An overview of double perovskites A2B′B″O6 with small ions at A site: Synthesis, structure and magnetic properties

Layered oxides, A2B'B″O6, with small ions at A-site mostly occupied by unusual-metals like transitional metals are of great importance due to their strong and unusual magnetic interactions and technical applications. Due to small tolerance factors it is very difficult to synthesize such materials in ambient pressure and temperature. Depending upon the variation in temperature and pressure, same composition of the above mentioned materials can be crystallized with different structural arrangements. The effect of pressure and synthetic condition of different materials has been described in this review. The literature data on the effects of the A-site occupation by small ions on the structure and properties are summarized. Finally structural changes and dissimilar properties of high temperature and pressure synthesized recent developed materials are compared with the materials with usual B-site ordered double perovskite.