Structure and phase transition in BaThO3: A combined neutron and synchrotron X-ray diffraction study

被引：13

作者：

Murphy, Gabriel L. ^{[1
,2
]}

Kennedy, Brendan J. ^{[1
]}

Zhang, Zhaoming ^{[2
]}

Avdeev, Maxim ^{[2
]}

Brand, Helen E. A. ^{[3
]}

Kegler, Philip ^{[4
]}

Alekseev, Evgeny V. ^{[4
,5
]}

机构：

[1] Univ Sydney, Sch Chem, Sydney, NSW 2006, Australia

[2] Australian Nucl Sci & Technol Org, Lucas Heights, NSW 2234, Australia

[3] Australian Synchrotron, 800 Blackburn Rd, Clayton, Vic 3168, Australia

[4] Forschungszentrum Julich, Inst Energy & Climate Res IEK 6, D-52428 Julich, Germany

[5] Rhein Westfal TH Aachen, Inst Kristallog, D-52066 Aachen, Germany

来源：

JOURNAL OF ALLOYS AND COMPOUNDS | 2017年 / 727卷

基金：

澳大利亚研究理事会;

关键词：

Barium thorium oxide; Perovskite; Phase transition; Neutron diffraction; Synchrotron X-ray diffraction; RESOLUTION POWDER DIFFRACTION; THERMAL-EXPANSION; THERMODYNAMIC STABILITY; BARIUM THORATE; 1ST PRINCIPLES; PEROVSKITES; URANIUM; TEMPERATURE; SOLUBILITY; MINERALS;

D O I：

10.1016/j.jallcom.2017.08.200

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The structure of BaThO3, obtained by solid state synthesis, was refined for the first time by the Rietveld method using a combination of synchrotron X-ray and neutron powder diffraction data. BaThO3 has an orthorhombic structure at room temperature, in space group Pbnm with a alpha = 6.3491(5), b = 6.3796(4) and c = 8.9907(7) angstrom. Heating BaThO3 to above 700 degrees C results in a continuous transition to a second orthorhombic structure, in space group Ibmm, demonstrated by both in situ neutron and synchrotron X-ray powder diffraction measurements. The coefficient of volumetric thermal expansion for BaThO3 is determined to be 1.04 x 10(-5) degrees C-1 from 50 to 625 degrees C (Pbnm phase), and 9.43 x 10(-6) degrees C-1 from 800 to 1000 degrees C (Ibmm phase). BaThO3 was found to decompose upon exposure to atmospheric moisture resulting in the formation of ThO2. The thermal expansion of ThO2, which invariably co-exists with BaThO3, is also described. (C) 2017 Elsevier B.V. All rights reserved.

引用

页码：1044 / 1049

页数：6

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