High‐Temperature Mechanical Properties and Chemical Stability of Ba_1+xZr₄P_6–2xSi_2XO₂₄ Low‐Thermal‐Expansion Ceramics

The NaZr₂P₃O₁₂ (NZP) family of materials is attracting increasing attention due to its low‐thermal‐expansion behavior. The system Ba_1+xZr₄P_6–2xSi_2xO₂₄ (0 ≤x≤ 1), belonging to the NZP family, shows ultralow thermal expansion over a wide temperature range. It also shows anisotropy in its lattice thermal expansion. This causes microcracking as the sintered specimens are cooled, which results in degradation of the mechanical properties. In this work, the chemical stability, strength, and Young's modulus of Ba_1+xZr₄P_6–2xO₂₄ (X= 0.25 and 0.5) ceramics at high temperatures have been determined. An attempt has been made to correlate the mechanical properties to the thermal expansion anisotropy.