Synthesis, Thermal Expansion Behavior and Sintering of Sodium Zirconium Nickel and Calcium Zirconium Nickel Phosphates

New NZP-type solid solutions, Na1+2xZr2–xNix(PO4)3 and Ca0.5+xZr2–xNix(PO4)3 with x = 0.10, 0.25, and 0.50, have been prepared by solid-state reactions. The synthesized samples have been characterized by X-ray diffraction and IR spectroscopy. Crystal structure of the compound CaZr1.5Ni0.5(PO4)3 has been refined by full-profile X-ray diffraction analysis method, reliability factors is Rp = 4.78% and Rwp = 6.45%, respectively. Thermal expansion of the phosphates has been studied by high-temperature X-ray diffraction in the temperature range 25–700°C. The synthesized compounds have been shown to be intermediate- and low-thermal-expansion materials. Using SPS method we have produced ceramic samples with a high relative density (ρrel > 97%), based on phosphate powders. Strength characteristics (microhardness and fracture toughness) of the ceramics have been determined.