X-ray and IR characterisation of Nasicon solid solution, Na_1+xZr₂Si_xP_3−xO₁₂

Abstract

X-ray and IR studies on Nasicon solid solutions, Na_1+xZr₂Si_xP_3−xO₁₂, are carried out as a function of composition x. X-ray diffraction studies show that the unit cell volume increases as x increases and exhibits a maximum at x ≈ 2. On further increase in x the unit cell volume decreases. The infrared absorption peak positions and the splitting of these absorption peaks suggest a distortion of the PO₄ and SiO₄ tetrahedra. But the distortion is not large enough to change the local symmetry around the phosphorus or silicon ion from T_d to C_3v.