Hydrothermal synthesis and characterization of nanocrystalline pyrochlore oxides M2Sn2O7 (M = La, Bi, Gd or Y)

A family of pyrochlore stannates, M2Sn2O7 (M = La, Bi, Gd or Y) has been prepared from hydrothermal systems at 240 degrees C and structurally characterized by powder X-ray diffraction, transmission electron microscopy and differential thermal analysis. The La and Bi stannates showed nanocrystalline characteristics with average particle sizes of ca. 20 nm. Hydrothermally synthesized pyrochlore stannates were thermally stable and showed ionically conducting properties at high temperatures.