High-strength and low-thermal conductivity La-doped BaZrO3-based composite ceramic and its thermodynamic stability evaluation

In this study, La-doped BaZrO3-based composite ceramics Ba1-xLaxZr1-0.25xO3 (x = 0–0.2) were successfully fabricated. The structure, phase composition, sintering behavior, and mechanical and thermal properties of the materials were investigated, and their thermodynamic stability was evaluated. The results revealed that the doping of La facilitated the formation of solid solution (Ba,La)ZrO3, and La2Zr2O7, leading to grain refinement and enhanced structural densification as well as grain boundary bonding of the samples. As La doping x ranging from 0 to 0.20, the average grain size of the specimens decreased from 6.14 μm to a minimum of 2.58 μm, the cold modulus of rupture increased significantly from 84.1 to 155.6 MPa. Moreover, the apparent porosity decreased from 11.2% to a minimum of 1.7% with a thermal conductivity gradually decreased from 5.501 W/mK to 2.802 W/mK. Additionally, thermodynamic calculations indicated the potential application of La-doped BaZrO3 ceramics in the field of highly reactive alloy melting.