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Title: Structural phase transition and magnetic properties of double perovskites Ba{sub 2}CaMO{sub 6} (M=W, Re, Os)

Abstract

Structures and magnetic properties for double perovskites Ba{sub 2}CaMO{sub 6} (M=W, Re, Os) were investigated. Both Ba{sub 2}CaReO{sub 6} and Ba{sub 2}CaWO{sub 6} show structural phase transitions at low temperatures. For Ba{sub 2}CaReO{sub 6}, the second order transition from cubic Fm3-bar m to tetragonal I4/m has been observed near 120K. For Ba{sub 2}CaWO{sub 6}, the space group of the crystal structure is I4/m at 295K and the transition to monoclinic I2/m has been observed between 220K. Magnetic susceptibility measurements show that Ba{sub 2}CaReO{sub 6} (S=1/2) and Ba{sub 2}CaOsO{sub 6} (S=1) transform to an antiferromagnetic state below 15.4 and 51K, respectively. Anomalies corresponding to their structural phase transition and magnetic transition have been also observed through specific heat measurements.

Authors:
 [1];  [2];  [2]
  1. Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan). E-mail: wake@sci.hokudai.ac.jp
  2. Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan)
Publication Date:
OSTI Identifier:
20784901
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 179; Journal Issue: 3; Other Information: DOI: 10.1016/j.jssc.2005.10.003; PII: S0022-4596(05)00463-9; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANTIFERROMAGNETISM; BARIUM COMPOUNDS; CUBIC LATTICES; MAGNETIC SUSCEPTIBILITY; MONOCLINIC LATTICES; OSMIUM COMPOUNDS; OXIDES; PEROVSKITE; PHASE TRANSFORMATIONS; RHENIUM COMPOUNDS; SPACE GROUPS; SPECIFIC HEAT; TETRAGONAL LATTICES; TUNGSTEN COMPOUNDS

Citation Formats

Yamamura, Kazuhiro, Wakeshima, Makoto, and Hinatsu, Yukio. Structural phase transition and magnetic properties of double perovskites Ba{sub 2}CaMO{sub 6} (M=W, Re, Os). United States: N. p., 2006. Web. doi:10.1016/j.jssc.2005.10.003.
Yamamura, Kazuhiro, Wakeshima, Makoto, & Hinatsu, Yukio. Structural phase transition and magnetic properties of double perovskites Ba{sub 2}CaMO{sub 6} (M=W, Re, Os). United States. doi:10.1016/j.jssc.2005.10.003.
Yamamura, Kazuhiro, Wakeshima, Makoto, and Hinatsu, Yukio. Wed . "Structural phase transition and magnetic properties of double perovskites Ba{sub 2}CaMO{sub 6} (M=W, Re, Os)". United States. doi:10.1016/j.jssc.2005.10.003.
@article{osti_20784901,
title = {Structural phase transition and magnetic properties of double perovskites Ba{sub 2}CaMO{sub 6} (M=W, Re, Os)},
author = {Yamamura, Kazuhiro and Wakeshima, Makoto and Hinatsu, Yukio},
abstractNote = {Structures and magnetic properties for double perovskites Ba{sub 2}CaMO{sub 6} (M=W, Re, Os) were investigated. Both Ba{sub 2}CaReO{sub 6} and Ba{sub 2}CaWO{sub 6} show structural phase transitions at low temperatures. For Ba{sub 2}CaReO{sub 6}, the second order transition from cubic Fm3-bar m to tetragonal I4/m has been observed near 120K. For Ba{sub 2}CaWO{sub 6}, the space group of the crystal structure is I4/m at 295K and the transition to monoclinic I2/m has been observed between 220K. Magnetic susceptibility measurements show that Ba{sub 2}CaReO{sub 6} (S=1/2) and Ba{sub 2}CaOsO{sub 6} (S=1) transform to an antiferromagnetic state below 15.4 and 51K, respectively. Anomalies corresponding to their structural phase transition and magnetic transition have been also observed through specific heat measurements.},
doi = {10.1016/j.jssc.2005.10.003},
journal = {Journal of Solid State Chemistry},
number = 3,
volume = 179,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • Structures of the double perovskites Ba{sub 2}M(II)M '(VI)O{sub 6} (M=Ca, Sr, M'=Te, W, U) at room temperature have been investigated by the Rietveld method using X-ray and neutron powder diffraction data. For double perovskites with M=Sr, the observed space groups are I2/m (M' =W) and R3-bar (M'=Te), respectively. In the case of M=Ca, the space groups are either monoclinic P2{sub 1}/n (M'=U) or cubic Fm3-bar m (M'=W and Te). The tetragonal and orthorhombic symmetry reported earlier for Ba{sub 2}SrTeO{sub 6} and Ba{sub 2}CaUO{sub 6}, respectively, were not observed. In addition, non-ambient X-ray diffraction data were collected and analyzed for Ba{submore » 2}SrWO{sub 6} and Ba{sub 2}CaWO{sub 6} in the temperature range between 80 and 723 K. It was found that the rhombohedral R3-bar structure exists in Ba{sub 2}SrWO{sub 6} above room temperature between the monoclinic and the cubic structure, whereas the cubic Ba{sub 2}CaWO{sub 6} undergoes a structural phase transition at low temperature to the tetragonal I4/m structure. - Graphical abstract: Evolution of structures as function of temperature in Ba{sub 2}SrWO{sub 6} (left) and Ba{sub 2}CaWO{sub 6} (right). The existence of two phase region in Ba{sub 2}SrWO{sub 6} can be clearly seen by the progressive increase of the rhombohedral R3-bar phase marked by asterisk (*)« less
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  • Uranium complex oxides with the ordered perovskite structure Ba[sub 2]MUO[sub 6] (M = Sc, Y, Gd, Yb, Mn) were prepared, and their magnetic susceptibilities and electron paramagnetic resonance (EPR) spectra were measured. The lattice parameter of the compounds varied linearly with the ionic radius of M[sup 3+]. The effective magnetic moments of U[sup 5+] in Ba[sub 2]YUO[sub 6] and Ba[sub 2]ScUO[sub 6] were very small. The moments of Ba[sub 2]GdUO[sub 6] and Ba[sub 2]YbUO[sub 6] were 7.74 and 4.69 [mu][sub B], respectively, close to the theoretical values for Gd[sup 3+] and Yb[sup 3+]. The electron paramagnetic resonance spectrum was observedmore » for Ba[sub 2]GdUO[sub 6], its g-value was 1.92. In Ba[sub 2]MnUO[sub 6], ferrimagnetic behavior was found below ca. 55 K. The effective magnetic moment was 5.52 [mu][sub B] and the g-value of EPR was 2.00. These results show that the manganese ion is divalent at a high spin state and that the uranium ion is in the hexavalent state. 20 refs., 8 figs., 1 tab.« less
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