Abstract
We have investigated in situ an orthorhombic (
o)–tetragonal (
t) phase transition of double perovskite-structured La
0.68(Ti
0.95,Al
0.05)O
3 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
T
c=350±2 °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.