Ambient-temperature high-pressure-induced ferroelectric phase transition in CaMnTi2O6

J. Ruiz-Fuertes, T. Bernert, D. Zimmer, N. Schrodt, M. Koch-Mueller, B. Winkler, L. Bayarjargal, C. Popescu, S. MacLeod, K. Glazyrin

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Abstract

The ferroelectric to paraelectric phase transition of multiferroic CaMnTi2O6 has been investigated at high pressures and ambient temperature by second-harmonic generation (SHG), Raman spectroscopy, and powder and single-crystal x-ray diffraction. We have found that CaMnTi2O6 undergoes a pressure-induced structural phase transition (P4(2)mc. P4(2)/nmc) at similar to 7GPa to the same paraelectric structure found at ambient pressure and T-c = 630 K. The continuous linear decrease of the SHG intensity that disappears at 7 GPa and the existence of a Raman active mode at 244 cm(-1) that first softens up to 7 GPa and then hardens with pressure are used to discuss the nature of the phase transition of CaMnTi2O6, for which a dT(c)/dP = -48 K/GPa has been found. Neither a volume contraction nor a change in the normalized pressure on the Eulerian strain is observed across the phase transition with all the unit-cell volume data following a second-order Birch-Murnaghan equation of state with a bulk modulus of B-0 = 182.95(2) GPa.

Original languageEnglish
Article number094101
Number of pages7
JournalPhysical Review B
Volume96
Issue number9
DOIs
Publication statusPublished - 5 Sep 2017

Keywords

  • DIELECTRIC-PROPERTIES
  • DIFFRACTION

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