Anomalous Thermal Expansion of HoCo0.5Cr0.5O3 Probed by X-ray Synchrotron Powder Diffraction

Autor: Vasyl Hreb, Leonid Vasylechko, Vitaliya Mykhalichko, Yurii Prots
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: Nanoscale Research Letters, Vol 12, Iss 1, Pp 1-6 (2017)
Druh dokumentu: article
ISSN: 1931-7573
1556-276X
DOI: 10.1186/s11671-017-2213-7
Popis: Abstract Mixed holmium cobaltite-chromite HoCo0.5Cr0.5O3 with orthorhombic perovskite structure (structure type GdFeO3, space group Pbnm) was obtained by solid state reaction of corresponding oxides in air at 1373 K. Room- and high-temperature structural parameters were derived from high-resolution X-ray synchrotron powder diffraction data collected in situ in the temperature range of 300–1140 K. Analysis of the results obtained revealed anomalous thermal expansion of HoCo0.5Cr0.5O3, which is reflected in a sigmoidal temperature dependence of the unit cell parameters and in abnormal increase of the thermal expansion coefficients with a broad maxima near 900 K. Pronounced anomalies are also observed for interatomic distances and angles within Co/CrO6 octahedra, tilt angles of octahedra and atomic displacement parameters. The observed anomalies are associated with the changes of spin state of Co3+ ions and insulator-metal transition occurring in HoCo0.5Cr0.5O3.
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