Electron diffraction investigation of phase transformations in thin Y2O3-Al2O3 films

Studied have been the phase transformations in the Y2O3-Al2O3 system. This system is promising for the heat-resistant coating materials and for the ceramic and semi-conductor technology. The electron diffraction phase analysis method has been used. The data obtained have shown that in the thin yttrium-aluminium oxide films of all the researched compositions at 900 deg C, the YAlO3 compound is formed, in the contact between the aluminium and yttrium oxides, first, then the Y4Al2O9 compound is formed. Judging by the electron-diffraction data, the YAlO3 compound is stable and is in equilibrium with the Y4Al2O9 compound in the 9O0-1000 deg C range. However, at 1050 deg C it decays into Y4Al2O9 and Y3Al5O12. The Y4Al2O9 compound decays into Y3Al5O12 and the sesquioxide of yttrium at 12O0-1300 deg C. In thin films, the Y3Al5O12 compound is formed from the Y2O3 and Al2O3 solid oxides of any composition at 1050 deg C. This formation is stable in the researched temperature range (20-140 deg C)