A study of the crystal structures and the phase transitions of the ordered double perovskites Sr2ScSbO6 and Ca2ScSbO6

作者：Faik A^*; Orobengoa D; Iturbe Zabalo E; Igartua J M

来源：Journal of Solid State Chemistry, 2012, 192: 273-283.

DOI：10.1016/j.jssc.2012.04.019

• Double perovskite
• X-ray and neutron powder diffraction
• Crystal structure
• Phase transitions
• Symmetry adopted modes

The crystal structures and phase transitions of the two ordered double perovskites Sr2ScSbO6 and Ca2ScSbO6 were studied using conventional X-ray and neutron powder-diffraction methods. The crystal structures of both compounds have the P2(1)/n space group symmetry at room temperature, resulting from Sc/Sb ordering. The evolution with temperature of the structure of the Sr containing compound shows the presence of three phase transitions with the following sequence: P2(1)/n -%26gt; 12/m -%26gt; 14/m -%26gt; Fm (3) over barm, at about 400, 560 and 650 K. respectively. The smaller size of Ca cation, with respect to that of Sr cation, leads to a large distortion of Ca2ScSbO6 at room temperature. This fact in turn causes that the Ca containing compound shows only the first phase transition from P2(1)/n to 12/m at high temperature at about 1440 K. The analysis of the phase transitions and the refinements have done using the symmetry-adapted modes and the tools of the Bilbao Crystallographic Server.

• 出版日期2012-8