Thermal analysis of rare earth gallates and aluminates

Dilatometry, high-temperature x-ray diffraction, differential thermal analysis, and differential scanning calorirmetry have been performed on LaGaO₃, NdGaO₃, PrGaO₃, SmAlO₃, and LaAlO₃ single crystals grown by the Czochralski technique. First order phase transitions have been located at 145°C for LaGaO₃ and 785°C for SmAlO₃, and ΔH has been measured for the LaGaO₃ transition. Second order transitions have been identified for LaGaO₃, PrGaO₃, NdGaO₃, and LaAlO₃. The usefulness of these compounds as substrates for high temperature superconducting films is discussed in terms of thermal expansion matching.