Bi2O3-Modified Ceramics Based on BaTiO3 Powder Synthesized in Water Vapor

Abstract

Bi2O3 was investigated in the role of a modifier for BaTiO3 powder synthesized in a water vapor atmosphere at 200 °C and 1.55 MPa. Modification was aimed at increasing the sinterability of the powder as well as improving the structural and dielectric properties of the obtained ceramics. The morphology and phase contents of the synthesized BaTiO3 powder were controlled by the methods of SEM and XRD. Properties of pure and Bi-doped BaTiO3 ceramics were comprehensively studied by XRD, SEM, dielectric spectroscopy, and standard approaches for density and mechanical strength determination. Doping with Bi2O3 favored BaTiO3 ceramic densification and strengthening. The room-temperature dielectric constant and the loss tangent of Bi-doped BaTiO3 were shown to stabilize within the frequency range of 20 Hz to 2 MHz compared to non-doped material. The drop of dielectric constant between room temperature and Curie point was significantly reduced after Bi2O3 addition to BaTiO3. Bi2O3 appeared to be an effective modifier for BaTiO3 ceramics produced from non-stoichiometric powder synthesized in water vapor.

Effect of Gamma Irradiation on the Structural, Optical, Electrical, and Ferroelectric Characterizations of Bismuth-Modified Barium Titanate Ceramics

“…On the other hand, Bi ion doping in the BaTiO 3 lattice had an effect. It was previously [29,33] reported that the positive charge of oxygen vacancies would compensate for the presence of negatively charged Ba 2+ -vacancies in nondoped BaTiO 3 . Compared with the ideal BaTiO 3 crystal, this defect can shrink the unit cell.…”

“…A low melting oxide such as Bi 2 O 3 used as a donor doping in the Ba-site can improve the sinterability of BaTiO 3 ceramics, and the sintering temperature of barium titanate can be reduced. Solubility limits of Bi 3+ in BaTiO 3 have been reported of up to 5% [28,29]. During the charge compensation process, barium vacancies are formed, which enhanced solid-state mobility and thus reduced the sintering energy requirement.…”

Sodium Potassium Niobate-Based Piezoelectrics Sintered in Humid Air

“…KNN sintered in laboratories located in a region with humid climate showed lower densities than KNN sintered by the same procedure in a drier climate [27]. The effect of water vapour on the synthesis, densification, grain growth and ionic diffusion has been studied for different inorganic systems such as PbZrTiO3 (PZT) [28], BaTiO3 [29], Ag nanoparticles [30], MgO [31], silicates [32], alumina [33] and titania [34]. Still, there are no systematic studies on how humidity during sintering affects KNN.…”