Solid solution effects on the thermal properties in the MgAl ₂O₄-MgGa₂O₄ system

Solid solution effects on thermal conductivity within the MgO-Al ₂O₃-Ga₂O₃ system were studied. Samples with systematically varied additions of MgGa₂O ₄-MgAl₂O₄ were prepared and the laser flash technique was used to determine thermal diffusivity at temperatures between 200°C and 1300°C. Heat capacity as a function of temperature from room temperature to 800°C was also determined using differential scanning calorimetry (DSC). Solid solution in the MgAl₂O₄-MgGa ₂O₄ system decreases the thermal conductivity up to 1000°C. At 200°C thermal conductivity decreased 24% with a 5 mol% addition of MgGa₂O₄ to the system. At 1000°C, the thermal conductivity decreased 13% with a 5 mol% addition. Steady-state calculations showed a 12.5% decrease in heat flux with 5 mol% MgGa ₂O₄ considered across a 12 inch thickness.