X-ray diffraction rocking curves of titanite, CaTiSiO5, were measured using a novel high-resolution diffractometer. Three Bragg reflections were recorded as a function of temperature and their profiles analyzed in terms of a Gaussian Bragg peak and a diffuse scattering component with an overall Lorentzian shape. The temperature dependence of the Gaussian intensities of the rocking peaks of superstructure reflections, hkl with k + l odd, scale with the long-range order parameter as I ∝ Q2 ∝ |T – Tc|2β, where β = 0.14(1) is the effective order parameter exponent.
The diffuse scattering intensity changes little with temperature at T < Tc – 20 K. Strong diffuse scattering is found at T > Tc with centers of their Lorentzian diffraction profiles shifted by Δω ≈ 0.5° with respect to the position of the equivalent Bragg peak. A second phase transition at 825 K is confirmed and the possibility of a third transition at ~1150 K is discussed. This content is PDF only. Please click on the PDF icon to access.