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

Abstract

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.

Oxygen vacancy-related dielectric relaxation and electrical conductivity in La-doped Ba(Zr0.9Ti0.1)O3 ceramics

“…Some new bands appear in the BLZT system compared with pure BZT. The antiresonance band at *183 cm -1 shifts to *188 cm -1 (a signature of ferroelectric BaTiO 3 ceramic) [24] in the sample with x = 0.08. Bands of the BLZT ceramics in the 200-600 cm -1 spectral regions are weak due to a slight local distortion of the oxygen octahedral, which results in the breakdown of Raman selection rules.…”

“…Bands of the BLZT ceramics in the 200-600 cm -1 spectral regions are weak due to a slight local distortion of the oxygen octahedral, which results in the breakdown of Raman selection rules. In addition, directions of phonon wave vectors are randomly distributed with respect to the crystallographic axes from one grain to another and the mode mixing together with long-range electrostatic force effects [24]. Therefore, the bands become broad in 200-600 cm -1 .…”

Structural, dielectric and ferroelectric studies of Ba1−xSrxTiO3 ceramics prepared by mechanochemical activation technique

“…site [12]. It has also been known that mode frequency of this mode changes with the change in perovskite unit cell and ionic radii of substituent atom [15]. An increase in intensity and decrease in the broadening of A 1 (TO 3 ) mode is observed with subsequent increase in Sr content.…”

“…The E (LO) mode arises simultaneously with A 1 (LO 3 ) at 714 cm -1 indicates the propagation of phonon along the a-b axis. The E (TO 2 ) mode was found at 299 cm -1 , which is related to tetragonal to cubic phase transition [15]. The modes at 164, 299 and 714 cm -1 signifies long-range ferroelectric ordering.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part IV

“…Kumar et al [196] characterized the structure of the lead-free relaxor Ba(Ti 0.70 Sn 0.30 )O 3 using micro-Raman spectroscopy from 80 to 500 K, which indicated three local phase sequences. Raman spectral studies of the Zr 4+ -rich BaZr x Ti 1−x O 3 phase diagram are described by Karan et al [197] Lorenc et al [198] investigated the rotational disorder in 2-piperidyl-5-nitro-6-methylpyridine to specify its structural phase transition and its vibrational characteristics. Trzebiatowska-Gusowska et al [199] obtained a new complex containing sarcosine (CH 3 NH 2+ CH 2 COO − ) and barium(2+) dibromide (TSBB) in a 3 : 1 molar ratio, as well as its deuterated analog.…”