Dielectric relaxation in BaTi0.85(Fe1∕2Nb1∕2)0.15O3 perovskite ceramic

Abstract

A polycrystalline sample of BaTi0.85(Fe1∕2Nb1∕2)0.15O3 is synthesized by high temperature solid state reaction technique. This sample crystallizes in cubic pervoskite structure at room temperature. The dielectric properties have been investigated at temperature range from 80to450K at various frequencies (100–107Hz). Frequency dielectric dispersion phenomena in a BaTi0.85(Fe1∕2Nb1∕2)0.15O3 ceramic has been analyzed by impedance spectroscopy in the temperature range from 250to450K. The Cole-Cole relaxation equation modified by introducing the conductivity was used to describe the experimental dielectric spectra of a high permittivity. Excellent agreement has been obtained in wide frequency domain (100–107Hz) between the measured and calculated permittivities in the 250–450K temperature range. The dielectric relaxation frequency obeys the Arrhenius behavior with activation energy of 0.181eV. A separation of the grain and grain boundary properties has been achieved using an equivalent circuit model. The different parameters of this circuit have been determined using impedance and modulus spectroscopy studies. The inner grain conductivity also obeys the Arrhenius low behavior with activation energy of 0.183eV. The dielectric relaxation and the inner grain conductivity have thus similar activation energies which suggest a link between these two phenomena.

Effect of Ni doped BaTiO3 on the dielectric properties in the Ba(Ni1/3Nb2/3)xTi1−xO3 solid solution

“…In this solution one notices the absence of the phenomenon of conductivity when x increases because of the stability of the valence of nickel contrary to that observed by the Fe in the solid solution Ba(Fe 1/2 Nb 1/2 ) x Ti 1−x O 3 which presents that phenomena when the rate of substitution increases to 0.15 [12].…”

“…In addition, for our material the value of the maximum of ε r is approximately the same as BaTi 1−x (Zn 1/3 Nb 2/3 ) x O 3 , but it is less than Ba(Fe 1/2 Nb 1/2 ) x Ti 1−x O 3 because of conductivity contribution in this latter system. If we compare these results to those obtained in Ba(Nb x Ti 1−x )O 3 in which the relaxor character was [11] 0 ≤ x ≤ 0.05 0.075 ≤ x ≤ 0.2, 0.75 ≤ x ≤ 0.975 Ba(Fe 1/2 Nb 1/2 )xTi1−xO3 [12] 0 ≤ x < 0.125 0.125 ≤ x < 0.15 obtained for compositions larger than ≈6% [13], we can deduce that the appearance of relaxor effect in our material is not due only to the substitution Ni but it can be caused by the Nb.…”

High dielectric constant observed in (1−x)Ba(Zr0.07Ti0.93)O3–xBa(Fe0.5Nb0.5)O3 binary solid-solution

“…Further, these samples displayed a strong frequency dispersion. This characteristic is similar to that observed for some giant dielectric constant materials, such as BaTi 0.85 (-Fe 0.5 Nb 0.5 ) 0.15 O 3 [14]. Normally BFN is a relaxor dielectric material and BZT07 shows a small dielectric-frequency dependence, therefore the increased amount of BFN could generate a higher degree of frequency dispersion for the BZT07-BFN system.…”

Dielectric properties of tetragonal tungsten bronze films deposited by RF magnetron sputtering

“…This type of variation is often observed in disordered systems and is attributed to hopping transport between localized states close to Fermi level [40]. In the investigated sample, the statistical distribution of Fe 3þ and Nb 5þ within the octahedral framework could trigger such a mechanism [41].…”