Raman scattering in sol-gel derived PbTiO3 films modified with Ca


X-ray diffraction (XRD) and Raman scattering in sol-gel derived Ph1-x CaxTiO3(PCT)thin films are studied as a function of Ca content x. It is found that Ca2+ addition to PbTiO3 films results in a gradual decrease of tetragonality of the perovskite lattice accompanied with a considerable modification of the Raman spectra. A significant difference in Raman spectra of PCT films and available reference data for single crystals (x = 0) is explained in terms of the large internal stress, small grain size, and structural disorder produced by Ca2+ substitution. It is found that the shift of the frequency of ferroelectric soft mode correlates well with the variation of tetragonality for x less than or equal to x(c) = 0.4. The concentration dependence of the shift is strongly non-linear being qualitatively different from that observed earlier in other A-site doped lead fitanate-based systems. According to XRD data, the averaged crystal structure for x(c) approximate to 0.4 appears as pseudo-cubic, while Raman scattering revealed short-range order tetragonal distortion. The structural characteristics of PCT films are linked to their electromechanical properties measured earlier by interferometric technique. (C) 2004 Elsevier B.V. All rights reserved.




Materials Science


Kholkin, AL; Bdikin, I; Yuzyuk, YI; Almeida, A; Chaves, MR; Calzada, ML; Mendiola, J

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