Thermal expansion behaviour of sodium zirconium phosphate structure type phosphates containing tin

Thermal expansion behaviour of sodium zirconium phosphate structure type phosphates of the formula AM3+SnP3O12 (A=Ca, Sr and Ba; M3+=Cr and Fe) was studied by high temperature X-ray diffraction and dilatometry in the temperature range 298–1073 K. The variation in the hexagonal lattice parameters of the Ca-containing compounds is in line with the ‘sodium zirconium phosphate behaviour’. However, the strontium- and barium-containing compounds display an altogether different behaviour of axial expansion. The results are explained based on the crystal chemistry of these compounds.