Studies on ferroelectric perovskites and Bi‐layered compounds using micro‐Raman spectroscopy

Abstract

and their solid solutions useful in a broad range of device applications. Various factors that influence the material properties such as particle size, stresses, stoichiometry, compositional homogeneity and their effects on phase transition were investigated. The processing conditions, A-and B-site substitution, size-dependent Raman spectra and the structure-property correlations are discussed in the bulk, thin film and nano-crystalline forms of these materials. A film thickness dependence stress study on lead titanate (PT) and lead zirconate titanate (PZT) films indicated that the nature of stress depends strongly on the lattice parameters of the film and substrate. The size effect was found to decrease the ferroelectric transition temperature in lead-based perovskite materials. Both ionic charge and radii induced changes in the Raman spectra of A-and B-site substituted perovskites and layered compounds were studied. A-site substitution in strontium bismuth tantalite (SBT) was found to induce a relatively linear variation of transition temperature compared with the B-site substituted SBT.Raman spectra of layered compounds and their solid solutions exhibited a strong dependence on dopants resulting in structural modifications.

Effects of site substitutions and concentration on upconversion luminescence of Er^3+-doped perovskite titanate

“…BTO exhibits tetragonal structure belonging to the space group C 4v symmetry. All of the features observed in the tetragonal phase have been reported in the literature [16] 3+ doping concentration (0.5-5 mol% for BTO: B), the emission intensity reaches a maximum value at 1 mol%, and then decreases with an increase in doping concentration. There are two reasons responsible for this observation.…”

Strain and vacancy cluster behavior of vanadium and tungsten-doped Ba[Zr0.10Ti0.90]O3 ceramics

“…9,10 The spectrum shows the stretching mode of A 1 ͑TO 1 ͒ and A 1 ͑TO 3 ͒ at around 193 and 517 cm −1 , according to the Refs. 11 and 12.…”

Electronic Band Structures and Phase Transitions of Ferroelectric and Multiferroic Oxides

“…The broadening band can be assigned to a rigid sublattice mode, in which all the positive and negative ion displacements are equal and opposite. [48] It is found that a strong broadening peak can be observed at 80 K due to the combined effects of two modes splitting from the E g character mode. However, with increasing the temperature, the frequency and intensity of the mode present a decreasing trend.…”