Effect of annealing on microstructure of CuO-doped (Zr0.8Sn0.2)TiO4

Zirconium tin titanate ceramics, and specifically the (Zr0.8Sn0.2)TiO4 (ZST) are the preferred materials for use in resonators or filters working at microwave frequency. However, the problem with these materials is their high sintering temperature which is as high as 1550 °C. In this research, the influence of different amounts of CuO additions on the densification and microstructure evaluations of ZST ceramics modified with 1 wt% ZnO has been studied in two different states: before and after annealing. Results showed that annealing process at 1250 °C resulted in some changes in density, grain size and shape due to the rearrangement of liquid phase and its reactivation, but no secondary phase was detected. Also, variations in lattice parameters during annealing compared to those of as-sintered specimens suggested the possibility of disorder–order transformation during long time high temperature heat treatment process.

Research highlights▶ No secondary phase was formed during annealing. ▶ Heat treatment process increases the density of all samples. ▶ Slight increase in grain size and changes in its shape are other effects of annealing. ▶ Variations in lattice parameters during annealing compared to those of as-sintered specimens suggested the possibility of disorder–order transformation during long time high temperature heat treatment process.