Crystal structure and thermal expansion of LaCr 1-xMg xO 3, 0 < x ≤ 0.25

S. Ya Istomin, A. V. Kurlov, S. M. Kazakov, E. V. Antipov

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Solid solution LaCr 1-xMg xO 3, 0 < ≤ 0.25 was prepared by heating stoichiometric amounts of appropriate oxides in air at 1400 °C, 48 h. At room temperature it crystallizes in orthorhombically distorted GdFeO 3-type structure (a ≈ √2 × a per; b ≈ √2 × a pe; c ≈ 2 × a per, where a per - perovskite subcell parameter). High-temperature X-ray powder diffraction (HT XRPD) and dilatometry revealed first order phase transition to rhombohedral perovskite phase (R-3c, a ≈ √2 × a per, c ≈ 2√3 × a per) at 260-311 °C (OR phase transition). Crystal structures of room-temperature orthorhombic and high-temperature rhombohedral phases for LaCr 0.75Mg 0.25O 3 were refined using HT XRPD data. Temperature of OR phase transition increases gradually with increasing of magnesium content. Low-temperature orthorhombic phase exhibits TEC lower in comparison with high-temperature rhombohedral one (e.g. for LaCr 0.85Mg 0.15O 3 TEC(O) = 8.8 ppm K -1; TEC(R) = 11.6 ppm K -1). TEC for rhombohedral phase increases with increasing magnesium content from 10.4 ppm K -1 for LaCr 0.95Mg 0.05O 3 to 12.1 ppm K -1 for LaCr 0.75Mg 0.25O 3.

Original languageEnglish
Pages (from-to)1176-1180
Number of pages5
JournalMaterials Research Bulletin
Volume47
Issue number5
DOIs
Publication statusPublished - May 2012
Externally publishedYes

Keywords

  • A. Inorganic compounds
  • A. Oxides
  • C. X-ray diffraction
  • D. Crystal structure
  • D. Thermal expansion

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