Abstract
We have investigated in situ an orthorhombic (o)-tetragonal (t) phase transition of double perovskite-structured La0.68(Ti0.95,Al0.05)O3 by high-resolution (Δd/d≈0.0002) synchrotron powder diffraction technique. The unit-cell parameters increased continuously with temperature also near the o-t transition point. Good agreement was obtained in the unit-cell parameter values between heating and cooling. These results indicate that the o-t phase transition occurs reversibly and continuously at 349.3±0.6°C. We demonstrate that the present synchrotron X-ray powder diffraction technique is very powerful to determine both the transition temperature of a continuous transformation and precise unit-cell parameters even near the continuous transition point.
