Effect of CaO doping on densification and microstructure control of highly transparent La 0.4 Gd 1.6 Zr 2 O 7 ceramics

Calcium oxide (CaO) as sintering additive was first used to fabricate La0.4Gd1.6Zr2O7 transparent ceramics by a simple solid-state reaction and one-step vacuum sintering method. The effects of CaO dopant amount on the densification, as well as sintering behaviors and microstructure evolution of the as-fabricated La0.4Gd1.6Zr2O7 ceramics, were systematically investigated. Under the different sintering temperatures, the relationships during the sintering process between grain growth and zpore elimination were analyzed as well. It was found that 0.1 wt% CaO doping can effectively control the rate of grain growth and promote densification dominated by surface diffusion. Furthermore, Ca2+ entered the lattice of La0.4Gd1.6Zr2O7 ceramics to accelerate ion diffusion and suppress grain boundary migration. With the introduction of 0.1 wt% CaO doping, the highly transparent La0.4Gd1.6Zr2O7 ceramics (T = 80.4% at 1100 nm) were successfully fabricated at the traditional sintering temperature (1850°C).