查看文章

The low-frequency mechanical properties of single crystal LaAlO₃ have been investigated as a function of temperature, frequency and applied force using the technique of dynamical mechanical analysis (DMA) in three-point bend geometry. LaAlO₃ undergoes a cubic to rhombohedral phase transition below 550°C. The mechanical response in the low-temperature rhombohedral phase is shown to be dominated by the viscous motion of transformation twin domain walls, resulting in a factor of 10 decrease in the storage modulus relative to the high-temperature cubic phase (super-elastic softening) and a significant increase in attenuation. Super-elastic softening is observed down to 200°C, below which the mobility of the domain walls decreases markedly, causing a rapid increase in storage modulus and a pronounced peak in attenuation (domain wall freezing). The frequency dependence of the storage modulus …