The addition of different dopants e.g., Mg, Ce, Yb can significantly affect the thermal conductivity and mechanical properties of alumina ceramics intended for use in high-temperature applications. These dopants can alter the microstructure, grain size, and grain boundary characteristics of the alumina ceramics, leading to changes in their properties. Here is a brief overview of how these dopants can affect the properties of alumina ceramics:1. Magnesium Mg : The addition of Mg as a dopant in alumina ceramics can lead to the formation of magnesium aluminate MgAl2O4 spinel phase. This spinel phase can improve the mechanical properties of alumina ceramics, such as fracture toughness and flexural strength, by inhibiting grain growth and enhancing the grain boundary strength. However, the presence of MgAl2O4 spinel phase can also reduce the thermal conductivity of alumina ceramics due to the lower thermal conductivity of MgAl2O4 compared to pure alumina.2. Cerium Ce : Ce doping in alumina ceramics can result in the formation of cerium aluminate CeAlO3 phase. The presence of CeAlO3 phase can improve the mechanical properties of alumina ceramics, such as hardness and fracture toughness, by refining the grain size and enhancing the grain boundary strength. However, the thermal conductivity of alumina ceramics can be reduced due to the lower thermal conductivity of CeAlO3 compared to pure alumina.3. Ytterbium Yb : Yb doping in alumina ceramics can lead to the formation of ytterbium aluminate YbAlO3 phase. The presence of YbAlO3 phase can improve the mechanical properties of alumina ceramics, such as hardness and fracture toughness, by refining the grain size and enhancing the grain boundary strength. Moreover, Yb doping can also increase the thermal conductivity of alumina ceramics due to the higher thermal conductivity of YbAlO3 compared to pure alumina.In summary, the addition of different dopants can have varying effects on the thermal conductivity and mechanical properties of alumina ceramics. Mg and Ce doping can improve the mechanical properties but reduce the thermal conductivity, while Yb doping can improve both mechanical properties and thermal conductivity. The choice of dopant depends on the specific requirements of the high-temperature application, and a balance between the desired properties must be achieved.