A neutron study of diffuse scattering in cubic KNbO3

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Abstract
The present work describes an inelastic neutron scattering study of the diffuse excitation associated with the ferroelectric phase transition in cubic KNbO3 (T > Tc = 423°C). As in BaTiO3, strong an isotropic quasielastic scattering is observed. Variation of diffuse mode scattering with temperature and wave vector is studied. The temperature dependence of the integrated intensity is consistent with a Curie-Weiss temperature of T0 = 368 ± 10°C, which is in good agreement with the value determined from measurements of the dielectric constant. Qualitatively the behavior appears to be very similar to that of BaTiO3, and in particular no evidence is found to support the existence of statically disordered domains in cubic KNbO3.