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Crystal structures and phase transitions of the double-perovskite oxides Sr 2 CaWO 6 and Sr 2 MgWO 6

2004; IOP Publishing; Volume: 16; Issue: 37 Linguagem: Inglês

10.1088/0953-8984/16/37/001

1361-648X

Milen Gateshki, J. M. Igartua,

Multiferroics and related materials

In the present work we report x-ray powder diffraction measurements of Sr2CaWO6 and Sr2MgWO6, at different temperatures. The crystal structures at room temperature of both compounds are determined; and results showing the existence of phase transitions in them are presented. For the structure at room temperature of the Ca containing compound, the space group P 21/n is obtained, which is different from that previously suggested. The evolution with temperature of the structure of this compound shows the presence of two phase transitions, a discontinuous one at 1130 K and a continuous one at 1250 K, with the following phase transition sequence: . The crystal structure of the Mg containing compound at room temperature has the I4/m space group. The temperature evolution of the structure has revealed a continuous phase transition at 570 K, changing the symmetry from tetragonal (I4/m) to cubic ().