Influence of Er3+ doping on the mechanical and thermophysical properties of (ErxY1-x)3Al5O12 ceramics

In this work, Er3+ was selected to replace Y3+ in the yttrium aluminium garnet (YAG) in order to improve its mechanical and thermophysical properties. A series of (ErxY1-x)3Al5O12 (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) ceramics were prepared by solid-state synthesis method at 1000 ?C and finally sintered at 1600 ?C for 5 h. The microstructure and morphology of the prepared ceramics were investigated. The results showed that all Er3+ doped Y3Al5O12 ceramics exhibited single garnet-type YAG phase and good compactness. With the increase of Er3+ doping concentration, the thermal conductivity of the (ErxY1-x)3Al5O12 ceramics decreased slowly and then increased subsequently. Among the investigated specimens, the (Er0.7Y0.3)3Al5O12 had the lowest thermal conductivity (1.51W/m?K, at 1000 ?C), which was about 28% lower than that of the pure YAG (2.1W/m?K, at 1000 ?C). As the Er3+ doping concentration increased, the thermal expansion coefficient of the (ErxY1-x)3Al5O12 ceramics hardly changed, remaining around 9.08 ? 10?6 K?1 at 1200 ?C. Moreover, when the Er3+ doping concentration exceeded 0.5, the mechanical properties of the (ErxY1-x)3Al5O12 ceramics increased suddenly. Specifically, the hardness increased from 14.28 to 16.53GPa and the bending strength increased from 231.74 to 324.49MPa.