New phosphates with the general formula M_{0.5(1 + x} )Fe _x Ti_{2 − x} (PO₄)₃ (M = Co, Ni, Cu; 0 ≤ x ≤ 2) have been synthesized by a sol-gel process. We have studied phase relations in these systems and determined the composition stability limits of NASICON-type solid solutions. The catalytic properties of the phosphates for methanol dehydration and dehydrogenation reactions have been investigated in an inert atmosphere.

The phosphates M_0.5+x M′ _x Zr_2−x (PO₄)₃ (M–Ca, Mn, Co, Sr, Cd, Ba, Pb; M′–Mg, Mn, Co) were synthesized by sol-gel method with the following thermal treatment of reaction mixtures. X-ray diffraction, IR spectroscopy and electron microprobe analysis showed that the obtained phosphates crystallized in Sc₂(WO₄)₃ (SW) and NaZr₂(PO₄)₃ (NZP) structural types. Both types of crystal structures are based on a framework comprised of octahedra and tetrahedra, the difference between them is fragments orientation. Thermal expansion of the phosphates was studied in the temperature range 20–800°C. Some compounds were found to belong to low-expanding materials (α_av ~2·10⁻⁶°C⁻¹).

Phosphates M_0.5Ti₂(PO₄)₃ (M = Ni, Zn) were synthesized by the sol-gel method and characterized by the methods of X-ray diffraction, IR spectroscopy, and electronic microprobe analysis. Structures of Ni_0.5Ti₂(PO₄)₃ and Zn_0.5Ti₂(PO₄)₃ were studied by Rietveld method using the X-ray powder diffraction data.