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

作者：Ruiz Fuertes J^*; Bernert T; Zimmer D; Schrodt N; Koch Mueller M; Winkler B; Bayarjargal L; Popescu C; MacLeod S; Glazyrin K

来源：Physical Review B, 2017, 96(9): 094101.

DOI：10.1103/PhysRevB.96.094101

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.

• 出版日期2017-9-5