Synthesis and Thermophysical Properties of (La1-xMgx)(2)Ce2O7-x

Doping magnesium into La2Ce2O7 can increase its thermal expansion coefficient (TEC) and decrease its thermal conductivity (TC), thus improve its performance for thermal barrier coating (TBC). (La1-xMgx)(2)Ce2O7, ceramics were prepared by Sol-Gel method. Powder X-Ray diffraction results revealed that (La1-xMgx)(2)Ce2O7, showed the identical structure as La2Ce2O7 (defect-fluorite type), and the crystal parameter decrease with increasing x value in the range of 0 <= x <= 0.4, and MgO occurred in the product when x>0.4. The TEC of (La1-xMgx)(2)Ce2O7-x sample (0 <= x <= 0.4) with the same composition increases with the increasing temperature, whereas the TC presents the opposite trend. At the same temperature, the TEC of the (La1-xMgx)(2)Ce2O7. sample (0 <= x <= 0.4) with different composition increases with increasing x value whereas the TC increases firstly and then decreases with the increasing ofx value, where x=0.2 nearby as turning point. In addition, possible mechanisms of the influence of Mg doping on the structure, crystal parameter, TEC and TC of La2Ce2O7 are discussed.