Abstract: Ca_1-xBa_xZr₄(PO₄)₆(0≤ x≤1, abbrev CBZP) which belongs to NZP family is a new
crystalline soild-solution, it may be possible to utilize the opposite anisotropic behavior of thermal expansion in CaZr₄(PO₄)₆ and
BaZr₄(PO₄)₆ to make the magnitude of thermal expansion coefficient be tailored. The main objective of this study was to prepare the material
with near-zero thermal expansion and lower anisotropy by adjusting composition, and the single phase CBZP was synthesized by
copreciptate methods. The compacts were sintered at temperatures of 1100℃ or 1300℃ with the addition of 3%ZnO or 4%MgO for 2h. Their average thermal expansion coefficients from
20～1000℃ and their thermal expansion curves during heating (from 20～1000℃)and cooling(from 1000～--400℃) were measured by TMA compressing method. The results show that some
compositions with near-zero thermal expansion are Ca_0.85Ba_0.15Zr₄(PO₄)₆ when addition of 3%ZnO and CaZr₄(PO₄)₆ when addition of 4%MgO,
the linear expansion coefficients is 0.6×10^-6/℃ and --0.8×10^-6/℃ respectively. But their thermal expansion curves show hysteresis loops due to microcracking, and the property of thermal
shock resistance is not perfect. It can be concluded that it is difficult to minimize their anisotropy by adjusting composition, though the near-zero
compositions can be abstained by this means. The useful route of improving their property of thermal shock resistance is properly to suppress the grain
growth beyond the transition grain size with an additive (example for SiO₂) during the sintering period to decrease microcracking.

Key words: CBZP, copreciptate method, near-zero thermal expansion material, microcracking, thermal shock resistance