2,924 research outputs found
Genetic and Environmental Influences on the Wisconsin Card Sorting Test Performance in Healthy Adolescents: A Twin/sibling Study.
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Systematic and material independent variation of electrical, optical, and chemical properties of Ln-materials over the Ln-series (Ln=La,Ce,Pr,..,Lu)
No full textA model is presented that successfully predicts electro-optical properties of Lanthanide materials, irrespective whether these materials are inorganic or organic, diluted or concentrated, metallic, semi-conducting or insulating. The model is firmly based on recent experimental data revealing that the variation in 4f and 5d energies relative to the valence band over the Ln series (La, Ce, Pr,.. ,Lu) is universal. Application to LnS and the oxides LnO, Ln2O3 and LnO2 demonstrates its potential by correctly predicting the ground state electron configuration, metallic, insulating or semi-conducting behavior, Ln ion valence state and band-gap of these model Ln systems.Radiation, Radionuclides and ReactorsApplied Science
High-temperature X-ray diffraction measurements of fluorite-related rare earth antimonates Ln(3)SbO(7) (Ln = Nd, Tb) and their magnetic properties
Full text linkTernary rare-earth antimonates Ln(3)SbO(7) (Ln=rare earths) were prepared, and their structures were determined by X-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln=La, Pr; Ccmm for Ln=Sm-Dy), in which Ln(3+) ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated). For Ln=Nd, two phases with the Cmcm and Cam space groups coexist at room temperature. When the temperature was increased, the Nd3SbO7 compound transformed into a single phase with the space group Cmcm. Through magnetic susceptibility measurements, an antiferromagnetic transition was observed at 3.0 K (Ln=Nd) and 7.8 K (Ln=Tb). Analysis of the magnetic specific heat for Tb3SbO7 indicates that the 8-coordinated Tb ions magnetically orders at 7.8 K, and with furthermore decreasing temperature, the 7-coordinated Tb ions shows antiferromagnetic ordering at 3.0 K
Synthesis and magnetic properties of 12L-perovskites Ba4LnIr3O12 (Ln = lanthanides)
Full text linkNew quadruple perovskite oxides Ba4LnIr3O12 (Ln = lanthanides) were prepared and their magnetic properties were investigated. They crystallize in the monoclinic 12L-perovskite-type structure with space group C2/m. The Ir3O12 trimers and LnO6 octahedra are alternately linked by corner-sharing and form the perovskite-type structure with 12 layers. The Ln and Ir ions are both in the tetravalent state for Ln = Ce, Pr, and Tb compounds (Ba4Ln^[4+]Ir^[4+]3O12), and for other compounds (Ln = La, Nd, Sm-Gd, Dy-Lu), Ln ions are in the trivalent state and the mean oxidation state of Ir ions is +4.33(Ba4Ln^[3+]Ir^[4.33+]3O12). An antiferromagnetic transition has been observed for Ln = Ce, Pr, and Tb compounds at 10.5, 35, and 16 K, respectively, while the other compounds are paramagnetic down to 1.8 K
Designing LiTaO<sub>3</sub>:Ln<sup>3+</sup>,Eu<sup>3+</sup> (Ln = Tb or Pr) perovskite dosimeter with excellent charge carrier storage capacity and stability for anti-counterfeiting and flexible X-ray imaging
No full textDeveloping X-ray charged dosimeters with excellent charge carrier storage capacity and stability is challenging. Such energy storage dosimeters have fascinating use in developing novel applications, for instance, in radiation detection, advanced multimode anti-counterfeiting, and flexible X-ray imaging of curved objects. Herein, novel LiTaO3:Ln3+,Eu3+ (Ln = Tb or Pr) perovskite dosimeters are reported by combining the vacuum referred binding energy (VRBE) diagram of LiTaO3 and the optimization of dopant's concentration and compound synthesis condition. Based on the VRBE diagram prediction, charge carrier capturing and de-trapping processes in Eu3+ and/or Ln3+ (Ln = Tb or Pr) doped LiTaO3 will be studied to unravel the role of Eu3+ as a good electron trapping centre and to discover a record storage phosphor. The ratios of the thermoluminescence intensity of the optimized LiTaO3:0.005Tb3+,0.001Eu3+ to that of the state-of-the-art BaFBr(I):Eu2+, Al2O3:C, or NaLuF4:Tb3+ are 5.2, 8.8, or 2.8, respectively. The charge carriers can be stored more than 1000 h in LiTaO3:0.005Tb3+,0.001Eu3+. Proof-of-concept anti-counterfeiting application will be demonstrated by combining the colour-tailorable photoluminescence, afterglow, thermally, or optically stimulated luminescence in LiTaO3:0.005Tb3+,xEu3+ and LiTaO3:0.005Pr3+,0.001Eu3+. Multimode anti-counterfeiting application will be proposed by combining a high absolute X-ray scintillation light yield of 19000 ± 1800 ph/MeV of LiTaO3:0.005Tb3+,0.001Eu3+. Proof-of-concept flexible X-ray imaging application will be demonstrated by using the optimized LiTaO3:0.005Tb3+, 0.001Eu3+ dispersed in a silicone gel film.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.RST/Luminescence Material
ln s physics, knowledge and problems
No full textThe author discusses the ln s behaviour of cross-sections in high- energy hadron physics. Topics dealt with are rising cross-sections, scaling and short-range order and inelastic diffractive processes. (14 refs)
Magnetic properties of EuLn2O4 (Ln = rare earths)
Full text linkTernary rare earth oxides EuLn2O4 (Ln = Gd, Dy-Lu) were prepared. They crystallized in an orthorhombic CaFe2O4-type structure with space group Pnma. 151Eu Mössbauer spectroscopic measurements show that the Eu ions are in the divalent state. All these compounds show an antiferromagnetic transition at 4.2-6.3K. From the positive Weiss constant and the saturation of magnetization for EuLu2O4, it is considered that ferromagnetic chains of Eu2+ are aligned along the b-axis of the orthorhombic unit cell, with neighboring Eu2+ chains antiparallel. When Ln = Gd-Tm, ferromagnetically aligned Eu2+ ions interact with the Ln3+ ions, which would overcome the magnetic frustration of triangularly aligned Ln3+ ions and the EuLn2O4 compounds show a simple antiferromagnetic behavior
Antiferromagnetic transitions of osmium-containing rare earth double perovskites Ba(2)LnOsO(6) (Ln=rare earths)
Full text linkThe perovskite-type compounds containing both rare earth and osmium Ba(2)LnOsO(6) (Ln=Pr, Nd, Sm-Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln(3+) and Os5+ ions are structurally ordered at the M site of the perovskite BaMO3. Magnetic susceptibility and specific heat measurements show that an antiferromagnetic ordering of Os5+ ions has been observed for Ba(2)LnOsO(6) (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65-71 K. Magnetic ordering of Ln(3+) moments occurs when the temperature is furthermore decreased. (C) 2013 Elsevier Inc. All rights reserved
Magnetic properties of orthorhombic fluorite-related oxides Ln3SbO7 (Ln = rare earths)
Full text linkTernary rare earth antimonates Ln3SbO7 (Ln = rare earths) were prepared and their structures were determined by x-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln = La, Pr, Nd; C-222_[1] for Ln = Nd～Lu), in which Ln3+ ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated sites). Their magnetic properties were characterized by magnetic susceptibility and specific heat measurements from 1.8 to 400 K. The Ln3SbO7 (Ln = Nd, Gd-Ho) compounds show an antiferromagnetic transition at 2.2～3.2 K. Sm3SbO7 and Eu3SbO7 show van Vleck paramagnetism. Measurements of the specific heat down to 0.4 K for Gd3SbO7 and the analysis of the magnetic specific heat indicate that the antiferromagnetic ordering of the 8-coordinated Gd ions occur at 2.6 K, and the 7-coordinated Gd ions order at a furthermore low temperature
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