The influence of Gd doping on thermophysical properties, elasticity modulus and phase stability of garnet-type (Y1-xGdx)3Al5O12 ceramics

In this work, Gd3+ was selected to partially substitute the Y3+ in yttrium aluminum garnet (YAG) in order to improve the thermophysical properties of YAG. A series of (Y1-xGdx)3Al5O12 (x = 0, 0.1, 0.2, 0.3, 0.4) ceramics were synthesized through chemical co-precipitation route. The microstructure, thermophysical properties and elasticity modulus of (Y1-xGdx)3Al5O12 were investigated. The (Y1-xGdx)3Al5O12 ceramics was comprised of single garnet-type Y3Al5O12 phase. The thermal conductivities of (Y1-xGdx)3Al5O12 bulk samples decreased with increasing doping concentration to 0.2, but increased with furthering increasing the concentration to 0.4. The thermal conductivity of (Y0.8Gd0.2)3Al5O12 was 1.51 W m−1 K−1 at 1200 °C. The average thermal expansion coefficient of (Y0.8Gd0.2)3Al5O12 was slightly larger than that of Y3Al5O12. (Y0.8Gd0.2)3Al5O12 bulk sample exhibited the lowest elasticity modulus among the investigated (Y1-xGdx)3Al5O12. In addition, (Y0.8Gd0.2)3Al5O12 ceramic remained good phase stability from room temperature to 1600 °C.