Enhanced dielectric properties of bismuth titanate/silver composites

Abstract

Bismuth titanate (BiT) based composites containing silver particles are fabricated by a solution chemical process. Incorporation of silver particles does not result in unwanted reaction phase. SEM micrographs reveal fine silver particles distribute at BiT grain boundaries and into larger BiT plate-like grains. With the addition of silver, the dielectric constant increases up to ∼10 times higher than that of pure BiT ceramic, which can be attributed to the effective electric fields developed around the dispersed metal particles and the percolation effect. Additionally, the dielectric losses are significantly reduced by incorporating silver particles, and the values of BiT/Ag composites are lower than 0.5%. The dielectric properties of BiT/Ag composites are nearly frequency independent in the measured frequency range (1 kHz to 1 MHz).

Percolative BaTiO3–Ni composite nanopowders from alkoxide-mediated synthesis

“…It is noted that the effective dielectric field developed around the conducting particles causes an increase in the dielectric constant of ceramic-metal composites. 16 Thus, it is apparent that effective dielectric field was not well formulated in BaTiO 3 -Ni composite due to the formation of nickel oxide on the surface of nickel particles. It is expected, however, that advanced sintering techniques such as spark plasma sintering will enable the preparation of fully densified percolative BaTiO 3 -Ni nanocomposite without oxidation of nickel and enhanced dielectric performance.…”

“…Up to the present it was very difficult to experimentally observe the phenomena occurring directly at the percolation threshold and only a few groups have reported the effect of a strongly enhanced dielectric constant for ceramic-metal composites in the neighborhood of the percolation threshold. [11][12][13][14][15][16] Only microcomposites, however, have been reported in the literature up to now. A more efficient approach to the percolative threshold, for which the highest performance is anticipated, can be achieved for much more intimate and homogeneous mixtures of the dielectric and conductive phases.…”

Fabrication and thermoelectric properties of Ca3Co4O9/Ag composites

“…The dried mixture was pressed into pellets and calcined at 1173 K for 20 h in air atmosphere, and then ground and calcined again at 1173 K for 10 h to obtain a pure Ca349 phase. Preparation of Ca349/Ag composite powder was similar to that of Bi 4 Ti 3 O 12 /Ag composite powder [18]. High-purity AgNO 3 (99.8%, Wako Pure Chem.…”

Optical anisotropy in bismuth titanate: An experimental and theoretical study

“…2,3 Dielectric, optical, and optoelectronic properties of BiT are of further interest in the area of optical memories since its band gap (E g $ 3.6 eV), 4 similar to most ferroelectric perovskite oxides, lies in the visible spectrum region. As a result, dielectric [5][6][7][8][9][10][11][12][13] and optical properties [13][14][15][16][17][18][19] of BiT have been extensively investigated for decades. In addition, there has been a renewed interest in the optical properties of ferroelectric BiT as noncentrosymmetric crystal structure of room temperature BiT could trigger asymmetric electron excitation, relaxation, and scattering leading to photovoltaic effect.…”