Neutron diffraction study of the crystal structure and structural phase transition of La{sub 0.7}Ca{sub 0.3-x}Sr{sub x}CrO{sub 3} (0<=x<=0.3)

Journal Article · Mon Feb 15 00:00:00 EST 2010 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.11.028· OSTI ID:21372496

Omoto, Kazuki ^[1]; Norberg, Stefan T ^[2]; Hull, Steve ^[3]; Aoto, Akimitsu ^[1]; Hashimoto, Takuya ^[1]

---

1. Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University, 3-25-40 Sakurajousui, Setagaya-ku, Tokyo 156-8550 (Japan)
2. Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden)
3. ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX (United Kingdom)

The crystal structure of the La{sub 0.7}Ca{sub 0.3-x}Sr{sub x}CrO{sub 3} series, including the compositional and temperature dependence of the structural parameters, has been studied by variable temperature neutron diffraction measurements. The extent of the distortions from the ideal cubic perovskite structure has been evaluated quantitatively using the average bond lengths and the mean volumes of the [CrO{sub 6}] octahedron and [(La/Ca/Sr)O{sub 12}] polyhedron, and has been shown to decrease with increase of Sr content or temperature. At the structural phase transition from the orthorhombic (Pnma) structure to the rhombohedral (R3-barc) one, the volume of the [CrO{sub 6}] octahedron decreases whereas that of the [(La/Ca/Sr)O{sub 12}] polyhedron shows little difference, resulting in an overall decrease in the level of distortion. The change in the degree of distortion at the phase transition decreases with increase of Sr content, in agreement with the smaller variation of the enthalpy and volume for the specimens with higher Sr content. - Graphical abstract: Temperature dependence of parameter, PHI, representing the extent of distortion from the ideal cubic perovskite structure, for La{sub 0.7}Ca{sub 0.3}CrO{sub 3} (diamonds) and La{sub 0.7}Ca{sub 0.15}Sr{sub 0.15}CrO{sub 3} (circles) calculated from neutron diffraction patterns.

• OSTI ID: 21372496
• Journal Information: Journal of Solid State Chemistry, Vol. 183, Issue 2; Other Information: DOI: 10.1016/j.jssc.2009.11.028; PII: S0022-4596(09)00557-X; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BOND LENGTHS
CALCIUM OXIDES
CHROMIUM COMPOUNDS
ENTHALPY
LANTHANUM COMPOUNDS
NEUTRON DIFFRACTION
ORTHORHOMBIC LATTICES
PEROVSKITE
PHASE TRANSFORMATIONS
SOLID OXIDE FUEL CELLS
STRONTIUM OXIDES
TEMPERATURE DEPENDENCE
TRIGONAL LATTICES
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
DIMENSIONS
DIRECT ENERGY CONVERTERS
ELECTROCHEMICAL CELLS
FUEL CELLS
HIGH-TEMPERATURE FUEL CELLS
LENGTH
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PEROVSKITES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
SOLID ELECTROLYTE FUEL CELLS
STRONTIUM COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS