The monoclinic phase of PZT ceramics: Raman and phenomenological theory studies

This work reports on the first Raman detection of the tetragonal to monoclinic phase transition in PZT ceramics near morphotropic phase boundary at low temperatures. The transition is characterized by changes in the frequency of lattice modes with the temperature. The results presented here confirm the previous one recently reported by Noheda et al. using high-resolution synchrotron X-ray powder diffraction technique and dielectric measurements. The stability of the new phase is discussed within the framework of phenomenological Landau-Devonshire Theory.Comment: 6 pages including 4 figures, Latex, submitted to Applied Physics Letter

Measurement of quadratic electrooptic coefficients in LiNbO3 using a variation of the FDEOM method

Calculations on the optical index ellipsoid yield that in LiNbO3, a quadratic electrooptic effect free of its linear counterpart exists only for propagation along the X-crystal axis with a longitudinal electric field and in that case the quadratic coefficients Rc=R12-R31 and R41 are exclusively involved. Because of their low values, we have measured these coefficients using a specific novel variation of the accurate frequency-doubling electrooptic modulation (FDEOM) method. After a presentation of the theoretical formulation and practical implementation of this method, results for Rc and R41 are given and discussed in relation to theoretically expected values. © 1994 Chapman & Hall