Decomposition of garnet epitaxial layers caused by annealing

Abstract
The changes in chemical composition which accompany the process of stress relief in garnet epitaxial layers during annealing have been studied. It is shown that the process involves the evaporation of PbO and formation of Fe2O3 crystals on the layer surface. The associated volume reduction of the garnet layer results in the observed decrease in the lattice‐misfit stress. Weight‐loss measurements with a thermobalance have been employed to monitor the evaporation of PbO, and a quantitative comparison with the amount of Fe2O3 observed by optical microscopy has been made. These results are interpreted in terms of a specific decomposition reaction and are found to be in numerical agreement with x‐ray diffraction measurements of the lattice changes.