Sintering and characterization of alkaline-earth-doped and zirconium-defficient Na3Zr2Si2PO12

The sintering behavior of Na₃Zr₂Si₂PO₁₂, Na_3.08Zr_1.96X_0.04Si₂PO₁₂ (X = Mg, Ca, Sr, Ba), Na₃Zr_1.5 Si₂PO₁₂, and Na₃Zr_1.3Si₂PO₁₂ was studied between 900 and 1300°C. Microstructural examination indicated that liquid-phase sintering had occurred and that free ZrO₂ was present in all of the samples. X-ray diffraction indicated that the NASICON and ZrO₂ were monoclinic and that doping the Na₃Zr₂Si₂PO₁₂ with 0.02 mole% alkaline-earth ions (compared to the ZrO₂ content) did not significantly increase the unit-cell volume.