Thermal expansion and phase transformation in the rare earth di-titanate (R2Ti2O7) system

Benjamin S. Hulbert, Scott J. McCormack, Kuo Pin Tseng, Waltraud M. Kriven

Research output: Contribution to journalReview articlepeer-review

Abstract

Characterization of the thermal expansion in the rare earth di-titanates is important for their use in high-temperature structural and dielectric applications. Powder samples of the rare earth di-titanates R2Ti2O7 (or R2O3.2TiO2), where R = La, Pr, Nd, Sm, Gd, Dy, Er, Yb, Y, which crystallize in either the monoclinic or cubic phases, were synthesized for the first time by the solution-based steric entrapment method. The three-dimensional thermal expansions of these polycrystalline powder samples were measured by in situ synchrotron powder diffraction from 25C to 1600C in air, nearly 600C higher than other in situ thermal expansion studies. The high temperatures in synchrotron experiments were achieved with a quadrupole lamp furnace. Neutron powder diffraction measured the monoclinic phases from 25C to 1150C. The La2Ti2O7 member of the rare earth di-titanates undergoes a monoclinic to orthorhombic displacive transition on heating, as shown by synchrotron diffraction in air at 885C (864C–904C) and neutron diffraction at 874C (841C–894C).

Original languageEnglish (US)
Pages (from-to)307-308
Number of pages2
JournalActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials
Volume77
DOIs
StatePublished - Jun 1 2021

Keywords

  • High-temperature
  • LaTiO
  • Neutron diffraction
  • Phase transition
  • Rare earth di-titanate
  • Thermal expansion
  • X-ray diffraction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Metals and Alloys
  • Materials Chemistry

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