Dielectric Dispersion of Some Perovskite Zirconates

Perry, C. H.; McCarthy, David; Rupprecht, G.

doi:10.1103/physrev.138.a1537

Cited by 133 publications

(46 citation statements)

References 11 publications

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“…The asymmetrical shape of the line extending from 210 to 290 cm −1 should be related with the high phonon density of states which prevails in this frequency region [7]. However, an additional feature at 119 cm −1 comes out in the rhombohedral phase of BTZ05 on cooling down to 15 K. This line was never reported before in BT, but previously detected from IR measurements in barium zirconate [8]. According to the mass ratio Zr/Ti (= 1.9), which is not very far from the square of the frequency ratio 180/119 (= 2.3), it could be associated with a normal mode involving Zr ions motion against the oxygen octahedra.…”

Section: Raman Scatteringmentioning

confidence: 71%

A Raman and dielectric study of ferroelectric ceramics

et al. 1999

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Dielectric and Raman scattering experiments were performed on various ceramics with composition Ba(Ti1−xZrx)O3. Such lead-free, environmental-friendly materials were shown, from dielectric measurements, to exhibit behaviours extending from conventional to relaxor ferroelectrics on increasing the zirconium concentration. The evolution of the Raman spectra was studied as a function of temperature for various compositions, and the spectroscopic signature of the corresponding phases was determined. In the relaxor state, the variation of the integrated intensity of the Raman lines with temperature showed a plateau at low temperature. This anomaly was also detected as a peak in depolarization current measurements, and attributed to ergodicity breaking which characterizes usual relaxor systems. Raman results hint at locally rhombohedral polar nanoregions resulting from the random fields associated with Zr ions.

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Section: Raman Scatteringmentioning

confidence: 71%

A Raman and dielectric study of ferroelectric ceramics

et al. 1999

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“…[15,27] This feature had never been reported before in BT, but was previously detected in the infrared spectrum of BaZrO 3 . [34] On the basis of this observation, Farhi et al [27] have proposed that the feature arose from a normal mode involving Zr ions, which implies that nanometer-sized Zr (or Zr rich) zones exist, because otherwise the phonon lifetime would have been too short to result in a defined, separated Raman feature. On the other hand, on the basis of high-pressure Raman studies Kreisel et al [33] had excluded local pure BaZrO 3 zones and rather proposed Zr-rich domains, because of the fact that BaZrO 3 shows (for p > 12 Gpa) a well-defined Raman signature with sharp and intense bands at ∼400 and ∼620 cm −1 , which were not observed in the high-pressure Raman spectra.…”

Section: Resultsmentioning

confidence: 99%

Raman spectral studies of Zr⁴⁺‐rich BaZr_xTi_1−xO₃(0.5⩽x⩽1.00) phase diagram

Karan

Katiyar

Maiti

et al. 2008

J Raman Spectroscopy

107

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This paper reports a systematic study of the composition and the temperature-dependent-Raman spectra of Zr 4+ -rich BaZr x Ti 1−x O 3 (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, Ti 4+ -rich polar regions in a Zr 4+ -rich nonpolar matrix. Beyond an optimum concentration of BaTiO 3 (BT) in the nonpolar matrix of BaZrO 3 (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 temperaturedependent 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.

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“…The infrared-reflectivity spectra of SrTiO 3 and CaTiO 3 are shown, for comparison; the spectra of each end member are comparable to the literature (15,19 , which are assigned to the O-Ti-O bend and Figure 5a shows the Raman spectra of Sr 1Ϫx Ca x TiO 3 (x ϭ 0-1) in the frequency range 150-850 cm Ϫ1 . The Racation-TiO 3 lattice vibration, it seems hard to comment on their x dependence.…”

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confidence: 98%