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Powder X-ray diffraction study of ferroelectric phase transition in perovskite oxide CdTiO3

Abstract The ferroelectricity of perovskite oxide CdTiO3 was ascertained by the measurements of the dielectric constant, D-E loops, and pyroelectricity. The ferroelectric Curie temperature TC was about 80 K and the residual electrical polarization was 0.2 μC/cm2. Below TC , the temperature dependence of the lattice parameter a turned negative while the parameters b and c showed very small temperature dependence. The Rietveld analyses of the powder X-ray diffraction date at 15 K were carried out for the space groups Pnm21, Pn21 a and P21 ma, which are noncentrosymmetric subgroups of the space group of the paraelectric structure. The spontaneous polarizations calculated from the refined structural parameters indicated that the space groups Pn21 a and P21 ma were possible for the ferroelectric state of CdTiO3.