Raman spectral studies of Zr4+-rich BaZrxTi1-xO3 (0.5 ≤ x ≤ 1.00) phase diagram

This paper reports a systematic study of the composition and the temperature-dependent-Raman spectra of Zr4+-rich BaZrxTi1-xO3 (BZT) ceramic compositions (0.50 <= x <= 1.00). On the basis of the dielectric behavior of Zr rich BZT ceramics, the observed relaxor behavior has been hypothesized as a result of increasing long-range interactions of nanosized, Ti4+-rich polar regions in a Zr4+-rich nonpolar matrix. Beyond an optimum concentration of BaTiO3 (BT) in the nonpolar matrix of BaZrO3 (x <= 0.75), a critical size and density of the polar regions is reached when the polar clusters start showing the relaxor like behavior, which finally show classical relaxor behavior for compositions with x = 0.5 and 0.6. This hypothesis is strongly supported from the Raman data on Zr-rich BZT presented in this paper. Well-defined BT Raman spectra for 5% BT in BZT composition were recorded which followed completely up to the 50% Ti addition in the BZT samples. The temperature-dependent Raman spectra collected on the BZT ceramics far beyond the dielectric transition temperatures supported the existence of the nano-polar BT regions, like in typical relaxor samples. The full width at half-maximum (FWHM), integrated intensity of the peaks in the Raman spectra has been analyzed to further support the conclusions. Copyright (C) 2008 John Wiley & Sons, Ltd.