Dresden 2011 – wissenschaftliches Programm

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KR: Fachgruppe Kristallographie

KR 1: Multiferroics I (Joint Session of MA, DF, DS, KR, TT)

KR 1.3: Vortrag

Montag, 14. März 2011, 15:15–15:30, HSZ 04

Pressure induced phase transitions in MnTiO₃: Insights from First Principles calculations — •Carmen Quiroga and Rossitza Pentcheva — Section Crystallography, Dept. of Earth and Environmental Sciences, University of Munich

MnTiO₃ crystallizes in the ilmenite structure at ambient conditions and remains stable at least up to 26 GPa [1]. A denser LiNbO₃ phase can be quenched from high pressure and high temperature experiments to ambient conditions [2]. Our density functional theory calculations, including an on-site Coulomb repulsion term (LDA/GGA+U), show a transition from the LiNbO₃ to the perovskite phase at 2.5 GPa in agreement with experiments [3]. A transition from perovskite to the post-perovskite phase (CaIrO₃-type) is predicted at pressures above 50 GPa. Furthermore, the magnetic coupling of the Mn ions and the possibility of spin transitions in the different phases are explored.

Funding by DFG SPP1236 (PE883/8-1) is acknowledged.

[1] X. Wu et al. Geoscience Frontiers, in press (2010).

[2] J. Ko and C.T. Prewitt. Phys. Chem. Minerals 15, 355 (1988).

[3] N. Ross et al. Phys Chem Minerals 16, 621 (1989).