Study of dielectric and ferroelectric properties of five-layer Aurivillius oxides: A2Bi4Ti5O18 (A = Ba, Pb and Sr) synthesized by solution combustion route

Abstract

This paper presents the ferroelectric and dielectric properties of five-layer Aurivillius oxides (Ba 2 Bi 4 Ti 5 O 18 , Pb 2 Bi 4 Ti 5 O 18 and Sr 2 Bi 4 Ti 5 O 18) prepared by a solution combustion route with glycine as a fuel at low calcination temperature. The phase formation of these materials with pseudo-tetragonal structure was achieved after calcination at 750 • C for 3 h; as confirmed by X-ray diffraction studies. Scanning electron microscopy of the sintered ceramics shows that the grains exhibit a plate-like morphology. The ferroelectric to paraelectric transition temperature (T c) for Ba-, Pb-and Sr-based bismuth titanate ceramics was found to be 350, 280 and 260 • C, respectively. All three materials show multiple relaxation phenomena and their electrical conductivity was found to be temperature dependent. The Pb 2 Bi 4 Ti 5 O 18 ceramic possessed the highest value of activation energy (0.68 eV) and hence shows better ferroelectric properties, as compared to barium and strontium bismuth titanates.

Dielectric studies on Sm-modified two-layered BLSF ceramics

“…The complex dipoles require high electric fields to switch the polarization process, and hence, the samples should have high dielectric strength, so that the sample can withstand even at a higher applied electric field. Similar results were observed in five layer compound [13].…”

“…The enhancement of dielectric constant can be attributed to the Bi-vacancy, produced by La-doping at the Bi-site (A-site) in the perovskite cell, which makes the domain wall movement more easier. In addition, the mechanical quality factors (Q r ) of these samples were found to be comparable to that of Pb-based materials [13]. Keeping in view of all aforementioned, we have prepared Bi 3−x Sm x TiNbO 9 (x = 0.2, 0.4, 0.6, 0.8, 1.0) ceramics by a solid-state reaction method.…”

“…Newnham et al [8] reported that Sr 2+ and Ba 2+ substituted layered compounds showed lower Curie temperature, compared to the parent compound (Bi 3 TiNbO 9 ). 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].…”

“…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].…”

“…A noteworthy aspect from the literature is that the spontaneous polarization (P s ) lies along the c-axis. The value of polarization (P s ) varies depending on whether there is an even or odd number of layers (n) in the BLSF compound [13]. Earlier studies predicted that donor and acceptor doping would affect the ferroelectric properties.…”