Synthesis, Crystal Structure, and Thermal Expansion of Sodium Barium Zirconium Phosphate–Sulfate

The phosphate–sulfate synthesis approach preventing the elimination of sulfur in the process of synthesis has been tested for NaBa 6 Zr(PO 4 ) 5 SO 4 as an example. The phase formation and thermal stability of phosphate–sulfate have been studied by X-ray diffraction and DTA-TG. The NaBa 6 Zr(PO 4 ) 5 SO 4 structure (space group I 3 d , a = 10.5449(3) Å, V = 1172.54(5) Å 3 , Z = 4) allied to the eulytite mineral has been refined by the Rietveld method. The structure is formed by wavy chains of edge-sharing (Na,Ba,Zr)O 6 -octahedra and (P,S)O 4 -tetrahedra sharing apices with the octahedra. Using thermal X-ray diffraction, it has been established that phosphate–sulfate is a strongly expanding material (α а = α b = α c = 13.3 × 10 –6 °C –1 ).