Impedance and Raman Spectroscopic Studies on La-modified BLSF Ceramics

Abstract

The bismuth layer structured ferroelectric (BLSF) ceramics consisting of four-layers (BaLa 0.75 Bi 3.25 Ti 4 O 15 ) and five-layers (Ba 2 La 0 . 75 Bi 3.25 Ti 5 O 18 ) were prepared by the conventional solid-state reaction method. Summerfield ac-conductivity scaling analysis was used to evaluate the electrical behavior and the ac-conductivity isotherm curves. The relaxation results were corroborated with the Raman Peak positions and full width at half maximum was obtained by using Lorentzian peak fit method. Finally, the results were compared with the two-layered relaxor-compound (Bi 2.45 La 0.55 TiNbO 9 ) and technologically standard three-layered compounds (La 0.75 Bi 3.25 Ti 3 O 12 ; BLT). The dielectric relaxation of Bi 2.45 La 0.55 TiNbO 9 was verified using modified Curie-Weiss law and V€ ogel-Fulcher relationship. An attempt is made to realize the typical collective nature of the ionic conductivity of the samples.

Dielectric studies on Sm-modified two-layered BLSF ceramics

“…Since the moment of these defect dipoles is difficult, one cannot observe any humps in dielectric as well as saturation in hysteresis loops. The results were consistent with our earlier results [13][14][15][16]25]. The observation of a small hump in dielectric data (shown as arrow in figure 4) above 400 • C is attributed to the rotation of oxygen octahedra.…”

“…The increase in the size of the A-site cation certainly affects the rattling space of the B-site ion. The results were indeed consistent with the dielectric data of Bi 2.45 La 0.55 TiNbO 9 , where a broad dielectric peak was observed [14].…”

“…In their investigation, Sm x Bi 2 TiNbO 9 (where x = 0−1) compound of all the compositions showed a higher transition temperature in the range of 800-950 • C. It has been reported that the Curie temperature can be decreased by decreasing the size of the Asite cation modification for the Bi-site [5]. Our recent report [14] on La-modified BTN (Bi 2.45 La 0.55 TiNbO 9 ) and similar compounds showed a relaxor-kind behaviour. The dielectric peaks were found to be broad and well-fit to the modified Curie-Weiss law and Vogel-Fulcher relation.…”

“…Later, many researchers demonstrated that Bi-site modified Bi 3 TiNbO 9 is a good ferroelectric with the highest Curie temperature (940 • C) among the other materials reported in the BLSF family [9][10][11][12][13]. One of the factors for observing such phenomenon was attributed to reduced-distortion in the perovskite units [9][10][11][12][13][14][15][16][17]. Among BLSF systems, strontium bismuth-tantalate (SrBi 2 Ta 2 O 9 ) and strontium bismuth-niobate (SrBi 2 Nb 3 O 9 ) are found to be the most promising candidates for non-volatile FeRAM devices [9,12].…”

Review on energy storage in lead‐free ferroelectric films

“…The aurivillius family of compounds are bismuth‐layered structure ferroelectrics (BLSFs), which are built with layered bismuth oxides consisting of regular inter growth of (Bi 2 O 2 ) 2+ layers with perovskite (A n − 1 B n O 3 n + 1 ) 2− layers. Here in this perovskite layers A = Bi 3+ and B = Fe 3+ , Ti 4+ and n in (A n − 1 B n O 3 n + 1 ) 2− refers to the number of perovskite‐like packets between the Bi 2 O 2 layers 77‐79 . A combination of 1 mol of a three‐layered monoclinic Bi 4 Ti 3 O 12 and m moles of rhombohedral perovskite BiFeO 3 , with m = 1, 2, and 5, are considered as four‐, five‐, and eight‐layered compounds: Bi 5 FeTi 3 O 15 , Bi 6 Fe 2 Ti 3 O 18 , and Bi 9 Fe 5 Ti 3 O 27 and these are simultaneously ferroelectric and AFE in nature 80 .…”