GdSi{sub 1.7} grains have an epitaxial texture on both Si 1 0 0 and Si 1 1 1. • Formation temperature of h-RESi{sub 1.7} correlates with lattice parameter of the h-phase. - Abstract: A systematic study was performed of the solid state reaction between a 100 nm thick layer of a rare earth metal and a Si substrate. The solid state reaction of five different rare earth metals (yttrium, gadolinium, dysprosium, erbium and ytterbium) were studied by in situ X-ray diffraction measurements on Si(1 0 0), Si(1 1 1) and poly-Si. This allowed us to make a comparison between the different systems. The formation temperature of h-RESi{sub 1.7} are the highest on Si(1 1 1) and the lowest on poly-Si for all examined RE metals. Additionally, the texture of the Gd disilicide phase on Si(1 0 0) and Si(1 1 1) was investigated by means of ex situ pole figure measurements. The epitaxial relationship of hexagonal GdSi{sub 1.7} and orthorhombic GdSi{sub 2} on the different Si substrates is determined. The epitaxial growth is the strongest on Si(1 1 1)

Temperature effects on separation of Gd3+ from Gd-DTPA-folate using nanofiltration method

Science.gov (United States)

Rahayu, I.; Indraneli, R. P.; Yuliyati, Y. B.; Anggraeni, A.; Soedjanaatmadja, U. M. S.; Bahti, H. H.

2018-05-01

MRI is one of the best techniques in medical diagnostics. Contrast agents are used to improve the visual of organs that are difficult to distinguish through MRI. Gd-DTPA-folate is one of the specific contrast agents against cancer diagnosis, because it has a high affinity to folate receptors. In the complexing Gd-DTPA-folate, does not rule out the complexity step runs imperfectly, so there is still Gd3+ in the Gd-DTPA-folate complex. The separation of Gd3+ from the Gd-DTPA-folate complex is important to eliminate toxic effects on the contrast agent. This study aims to determine the effect of temperature on the separation of Gd-DTPA-folate from Gd3+ with nanofiltration. The method are preparation Gd-DTPA-folate from GdCl3.6H2O and DTPA-folate by reflux method, then separated Gd-DTPA-folate complex from Gd3+ with nanofiltration at variation temperature (40, 41, 42, 43, 44oC ). Then, the values of flux and rejection coefficients were analyzed. The results showed that the optimum temperature for the separation of Gd3+ from Gd-DTPA-folate was achieved at 42.6°C with the rejection coefficient of 24% and the permeate flux of 403 L.m-2.h-1.

Addition compounds between same phosphinoxides and hexafluorophosphates of rare earths (III)

International Nuclear Information System (INIS)

Silva, A.M. da; Melo, S.M.; Souza, E.F. de; Almeida, M.A. de

1984-01-01

Coordination compounds were prepared from salts of lanthanide hexafluorophosphates and three different phosphine oxides: methyldiphenylphosphine oxide (MDPPO), diphenylcyclohexylphosphine oxide (DPcHPO) and phosphoric acid trimethylester (TMxPO). The analytical results indicated the following general formulae : Ln(PF 6 ) 3 .5DPChPO where Ln = La, Eu, Gd, Tb and Dy; Ln(PF 6 ) 3 6MDPPO, where Ln = La, Ce, Nd, Eu, Gd, and Tm; Ln(PF 6 ) 3 .7TMxPO, where Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb. The vibrational studies in the infrared region showed that all the phosphine oxides coordination are through the oxygen of the phosphoryl group and confirmed the non-coordination character of the PF - 6 ion. Fluorescence spectra in the visible region for the Eu (III) compounds, at the liquid nitrogen temperature indicated the microsymmetry C sub(3v) as the most probable for the Eu (III) in the compounds Eu (PF 6 ) 3 .5DPChPO and Eu (PF 6 ) 3 .7TMxPO. The symmetry site of the Eu (PF 6 ) 3 .6MDPPO compound is octahedral with tetragonal distortion. (Author) [pt

Time domain simulation of Gd3+-Gd3+ distance measurements by EPR

Science.gov (United States)

Manukovsky, Nurit; Feintuch, Akiva; Kuprov, Ilya; Goldfarb, Daniella

2017-07-01

Gd3+-based spin labels are useful as an alternative to nitroxides for intramolecular distance measurements at high fields in biological systems. However, double electron-electron resonance (DEER) measurements using model Gd3+ complexes featured a low modulation depth and an unexpected broadening of the distance distribution for short Gd3+-Gd3+ distances, when analysed using the software designed for S = 1/2 pairs. It appears that these effects result from the different spectroscopic characteristics of Gd3+—the high spin, the zero field splitting (ZFS), and the flip-flop terms in the dipolar Hamiltonian that are often ignored for spin-1/2 systems. An understanding of the factors affecting the modulation frequency and amplitude is essential for the correct analysis of Gd3+-Gd3+ DEER data and for the educated choice of experimental settings, such as Gd3+ spin label type and the pulse parameters. This work uses time-domain simulations of Gd3+-Gd3+ DEER by explicit density matrix propagation to elucidate the factors shaping Gd3+ DEER traces. The simulations show that mixing between the |+½, -½> and |-½, +½> states of the two spins, caused by the flip-flop term in the dipolar Hamiltonian, leads to dampening of the dipolar modulation. This effect may be mitigated by a large ZFS or by pulse frequency settings allowing for a decreased contribution of the central transition and the one adjacent to it. The simulations reproduce both the experimental line shapes of the Fourier-transforms of the DEER time domain traces and the trends in the behaviour of the modulation depth, thus enabling a more systematic design and analysis of Gd3+ DEER experiments.

Air stability and magnetic properties of GdN, TiN, and (Gd,Ti)N nanoparticles

International Nuclear Information System (INIS)

Si Pingzhan; Choi, C. J.; Tegus, O.; Brueck, E.; Geng, D. Y.; Zhang, Z. D.

2008-01-01

GdN, TiN, and (Gd,Ti)N nanoparticles were prepared by arc evaporating Gd, Ti, and Gd-Ti alloys in N 2 , respectively. Most of these nanoparticles show narrow size distribution with average diameter of 20 nm. Shell/core structure was observed in the (Gd,Ti)N nanoparticles, in which the shell was formed by surface reaction with air. (Gd,Ti)N nanoparticles are more stable than GdN nanoparticles in air due partially to the formation of the protective shell. The Curie temperature of GdN nanoparticles is lower than that of the bulk GdN. Both GdN and (Gd, Ti)N nanoparticles are difficult to reach magnetic saturation and show zero coercivity

Isothermal section of the Er-Fe-Al ternary system at 800 oC

International Nuclear Information System (INIS)

Jemmali, M.; Walha, S.; Pasturel, M.; Tougait, O.; Ben Hassen, R.; Noel, H.

2010-01-01

Physico-chemical analysis techniques, including X-ray diffraction and Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy, were employed to construct the isothermal section of the Er-Fe-Al system at 800 o C. At this temperature, the phase diagram is characterized by the formation of five intermediate phases, ErFe 12-x Al x with 5 ≤ x ≤ 8 (ThMn 12 -type), ErFe 1+x Al 1-x with -0.2 ≤ x ≤ 0.75 (MgZn 2 -type), ErFe 3-x Al x with 0.5 2 Al-type), Er 2 Fe 17-x Al x with 4.74 ≤ x ≤ 5.7 (TbCu 7 -type) and Er 2 Fe 17-x Al x with 5.7 2 Zn 17 -type), seven extensions of binaries into the ternary system; ErFe x Al 3-x with x 3 Cu-type), ErFe x Al 2-x with x ≤ 0.68 (MgCu 2 -type), Er 2 Fe x Al 1-x with x ≤ 0.25 (Co 2 Si-type), ErFe 2-x Al x with x ≤ 0.5 (MgCu 2 -type), ErFe 3-x Al x with x ≤ 0.5 (Be 3 Nb-type), Er 6 Fe 23-x Al x with x ≤ 8 (Th 6 Mn 23 -type), and Er 2 Fe 17-x Al x with x ≤ 4.75 (Th 2 Ni 17 -type) and one intermetallic compound; the ErFe 2 Al 10 (YbFe 2 Al 10 -type).

Synthesis, density functional theory calculations and luminescence of lanthanide complexes with 2,6-bis[(3-methoxybenzylidene)hydrazinocarbonyl] pyridine Schiff base ligand.

Science.gov (United States)

Taha, Ziyad A; Ababneh, Taher S; Hijazi, Ahmed K; Abu-Salem, Qutaiba; Ajlouni, Abdulaziz M; Ebwany, Shroq

2018-02-01

A pyridine-diacylhydrazone Schiff base ligand, L = 2,6-bis[(3-methoxy benzylidene)hydrazinocarbonyl]pyridine was prepared and characterized by single crystal X-ray diffraction. Lanthanide complexes, Ln-L, {[LnL(NO 3 ) 2 ]NO 3 .xH 2 O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er)} were prepared and characterized by elemental analysis, molar conductance, thermal analysis (TGA/DTGA), mass spectrometry (MS), Fourier transform infra-red (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. Ln-L complexes are isostructural with four binding sites provided by two nitro groups along with four coordination sites for L. Density functional theory (DFT) calculations on L and its cationic [LnL(NO 3 ) 2 ] + complexes were carried out at the B3LYP/6-31G(d) level of theory. The FT-IR vibrational wavenumbers were computed and compared with the experimentally values. The luminescence investigations of L and Ln-L indicated that Tb-L and Eu-L complexes showed the characteristic luminescence of Tb(III) and Eu(III) ions. Ln-L complexes show higher antioxidant activity than the parent L ligand. Copyright © 2017 John Wiley & Sons, Ltd.

Testing for TB Infection

Science.gov (United States)

... Adverse Events TB Treatment of Persons Living with HIV TB Treatment and Pregnancy TB Treatment for Children Drug-Resistant TB Research TB Epidemiologic Studies Consortium Research Projects Publications TB Trials Consortium Study ...

Photoluminescence related to Gd3+:N-vacancy complex in GaN:Gd multi-quantum wells

International Nuclear Information System (INIS)

Almokhtar, Mohamed; Emura, Shuichi; Koide, Akihiro; Fujikawa, Takashi; Asahi, Hajime

2015-01-01

Highlights: • We grew Gd-doped GaN multi-quantum wells (MQWs) with quantum layer thickness of one nm by MBE. • The X-ray absorption near edge structure spectra observed at Gd LIII-edge indicate a nitrogen vacancy adjacent to Gd substituting the Ga ion in Gd-doped GaN MQW. • The photoluminescence of the samples is discussed considering the formation of a Gd 3+ :Nitrogen-vacancy complex. • A model is presented considering exciton-polaron formation trapped in defect sites around the Gd 3+ :N-vacancy complex in Gd-doped GaN MQWs. - Abstract: The photoluminescence of Gd-doped GaN multi-quantum wells (MQWs) is presented and discussed considering the formation of a Gd 3+ :Nitrogen-vacancy (N-vacancy) complex. A lower energy photoluminescence peak was observed for the Gd-doped GaN MQW sample with respect to the main peak assigned to a neutral donor bound exciton (D 0 X) of the undoped GaN MQW sample. The X-ray absorption near edge structure spectrum observed at Gd L III -edge indicates a nitrogen vacancy adjacent to the Gd substituting the Ga ion in Gd-doped GaN MQW sample. Local stresses around the Gd dopants in Gd-doped GaN matrix generated due to the larger diameter of the Gd 3+ ion with respect to the Ga 3+ ion can be relieved by the creation of vacancies. The lower formation energy of N-vacancies in GaN matrix introduce them as a preferred candidate to relieve the generated stresses. A Gd 3+ :N-vacancy complex consisting of a Gd 3+ ion and the created nitrogen vacancy adjacent to the Gd 3+ dopant is likely to form in GaN:Gd matrix. The lower photoluminescence peak energy observed in the Gd-doped GaN MQW sample is assigned to the recombination of an exciton captured at the Gd 3+ :N-vacancy complex forming a small polaron-like state. A model is presented considering the small exciton-polaron population in defect sites captured around the Gd 3+ ions in the Gd-doped GaN

NMR measurements in milled GdCo2 and GdFe2 intermetallic compounds

International Nuclear Information System (INIS)

Tribuzy, C.V.B.; Guimaraes, A.P.; Biondo, A.; Larica, C.; Alves, K.M.B.

1998-12-01

We have used the nuclear magnetic resonance technique to study the magnetic and structural properties of the Gd-Co and Gd-Fe metallic systems, starting with the C15 laves phase intermetallic compounds, and submitting them to a high energy milling process. This leads to the amorphization of the samples, as determined by the X-ray diffraction spectra. For the Gd-Co system the NMR study used the 59 Co nucleus; in the Gd-Fe system, 155,157 Gd and 57 Fe were used. Both systems showed segregation of the pure elements, after a few hours of milling. In the Gd-Co system, a single line, of increasing width, was observed in the 59 Co spectrum. In the Gd-Fe system, the 155 Gd and 157 Gd resonances show three lines, arising from electrical quadrupole interaction. With increasing milling time, the lines broaden, and extra lines appear attributed to a cubic phase of Gd; this interpretation is supported by the X-ray analysis of the samples. The 57 Fe NMR spectrum of this system also informs on the direction of magnetization of the samples in the early stages of milling. From 1 h to 7 h of milling, a spectrum of α-Fe was observed. The study of the NMR line intensity as a function of radio frequency (r.f.) power in Gd Co 2 suggests the existence of regions of the samples with different degrees of disorder. We have observed the persistence of NMR signals from the original intermetallic compounds in the samples with up to 10 h and 7 h of milling, respectively, for Gd Co 2 and Gd Fe 2 . (author)

Luminescence Properties of Self-Aggregating TbIII-DOTA-Functionalized Calix[4]arenes

Directory of Open Access Journals (Sweden)

Florian Mayer

2018-01-01

Full Text Available Self-aggregating calix[4]arenes carrying four DOTA ligands on the upper rim for stable complexation of paramagnetic GdIII-ions have already been proposed as MRI probes. In this work, we investigate the luminescence properties of TbIII-DOTA-calix[4]arene-4OPr containing four propyl-groups and compare them with those of the analog substituted with a phthalimide chromophore (TbIII-DOTA-calix[4]arene-3OPr-OPhth. We show that, given its four aromatic rings, the calix[4]arene core acts as an effective sensitizer of Tb-centered luminescence. Substituents on the lower rim can modulate the aggregation behavior, which in turn determines the luminescence properties of the compounds. In solid state, the quantum yield of the phthalimide derivative is almost three times as high as that of the propyl-functionalized analog demonstrating a beneficial role of the chromophore on Tb-luminescence. In solution, however, the effect of the phthalimide group vanishes, which we attribute to the large distance between the chromophore and the lanthanide, situated on the opposite rims of the calix[4]arene. Both quantum yields and luminescence lifetimes show clear concentration dependence in solution, related to the strong impact of aggregation on the luminescence behavior. We also evidence the variability in the values of the critical micelle concentration depending on the experimental technique. Such luminescent calix[4]arene platforms accommodating stable lanthanide complexes can be considered valuable building blocks for the design of dual MR/optical imaging probes.

HIV/TB co-infection:perspectives of TB patients and providers on the integrated HIV/TB pilot program in Tamilnadu, India

OpenAIRE

Lakshminarayanan, Mahalakshmi

2009-01-01

The WHO recommends routine HIV testing among TB patients as a key strategy to combat the dual HIV/TB epidemic. India has integrated its HIV and TB control programs and is offering provider initiated HIV testing for all TB patients since 2007. Using a mixed methods approach, this study aims to understand the perspectives of TB patients and providers on the integrated HIV/TB pilot program in Tamilnadu, India. A survey conducted by the Tuberculosis Research Center, India on 300 TB patients is th...

The association between ARV and TB drug resistance on TB treatment outcome among Kazakh TB/HIV patients.

Science.gov (United States)

Mishkin, Kathryn; Alaei, Kamiar; Alikeyeva, Elmira; Paynter, Christopher; Aringazina, Altyn; Alaei, Arash

2018-02-26

TB drug resistance poses a serious threat to the public health of Kazakhstan. This paper presents findings related to TB treatment outcome and drug resistant status among people coinfected with HIV and TB in Kazakhstan. Cohort study using data were provided by the Kazakhstan Ministry of Health's National Tuberculosis Program for 2014 and 2015. Chi-square and logistical regression were performed to understand factors associated with drug resistant TB status and TB treatment outcome. In bivariate analysis, drug resistant status was significantly associated with year of TB diagnosis (p=0.001) viral load (p=0.03). TB treatment outcome was significantly associated with age at diagnosis (p=01), ARV treatment (p <0.0001), and TB drug resistant status (p=0.02). In adjusted analysis, drug resistance was associated with increased odds of successful completion of treatment with successful result compared to treatment failure (OR 6.94, 95% CI: 1.39-34.44) CONCLUSIONS: Our results suggest that being drug resistant is associated with higher odds of completing treatment with successful outcome, even when controlling for receipt of ARV therapy. Copyright © 2018. Published by Elsevier Ltd.

Energies, Wavelengths, and Transition Rates for Ga-Like Ions (Nd XXX-Tb XXXV)

Science.gov (United States)

El-Sayed, Fatma; Attia, S. M.

2016-03-01

Energies, wavelengths, transition probabilities, oscillator strengths, and line strengths have been calculated for 4s24p-4s4p2 and 4s24p-4s24d transitions in gallium-like ions from Z = 60 to 65, for Nd XXX, Pm XXXI, Sm XXXII, Eu XXXIII, Gd XXXIV, and Tb XXXV using the fully relativistic multiconfi guration Dirac-Fock method. The correlation with the n = 4 complex and the quantum electrodynamic effects have been considered in the calculations. The obtained results have been compared with the available experimental and other theoretical results.

n-aminobenzoates of rare earths

International Nuclear Information System (INIS)

Efremova, G.I.; Buchkova, R.T.; Lapitskaya, A.V.; Pirkes, S.B.

1977-01-01

N-aminobenzoates of r.e.e. have been synthesized. Their composition corresponds to the general formula Me(C 6 H 4 NH 2 COO) 3 xnH 2 O, where Me stands for La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; n=1.2. The compounds obtained are identified by chemical analysis and roentgenographically. Their solubility products, which are values of the order of 10 -9 -10 -10 , are determined

Systematics on incomplete fusion dynamics at low energy

International Nuclear Information System (INIS)

Rahbar Ali; Afzal Ansari, M.; Kumar, Harish

2016-01-01

In the present work, an attempt has been made to study CF and ICF reaction dynamics extensively by using activation and particle-γ coincidence techniques. The excitation functions (EFs) of evaporation residues (ERs) in 20 Ne + 55 Mn, 19 F + 144 Sm, 20 Ne + 159 Tb and 16 O + 156 Gd systems in the energy range ∼ 3-8 MeV/nucleon have been measured by using recoil catcher activation technique followed by γ-ray spectrometry

Measurement of formation cross sections of short-lived nuclei by 14 MeV neutron. Nd, Sm, Dy, Er, Yb

Energy Technology Data Exchange (ETDEWEB)

Sakane, H.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan). School of Engineering; Iida, T.; Takahashi, A.

1997-03-01

Eight neutron activation cross sections producing the nuclei with half-lives between 3 min and 24 min were obtained at the energy range between 13.4 and 14.9 MeV by activation method. The cross sections were {sup 146}Nd(n,p){sup 146}Pr, {sup 154}Sm(n,{alpha}){sup 151}Nd, {sup 162}Dy(n,p){sup 162}Tb, {sup 163}Dy(n,np){sup 162}Tb, {sup 163}Dy(n,p){sup 163}Tb, {sup 164}Dy(n,p){sup 164}Tb, {sup 170}Er(n,{alpha}){sup 167}Dy, {sup 174}Yb(n,p){sup 170}Tm. {sup 163}Dy(n,np){sup 162}Tb (T{sub 1/2}=7.7 min) was obtained for the first time. Present results are compared with previous results and the evaluated data of JENDL-3 and ENDF/B-VI. There are some discrepancies between present results and the JENDL-3 and ENDF/B-VI. (author)

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.)

Exchange interaction in the heavy rare-earth metals calculated from energy bands

International Nuclear Information System (INIS)

Lindgard, P.A.; Liu, S.H.

1973-01-01

The exchange interaction in the ordered phases was calculated and found to be significantly influenced by the magnetic perturbation of the conduction electron states. The exchange interaction is intrinsically temperature dependent and is anisotropic. The effect explains how it is possible to have a spiral phase of Tb, although spin wave measurements show no maximum in J/sub q/ for q not equal to 0. The energy difference between the ferromagnetic and spiral phases is of correct order of magnitude to be counterbalanced by the magnetoelastic energy. The wave vector dependent matrix element is found to be similar for Gd, Tb, Dy, and Er with a narrow central conduction electron contribution and a flat region. (U.S.)

Studies on the electrochemical behavior of heavy lanthanide ions and the synthesis, characterization of heavy metal chelate complexes

International Nuclear Information System (INIS)

Kang, Sam Woo; Chang, Choo Hwan; Son, Byung Chan; Suh, Moo Yul; Kim, Chae Kyun

1991-01-01

Electrochemical behavior of some heavy lanthanide ions(Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ , Yb 3+ and Lu 3+ ) in various supporting electrolytes has been investigated by dc polarography, differential pulse polarography and cyclic voltammetry. The peak potentials and the peak currents, their dependency on the concentration and pH effects, the reversibility of the electrode reactions are described. The reduction of Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ and Lu 3+ ions in 0.1M lithium chloride solution proceeds by a three-electron change directly to the metallic state, whereas the reduction of Yb 3+ proceeds by a one-electron change followed by a two-electron change. It was found that, in differential pulse polarography and cyclic voltammetry, the peak potential, peak current and current function showed constant value in the pH range of 4.0-6.0 by varying pH and scan rates. And also the current function is found to decrease as the sweep rate is increased when the pH reaches 4.0. This fact may indicate a chemical reaction coupled with the electrochemical reaction at lower pH values(pH 3+ ion is possible to determine voltammetrically within the error of ±3.5% in the presence of other competitive lanthanide ions. (Author)

Defect induced visible-light-activated near-infrared emissions in Gd3-x-y-zYbxBiyErzGa5O12

Science.gov (United States)

Tong, Liping; Saito, Katsuhiko; Guo, Qixin; Zhou, Han; Fan, Tongxiang; Zhang, Di

2017-11-01

Visible-light-activated near-infrared luminescent materials are promising photoluminescent materials due to their convenience and low cost. Crystal defects can seriously affect the performance of luminescent materials, and better understanding of the complexity of the structural disorder and electronic structures of such materials opens up new possibilities in luminescent material development. In this work, we successfully design a novel, effective, visible-light-activated near-infrared luminescent Gd3Ga5O12: 4.2%Yb3+, 8.4%Er3+, and 4.2%Bi3+ system based on first principles. This exhibits strong emission intensity and high luminous efficiency (0.993) and also has a lifetime (7.002 ms) that is at least twice as long as the longest lifetime reported in published papers. We utilize density functional theory with an effective LSDA + U method to study the structural properties of Gd3-x-y-zGa5O12: xYb3+, yBi3+, zEr3+ (GGG: Yb3+, Bi3+, Er3+). The d and f electron orbits of rare-earth ions are considered for an effective Hund exchange. Detailed analysis reveals that GGG: 4.2%Yb3+, 8.4%Er3+, 4.2%Bi3+ has the smallest cell volume because of the strong covalent bonds of Bi-O, Er-O, and Yb-O. Bi 3d is a hybridized state that acts as sensitizing ions during the process of luminescence in GGG: Yb3+, Bi3+, Er3+. Together with experimental and theoretical results, we analyze the influence of defects on emission intensity. The locations of Yb3+, Er3+, and Bi3+ are determined by X-ray absorption fine structure measurements, which are in agreement with the model constructed using first principles. This work may provide innovative guidance for the design of high-performance visible-light-activated near-infrared luminophores based on calculations and a new methodology for application of coherent laser radar and optical communication.

Interaction of xenone difluoride with the fluorocomplexes of lanthanides and rubidium of the Rb3M3F6 composition

International Nuclear Information System (INIS)

Goryachenkov, S.A.; Fadeeva, N.E.; Kiselev, Yu.M.; Martynenko, L.I.; Spitsyn, V.I.

1984-01-01

The possibility of preparing rubidium fluorocomplexes of tetravalent lanthanides of the Rb 3 M 4 F 7 composition from Rb 3 M 3 F 6 (M 3 =Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb) with XeF 2 has been studied. By the DTA method it is shown that Ce and Pr salts are fluorinated respectively at approximately 100 and approximately 235 deg C with a noticeable exoeffect. Tb and Dy salts fluorination proceeds with considerable kinetic difficulties. The fluorination products composition, Rb 3 M 4 F 7 (M 4 =Ce, Pr, Tb, Dy) is confirmed by the methods of chemical, IR-spectroscopic and X-ray phase analyses. XeF 2 interaction with Rb 3 M 3 F 6 salts of other lanthanides up to 400 deg C has not been observed

Ni3d-Gd4f correlation effects on the magnetic behaviour of GdNi

Energy Technology Data Exchange (ETDEWEB)

Paulose, P L [Tata Inst. of Fundamental Research, Bombay (India); Patil, Sujata [Tata Inst. of Fundamental Research, Bombay (India); Mallik, R [Tata Inst. of Fundamental Research, Bombay (India); Sampathkumaran, E V [Tata Inst. of Fundamental Research, Bombay (India); Nagarajan, V [Tata Inst. of Fundamental Research, Bombay (India)

1996-07-01

The results of magnetization and heat-capacity measurements on the alloys, Gd{sub 1-x}Y{sub x}Ni (x=0.0, 0.25, 0.5, 0.75 and 0.9) are reported. The data suggest that there is a Gd induced magnetic moment on Ni, which may in turn enhance Gd-Gd exchange interaction strength in GdNi. The induced moment (on Ni) apparently exhibits itinerant ferromagnetism in the magnetically ordered state of GdNi. (orig.).

Evaluation of Gd and Gd{sup 159} as new approaches for cancer treatment

Energy Technology Data Exchange (ETDEWEB)

Galvao, I.; Neves, M.J., E-mail: nevesmj@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Grupo de Desenvolvimento de Radiofarmacos; Santos, R.G., E-mail: santosr@cdtn.br [Instituto Nacional de Ciencia e Tecnologia em Medicina Molecular (INCT-MM), Belo Horizonte, MG (Brazil)

2011-07-01

Metal compounds have shown many biological activities and have been successfully used as anticancer agents such cisplatin. Actually gadolinium (Gd) complexed with a porphyrin Motexafin (MGd) has been investigated as redox-active compound for treatment of cancer. 1{sup 59G}d decays by beta emission with an energy of 970 keV and half-life of 18.59 hours. The de-excitation can be via gamma ray and internal conversion electron emission followed by auger electrons and x rays. Considering all of this 1{sup 59G}d could be a interesting radionuclide to be as a radio therapeutical agent. The aims of this works were to evaluate the cytotoxicity of Gd and 1{sup 59G}d on malignant brain tumors such as glioblastoma multiform, the most frequent brain tumors which has a very poor prognosis. For this purpose, it was used human glioblastoma cell lines T98 (mutant p53) and U87 (wild-type p53) to investigate the cytotoxicity of gadolinium on cell metabolism by MTT assay and also morphological changes, chromatin condensation by DAPI assay and ROS generation. Gadolinium was able to decrease cell viability, the cells presented morphological changes like round shapes and blebs formation after cell treatment with 5x10{sup -6}M of Gd. Nuclear changing and ROS generation occurred in a dose dependent way indicating the cytotoxic effect of Gd. Treatment with 1{sup 59G}d increased all of changes observed with treatment with Gd. These results state for an additive effect of metal toxicity and radioactivity inducing ROS generation as the main mechanism of anti tumoral action of 1{sup 59G}d. The results obtained indicated that the radioactive analogues of Gd have increased cytotoxic effects and gadolinium can be a metal of choice for development of new drugs for cancer treatment. (author)

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

Synthesis and investigation of rare earth tris-acetylacetonates addUcts with acetylaceoneimine

International Nuclear Information System (INIS)

Trembovetskij, G.V.; Smirnov, E.V.; Murav'eva, I.A.; Martynenko, L.I.

1983-01-01

Adducts of tris-acetylacetonates of pare earths With acetylacetonimine of the composition MA 3 x2L (M=La, Pr, Nd, Eu, Gd, Tb) and MA 3 XL (M=Dy, Ho, Er, Tm, Yb, LU) have been synthesized. The compounds prepared are studied using the methods of elemental analysis, IR spectroscopy, PMR spectroscopy, X-ray phase analysis. Volatile tris-acetylacetonates of the yttrium subgroUp rare earths have been prepared by thermal decomposition of MA 3 xL in vacuum

Electrochemical synthesis of transition element complexes with carboxyl- and carbonyl-containing ligands

International Nuclear Information System (INIS)

Frolov, V.Yu.; Bolotin, S.N.; Panyushkin, V.T.

2005-01-01

Complexes of d- and f-elements (E = Cu, Ni, Zn, Nd, Tb, Pr, Gd, Er) with carboxyl- and carbonyl-containing ligands were synthesized by the electrochemical method. The products were characterized by elemental analysis, thermal gravimetric analysis and IR spectra. The influence exerted by a number of factors on the process course was studied. The dependence of the electro synthesis parameters on the composition of the forming compounds was established. A new method for anodic synthesis of these compounds was developed [ru

Lanthanide oxide and phosphate nanoparticles for thermometry and bimodal imaging =

Science.gov (United States)

Debasu, Mengistie Leweyehu

Nesta tese relatam-se estudos de fotoluminescencia de nanoparticulas de oxidos e fosfatos dopados com ioes trivalentes de lantanideos, respectivamente, nanobastonetes de (Gd,Eu)2O3 e (Gd,Yb,Er)2O3 e nanocristais de (Gd,Yb,Tb)PO4, demonstrando-se tambem aplicacoes destes materiais em revestimentos inteligentes, sensores de temperatura e bioimagem. Estuda-se a transferencia de energia entre os sitios de Eu3+ C2 e S6 dos nanobastonetes Gd2O3. A contribuicao dos mecanismos de transferencia de energia entre sitios para o tempo de subida 5D0(C2) e descartada a favor da relaxacao directa 5D1(C2) 5D0(C2) (i.e., transferencia de energia entre niveis). O maior tempo de decaimento do nivel 5D0(C2) nos nanobastonetes, relativamente ao valor medido para o mesmo material na forma de microcristais, e atribuido, quer a existencia de espacos livres entre nanobastonetes proximos (factor de enchimento ou fraccao volumica), quer a variacao do indice de refraccao efectivo do meio em torno dos ioes Eu3+. A dispersao de nanobastonetes de (Gd,Eu)2O3 em tres resinas epoxi comerciais atraves da cura por UV permite obter nanocompositos epoxi- (Gd,Eu)2O3. Relatam-se estudos cineticos e das propriedades termicas e de fotoluminescencia destes nanocompositos. Estes, preservam as tipicas propriedades de emissao do Eu3+, mostrando o potencial do metodo de cura por UV para obter revistimentos inteligentes e fotoactivos. Considera-se um avanco significativo a realizacao de uma nanoplataforma optica, incorporando aquecedor e termometro e capaz de medir uma ampla gama de temperaturas (300-2000 K) a escala nano, baseada em nanobastonetes de (Gd,Yb,Er)2O3 (termometros) cuja superficie se encontra revestida com nanoparticulas de ouro. A temperature local e calculada usando, quer a distribuicao de Boltzmann (300-1050 K) do racio de intensidades da conversao ascendente 2H11=2!4I15=2/4S3=2!4I15=2, quer a lei de Planck (1200-2000 K) para uma emissao de luz branca atribuida a radiacao do corpo negro

Spontaneous polarization and pyroelectric effect in improper ferroelectrics-ferroelastics Gd2(MoO4)3 and Tb2(MoO4)3 at low temperature

International Nuclear Information System (INIS)

Matyjasik, S; Shaldin, Yu.V.

2013-01-01

Experimental dependencies for spontaneous polarization ΔP s (T) and pyroelectric coefficient γ s (T)for Gd 2 (MoO 4 ) 3 (GMO) and Tb 2 (MoO 4 ) 3 (TMO) reported here differs from those for intrinsic ferroelectrics. We found fundamental distinction in GMO and TMO samples behavior at their repolarization at the fixed temperatures 300 and 4.2 K. In TMO monodomainization temperature does not affect experimental data, while in GMO monodomainization at 4.2 K results in increase of ΔP s (T) by order of magnitude at 85 K and γ s (T) dependence shows well-defined anomalies, reaching a record magnitude of 3 centre dot 10 -4 C/(m 2 centre dot K) at T = 25 K. At T = 200 K the pyroelectric coefficients values are -1.45 centre dot 10 -6 C/(m 2 centre dot K) and-1.8 centre dot 10 -6 C/(m 2 centre dot K). Taking into account our data, results related to transformation of structure in (001) plane and symmetry reasons we suggested crystallographic model of GMO type improper ferroelectric. It is formed by four meso-tetrahedrons constructed of three coordination tetrahedrons MO 4 (a, b and c types). In the framework of this model we discuss the physical meaning of pseudodeviator Q 12 *, coefficient, that initiate the phase transition at T > 433 K from noncentrosymmetric phase (mm2) to another one (4-bar2m).

Calculation of the band structure of GdCo2, GdRh2 e GdIr2 by the APW method

International Nuclear Information System (INIS)

Carvalho, J.A.B. de.

1974-03-01

The band structure of GdCo 2 , GdRh 2 , GdIr 2 has been calculated by the APW method. A histogram of the density of states is presented for each compound. The bands are transition-metal-like, with s-d hybridization near the Fermi level. The 5d character near the Fermi level increases as one goes from Co to Ir

Electronic and magnetic structure of RENi{sub 2}Mn{sub x}-compounds (RE = rare earth, x = 0, 0.25, 0.5, 0.75, 1, 1.25) with respect to ErNi{sub 2}Mn{sub x}

Energy Technology Data Exchange (ETDEWEB)

Balinski, Kamil; Kuepper, Karsten [Department of Physics, Osnabrueck University (Germany); Chrobak, Artur [Department of Physics, University of Silesia in Katowice (Poland); Kuznetzsova, T.V.; Mushnikov, N.V.; Marchenkov, V.V. [Institute of Metal Physics, 620990 Ekaterinburg (Russian Federation)

2015-07-01

Rare earth (RE) and transition metal (T) compounds are research field since the 1960s. Because of huge magnetocalorical effect and giant magnetostriction the RE-T-compounds are excellent for applications like magnetic cooling or hydrogen storage devices. Besides of that RE-Ni{sub 2}-type of alloys are, due to the relatively simple crystal structure and the fact that Ni{sub 2} does not indicate any %behavior with result in an magnetic moment, excellent candidates for studies of magnetic behavior of RE's and their binding partners. The electronic structure of ErNi{sub 2}Mn{sub x} (x = 0, 0.25, 0.5, 0.75, 1, 1.25) is characterized by XPS and ResPES, the magnetic structure is investigated by SQUID and PPMS techniques, and resistivity measurements are made. Variation in Mn concentration revealed the position of Mn 3d-states at 1.7 eV. The XPS intensity at 1.7 eV can be correlated with the behavior of the Curie temperature and the resistivity. While similar RENi{sub 2}Mn{sub x}-systems, where RE had been replaced by Gd and Tb, highest resistivity, Curie temperature and the highest Mn 3d-valence band state intensity were observed at x = 0.5. ErNi{sub 2}Mn{sub x}-system behave different and show the mentioned maxima at x = 1.25.

94 β-Decay Half-Lives of Neutron-Rich _{55}Cs to _{67}Ho: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation.

Science.gov (United States)

Wu, J; Nishimura, S; Lorusso, G; Möller, P; Ideguchi, E; Regan, P-H; Simpson, G S; Söderström, P-A; Walker, P M; Watanabe, H; Xu, Z Y; Baba, H; Browne, F; Daido, R; Doornenbal, P; Fang, Y F; Gey, G; Isobe, T; Lee, P S; Liu, J J; Li, Z; Korkulu, Z; Patel, Z; Phong, V; Rice, S; Sakurai, H; Sinclair, L; Sumikama, T; Tanaka, M; Yagi, A; Ye, Y L; Yokoyama, R; Zhang, G X; Alharbi, T; Aoi, N; Bello Garrote, F L; Benzoni, G; Bruce, A M; Carroll, R J; Chae, K Y; Dombradi, Z; Estrade, A; Gottardo, A; Griffin, C J; Kanaoka, H; Kojouharov, I; Kondev, F G; Kubono, S; Kurz, N; Kuti, I; Lalkovski, S; Lane, G J; Lee, E J; Lokotko, T; Lotay, G; Moon, C-B; Nishibata, H; Nishizuka, I; Nita, C R; Odahara, A; Podolyák, Zs; Roberts, O J; Schaffner, H; Shand, C; Taprogge, J; Terashima, S; Vajta, Z; Yoshida, S

2017-02-17

The β-decay half-lives of 94 neutron-rich nuclei ^{144-151}Cs, ^{146-154}Ba, ^{148-156}La, ^{150-158}Ce, ^{153-160}Pr, ^{156-162}Nd, ^{159-163}Pm, ^{160-166}Sm, ^{161-168}Eu, ^{165-170}Gd, ^{166-172}Tb, ^{169-173}Dy, ^{172-175}Ho, and two isomeric states ^{174m}Er, ^{172m}Dy were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops of β-decay half-lives are observed at neutron-number N=97 for _{58}Ce, _{59}Pr, _{60}Nd, and _{62}Sm, and N=105 for _{63}Eu, _{64}Gd, _{65}Tb, and _{66}Dy. Features in the data mirror the interplay between pairing effects and microscopic structure. r-process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system.

Macrocyclic Gd(3+) complexes with pendant crown ethers designed for binding zwitterionic neurotransmitters.

Science.gov (United States)

Oukhatar, Fatima; Meudal, Hervé; Landon, Céline; Logothetis, Nikos K; Platas-Iglesias, Carlos; Angelovski, Goran; Tóth, Éva

2015-07-27

A series of Gd(3+) complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM(-1)  s(-1) at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by (1) H relaxometric titrations of the Gd(3+) complexes and by luminescence measurements on the Eu(3+) and Tb(3+) analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu(3+) complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non-amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tuberculosis Facts - Exposure to TB

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Tuberculosis (TB) Facts Exposure to TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

Tuberculosis Facts - Testing for TB

Science.gov (United States)

Tuberculosis (TB) Facts Testing for TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

DTA AND MOSSBAUER STUDIES IN RARE EARTH ORTHOFERRITES

Energy Technology Data Exchange (ETDEWEB)

Eibschuetz, M.; Gorodetsky, G.; Shtrikman, S.; Treves, D.

1963-11-15

Curie temperatures of 14 different orthoferrites with the chemical formula RFeO/sub 3/ (R = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were measured by differential thermal analysis. Hyperfine interactions of the Fe/ sup 57/ nucleus in the same materials were determined from their Mossbauer spectra. It is found that the quadrupole splitting with the exception of the case of Sm, isomer shift, Curie temperature, and internal field vary regularly with the ionic size of R. (auth)

Gibbs free energy of formation of liquid lanthanide-bismuth alloys

International Nuclear Information System (INIS)

Sheng Jiawei; Yamana, Hajimu; Moriyama, Hirotake

2001-01-01

The linear free energy relationship developed by Sverjensky and Molling provides a way to predict Gibbs free energies of liquid Ln-Bi alloys formation from the known thermodynamic properties of aqueous trivalent lanthanides (Ln 3(5(6+ ). The Ln-Bi alloys are divided into two isostructural families named as the LnBi 2 (Ln=La, Ce, Pr, Nd and Pm) and LnBi (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb). The calculated Gibbs free energy values are well agreed with experimental data

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.

Effect of Al2Gd on microstructure and properties of laser clad Mg–Al–Gd coatings

International Nuclear Information System (INIS)

Chen, Hong; Zhang, Ke; Yao, Chengwu; Dong, Jie; Li, Zhuguo; Emmelmann, Claus

2015-01-01

Highlights: • Mg–Al–Gd coatings with different Gd contents were fabricated by fiber laser cladding. • Chemical compositions and crystal structures of the second phases were characterized. • Dispersion of Al 2 Gd led to further grain refining and elevated mechanical properties. • Al 2 Gd improved high-temperature performances by preventing tiny liquation. - Abstract: In order to investigate the effects of Gd addition on the microstructures and properties of magnesium coatings, the Mg–7.5Al–xGd (x = 0, 2.5, 5.0 and 7.5 wt.%) coatings on cast magnesium alloy were fabricated by laser cladding with wire feeding. The results indicated that the gadolinium (Gd) addition led to the formation of a cubic Al 2 Gd phase as well as suppressed the precipitation of eutectic Mg 17 Al 12 phase. The laser clad coating containing nominally 7.5 wt.% Gd presented the highest microhardness, ultimate tensile strength and yield strength at both room temperature and high temperatures. The enhancement of heat resistant capacities was chiefly attributed to the existence of thermally stable Al 2 Gd particles, which prevented tiny liquation of eutectic phases along the grain boundaries and made great contributions on maintaining high yield ratio during high-temperature deformation

ERS/ECDC Statement: European Union standards for tuberculosis care, 2017 update.

Science.gov (United States)

Migliori, Giovanni Battista; Sotgiu, Giovanni; Rosales-Klintz, Senia; Centis, Rosella; D'Ambrosio, Lia; Abubakar, Ibrahim; Bothamley, Graham; Caminero, Jose Antonio; Cirillo, Daniela Maria; Dara, Masoud; de Vries, Gerard; Aliberti, Stefano; Dinh-Xuan, Anh Tuan; Duarte, Raquel; Midulla, Fabio; Solovic, Ivan; Subotic, Dragan R; Amicosante, Massimo; Correia, Ana Maria; Cirule, Andra; Gualano, Gina; Kunst, Heinke; Palmieri, Fabrizio; Riekstina, Vija; Tiberi, Simon; Verduin, Remi; van der Werf, Marieke J

2018-05-01

The International Standards for Tuberculosis Care define the essential level of care for managing patients who have or are presumed to have tuberculosis, or are at increased risk of developing the disease. The resources and capacity in the European Union (EU) and the European Economic Area permit higher standards of care to secure quality and timely TB diagnosis, prevention and treatment. On this basis, the European Union Standards for Tuberculosis Care (ESTC) were published in 2012 as standards specifically tailored to the EU setting. Since the publication of the ESTC, new scientific evidence has become available and, therefore, the standards were reviewed and updated.A panel of international experts, led by a writing group from the European Respiratory Society (ERS) and the European Centre for Disease Prevention and Control (ECDC), updated the ESTC on the basis of new published evidence. The underlying principles of these patient-centred standards remain unchanged. The second edition of the ESTC includes 21 standards in the areas of diagnosis, treatment, HIV and comorbidities, and public health and prevention.The ESTC target clinicians and public health workers, provide an easy-to-use resource and act as a guide through all the required activities to ensure optimal diagnosis, treatment and prevention of TB. The content of this work is copyright of the authors or their employers. Design and branding are copyright ©ERS 2018.

Experimental investigation and crystal-field modeling of Er{sup 3+} energy levels in GSGG crystal

Energy Technology Data Exchange (ETDEWEB)

Gao, J.Y., E-mail: jygao1985@sina.com [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Sun, D.L.; Zhang, Q.L. [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Wang, X.F. [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Liu, W.P.; Luo, J.Q.; Sun, G.H.; Yin, S.T. [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China)

2016-06-25

The Er{sup 3+}-doped Gd{sub 3}Sc{sub 2}Ga{sub 3}O{sub 12} (Er{sup 3+}:GSGG) single crystal, a excellent medium of the mid-infrared and anti-radiation solid state laser pumped by laser diode, was grown by Czochralski method successfully. The absorption spectra were measured and analyzed in a wider spectral wavelength range of 350–1700 nm at different temperatures of 7.6, 77, 200 and 300 K. The free-ions and crystal-field parameters were fitted to the experimental energy levels with the root mean square deviation of 9.86 cm{sup −1}. According to the crystal-field calculations, 124 degenerate energy levels of Er{sup 3+} in GSGG host crystals were assigned. The fitting results of free-ions and crystal-field parameters were compared with those already reported of Er{sup 3+}:YSGG. The results indicated that the free-ions parameters for Er{sup 3+} in GSGG host are similar to those in YSGG host crystals, and the crystal-field interaction of GSGG is weaker than that of YSGG, which may result in the better laser characterization of Er{sup 3+}:GSGG crystal. - Highlights: • The efficient diode-end-pumped laser crystal Er:GSGG has been grown successfully. • The absorption spectra of Er:GSGG have been measured in range of 350–1700 nm. • The fitting result is very well for the root mean square deviation is 9.86 cm{sup −1}. • The 124 levels of Er:GSGG have been assigned from the crystal-field calculations.

Tuberculosis Facts - You Can Prevent TB

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Tuberculosis (TB) Facts You Can Prevent TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination TB Facts: You Can Prevent TB What ...

Tuberculosis Facts - TB Can Be Treated

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Tuberculosis (TB) Facts TB Can Be Treated What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination Page 1 of 2 TB Facts: TB ...

A comparison of Gd-BOPTA and Gd-DOTA for contrast-enhanced MRI of intracranial tumours

International Nuclear Information System (INIS)

Colosimo, C.; Knopp, M.V.; Barreau, X.; Gerardin, E.; Kirchin, M.A.; Guezenoc, F.; Lodemann, K.P.

2004-01-01

A two-centre intra-individual crossover study was performed in 23 patients with suspected high-grade glioma or metastases to assess and compare the safety and enhancement characteristics of two different MRI contrast media (gadobenate dimeglumine, Gd-BOPTA and gadoterate meglumine, Gd-DOTA) at equivalent doses of 0.1 mmol/kg body weight. T1-weighted spin-echo (SE) and T2-weighted fast SE images were obtained before and T1-weighted images 0, 2, 4, 6, 8 and 15 min after injection. T1-weighted images with magnetisation transfer contrast were acquired 12 min after injection. Qualitative assessment by blinded, off-site readers (reader 1: 19 patients; reader 2: 21) and on-site investigators (23) revealed significant (P ≤0.005) overall preference for Gd-BOPTA over Gd-DOTA for contrast enhancement (Gd-BOPTA preferred in 18, 15 and 18 cases; Gd-DOTA in 0, 1 and 1 and no preference in 1, 5 and 4; off-site readers 1 and 2, and on-site investigators, respectively). A similar significant preference for Gd-BOPTA was expressed by off-site readers and on-site investigators for lesion-to-brain contrast, lesion delineation, internal lesion structure, and overall image preference. Quantitative assessment by off-site readers revealed significantly (p<0.05) greater lesion enhancement with Gd-BOPTA than with Gd-DOTA at all times from 2 min after injection. (orig.)

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).

Lanthanide phosphonates: Synthesis, thermal stability and magnetic characterization

Energy Technology Data Exchange (ETDEWEB)

Amghouz, Z., E-mail: amghouz.uo@uniovi.es [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Garcia, J.R.; Garcia-Granda, S. [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Clearfield, A. [Department of Chemistry, Texas A and M University, College Station, TX 77842-3012 (United States); Rodriguez Fernandez, J.; Pedro, I. de [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)

2012-09-25

Highlights: Black-Right-Pointing-Pointer Report of the complete series of lanthanide 1,4-phenylbis(phosphonate). Black-Right-Pointing-Pointer Synthesis under conventional hydrothermal synthesis or microwave-assisted hydrothermal synthesis. Black-Right-Pointing-Pointer Cation size is the key factor for the structural and particles size variations. Black-Right-Pointing-Pointer Thermal behaviour is characterized by unusual very high thermal stability. - Abstract: Series of novel organic-inorganic hybrids materials based on trivalent lanthanides (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and 1,4-phenylbis(phosphonate) obtained under hydrothermal conditions either by oven heat or microwave irradiation. The anhydrous compounds containing La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho, are isostructural. However, the compounds based on Y, Er, Tm, Yb, and Lu are hydrated and their structures have not yet been solved. The series of compounds are characterized by PXRD, TEM, SEM-EDX and thermal analyses (TG-MS and DSC). TEM study show a variable particles size with a minimum mean-particle size of ca. 30 nm. These compounds exhibit unusual very high thermal stability. The size of particles and the thermal stability are depending on lanthanide(III) cation features. All the investigated materials show paramagnetic behaviour. The magnetic susceptibility data follow a Curie-Weiss laws with paramagnetic effective moments in good agreement with those expected for Ln{sup 3+} free ions.

Peculiarity of component interaction in {l_brace}Y, Dy{r_brace}-Mn-Sn ternary systems

Energy Technology Data Exchange (ETDEWEB)

Romaka, V.V. [Department of Materials Engineering and Applied Physics, Lviv Polytechnic National University, Ustyyanovycha Str. 5, 79013 Lviv (Ukraine); Konyk, M. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine); Romaka, L., E-mail: romakal@franko.lviv.ua [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine); Pavlyuk, V. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine); Jan Dlugosz University, Institute of Chemistry, Environmental Protection and Biotechnology, al. Armii Krajowej 13/15, 42200 Czestochowa (Poland); Ehrenberg, H. [Institute for Complex Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Tkachuk, A. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya Str. 6, 79005 Lviv (Ukraine)

2011-07-14

Highlights: > {l_brace}Y, Dy{r_brace}-Mn-Sn ternary systems at 770 K are characterized by formation of stannides with general compositions RMn{sub 6}Sn{sub 6} and R{sub 4}Mn{sub 4}Sn{sub 7}. > The crystal structure of YMn{sub 6}Sn{sub 6} was determined by single crystal and powder diffraction methods. > Structural analysis showed that Dy{sub 4}Mn{sub 4}Sn{sub 7} compound is disordered. > Isostructural R{sub 4}Mn{sub 4}Sn{sub 7} compounds were also found with Gd, Tb, Ho, Er, Tm(confirmed), Yb, and Lu. - Abstract: The phase equilibria in the Y-Mn-Sn and Dy-Mn-Sn ternary systems were studied at 770 K by means of X-ray and metallographic analyses in the whole concentration range. Both Y-Mn-Sn and Dy-Mn-Sn systems are characterized by formation of two ternary compounds RMn{sub 6}Sn{sub 6} (MgFe{sub 6}Ge{sub 6}-type, space group P6/mmm) and R{sub 4}Mn{sub 4}Sn{sub 7} (Zr{sub 4}Co{sub 4}Ge{sub 7}-type, space group I4/mmm). The disorder in Dy{sub 4}Mn{sub 4}Sn{sub 7} compound was found by single crystal method. Compounds with the same type of structure were also found with Gd, Tb, Ho, Er, Tm (confirmed), Yb, and Lu and their lattice parameters were determined.

Exchange coupling and magnetic anisotropy in a family of bipyrimidyl radical-bridged dilanthanide complexes: density functional theory and ab initio calculations.

Science.gov (United States)

Zhang, Yi-Quan; Luo, Cheng-Lin; Zhang, Qiang

2014-05-05

The origin of the magnetic anisotropy energy barriers in a series of bpym(-) (bpym = 2,2'-bipyrimidine) radical-bridged dilanthanide complexes [(Cp*2Ln)2(μ-bpym)](+) [Cp* = pentamethylcyclopentadienyl; Ln = Gd(III) (1), Tb(III) (2), Dy(III) (3), Ho(III) (4), Er(III) (5)] has been explored using density functional theory (DFT) and ab initio methods. DFT calculations show that the exchange coupling between the two lanthanide ions for each complex is very weak, but the antiferromagnetic Ln-bpym(-) couplings are strong. Ab initio calculations show that the effective energy barrier of 2 or 3 mainly comes from the contribution of a single Tb(III) or Dy(III) fragment, which is only about one third of a single Ln energy barrier. For 4 or 5, however, both of the two Ho(III) or Er(III) fragments contribute to the total energy barrier. Thus, it is insufficient to only increase the magnetic anisotropy energy barrier of a single Ln ion, while enhancing the Ln-bpym(-) couplings is also very important. Copyright © 2014 Wiley Periodicals, Inc.

Thermodynamic calculation of Al-Gd and Al-Gd-Mg phase equilibria checked by key experiments

International Nuclear Information System (INIS)

Groebner, J.; Kevorkov, D.; Schmid-Fetzer, R.

2001-01-01

The binary Al-Gd and the ternary Al-Gd-Mg systems were calculated using the Calphad method. It is demonstrated that previous interpretation of ternary liquidus temperatures below 700 C must be related to other phase equilibria. The actual ternary liquidus temperatures are much higher, up to some 600 C above the previous interpretation in literature. They are widely governed by the high-melting compounds Al 2 Gd and Al 3 Gd with liquidus surfaces stretching far into the ternary system. A small number of key experiments in this work confirmed the calculated liquidus temperature and the phase relations. The available experimental data in literature fit excellently with the calculation in the binary Al-Gd system. In the ternary Al-Gd-Mg system, which is shown in several sections of the phase diagram, a good agreement can be observed too, considering the necessary reinterpretation of the liquidus temperatures suggested by Rokhlin et al. Ternary solubilities were not found experimentally. The ternary compound Al 4 GdMg (τ) forms in a ternary peritectic reaction at 761 C. (orig.)

Studies of the energy transfer processes from Er{sup 3+} and Ho{sup 3+} to Nd{sup 3+}, Tb{sup 3+} or Eu{sup 3+} in LiYF{sub 4} crystal and ZBLAN glass for the laser media optimization operating near 3{mu}m region; Estudos dos processos de transferencia de energia dos ions de Er{sup 3+} e Ho{sup 3+} para os ions de Nd{sup 3+}, Tb{sup 3+} e Eu{sup 3+} no cristal de LiYF{sub 4} e no vidro ZBLAN para a otimizacao de meios laser ativos que operam na regiao de 3{mu}m

Energy Technology Data Exchange (ETDEWEB)

Jagosich, Fabio Henrique

2006-07-01

The energy transfer processes (ET) from the {sup 4}I{sub 13/2}; {sup 4}I{sub 11/2} levels of Er{sup 3+} and {sup 5}I{sub 6} levels of Ho{sup 3+} ions in LiYF{sub 4} (YLF) crystal and ZBLAN glass to Nd{sup 3+}, Tb{sup 3+} or Eu{sup 3+} deactivators ions were studied. The micro parameters of these energy transfer processes were determined using the overlap integral method, and showed that Eu{sup 3+} ion is the best deactivator of the first excited state of the Ho{sup 3+} in YLF, and Nd{sup 3+} is the best deactivator of the Er{sup 3+} in YLF and ZBLAN materials. The 1.5 and 2.7{mu}m emissions of Er{sup 3+} and 2.1 and 2.9{mu}m fluorescence of Ho{sup 3+} were measured using short laser pulses excitations from a tunable OPO pumped 2w-Nd:YAG laser system. We proposed a criterion for discriminating the energy transfer processes assisted by excitation migration (diffusion or hopping) among donors. It was observed that diffusion model describes the ET process from the second excited state of the donor (Er{sup 3+} or Ho{sup 3+}) independently of the C{sub D-D}/C{sub D-A} ratio, while the hopping model can describe the ET process involving the first excited state of donor. We proposed a modification of the hopping model in order to describe the experimental results for systems having C{sub D-D}/C{sub D-A} {>=} 10. Using the ET parameters, we determined that the best systems for laser action at 3{mu}m are the Ho:Eu:YLF, Ho:Nd:YLF and Er:Nd:YLF systems. On the other hand, we found that Er{sup 3+} doped (1.5 mol%) ZBLAN glasses, single and co-doped with Nd{sup 3+}, Tb{sup 3+} or Eu{sup 3+}, do not show potential for laser action at 2.8{mu}m. The up-conversion processes were studied in Er:YLF systems as a function of the Er{sup 3+} concentration, and the excited state absorption (ESA) and up conversion by energy transfer (ETU) processes were discriminated using a time resolved fluorescence decays. It was observed that 980 nm is the most convenient wavelength for pumping the Er

Effect of Al{sub 2}Gd on microstructure and properties of laser clad Mg–Al–Gd coatings

Energy Technology Data Exchange (ETDEWEB)

Chen, Hong; Zhang, Ke; Yao, Chengwu [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Dong, Jie [National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Emmelmann, Claus [Institute of Laser and System Technologies, Hamburg University of Technology, Hamburg, 21073 (Germany)

2015-03-01

Highlights: • Mg–Al–Gd coatings with different Gd contents were fabricated by fiber laser cladding. • Chemical compositions and crystal structures of the second phases were characterized. • Dispersion of Al{sub 2}Gd led to further grain refining and elevated mechanical properties. • Al{sub 2}Gd improved high-temperature performances by preventing tiny liquation. - Abstract: In order to investigate the effects of Gd addition on the microstructures and properties of magnesium coatings, the Mg–7.5Al–xGd (x = 0, 2.5, 5.0 and 7.5 wt.%) coatings on cast magnesium alloy were fabricated by laser cladding with wire feeding. The results indicated that the gadolinium (Gd) addition led to the formation of a cubic Al{sub 2}Gd phase as well as suppressed the precipitation of eutectic Mg{sub 17}Al{sub 12} phase. The laser clad coating containing nominally 7.5 wt.% Gd presented the highest microhardness, ultimate tensile strength and yield strength at both room temperature and high temperatures. The enhancement of heat resistant capacities was chiefly attributed to the existence of thermally stable Al{sub 2}Gd particles, which prevented tiny liquation of eutectic phases along the grain boundaries and made great contributions on maintaining high yield ratio during high-temperature deformation.

Buffer layers and articles for electronic devices

Science.gov (United States)

Paranthaman, Mariappan P.; Aytug, Tolga; Christen, David K.; Feenstra, Roeland; Goyal, Amit

2004-07-20

Materials for depositing buffer layers on biaxially textured and untextured metallic and metal oxide substrates for use in the manufacture of superconducting and other electronic articles comprise RMnO.sub.3, R.sub.1-x A.sub.x MnO.sub.3, and combinations thereof; wherein R includes an element selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and A includes an element selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Ra.

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

International Nuclear Information System (INIS)

Lordello, A.R.; Abrao, A.

1979-01-01

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

HfO2 - rare earth oxide systems in the region with high content of rare earth oxide

International Nuclear Information System (INIS)

Shevchenko, A.V.; Lopato, L.M.

1982-01-01

Using the methods of annealing and hardenings (10 2 -10 4 deg/s cooling rate) and differential thermal analysis elements of state diagrams of HfO 2 - rare earth oxide (rare earths-La, Pr, Nd, Sm, Gd, Tb, Dy, Y, Er, Yb, Lu, Sc) systems from 1800 deg C up to melting in the range of 60-100 mol% rare earth oxide concentration were constructed. Regularities of HfQ 2 addition effect on high-temperature polymorphic transformations of rare earth oxides were studied. Results of investigation were discussed from viewpoint of crystal chemistry

Host markers in Quantiferon supernatants differentiate active TB from latent TB infection: preliminary report

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Walzl Gerhard

2009-05-01

Full Text Available Abstract Background Interferon gamma release assays, including the QuantiFERON® TB Gold In Tube (QFT have been shown to be accurate in diagnosing Mycobacterium tuberculosis infection. These assays however, do not discriminate between latent TB infection (LTBI and active TB disease. Methods We recruited twenty-three pulmonary TB patients and 34 household contacts from Cape Town, South Africa and performed the QFT test. To investigate the ability of new host markers to differentiate between LTBI and active TB, levels of 29 biomarkers in QFT supernatants were evaluated using a Luminex multiplex cytokine assay. Results Eight out of 29 biomarkers distinguished active TB from LTBI in a pilot study. Baseline levels of epidermal growth factor (EGF soluble CD40 ligand (sCD40L, antigen stimulated levels of EGF, and the background corrected antigen stimulated levels of EGF and macrophage inflammatory protein (MIP-1β were the most informative single markers for differentiation between TB disease and LTBI, with AUCs of 0.88, 0.84, 0.87, 0.90 and 0.79 respectively. The combination of EGF and MIP-1β predicted 96% of active TB cases and 92% of LTBIs. Combinations between EGF, sCD40L, VEGF, TGF-α and IL-1α also showed potential to differentiate between TB infection states. EGF, VEGF, TGF-α and sCD40L levels were higher in TB patients. Conclusion These preliminary data suggest that active TB may be accurately differentiated from LTBI utilizing adaptations of the commercial QFT test that includes measurement of EGF, sCD40L, MIP-1β, VEGF, TGF-α or IL-1α in supernatants from QFT assays. This approach holds promise for development as a rapid diagnostic test for active TB.

Treatment Outcomes of Patients with Multidrug-Resistant Tuberculosis (MDR- TB) Compared with Non-MDR-TB Infections in Peninsular Malaysia.

Science.gov (United States)

Elmi, Omar Salad; Hasan, Habsah; Abdullah, Sarimah; Mat Jeab, Mat Zuki; Ba, Zilfalil; Naing, Nyi Nyi

2016-07-01

Treating patients with multidrug-resistant tuberculosis (MDR-TB) strains is more complicated, complex, toxic, expensive, than treating patients with susceptible TB strains. This study aims to compare the treatment outcomes and potential factors associated between patients with MDR-TB and non MDR TB infections in peninsular Malaysia. This study was a retrospective cohort study. Data were collected from the medical records of all registered MDR-TB patients and Non-MDR-TB patients at five TB hospitals in peninsular Malaysia from January 2010 to January 2014. A total of 314 subjects were studied, including 105 MDR-TB cases and 209 non-MDR-TB. After TB treatment, 24.8% of the MDR-TB patients and 17.7% of non MDR TB relapsed; 17.1% of the MDR-TB patients and 16.3% of non MDR TB defaulted from TB treatment. A significant difference seen in treatment success rate 17.1% for MDR-TB; 63.1% for non MDR TB (P history of TB treatment, and presence of HIV infection.

Mycobacteria and TB

National Research Council Canada - National Science Library

Kaufmann, S. H. E. (Stephan H. E.); Hahn, Helmut

2003-01-01

.... Scientists investigating the epidemiology, immunology and molecular biology of TB or engaged in vaccine and drug development as well as physicians and social workers treating TB patients will benefit...

Lay beliefs of TB and TB/HIV co-infection in Addis Ababa, Ethiopia: a qualitative study

Directory of Open Access Journals (Sweden)

Frich Jan C

2011-08-01

Full Text Available Abstract Background Knowledge about lay beliefs of etiology, transmission and treatment of TB, and lay perceptions of the relationship between TB and HIV is important for understanding patients' health seeking behavior and adherence to treatment. We conducted a study to explore lay beliefs about TB and TB/HIV co-infection in Addis Ababa, Ethiopia. Findings We conducted a qualitative study using in-depth interviews with 15 TB/HIV co-infected patients and 9 health professionals and focus group discussions with 14 co-infected patients in Addis-Ababa, Ethiopia. We found that a predominant lay belief was that TB was caused by exposure to cold. Excessive sun exposure, exposure to mud, smoking, alcohol, khat and inadequate food intake were also reported as causes for TB. Such beliefs initially led to self-treatment. The majority of patients were aware of an association between TB and HIV. Some reported that TB could transform into HIV, while others said that the body could be weakened by HIV and become more susceptible to illnesses such as TB. Some patients classified TB as either HIV-related or non-HIV-related, and weight loss was a hallmark for HIV-related TB. The majority of patients believed that people in the community knew that there was an association between TB and HIV, and some feared that this would predispose them to HIV-related stigma. Conclusion There is a need for culturally sensitive information and educational efforts to address misperceptions about TB and HIV. Health professionals should provide information about causes and treatment of TB and HIV to co-infected patients.

Tuberculosis Facts - TB and HIV/AIDS

Science.gov (United States)

Tuberculosis (TB) Facts TB and HIV/AIDS What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

Interaction of xenon difluoride with the fluorocomplexes of lanthanides and rubidium of the Rb/sub 3/M/sup 3/F/sub 6/ composition

Energy Technology Data Exchange (ETDEWEB)

Goryachenkov, S.A.; Fadeeva, N.E.; Kiselev, Yu.M.; Martynenko, L.I.; Spitsyn, V.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

The possibility of preparing rubidium fluorocomplexes of tetravalent lanthanides of the Rb/sub 3/M/sup 4/F/sub 7/ composition from Rb/sub 3/M/sup 3/F/sub 6/ (M/sup 3/=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb) with XeF/sub 2/ has been studied. By the DTA method it is shown that Ce and Pr salts are fluorinated respectively at approximately 100 and approximately 235 deg C with a noticeable exoeffect. Tb and Dy salts fluorination proceeds with considerable kinetic difficulties. The fluorination products composition, Rb/sub 3/M/sup 4/F/sub 7/ (M/sup 4/=Ce, Pr, Tb, Dy) is confirmed by the methods of chemical, IR-spectroscopic and X-ray phase analyses. XeF/sub 2/ interaction with Rb/sub 3/M/sup 3/F/sub 6/ salts of other lanthanides up to 400 deg C has not been observed.

Measurement of Gd content in (U,Gd)O2 using thermal gravimetric analysis

International Nuclear Information System (INIS)

Kim, Keon Sik; Yang, Jae Ho; Kang, Ki Won; Song, Kun Woo; Kim, Gil Moo

2004-01-01

We propose a simple and precise method for measuring the Gd content in the (U,Gd)O 2 pellet by only measuring the weight variation of the pellet during thermal heat treatment in air. The (U,Gd)O 2 fuel pellets were oxidized at 475 deg. C, subsequently heat treated at 1300 deg. C, and then cooled to room temperature in air. The accompanying weight variations were measured using thermo gravimetric analysis (TGA). The measured weight variations were mathematically analyzed with reference to the successive phase reactions during the heat treatment. This method provides an advantage in that the rare-earth element content including Gd can be measured using relatively simple equipment such as an electric furnace and a balance

CW laser properties of Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG mixed crystals

Science.gov (United States)

Di, J. Q.; Xu, X. D.; Li, D. Z.; Zhou, D. H.; Wu, F.; Zhao, Z. W.; Xu, J.; Tang, D. Y.

2011-10-01

Three mixed crystals, Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG, were grown by Czochralski method. We report the continuous-wave (CW) Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG laser operation under laser diode pumping. The maximum output powers are 4.11, 5.31, and 7.47 W, with slope efficiency of 73.0, 55.3, and 57.1%, respectively. With replacing Lu3+ or Y3+ ions with large Gd3+ ions, the pump efficiency increases.

Cross-relaxation solid state lasers

International Nuclear Information System (INIS)

Antipenko, B.M.

1989-01-01

Cross-relaxation functional diagrams provide a high quantum efficiency for pumping bands of solid state laser media and a low waste heat. A large number of the cross-relaxation mechanisms for decay rare earth excited states in crystals have been investigated. These investigations have been a starting-point for development of the cross-relaxation solid state lasers. For example, the cross-relaxation interactions, have been used for the laser action development of LiYF 4 :Gd-Tb. These interactions are important elements of the functional diagrams of the 2 μm Ho-doped media sensitized with Er and Tm and the 3 μm Er-doped media. Recently, new efficient 2 μm laser media with cross-relaxation pumping diagrams have been developed. Physical aspects of these media are the subject of this paper. A new concept of the Er-doped medium, sensitized with Yb, is illustrated

In vivo radiochemical properties of Tb-149: A new radiolanthanide for targeted cancer therapy

International Nuclear Information System (INIS)

Allen, B.J.; Beyer, G.J.; Morel, C.H.; Aleksandrova, Y.; Jahn, S.

1996-01-01

Full text: 149 Tb (4.15 h) decays by the emission of both 3.9 MeV alpha particles (17% branching) and positrons (4% branch), and uniquely combines both therapeutic and PET diagnostic properties. In this paper we report the production route, systemic studies of radio-lanthanides with ethylenediaminetetra methylene phosphonate (EDTMP) ligand, and the first 149 Tb phantom studies using PET. The radio-lanthanides used in this study were produced at the ISOLDE (isotope separator on-line) facility at CERN. They are produced carrier free, isotopically and chemically separated (isobaric separation using cation exchange chromatography) in a form suitable for protein labelling. Batches up to 20 mCi of 1 4 9T b are available. We have established relationships between biokinetics, EDTMP concentration, and the ionic radius of the radiolanthanide used. The tumour to liver ratio in mice reaches a maximum value at 1 mM 10 mM and decreases from 10 by almost two decades according to the ionic radius of the lanthanide. For Tb, a tumour to liver ratio of 5 can be obtained, similar to Gd. No significant differences in the uptake in bone for all lanthanides in the EDTMP system were observed. A fast blood clearance allows clear bone images to be obtained via PET at 60-90 min post-injection, as shown with rabbits using 142 Sm-EDTMP. The first phantom PET studies with 149 Tb are also reported. We conclude that the fast biokinetics and the alpha decay mode open up new possibilities for a more efficient endo-radionuclide therapy using EDTMP. The high purity of the 149T b (isotopically separated and carrier free) produced in this way makes it very suitable for the labelling of octretides

Peculiar features of thermal emission of GdB4 and GdB6 single crystals

International Nuclear Information System (INIS)

Ostrovskij, E.K.; Taran, A.A.; Kovalev, A.V.; Tkachenko, V.F.; Dudnik, E.M.; Matvienko, A.A.

1990-01-01

Thermoemission parameters of single crystals (410) GdB 4 and (110) GdB 6 are studied. Work function is calculated by total current. It is stated that work function of GdB 6 within temperature range of 1500-1880 K after 80 h of annealing varies from 2.95 to 3.10 eV practically with the same temperature coefficient as GdB 4 , i.e. 4.1x10 -4 eV/K. It is shown that single crystal gadolinium hexaboride during the high-temperature annealing in the surface region (∼70 mm) is transformed into gadolinium tetraboride. Influence of free air has been first studied on the GdB 4 emissivity which is determined to increase to p=1.3x10 -2 Pa within the range of T=1640-1840 K

The role of antiretroviral therapy in reducing TB incidence and mortality in high HIV-TB burden countries

Directory of Open Access Journals (Sweden)

Anthony D Harries

2016-03-01

Full Text Available With the adoption of the new Sustainable Development Goals in 2016, all countries have committed to end the tuberculosis (TB epidemic by 2030, defined as dramatic reductions in TB incidence and mortality combined with zero TB-induced catastrophic costs for families. This paper explores how antiretroviral therapy (ART in high HIV-TB burden countries may help in reducing TB incidence and mortality and thus contribute to the ambitious goal of ending TB. ART in people living with HIV has a potent TB preventive effect, with this being most apparent in those with the most advanced immunodeficiency. Early ART also significantly reduces the risk of TB, and with new World Health Organization guidance released in 2015 about initiating ART in all persons living with HIV irrespective of CD4 count, there is the potential for enormous benefit at the population level. Already, several countries with high HIVTB burdens have seen dramatic declines in TB case notification rates since ART scale up started in 2004. In patients already diagnosed with HIV-associated TB, mortality can be significantly decreased by ART, especially if started within 2–8 weeks of anti-TB treatment. The benefits of ART on TB incidence and TB mortality can be further augmented respectively by the addition of isoniazid preventive therapy and cotrimoxazole preventive therapy. These interventions must be effectively implemented and scaled up in order to end the TB epidemic by 2030.

The effect of Gd doping on the electrical and photoelectrical properties of Gd:ZnO/p-Si heterojunctions

Energy Technology Data Exchange (ETDEWEB)

Baturay, Silan [Department of Physics, Faculty of Science, Dicle University, 21280 Diyarbakir (Turkey); Ocak, Yusuf Selim, E-mail: yusufselim@gmail.com [Department of Science, Faculty of Education, Dicle University, 21280 Diyarbakir (Turkey); Science and Technology Application and Research Center, Dicle University, 21280 Diyarbakir (Turkey); Kaya, Derya [Department of Physics, Institute of Natural Applied Sciences, Dicle University, 21280 Diyarbakir (Turkey)

2015-10-05

Highlights: • Undoped and Gd doped ZnO thin films were deposited onto p-Si semiconductor. • The Gd:ZnO/p-Si heterojunctions were compared with undoped ZnO/p-Si heterojunction. • A strong effect of Gd doping on the performance of the devices were reported. - Abstract: Undoped ZnO thin films, as well as 1%, 3% and 5% Gd-doped ZnO films, were deposited on p-type Si using spin coating. The structural properties of these thin films were analysed using X-ray diffraction, and the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the Gd:ZnO/p-Si heterojunctions were compared with those of the undoped ZnO/p-Si heterojunctions. We found that Gd doping had a strong effect on the performance of the devices, and that the Gd:ZnO/p-Si heterojunctions formed with 1% Gd-doped ZnO were the most strongly rectifying, and had the highest barrier height and the lowest series resistance. Furthermore, the I–V measurements of the 1% Gd-doped ZnO/p-Si heterojunction exhibited the strongest response to light.

Stop TB in My Lifetime: A Call for a World Free of TB - World TB Day 2013

Centers for Disease Control (CDC) Podcasts

2012-03-12

In this podcast Dr. Kenneth Castro, Director of the Division of Tuberculosis Elimination, discusses World TB Day, the 2013 slogan and theme.  Created: 3/12/2012 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 3/13/2012.

Thermally stimulated properties in ZnSe:Tb and ZnSe:(Mn, Tb) phosphors

Science.gov (United States)

Mishra, A. K.; Mishra, S. K.; Pandey, S. P.; Lakshmi Mishra, Kshama

2018-02-01

Thermoluminescence studies were performed of ZnSe:Tb and ZnSe:(Mn, Tb) phosphors. A method of preparation for ZnSe phosphors doped with Tb and (Mn, Tb) has been discussed. The thermoluminescence (TL) properties of these phosphors have been studied from 100 to 370 K temperature after exciting by UV radiation (365 nm) at three uniform heating rates 0.4, 0.6 and 0.9 K/s. The trapping parameters like trap depth, lifetime of electrons and capture cross-section have also been determined using various methods.

Improved sensitivity for W-band Gd(III)-Gd(III) and nitroxide-nitroxide DEER measurements with shaped pulses

Science.gov (United States)

Bahrenberg, Thorsten; Rosenski, Yael; Carmieli, Raanan; Zibzener, Koby; Qi, Mian; Frydman, Veronica; Godt, Adelheid; Goldfarb, Daniella; Feintuch, Akiva

2017-10-01

Chirp and shaped pulses have been recently shown to be highly advantageous for improving sensitivity in DEER (double electron-electron resonance, also called PELDOR) measurements due to their large excitation bandwidth. The implementation of such pulses for pulse EPR has become feasible due to the availability of arbitrary waveform generators (AWG) with high sampling rates to support pulse shaping for pulses with tens of nanoseconds duration. Here we present a setup for obtaining chirp pulses on our home-built W-band (95 GHz) spectrometer and demonstrate its performance on Gd(III)-Gd(III) and nitroxide-nitroxide DEER measurements. We carried out an extensive optimization procedure on two model systems, Gd(III)-PyMTA-spacer-Gd(III)-PyMTA (Gd-PyMTA ruler; zero-field splitting parameter (ZFS) D ∼ 1150 MHz) as well as nitroxide-spacer-nitroxide (nitroxide ruler) to evaluate the applicability of shaped pulses to Gd(III) complexes and nitroxides, which are two important classes of spin labels used in modern DEER/EPR experiments. We applied our findings to ubiquitin, doubly labeled with Gd-DOTA-monoamide (D ∼ 550 MHz) as a model for a system with a small ZFS. Our experiments were focused on the questions (i) what are the best conditions for positioning of the detection frequency, (ii) which pump pulse parameters (bandwidth, positioning in the spectrum, length) yield the best signal-to-noise ratio (SNR) improvements when compared to classical DEER, and (iii) how do the sample's spectral parameters influence the experiment. For the nitroxide ruler, we report an improvement of up to 1.9 in total SNR, while for the Gd-PyMTA ruler the improvement was 3.1-3.4 and for Gd-DOTA-monoamide labeled ubiquitin it was a factor of 1.8. Whereas for the Gd-PyMTA ruler the two setups pump on maximum and observe on maximum gave about the same improvement, for Gd-DOTA-monoamide a significant difference was found. In general the choice of the best set of parameters depends on the D

Synthesis and Characterization of Hollow Magnetic Alloy (GdNi2, Co5Gd Nanospheres Coated with Gd2O3

Directory of Open Access Journals (Sweden)

Wang Li

2014-01-01

Full Text Available Uniform magnetic hollow nanospheres (GdNi2, Co5Gd coated with Gd2O3 have been successfully prepared on a large scale via a urea-based homogeneous precipitation method using silica (SiO2 spheres as sacrificed templates, followed by subsequent heat treatment. Nitrogen sorption measurements and scanning electron microscope reveal that these hollow-structured magnetic nanospheres have the mesoporous shells that are composed of a large amount of uniform nanoparticles. After reduction treatment, these nanoparticles exhibit superparamagnetism that might have potential applications in medicine. Furthermore, the developed synthesis route may provide an important guidance for the preparation of other multifunctional hollow spherical materials.

Giant magnetocaloric effect in Gd5(Si2Ge2 alloy with low purity Gd

Directory of Open Access Journals (Sweden)

Cleber Santiago Alves

2004-12-01

Full Text Available Gd5(Ge1-xSi x, x < 4 based alloys are potential candidates for magnetic refrigeration in the range ~20 - ~290 K. However, one of the greatest obstacles for the use of that technology in large scale is the utilization of high pure Gd metal (99.99 wt. (% to produce the GdGeSi alloys, since the impurity elements decrease the intensity of the magnetocaloric effect (EMC¹. In this work, we prove that annealing of the Gd5Ge2Si2 can promote remarkable values for the EMC in comparison to those obtained for the alloy with high pure Gd. Also, the as cast alloy and the annealed alloy are not monophasic, but have at least two crystalline phases in their microstructure. Results for X-ray analysis, optical and electronic microscopy and magnetization measurements are reported.

Phase-Transition and Magnetic Moment of the Gd3+ Ion in the Gd2Fe17 Compound

Institute of Scientific and Technical Information of China (English)

HAO Yan-Ming; FU Bin; ZHOU Yan; ZHAO Miao

2009-01-01

The structure and magnetic phase transitions of the Gd2Fe17 compound are investigated by using a differential thermal/thermogravimetric analyzer, x-ray diffraction, and magnetization measurements. The result shows that there are two phase structures for the Gd2Fe17 compound: the hexagonal Th2Ni17-type structure at high tem-peratures (above 1243℃), and the rhombohedrai Th2Zn17-type structure, respectively. A method to measure the magnetic moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound is presented. The moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound from 77 to 500 K are measured in this way with a vibrating sample magnetometer. A detailed discussion is presented.

Coloring problem and magnetocaloric effect of Gd{sub 3}Co{sub 2.2}Si{sub 1.8}

Energy Technology Data Exchange (ETDEWEB)

Yao, Jinlei, E-mail: materyao@gmail.com [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Morozkin, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Mozharivskyj, Yurij [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada)

2013-02-15

Highlights: Black-Right-Pointing-Pointer Gd{sub 3}Co{sub 2.2}Si{sub 1.8} adopts the Er{sub 3}Ge{sub 4} structure (space group Cmcm). Black-Right-Pointing-Pointer Si and Co show site preference. Black-Right-Pointing-Pointer The electronic factors determine the site occupation of Si and Co. Black-Right-Pointing-Pointer Gd{sub 3}Co{sub 2.2}Si{sub 1.8} order ferromagnetically below 172 K. - Abstract: The Gd{sub 3}Co{sub 2.2}Si{sub 1.8} compound was synthesized by arc melting the constituent elements and subsequent annealing at 1070 K for 120 h. It adopts the Dy{sub 3}Co{sub 2.2}Si{sub 1.8}-type structure with the space group Cmcm and the unit cell parameters of a = 4.1176(7) A, b = 10.305(2) A, c = 12.778(2) A and V = 542.2(2) A{sup 3}. The Co and Si atoms preferentially occupy the 8f and 4a/4c sites, respectively. The atomic electronegativity and electron density at a given site determine its site occupation, according to the analysis of the electronic structure. Gd{sub 3}Co{sub 2.2}Si{sub 1.8} orders ferromagnetically with the Curie temperature of 172 K. The isothermal magnetic entropy change, -{Delta}S{sub m}, reaches the maximum value of 7.09 J/kg K at 170 K for a field change of 0-50 kOe.

Phantom and animal studies of a new hepatobiliary agent for MR imaging: comparison of Gd-DTPA-DeA with Gd-EOB-DTPA.

Science.gov (United States)

Yoshikawa, Kohki; Inoue, Yusuke; Akahane, Masaaki; Shimada, Morio; Itoh, Sayaka; Seno, Atsushi; Hayashi, Sanshin

2003-08-01

To investigate the characteristics of Gd-DTPA-DeA as a hepatobiliary contrast agent for MR imaging in comparison with those of Gd-EOB-DTPA. We undertook phantom experiments to assess T1 relaxivity for Gd-DTPA-DeA, Gd-EOB-DTPA, and Gd-DTPA in human plasma. For Gd-DTPA-DeA and Gd-EOB-DTPA, we evaluated the contrast effect in rats using an SPGR sequence. The contrast ratios of liver and abdominal aorta were measured up to 21 minutes after intravenous administration of the agents. Visualization of the bile duct and renal pelvis was also assessed. In human plasma, T1 relaxivity was similar for Gd-DTPA-DeA and Gd-EOB-DTPA, and higher than those for Gd-DTPA. Whereas the contrast ratio of liver peaked about five minutes after the injection of Gd-EOB-DTPA and was followed by a subsequent decline, a continuous rise was shown for Gd-DTPA-DeA, resulting in a larger maximal contrast effect. Contrast ratios of the abdominal aorta were larger for Gd-DTPA-DeA. Biliary excretion was observed for both agents but occurred earlier with Gd-EOB-DTPA. While renal excretion was shown for all rats three minutes after the injection of Gd-EOB-DTPA, it was not observed for Gd-DTPA-DeA. Gd-DTPA-DeA may be used as a hepatobiliary contrast agent and shows different pharmacokinetics from Gd-EOB-DTPA. Copyright 2003 Wiley-Liss, Inc.

The production and use of a 148Gd charged particle target in a spectroscopic study of 147Gd

International Nuclear Information System (INIS)

Massey, T.N.

1988-01-01

This thesis discusses the nuclear structure of 147 Gd elucidated by the neutron pickup reactions (p,d), (d,t) and ( 3 He,α) on the unstable 148 Gd target. The neutron pickup reaction on 148 Gd probes the two-particle-one-hole states by the pickup of neutrons in the shell model orbitals below the N = 82 gap and one-particle states by pickup of neutrons in shell model orbitals above the N = 82 gap. Our experiments will provide information on the location of neutron single-particle energies which can be used for shell-model calculations in the 146 Gd region. The 2-particle-1-hole (2p-1h) states which are probed directly by the neutron transfer reaction in the experiments with the 148 Gd target, will bear indirectly on the energies of one-hole states in 145 Gd. They will also provide information on the strongest single-particle states in 147 Gd because all the single-particle states in the 148 Gd target are partially occupied because of the mixing by the pairing interaction. 107 refs., 23 figs., 20 tabs

Questions and Answers about TB

Science.gov (United States)

... disease. Introduction Testing and Treatment TB Disease Glossary Introduction Introduction What is TB? Why is TB still ... chest x-ray is made by exposing a film to x-rays that pass through the chest. ...

Structure and physical properties of RT{sub 2}Cd{sub 20} (R=rare earth, T=Ni, Pd) compounds with the CeCr{sub 2}Al{sub 20}-type structure

Energy Technology Data Exchange (ETDEWEB)

Burnett, V.W.; Yazici, D.; White, B.D. [Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093 (United States); Dilley, N.R. [Quantum Design, 6325 Lusk Boulevard, San Diego, CA 92121 (United States); Friedman, A.J.; Brandom, B. [Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093 (United States); Maple, M.B., E-mail: mbmaple@physics.ucsd.edu [Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093 (United States)

2014-07-01

Eleven new compounds, R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) and R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm), were grown as single crystals in high temperature cadmium-rich solutions. They crystallize in the cubic CeCr{sub 2}Al{sub 20}-type structure (Fd3{sup ¯}m, Z=8) as characterized by measurements of powder X-ray diffraction. Electrical resistivity, magnetization, and specific heat measurements were performed on R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals. Whereas YNi{sub 2}Cd{sub 20} and LaNi{sub 2}Cd{sub 20} exhibit unremarkable metallic behavior, when magnetic moments from localized 4f electron states (Gd{sup 3+}–Tb{sup 3+}) are embedded into this host, they exhibit ferromagnetic order with values of the Curie temperature T{sub C} for R Ni{sub 2}Cd{sub 20} (R=Gd, and Tb) which scale with the de Gennes factor. - Graphical abstract: Specific heat divided by temperature C/T vs. T for single crystals of R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Gd, and Tb). Left inset: Low temperature C/T vs. T{sup 2} for LaNi{sub 2}Cd{sub 20}. The solid line represents a linear fit of the data. Right inset: Low-temperature C/T data vs. T for R=Ce–Nd, Gd, and Tb; magnetic ordering temperatures are indicated by arrows. - Highlights: • R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals synthesized for the first time. • R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm) single crystals synthesized for the first time. • Single crystals are of good metallurgical quality (large RRR values). • NdNi{sub 2}Cd{sub 20} orders antiferromagnetically at T{sub N}=1.5 K. • R Ni{sub 2}Cd{sub 20} (R=Sm, Gd, Tb) order ferromagnetically.

Rare Earth Chalcogels NaLnSnS4 (Ln = Y, Gd, Tb) for Selective Adsorption of Volatile Hydrocarbons and Gases

KAUST Repository

Edhaim, Fatimah; Rothenberger, Alexander

2017-01-01

that the new materials have pores in the macro (above 50 nm) and meso (2–50 nm) regions. These aerogels show higher adsorption of toluene vapor over cyclohexane vapor and CO2 over CH4 or H2. The notable adsorption capacity for toluene (NaYSnS4: 1108 mg·g–1; NaGdSn

Rab7a modulates ER stress and ER morphology.

Science.gov (United States)

Mateus, Duarte; Marini, Elettra Sara; Progida, Cinzia; Bakke, Oddmund

2018-05-01

The Endoplasmic Reticulum (ER) is a membranous organelle with diverse structural and functional domains. Peripheral ER includes interconnected tubules, and dense tubular arrays called "ER matrices" together with bona fide flat cisternae. Transitions between these states are regulated by membrane-associated proteins and cytosolic factors. Recently, the small GTPases Rab10 and Rab18 were reported to control ER shape by regulating ER dynamics and fusion. Here, we present evidence that another Rab protein, Rab7a, modulates the ER morphology by controlling the ER homeostasis and ER stress. Indeed, inhibition of Rab7a expression by siRNA or expression of the dominant negative mutant Rab7aT22 N, leads to enlargement of sheet-like ER structures and spreading towards the cell periphery. Notably, such alterations are ascribable neither to a direct modulation of the ER shaping proteins Reticulon-4b and CLIMP63, nor to interactions with Protrudin, a Rab7a-binding protein known to affect the ER organization. Conversely, depletion of Rab7a leads to basal ER stress, in turn causing ER membrane expansion. Both ER enlargement and basal ER stress are reverted in rescue experiments by Rab7a re-expression, as well as by the ER chemical chaperone tauroursodeoxycholic acid (TUDCA). Collectively, these findings reveal a new role of Rab7a in ER homeostasis, and indicate that genetic and pharmacological ER stress manipulation may restore ER morphology in Rab7a silenced cells. Copyright © 2018 Elsevier B.V. All rights reserved.

Magnetic properties of ball-milled TbFe2 and TbFe2B

Indian Academy of Sciences (India)

Unknown

1. Introduction. The RFe2 (R = rare earth) Laves phase compounds are known to possess large cubic anisotropy (Clark et al 1972) and highest Curie temperature (TC) of all RT2 compounds. (T = transition metal). RFe2 ... TbFe2 and TbFe2B were prepared by arc melting the high pure elements (Tb and B, 99⋅9% purity; Fe, ...

Radiation characteristics of GD-2 fuel

International Nuclear Information System (INIS)

Chrapciak, V.

2008-01-01

The assembly WWER-440 type Gd-2 has radial profile of enrichment and has 6 pins with Gd 2 O 3 . The maximal enrichment is 4.4%. Some analyses are done for assembly with flat enrichment (4.4%) and without Gd 2 O 3 . In this article are compared some characteristics (decay heat, some nuclide concentration, photon and gamma sources) for real Gd-2 assembly and for flat 4.4% assembly. The TRITON module (in SCALE 5.1) was used. (Author)

Evaluation of Gd and Gd159 as new approaches for cancer treatment

International Nuclear Information System (INIS)

Galvao, I.; Neves, M.J.

2011-01-01

Metal compounds have shown many biological activities and have been successfully used as anticancer agents such cisplatin. Actually gadolinium (Gd) complexed with a porphyrin Motexafin (MGd) has been investigated as redox-active compound for treatment of cancer. 1 59G d decays by beta emission with an energy of 970 keV and half-life of 18.59 hours. The de-excitation can be via gamma ray and internal conversion electron emission followed by auger electrons and x rays. Considering all of this 1 59G d could be a interesting radionuclide to be as a radio therapeutical agent. The aims of this works were to evaluate the cytotoxicity of Gd and 1 59G d on malignant brain tumors such as glioblastoma multiform, the most frequent brain tumors which has a very poor prognosis. For this purpose, it was used human glioblastoma cell lines T98 (mutant p53) and U87 (wild-type p53) to investigate the cytotoxicity of gadolinium on cell metabolism by MTT assay and also morphological changes, chromatin condensation by DAPI assay and ROS generation. Gadolinium was able to decrease cell viability, the cells presented morphological changes like round shapes and blebs formation after cell treatment with 5x10 -6 M of Gd. Nuclear changing and ROS generation occurred in a dose dependent way indicating the cytotoxic effect of Gd. Treatment with 1 59G d increased all of changes observed with treatment with Gd. These results state for an additive effect of metal toxicity and radioactivity inducing ROS generation as the main mechanism of anti tumoral action of 1 59G d. The results obtained indicated that the radioactive analogues of Gd have increased cytotoxic effects and gadolinium can be a metal of choice for development of new drugs for cancer treatment. (author)

Promising therapy of XDR-TB/MDR-TB with thioridazine an inhibitor of bacterial efflux pumps

DEFF Research Database (Denmark)

Amaral, L; Martins, M; Viveiros, M

2008-01-01

-TB) - a M. tuberculosis organism that is resistant to the most effective second line drugs available for the treatment of TB. This review provides detailed, significant evidence that supports the use of an old neuroleptic compound, thioridazine (TZ), for the management of MDR-TB and XDR-TB infections...... therapy predictably ineffective and death is inevitable, compassionate therapy with TZ should be contemplated. The risks are small and the rewards great....

GdF Suez, the real energy champion;GdF Suez, le vrai champion de l'energie

Energy Technology Data Exchange (ETDEWEB)

Dupin, L.

2010-09-15

During summer 2010, France discovered that she owned a second energy giant, GdF Suez, ranked number two as a power producer just behind EdF, but world number one in the energy domain thanks to the taking over of International Power (UK) in 2010. Until now, GdF Suez and EdF were confronting with each other in a fair game, keeping their respective seizure on their historical monopolies, gas for GdF Suez and electricity for EdF. From now onward the two giants have started an open fight on all markets, with the exception of nuclear energy for which the French government continues to favour EdF. This paper recalls the main steps of the last 15 years of GdF Suez progress, from the Suez investment bank in 1995 to the merger with GdF in 2008 and the acquisition of International Power in 2010. Then it makes a comparative portrait of both GdF Suez and EdF energy groups with their respective advantages and, finally, it ends with an interview of G. Mestrallet, president of GdF Suez who explains the strategy of his group. (J.S.)

Detectemos la TB. Tratemos la TB. Trabajemos juntos para eliminar la TB. (Find TB. Treat TB. Working together to eliminate TB.)

Centers for Disease Control (CDC) Podcasts

2014-02-26

Este podcast trata sobre el Día Mundial de la Tuberculosis y el tema de los CDC para el año 2014.  Created: 2/26/2014 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 2/26/2014.

Experimental MR imaging with Gd-DOTA: Preliminary results

International Nuclear Information System (INIS)

Schouman-Claeys, E.; Kien, P.; Caille, J.M.; Bonnemain, B.; Frija, G.

1986-01-01

To evaluate the paramagnetic properties of a new gadolinium chelate, Gd-DOTA, in vitro and in vivo MR imaging was performed with a 0.5-T supraconductive magnet. The in vitro study consisted in measuring the MR signal obtained with various concentrations of Gd-DOTA and Gd-DTPA in different solutions. Potentialization of the paramagnetic properties of both DOTA and DTPA can be achieved by deuterium, glycerol, and protein solutions. The in vivo study was performed in rabbits with various experimental lesions. Enhancement of anatomic details was obtained with both Gd-DOTA and Gd-DTPA. There was no significant difference between Gd-DOTA and Gd-DTPA, both for in vitro and in vivo experiments. Gd-DOTA appears to be a potential paramagnetic agent for MR imaging

Protective effect of catechin in type I Gaucher disease cells by reducing endoplasmic reticulum stress

International Nuclear Information System (INIS)

Lee, Yea-Jin; Kim, Sung-Jo; Heo, Tae-Hwe

2011-01-01

Highlights: → Catechin reduces the expression level of ER stress marker protein in type I Gaucher disease cells. → Catechin induces the proliferation rate of GD cells similar levels to normal cells. → Catechin improves wound healing activity. → Catechin-mediated reductions in ER stress may be associated with enhanced cell survival. → We identified catechin as a protective agent against ER stress in GD cells. -- Abstract: Gaucher disease (GD) is the most common lysosomal storage disorder (LSD) and is divided into three phenotypes, I, II, and III. Type I is the most prevalent form and has its onset in adulthood. The degree of endoplasmic reticulum (ER) stress is one of the factors that determine GD severity. It has recently been reported that antioxidants reduce ER stress and apoptosis by scavenging the oxidants that cause oxidative stress. For this report, we investigated the possibility that catechin can act on type I GD patient cells to alleviate the pathogenic conditions of GD. We treated GD cells with catechin and examined the expression level of GRP78/BiP (an ER stress marker) by western blots and fluorescence microscopy, the proliferation rate of GD cells, and scratch-induced wound healing activity. Our results show that catechin reduces the expression level of GRP78/BiP, leads to cell proliferation rates of GD cells similar levels to normal cells, and improves wound healing activity. We conclude that catechin protects against ER stress in GD cells and catechin-mediated reductions in ER stress may be associated with enhanced cell survival.

Protective effect of catechin in type I Gaucher disease cells by reducing endoplasmic reticulum stress

Energy Technology Data Exchange (ETDEWEB)

Lee, Yea-Jin [Department of Biotechnology, Hoseo University, Baebang, Asan, Chungnam, 336-795 (Korea, Republic of); Kim, Sung-Jo, E-mail: sungjo@hoseo.edu [Department of Biotechnology, Hoseo University, Baebang, Asan, Chungnam, 336-795 (Korea, Republic of); Heo, Tae-Hwe, E-mail: thhur92@catholic.ac.kr [College of Pharmacy, The Catholic University of Korea, Bucheon 420-743 (Korea, Republic of)

2011-09-23

Highlights: {yields} Catechin reduces the expression level of ER stress marker protein in type I Gaucher disease cells. {yields} Catechin induces the proliferation rate of GD cells similar levels to normal cells. {yields} Catechin improves wound healing activity. {yields} Catechin-mediated reductions in ER stress may be associated with enhanced cell survival. {yields} We identified catechin as a protective agent against ER stress in GD cells. -- Abstract: Gaucher disease (GD) is the most common lysosomal storage disorder (LSD) and is divided into three phenotypes, I, II, and III. Type I is the most prevalent form and has its onset in adulthood. The degree of endoplasmic reticulum (ER) stress is one of the factors that determine GD severity. It has recently been reported that antioxidants reduce ER stress and apoptosis by scavenging the oxidants that cause oxidative stress. For this report, we investigated the possibility that catechin can act on type I GD patient cells to alleviate the pathogenic conditions of GD. We treated GD cells with catechin and examined the expression level of GRP78/BiP (an ER stress marker) by western blots and fluorescence microscopy, the proliferation rate of GD cells, and scratch-induced wound healing activity. Our results show that catechin reduces the expression level of GRP78/BiP, leads to cell proliferation rates of GD cells similar levels to normal cells, and improves wound healing activity. We conclude that catechin protects against ER stress in GD cells and catechin-mediated reductions in ER stress may be associated with enhanced cell survival.

Determination of Gd concentration profile in UO{sub 2}–Gd{sub 2}O{sub 3} fuel pellets

Energy Technology Data Exchange (ETDEWEB)

Tobia, D., E-mail: dina.tobia@cab.cnea.gov.ar [Laboratorio de Resonancias Magnéticas, Centro Atómico Bariloche – CNEA and CONICET, 8400 S.C. de Bariloche (Argentina); Winkler, E.L.; Milano, J.; Butera, A. [Laboratorio de Resonancias Magnéticas, Centro Atómico Bariloche – CNEA and CONICET, 8400 S.C. de Bariloche (Argentina); Kempf, R. [División Caracterización de Combustibles Avanzados, Gerencia Ciclo Combustible Nuclear, Centro Atómico Constituyentes – CNEA, 1650 San Martín, Pcia. de Buenos Aires (Argentina); Bianchi, L.; Kaufmann, F. [Departamento de Combustibles Avanzados, Gerencia Ciclo Combustible Nuclear, Centro Atómico Constituyentes – CNEA, 1650 San Martín, Pcia. de Buenos Aires (Argentina)

2014-08-01

A transversal mapping of the Gd concentration was measured in UO{sub 2}–Gd{sub 2}O{sub 3} nuclear fuel pellets by electron paramagnetic resonance spectroscopy (EPR). The quantification was made from the comparison with a Gd{sub 2}O{sub 3} reference sample. The nominal concentration in the pellets is UO{sub 2}: 7.5% Gd{sub 2}O{sub 3}. A concentration gradient was found, which indicates that the Gd{sub 2}O{sub 3} amount diminishes towards the edges of the pellets. The concentration varies from (9.3 ± 0.5)% in the center to (5.8 ± 0.3)% in one of the edges. The method was found to be particularly suitable for the precise mapping of the distribution of Gd{sup 3+} ions in the UO{sub 2} matrix.

Influence of the size of Gd211 starting powder on the critical current density of Gd-Ba-Cu-O bulk superconductor

International Nuclear Information System (INIS)

Nariki, S.; Seo, S.J.; Sakai, N.; Murakami, M.

2000-01-01

The relationship between the particle size of Gd211 powder in the precursor and the particle size of Gd211 inclusions in Gd-Ba-Cu-O bulk has been investigated. Gd211 starting powders with various diameters were prepared by the calcination of Gd 2 O 3 , BaO 2 and CuO powders at different temperatures between 800 and 1000 deg. C. The particle size of Gd211 in the melt-grown bulk was proportional to the particle size of the initial Gd211 powder. In conclusion, the employment of fine Gd211 powder led to a size reduction of 211 particles in the bulk, while largely enhancing the J c values in low magnetic fields. A large Gd-Ba-Cu-O/Ag bulk sample, 32 mm in diameter, could also be fabricated by the hot-seeding method. The maximum trapped field value revealed 1.5 T at 77 K. (author)

Antiferromagnetic coupling between rare earth ions and semiquinones in a series of 1:1 complexes.

Science.gov (United States)

Caneschi, Andrea; Dei, Andrea; Gatteschi, Dante; Poussereau, Sandrine; Sorace, Lorenzo

2004-04-07

We use the strategy of diamagnetic substitution for obtaining information on the crystal field effects in paramagnetic rare earth ions using the homologous series of compounds with the diamagnetic tropolonato ligand, Ln(Trp)(HBPz(3))(2), and the paramagnetic semiquinone ligand, Ln(DTBSQ)(HBPz(3))(2), (DTBSQ = 3,5-di-tert-butylsemiquinonato, Trp = tropolonate, HBPz(3)= hydrotrispyrazolylborate) for Ln = Sm(iii), Eu(iii), Gd(iii), Tb(iii), Dy(iii), Ho(iii), Er(iii) or Yb(iii). The X-ray crystal structure of a new form of tropolonate derivative is presented, which shows, as expected, a marked similarity with the structure of the semiquinonate derivative. The Ln(Trp)(HBPz(3))(2) derivatives were then used as a reference for the qualitative determination of crystal field effects in the exchange coupled semiquinone derivatives. Through magnetisation and susceptibility measurements this empirical diamagnetic substitution method evidenced for Er(iii), Tb(iii), Dy(iii) and Yb(iii) derivatives a dominating antiferromagnetic coupling. The increased antiferromagnetic contribution compared to other radical-rare earth metal complexes formed by nitronyl nitroxide ligands may be related to the increased donor strength of the semiquinone ligand.

Gd(III)-nanodiamond conjugates for MRI contrast enhancement

Science.gov (United States)

Manus, Lisa M.; Mastarone, Daniel J.; Waters, Emily A.; Zhang, Xue-Qing; Schultz-Sikma, Elise A.; MacRenaris, Keith W.; Ho, Dean

2010-01-01

A Gd(III)-nanodiamond conjugate [Gd(III)-ND] was prepared and characterized, enabling detection of nanodiamonds by MR imaging. The Gd(III)-ND particles significantly reduced the T1 of water protons with a per-Gd(III) relaxivity of 58.82 ± 1.18 mM−1s−1 at 1.5 Tesla (60 MHz). This represents a tenfold increase compared to the monomer Gd(III) complex (r1 = 5.42 ± 0.20 mM−1s−1) and is among the highest per-Gd(III) relaxivities reported. PMID:20038088

Measurements of defect structures by positron annihilation lifetime spectroscopy of the tellurite glass TeO2-P2O5-ZnO-LiNbO3 doped with ions of rare earth elements: Er3+, Nd3+ and Gd3+

Science.gov (United States)

Golis, E.; Yousef, El. S.; Reben, M.; Kotynia, K.; Filipecki, J.

2015-12-01

The objective of the study was the structural analysis of the TeO2-P2O5-ZnO-LiNbO3 tellurite glasses doped with ions of the rare-earth elements: Er3+, Nd3+ and Gd3+ based on the PALS (Positron Annihilation Lifetime Spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, such as vacancies, mono-vacancies, dislocations or pores, the sizes of which range from a few angstroms to a few dozen nanometres. Experimental positron lifetime spectrum revealed existence of two positron lifetime components τ1 and τ2. Their interpretation was based on two-state positron trapping model where the physical parameters are the annihilation velocity and positron trapping rate.

Non-adherence to anti-TB drugs among TB/HIV co-infected patients ...

African Journals Online (AJOL)

Non-adherence to anti-TB drugs among TB/HIV co-infected patients in Mbarara Hospital ... and its associated factors have not been studied in these patients in Uganda. ... Methods: A cross-sectional study with qualitative and quantitative data ...

Irradiation response of radio-frequency sputtered Al/Gd2O3/p-Si MOS capacitors

Science.gov (United States)

Kahraman, A.; Yilmaz, E.

2017-10-01

The usage of the Gadolinium oxide (Gd2O3) as sensitive region in the MOS (Metal-Oxide-Semiconductor)-based dosimeters was investigated in the presented study. The Gd2O3 films grown on p-type Si (100) by RF magnetron sputtering were annealed at 800 °C under N2 ambient. The back and front metal contacts were establishes to produce MOS capacitors. The fabricated Gd2O3 MOS capacitors were irradiated in the dose range 0.5-50 Gy by 60Co gamma source. The performed Capacitance-Voltage (C-V) curves of the Gd2O3 MOS capacitors shifted to right side relative to pre-irradiation one. While continuous increments in the oxide trapped charges with increasing in gamma dose were observed, interface trapped charges fluctuated in the studied dose range. However, the variation of the interface trapped charge densities was found in the order of 1011 cm-2 and no significant variation was observed with applied dose. These results confirm that a significant deterioration does not occur in the capacitance during the irradiation. The higher oxide trapped charges compared to interface trapped charges showed that these traps were more responsible for the shift of the C-V curves. The sensitivity and percentage fading after 105 min of the Gd2O3 MOS capacitor were found as 39.7±1.4 mV/Gy and 14.5%, respectively. The devices sensitivity was found to be higher than that of capacitors composed of Er2O3, Sm2O3, La2O3, Al2O3, and SiO2, but, the high fading values is seen as a major problem for these capacitors. Finally, the barrier height was investigated with gamma exposure and the results showed that its value increased with increasing in radiation dose due to possible presence of the acceptor-like interface states.

Preparation of extractive resins for producing terbium-161

International Nuclear Information System (INIS)

De la Cruz B, C. C.; Monroy G, F.

2009-10-01

This paper presents the development of a methodology for extractive resins preparation to base of HDEHP, which allows to separation of Tb from Gd generating an own technology of preparation of these resins. The study included the extractive resins preparation from 6 different supports: kieselguhr Dg, alumina, red volcanic rock, chiluca, quarry and fluorite; two treatment types of of supports and varied concentrations of HDEHP extractant (di(2-etil hexyl) orthophosphoric acid), in order to determine which resin has improved efficiency of Gd and Tb separation, and radionuclide purity of 161 Tb. Resins were prepared to base of kieselguhr to determine the most appropriate silicon deposition process. Two silicon deposition treatments were realized: treatment I , by contact with silicon deposition solution (dimethyldichlorosilane / heptane 1:30) and treatment II by contact with vapors of dimethyldichlorosilane in vacuum. The extractant retention was carried out to different concentrations of HDEHP / acetone: 1:4, 1:8, 1:15, 1:20, 1:30 and 1:40. According to the results, there is not direct relation of HDEHP concentration used in extractive resins preparation to base of kieselguhr over the efficiency of Gd and Tb separation and of radionuclide purity of 161 Tb. The effect of support in the efficiency of Gd and Tb separation was studied to prepare resins with the supports kieselguhr, alumina, quarry, chiluca, volcanic rock and fluorite, using the silicon deposition treatment II for the supports and a concentration of HDEHP / acetone 1:20, for extractant retention. Only resins based on kieselguhr could separate to Gd from Tb quantitatively, the resin at a concentration of HDEHP / Acetone 1:20 was the best results obtained in Gd and Tb separation, achieving a separation efficiency greater than 90% and a radionuclide purity higher than 99%. (Author)

Synthesis, characterization and thermal behavior: Gd(NO3)3.6H2O to Gd2O3

International Nuclear Information System (INIS)

Ghonge, Darshana K.; Sheelvantra, Smita S.; Kalekar, Bhupesh B.; Raje, Naina

2015-01-01

Gadolinium oxide finds its application in nuclear as well as medical industry. It has been prepared from the thermal decomposition of gadolinium nitrate hexahydrate. Surface area of the synthesized compound was measured as 19 m 2 /g. EDS data shows only the presence of gadolinium and oxygen in the synthesized compound with the Gd to O ratio as calculated for Gd 2 O 3 , suggests the formation of pure Gd 2 O 3 . XRD analysis confirms the formation of pure cubic phase Gd 2 O 3 . In the absence of any report on the thermal behavior of GdNH, present studies have been carried out to understand the decomposition mechanism using simultaneous TG - DTA - EGA measurements

Pleural tuberculosis in a patient with untreated type 1 Gaucher disease.

Science.gov (United States)

Dulgar, Ozgecan; Eskazan, Ahmet Emre; Ersen, Ezel; Demiroz, Ahu Senem; Turna, Akif; Oz, Buge; Tuzuner, Nukhet

2016-01-01

Gaucher disease (GD) is an autosomal recessive glycolipid storage disorder, due to deficiency of the lysosomal enzyme glucocerebrosidase, leading to accumulation of the substrate glucocerebroside in the cells of the macrophage-monocyte system. Patients with GD have alteration in their immune system and impaired microbicidal capacity of mononuclear phagocytes. It has also been demonstrated that monocyte dysfunction may correlate with the plasma glucocerebrosidase concentrations. Tuberculosis (TB) is a major public health problem in developing countries. Pleural TB is one of the most common forms of extra-pulmonary TB. Since immune system can be impaired due to the deficiency of glucocerebrosidase in various ways, TB can be observed in patients with GD especially when left untreated. Cytopenia(s) is also general finding in untreated Gaucher patients, and they may be observed most frequently due to the infiltration of the bone marrow with Gaucher cells together with the additional factor of splenomegaly. We herein present a case of an adult patient with heterozygous untreated GD1, who developed pleural TB complicated by ipsilateral pulmonary fibrosis. Before his admission to our clinic, pleurectomy operation was performed and 4-drug combination anti-TB therapy was initiated including isoniazid, rifampicin, ethambutol and pyrazinamide. Fever complaint was disappeared with anti-TB treatment but he also had fatigue and pain. After initiation of enzyme replacement therapy in addition to anti-TB treatment, clinical and hematological improvement was observed. To our knowledge, this is the first reported case of GD1 with pleural TB. Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

The Characteristics of TB Epidemic and TB/HIV Co-Infection Epidemic: A 2007-2013 Retrospective Study in Urumqi, Xinjiang Province, China.

Directory of Open Access Journals (Sweden)

Wang Wei

Full Text Available This study was aimed to find out epidemiologic characteristic of tuberculosis (TB cases, and Human Immunodeficiency Virus (HIV positive cases among TB patients (TB/HIV co-infection through demographic, temporal, and spatial study in Urumqi.Descriptive statistics and multivariate logistic regression were applied to identify the epidemiologic characteristics and risk factors of TB epidemic and TB/HIV co-infection epidemic. All addresses of each TB case, TB/HIV co-infection case, and administrative street were transformed into geographical coordinate. Subsequently, the geocoded address for 82 streets was transformed into a dot map used as the basis of spatial datasets. In addition, the paper also used quantile map and the spatial scan statistic in order to identify the spatial distribution and spatial clusters of TB epidemic and TB/HIV co-infection epidemic.There was a declining trend of the notification rates of TB epidemic from 2007 to 2009, as well as a rising trend from 2010 to 2013. However, the notification rates of TB/HIV co-infection epidemic showed a rising trend from 2007 to 2010, and a declining trend from 2011 to 2013. Moreover, a significant share of TB epidemic and TB/HIV co-infection epidemic happened between the age of 15 to 45 years old, indicating an increase in risk of TB and TB/HIV infection. It is worth noting that the risk of HIV infection for male TB patients was 2.947 times (95% CI [2.178, 3.988] than that of female patients. Han ethnicity and Uygur ethnicity in urban region accounted for a large proportion of total TB and TB/HIV co-infection cases. Most of the TB cases of minorities in Urumqi showed a statistically significant increase in risk of HIV infection than Han ethnicity in Urumqi. In addition, the spatial distribution of TB epidemic and TB/HIV co-infection epidemic was highly skewed. Most of the local clusters were located in urban area and rural-urban continuum where showed an increase in risk of TB and TB

TIME Impact - a new user-friendly tuberculosis (TB) model to inform TB policy decisions.

Science.gov (United States)

Houben, R M G J; Lalli, M; Sumner, T; Hamilton, M; Pedrazzoli, D; Bonsu, F; Hippner, P; Pillay, Y; Kimerling, M; Ahmedov, S; Pretorius, C; White, R G

2016-03-24

Tuberculosis (TB) is the leading cause of death from infectious disease worldwide, predominantly affecting low- and middle-income countries (LMICs), where resources are limited. As such, countries need to be able to choose the most efficient interventions for their respective setting. Mathematical models can be valuable tools to inform rational policy decisions and improve resource allocation, but are often unavailable or inaccessible for LMICs, particularly in TB. We developed TIME Impact, a user-friendly TB model that enables local capacity building and strengthens country-specific policy discussions to inform support funding applications at the (sub-)national level (e.g. Ministry of Finance) or to international donors (e.g. the Global Fund to Fight AIDS, Tuberculosis and Malaria).TIME Impact is an epidemiological transmission model nested in TIME, a set of TB modelling tools available for free download within the widely-used Spectrum software. The TIME Impact model reflects key aspects of the natural history of TB, with additional structure for HIV/ART, drug resistance, treatment history and age. TIME Impact enables national TB programmes (NTPs) and other TB policymakers to better understand their own TB epidemic, plan their response, apply for funding and evaluate the implementation of the response.The explicit aim of TIME Impact's user-friendly interface is to enable training of local and international TB experts towards independent use. During application of TIME Impact, close involvement of the NTPs and other local partners also builds critical understanding of the modelling methods, assumptions and limitations inherent to modelling. This is essential to generate broad country-level ownership of the modelling data inputs and results. In turn, it stimulates discussions and a review of the current evidence and assumptions, strengthening the decision-making process in general.TIME Impact has been effectively applied in a variety of settings. In South Africa, it

Preparation and characterization of Tb3+ and Tb(sal)3.nH2O doped PC:PMMA blend

International Nuclear Information System (INIS)

Dwivedi, Y.; Singh, A.K.; Prakash, Rajiv; Rai, S.B.

2011-01-01

Tb doped polycarbonate:poly(methyl methacrylate) (Tb-PC:PMMA) blend was prepared with varying proportions of PC and PMMA. Thermal and spectroscopic properties of the doped polymer have been investigated employing Fourier Transform Infrared (FTIR) absorption and differential scanning calorimetric (DSC) techniques. PC:PMMA blend (with 10 wt% PC and 90 wt% PMMA) shows better miscibility. Optical properties of the dopant Tb 3+ ions have been investigated using UV-vis absorption and fluorescence excited by 355 nm radiation. It is seen that luminescence intensity of Tb 3+ ion depends on PC:PMMA ratio and on Tb 3+ ion concentration. Concentration quenching is seen for TbCl 3 .6H 2 O concentration larger than 4 wt%. Addition of salicylic acid to the polymer blend increases the luminescence from Tb 3+ ions. Luminescence decay curve analysis affirms the non-radiative energy transfer from salicylic acid to Tb 3+ ions, which is identified as the reason behind this enhancement. - Highlights: → Blend formation is confirmed at PC/90PMMA, using FTIR and DSC techniques. → Absorption and bandgap studies of blend and parent components were studied. → Optical properties of Tb and Tb(sal) 3 .nH 2 O complex have been studied in PC/PMMA blend. → Luminescence decay curves confirm non-radiative energy transfer from Sal to Tb 3+ ions.

Ternary germanides RERhGe{sub 2} (RE = Y, Gd-Ho) – New representatives of the YIrGe{sub 2} type

Energy Technology Data Exchange (ETDEWEB)

Voßwinkel, Daniel; Heletta, Lukas; Hoffmann, Rolf-Dieter; Pöttgen, Rainer, E-mail: pottgen@uni-muenster.de

2016-11-15

The YIrGe{sub 2} type ternary germanides RERhGe{sub 2} (RE = Y, Gd-Ho) were synthesized from the elements by arc-melting and characterized by powder X-ray diffraction. The structure of DyRhGe{sub 2} was refined from single crystal X-ray diffractometer data: Immm, a = 426.49(9), b = 885.0(2), c = 1577.4(3) pm, wR2 = 0.0533, 637 F{sup 2} values, 30 variables (300 K data). The structure contains two crystallographically independent dysprosium atoms in pentagonal prismatic and hexagonal prismatic coordination. The three-dimensional [RhGe{sub 2}] polyanion is stabilized through covalent Rh–Ge (243–261 pm) and Ge–Ge (245–251 pm) bonding. The close structural relationship with the slightly rhodium-poorer germanides RE{sub 5}Rh{sub 4}Ge{sub 10} (≡ RERh{sub 0.8}Ge{sub 2}) is discussed. Temperature-dependent magnetic susceptibility measurements reveal Pauli paramagnetism for YRhGe{sub 2} and Curie-Weiss paramagnetism for RERhGe{sub 2} with RE = Gd, Tb, Dy and Ho. These germanides order antiferromagnetically at T{sub N} = 7.2(5), 10.6(5), 8.1(5), and 6.4(5) K, respectively. - Graphical abstract: The germanides RERhGe{sub 2} (RE = Y, Gd-Ho) are new representatives of the YIrGe{sub 2} type.

Lanthanide-activated Na5Gd9F32 nanocrystals precipitated from a borosilicate glass: Phase-separation-controlled crystallization and optical property

International Nuclear Information System (INIS)

Chen, Daqin; Wan, Zhongyi; Zhou, Yang; Chen, Yan; Yu, Hua; Lu, Hongwei; Ji, Zhenguo; Huang, Ping

2015-01-01

Highlights: • Na 5 Gd 9 F 32 nanocrystals embedded glass ceramics were fabricated for the first time. • Such glass ceramics were achieved by phase-separation-controlled crystallization. • Elemental mapping evidenced the segregation of activators into the Na 5 Gd 9 F 32 lattice. • Luminescent color could be tuned by controlling glass crystallization temperature. - Abstract: Lanthanide-activated cubic Na 5 Gd 9 F 32 nanocrystals were precipitated from a borosilicate glass with a specifically designed composition. The precursor glass is already phase-separated after melt-quenching, which is beneficial to the realization of the controllable glass crystallization for affording desirable size, morphology and activator partition. Elemental mapping in the scanning transmission electron microscopy evidenced that the segregation of lanthanide ions into the Na 5 Gd 9 F 32 lattice was in situ formed without the requirement of long-range ionic diffusion. Impressively, such fabricated glass ceramic co-doped with Yb 3+ /Er 3+ ions exhibited intense upconversion luminescence, which was about 500 times higher than that of the precursor glass, and its luminescent color could be easily tuned from red to green by controlling glass crystallization temperature. It is anticipated that such phase-separation synthesis strategy with precise control over nanostructure of glass ceramics offer a great opportunity to design other highly transparent nanocomposites with a wide range of tunable optical properties

Synthesis and characterization of Gd-doped magnetite nanoparticles

International Nuclear Information System (INIS)

Zhang, Honghu; Malik, Vikash; Mallapragada, Surya; Akinc, Mufit

2017-01-01

Synthesis of magnetite nanoparticles has attracted increasing interest due to their importance in biomedical and technological applications. Tunable magnetic properties of magnetite nanoparticles to meet specific requirements will greatly expand the spectrum of applications. Tremendous efforts have been devoted to studying and controlling the size, shape and magnetic properties of magnetite nanoparticles. Here we investigate gadolinium (Gd) doping to influence the growth process as well as magnetic properties of magnetite nanocrystals via a simple co-precipitation method under mild conditions in aqueous media. Gd doping was found to affect the growth process leading to synthesis of controllable particle sizes under the conditions tested (0–10 at% Gd"3"+). Typically, undoped and 5 at% Gd-doped magnetite nanoparticles were found to have crystal sizes of about 18 and 44 nm, respectively, supported by X-ray diffraction and transmission electron microscopy. Our results showed that Gd-doped nanoparticles retained the magnetite crystal structure, with Gd"3"+ randomly incorporated in the crystal lattice, probably in the octahedral sites. The composition of 5 at% Gd-doped magnetite was Fe_(_3_−_x_)Gd_xO_4 (x=0.085±0.002), as determined by inductively coupled plasma mass spectrometry. 5 at% Gd-doped nanoparticles exhibited ferrimagnetic properties with small coercivity (~65 Oe) and slightly decreased magnetization at 260 K in contrast to the undoped, superparamagnetic magnetite nanoparticles. Templation by the bacterial biomineralization protein Mms6 did not appear to affect the growth of the Gd-doped magnetite particles synthesized by this method. - Highlights: • Gd-doped magnetite nanoparticles are synthesized via aqueous co-precipitation method under mild conditions. • Gd doping affects growth of magnetite nanoparticles leading to tunable particle size. • Gd-doped magnetite nanoparticles exhibit ferrimagnetic properties.

New perspective for GdNCT. Gd-DTPA reaches the nucleus of glioblastoma cells in culture and in vivo

International Nuclear Information System (INIS)

Stasio, G. de; Gilbert, B.; Frazer, B.H.

2000-01-01

We investigated the prospects of gadolinium as a neutron capture therapy agent by combining three independent techniques to study the uptake of Gd-DTPA in vitro, in cultured glioblastoma cells, and in vivo, in the glioblastoma tissue sections after injection of Gd-DTPA and tumor extraction. We show that gadolinium not only penetrates the plasma membrane of glioblastoma cells grown in culture, but we also observe a statistically significant higher concentration of Gd in the nucleus relative to the cytoplasm. For the in vivo experiments, Gd-DTPA was administered to 6 glioblastoma patients before neurosurgery. The extracted bioptic tissue was then analyzed with spectromictroscopy, showing Gd localized in the nuclei of glioblastoma cells in 5 patients out of the 6 analyzed. (author)

Understanding social context on TB cases

Science.gov (United States)

Ariyanto, Y.; Wati, D. M.

2017-01-01

Tuberculosis (TB) nowadays still becomes one of the world’s deadliest communicable disease. More than half were in South-East Asia and Western Pacific Regions, including Indonesia. As developing country, Indonesia remains classic problems in overcoming TB, that is discontinuation on treatment. Most of discontinuation on treatment among TB patients are affected by diagnostic delay that caused by patient delay. These phenomena occur in many areas, rural to suburb, coastal to plantation, and so on, and they are related with social context among community that could be social capital for each community to deal with TB. Jember as one of county in East Java is known as plantation area. It also has a high prevalence of TB. This study focused on understanding about social context among community, especially on plantation area. This cross-sectional study involved in three districts of Jember, those are Tanggul, Pakusari, and Kalisat. The data were obtained directly from the TB patients, local community, and Primary Health Care (PHC) where the patients recorded. Spatial analysis and social network analysis (SNA) were applied to obtain health seeking behavior pattern among the TB patients coincide the community. Most of TB patients had already chosen health professionals to lead the treatment, although some of them remained to choose self-medication. Meanwhile, SNA showed that religious leader was considered as main part of countermeasures of TB. But they didn’t ever become central figures. So it can be concluded that there are other parts among community who can contribute due to combatting on TB.

tb diagnostics challenges of tb diagnosis and treatment in south africa

African Journals Online (AJOL)

2007-06-01