Fabrication of submicron Li-rich Li2(Ti,Zr)O3 solid solution ceramics with sluggish grain growth rate

Doping and forming solid solution is an effective approach to tailor densification and grain growth. In this study, submicron Li₂(Ti,Zr)O₃ solid solution ceramics was successfully fabricated by a modified solid-state route for the first time. The use of appropriate starting powders can greatly reduce the synthesis temperature, and the preparation of Li₂(Ti,Zr)O₃ with submicron grain size is possible. The substitution of Ti by Zr will inhibit the phase transition from cubic to monoclinic structure, as well as the grain growth and pore removal. By doping 10-at.% Zr, the grain size was significantly decreased from several μm to 400 nm at 900°C, which contributes to a high conductivity eight times that of pure Li₂TiO₃. Moreover, after being heated at 900°C for 10 days, the grain size of Li₂(Ti,Zr)O₃ only increases to 5 μm; however, the grains of Li₂TiO₃ grows up to 16 μm with abnormal grain growth. The compositions of Li₂(Ti,Zr)O₃ are high uniform with no element segregation, indicating the sluggish grain growth rate is caused by the slow diffusion of Zr rather than segregation-induced solute drag. By adding excess Li and two-step sintering, the Li-rich Li₂(Ti,Zr)O₃ ceramic pebbles with high crush load of 50–60 N and small grain size of 300–500 nm were successfully fabricated. This work demonstrates a simple method for the synthesis of Li₂(Ti,Zr)O₃, which makes this material more widely accessible for exploration and also help accelerate its engineering application to be an advanced solid breeder.