Thermal analysis and high-temperature X-ray diffraction study of BiNbO 4

N. A. Zhuk, B. A. Makeev, V. A. Belyy, M. G. Krzhizhanovskaya

Research output: Contribution to journalArticlepeer-review

Abstract

Phase transformations of bismuth orthoniobate BiNbO 4 were studied by the methods of differential scanning calorimetry and high-temperature X-ray diffraction. The DSC curve in the heating–cooling mode of the orthorhombic samples (α-BiNbO 4 ) showed endothermic and exothermic effects associated with the phase transition from the orthorhombic modification to the triclinic one at the temperatures of ~ 1328 K and ~ 1270 K. This phase transition passed through a high-temperature phase of γ-BiNbO 4 , in which reflections were indicated in the temperature range of 1323 K → 1353 K → 1263 K. The X-ray diffraction pattern of the sample quenched in air (77 K) and calcined at the temperature from this range, 1323 K, corresponded to the triclinic modification. During the heating, the triclinic modification (β-BiNbO 4 ) was transformed into the high-temperature phase of γ-BiNbO 4 , which was stable up to ~ 1270 K. Then, it was transformed into the triclinic modification again. The DSC curve of the sample of triclinic BiNbO 4 showed endo- and exothermic effects at temperatures of ~ 1274 K and ~ 1270 K associated with the transition into the high-temperature phase of γ-BiNbO 4 . The cooling of the sample leads to the phase transition from the triclinic to the orthorhombic modification of BiNbO 4 . Thermostating at 1223 K for 1 h and quenching in air the compact sample or dispersed powder of bismuth orthoniobate of the triclinic modification led to the formation of the orthorhombic modification.

Original languageEnglish
Pages (from-to)1513-1518
Number of pages6
JournalJournal of Thermal Analysis and Calorimetry
Volume137
Issue number5
DOIs
StatePublished - 15 Sep 2019

Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

Keywords

  • Ceramics
  • Phase transitions
  • Thermal analysis

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