Cubic tetragonal phase transition in Ca0.04Sr0.96TiO3: a combined specific heat and neutron diffraction study

The specific heat corresponding to the tetragonal-to-cubic transition in Ca 0.04 Sr 0.96 TiO 3 perovskite has been measured by conduction calorimetry. The order parameter of the transition has been obtained by means of neutron diffraction at low temperatures. Comparison of calorimetric data with the evolution of the order parameter indicates that this transition seems to follow a mean field Landau potential as in SrTiO 3 . The linear behaviour of the excess of entropy versus temperature suggests that a 2–4 Landau potential is sufficient to describe the transition.