Lattice Dynamics, Dielectric Constants, and Phase Diagram of Bismuth Layered Ferroelectric Bi₃Ti_1−xW_xNbO_9+δ Ceramics

Abstract

Lattice dynamics and phase transitions of Aurivillius ferroelectric Bi3Ti1−xWxNbO9+δ (BTWN100x, 0 ≤ x ≤ 15%) ceramics have been investigated by temperature‐dependent Raman spectra (80–800 K) and far‐infrared (FIR) reflectance spectra (6–300 K). The frequency, intensity, and line width of phonon modes as well as complex dielectric functions of BTWN100x ceramics have been extracted by fitting Raman and FIR reflectance spectra with the multi‐Lorentzian oscillator model. It was found that the dielectric constants at a certain frequency region become lower with increasing W compositions at room temperature due to the compressive stress on W–O bands. Moreover, the temperature‐dependent behavior of optical phonon modes in BTWN100x ceramics indicates that there are two intermediate phases during the phase transition from paraelectric I4/mmm to ferroelectric A21am phase on cooling. The phase diagram of BTWN100x ceramics as a function of W composition has been improved.

Exploring optoelectronic properties and mechanisms of layered ferroelectric K4Nb6O17 nanocrystalline films and nanolaminas

“…Among them, transition metal oxides possess numerous huge advantages, which can be prepared under oxygen atmosphere and endure high temperature 6, 7 . As a typical case, layered K 4 Nb 6 O 17 (abbreviated as KN) has attracted considerable concern owing to its charming features and widespread applications in energy conversion, environmental purification, catalysis, non-linear optics, etc.…”

“…Since the discovery of graphene, two-dimensional (2D) layered materials such as metal chalcogenides, black phosphorus, transition metal oxides, and other 2D materials have raised great research interest due to their unique optical and electrical properties 1 – 5 . Among them, transition metal oxides possess numerous huge advantages, which can be prepared under oxygen atmosphere and endure high temperature 6 , 7 . As a typical case, layered K 4 Nb 6 O 17 (abbreviated as KN) has attracted considerable concern owing to its charming features and widespread applications in energy conversion, environmental purification, catalysis, non-linear optics, etc.…”

Electrical and transparent properties induced by structural modulation in (Sr0.925Ca0.075)2.5–0.5Na Nb5O15 ceramics

“…Lead-free piezoelectric ceramics showing perovskite and bismuth-layered structures have been extensively studied [1][2]. Besides these two families, increasing attention has also been paid to ferroelectric crystals with tungsten bronze (TB) structures, which have diverse properties (e.g., nonlinear optic, pyroelectric, and piezoelectric) as a result of their compositional flexibility [3][4][5].…”