Phase transitions in leucite determined by high temperature, single crystal X-ray diffraction

Abstract

High temperature experimental study of a leucite single crystal was carried out using heating-quenching and heating-cooling-heating processes. We observed that in the heating process, the transition temperatures, Tc1 and Tc2 were 655°C and 675°C, respectively. After quenching, in heating process (before cooling), transition temperatures were found at 640°C and 660°C, respectively. It is concluded that this hysteresis is not due to the first order transition because there is no existence of hysteresis in heating-cooling-heating process nor an abrupt volume change at the transition. Moreover, the reflections of 200, 020, and 002 were always observed in the temperature range 21°C – 900°C. Our results do not confirm the existence of I41/a low temperature form, or Ia3d high temperature form including a transient phase I41/acd.