Influence of dysprosium oxide doping on thermophysical properties of LaMgAl_(11)O_(19) ceramics

摘要

This paper deals with the influence of dysprosium oxide doping on thermophysical properties of LaM-gAl_(11)O_(19) ceramics. LaMgA_(11)O_(19) ceramic powders doped with different contents of dysprosium oxide were pressureless-sintered at 1700℃ for 10 h in air to fabricate dense bulk ceramics. La_(1_x)Dy_xMgAl_(11)O_(19) (x = 0,0.1,0.2,0.3) ceramics have a relative density of 90.7-96.0%, and exhibit a single phase of magne-toplumbite structure. Thermal diffusivity and thermal expansion coefficients of La_(1-x)Dy_xMgAl_(11)O_(19) ceramics were measured with a laser flash method and a high-temperature dilatometer. Thermal diffusivity of La_(1-x)Dy_xMgAl(11)O_(19) ceramics decreases with increasing Dy_2O_3 content at identical temperature levels. The measured thermal conductivity of La_(1-x)Dy_xMgAl_(11)O_(19) ceramics is located in the range of 2.52-2.89 W m~(-1) K~(-1) at 1200 ℃. Thermal expansion coefficient of La_(0.8)gDy_(0.2)MgAl_(11)O_(19) ceramic is slightly higher than that of undoped LaMgAl_(11)O_(19) ceramic at identical temperature levels.