Phase transition and thermal expansion of the LaAlO3 single crystal at high temperatures.

Abstract: The structural evolution of lanthanum aluminum trioxide (LaAlO3) crystals grown by the Czochralski (CZ) method has been investigated by the in situ single-crystal X-ray diffraction method in the temperature range between 296 and 1195K. The square of the AlO6 octahedral rotation angle in the rhombohedral structure decreased linearly near the transition temperature, suggesting that a second-order phase transition occurs at circa 839K. Changes in the volumetric thermal expansion coefficient show a significant discontinuity at the transition point, supporting an experimental evidence by dilatometry in the literature. [Copyright &y& Elsevier]