High temperature induced phase transitions in SrCaCoTeO6 and SrCaNiTeO6 ordered double perovskites
Résumé
Two new double perovskites SrCaCoTeO6 and SrCaNiTeO6 have been successfully synthesized via the conventional solid state reaction method. The crystal structures and phase transitions of both materials have been investigated using conventional X-ray powder diffraction method at room- and hightemperatures. The Rietveld analysis has shown that both compounds crystallize at room temperature in a primitive monoclinic perovskite-type structure with P21=n (No. 14) space group and 1:1 ordered arrangement of the B-site cations (Co(Ni)/Te). The high temperature analysis has shown that these materials present temperature induced phase transitions following the next phase transition sequence: P21=nðaacþÞ ! I2=mðaac0Þ ! I4=mða0a0cÞ ! Fm 3mða0a0a0Þ.