Structural and thermoelastic properties of CaTiO3 perovskite between 7 K and 400 K

The structural and thermoelastic properties of CaTiO₃ perovskite have been studied using high-resolution powder neutron diffractometry at eighty temperatures in the range 7-400 K. The temperature variation of the unit cell volume, the thermodynamic Grüneisen parameter and the isobaric heat capacity are analysed using a two-term Debye model. Structural parameters are presented as the magnitudes of symmetry-adapted basis-vectors of seven normal modes with wavevectors that lie on the surface of the Brillouin zone of the primitive cubic aristotype phase, and a structural basis for the temperature-dependence of the bond lengths is proposed. A consistency between the vibrational Debye temperatures derived from the atomic displacement parameters and the mean values of the vibrational energies of the three atomic species calculated from the partial phonon densities of states has been found.