Effects of Y2O3 addition on microwave dielectric characteristics of Al2O3 ceramics

Microwave dielectric characteristics of alumina ceramics with yttria addition were investigated. The sintering temperature was lowered, and the dielectric constant (εr) did not remarkably change by adding yttria. The microwave dielectric loss (tan δ) increased from 8.4 × 10− 5 to 2.2 × 10− 4, due to the presence of Al5Y3O12 secondary phase. The grain size had significant effects on the dielectric loss, and there was an optimum grain size where the dielectric loss reached the minimum.