Thermal stability and thermal expansion behaviour of ZrO2/Y2O3 multilayers deposited by pulsed laser deposition technique

Multilayers of ZrO2/Y2O3 were prepared by pulsed laser deposition technique with variation in the ZrO2 layer thickness from 5 to 30 nm keeping the Y2O3 layer thickness constant (∼10 nm). The stability, phase evolution and thermal expansion behaviour of the multilayers were analyzed by high temperature x-ray diffraction technique, in the temperature range of 300-1373 K. Unlike the single layer of ZrO2 film, which shows a mixture of tetragonal and monoclinic phase, the ZrO2 layers in multilayers show tetragonal phase in case of all the multilayers investigated in the present work. The values of coefficient of thermal expansion (CTE) decrease with increase in the ZrO2 layer thickness. The CTE of both ZrO2 and Y2O3 are found to be influenced by their mutual solubility as well as due to interdiffusion of these oxides taking place along the interfaces of the multilayers, especially during high temperature heat-treatment.