Effects of Al2O3 additive on sintering behavior and microwave dielectric properties of ZnTa2O6 ceramics

Abstract

ZnTa2O6 ceramics with various amount of Al2O3 additive were synthesized by a conventional mixed-oxide route. The grain growth of ZnTa2O6 ceramics was accelerated with Al2O3 additive. However, excessive addition (>1.0 wt%) of Al2O3 leaded to abnormal grain growth. With Al2O3 addition, the Al2O3 additive did not solubilized into ZnTa2O6 structure but resulted in forming the second phase. The Al2O3 addition resulted in the lower sintering temperature of ZnTa2O6 ceramics and improved microwave dielectric properties. The dielectric constant (er) of the samples did not change much and ranged from 32.41 to 34.33 with different amount of Al2O3 addition. The optimized quality factor (Q × f) was higher than 70,000 GHz as a result of the denser ceramics. The temperature coefficient of resonant frequency (τf) of the doped ZnTa2O6 ceramics could be optimized to near-zero.