Temperature evolution of the ferroelastic order parameter of Li₂TiGeO₅

Abstract

The temperature dependence of the order parameter of Li 2 TiGeO 5 ferroelastic was determined on the basis of several independent measurements: specific heat, birefringence and IR spectroscopy. The estimated temperature evolution of order parameter is in very good agreement with mean field Landau theory in temperature range 40 5 T 5 233.5 K. The character of the above mentioned dependence unequivocally confirms the second-order phase transition in Li 2 TiGeO 5 at 233.5 K.