LAUSR

M0.5 + xM′x Zr2 − x(PO4)3 phosphates (M = Cd, Sr, Pb; M′ = Ni, Cu; 0 ≤ x ≤ 2) were synthesized by the sol-gel method with followed by heat treatment. The samples were studied by X-ray diffraction, electron microscopy, microprobe analysis, and IR spectroscopy. The formation of limited solid solutions with an NaZr2(PO4)3 (NZP) structure was established in the studied series. Some tendencies in their crystallographic characteristics depending on the chemical composition were elucidated. The crystal structures of Sr0.9M′0.4Zr1.6(PO4)3 phosphates (M′ = Ni, Cu; space group $$R\bar{3}$$R3¯, Z = 6) were refined using X-ray powder diffraction data by the Rietveld method. The effect of the size factor on the formation of phosphate structures was demonstrated.