Electric modulus approach to the analysis of electric relaxation in highly conducting (Na_0.75Bi_0.25)(Mn_0.25Nb_0.75)O₃ceramics

Abstract

Broadband dielectric spectroscopy is applied to investigate the electrical properties of disordered perovskite-like ceramics in a wide temperature range. From the x-ray diffraction analysis it was found that the newly obtained (Na0.75Bi0.25) (Mn0.25Nb0.75)O3 ceramics consist of two chemically different phases. The major perovskite one has an orthorhombic structure described by the Pbcm space group (No 57, in yxz setting). The minor phase shows an orthorhombic symmetry, all-face-centred lattice F, with the lattice parameters a = 10.797(4) Å, b = 7.601(3) Å and c = 7.691(3) Å. The electric modulus M* formalism used in the analysis enabled us to distinguish and separate the relaxation processes, dominated by marked conductivity in the ε*(ω) representation. In the ceramics studied, the relaxation times are thermally activated and the dipole process has a clearly non-Debye behaviour. The relaxation process described with the use of the activation energy of approximately 0.4 eV and the characteristic relaxation time, τ0 = 1 × 10−11 s, was found to be related to oxygen vacancies. The low frequency relaxation shows Debye behaviour with a slightly lower activation energy and a longer characteristic time.

Dielectric relaxation and magnetic properties of Cr doped GaFeO3

“…From the physical point of view, the electric modulus corresponds to the relaxation of the electric field in the materials when the electric displacement remains constant [29]. The logarithmic frequency dependence of the electric modulus M' and M'' for various temperature are shown in Figure 7 for GaFe 0.9 Cr 0.1 O 3 .In terms of the dielectric constant ( ), the electric modulus is given by…”

Influence of silver ion reduction on electrical modulus parameters of solid polymer electrolyte based on chitosan-silver triflate electrolyte membrane

“…On the other hand the modulus representation is still a matter of debate [11], although the relations among the different quantities are well defined. From the physical point of view, the electrical modulus corresponds to the relaxation of the electric field in the material when the electric displacement remains constant [12]. The usefulness of modulus representation is to suppress the signal intensity associated with electrode polarization or to emphasize small features at high frequencies [11].…”

On the high temperature phase transition in Ba(Zr0.20Ti0.80)O3ceramic

“…Such nature of the dielectric relaxation suggests that in the measured frequency region, dipolar relaxation is covered up by free charge relaxation. 40,41 The room temperature (25 C) values of " 0 and tan at 1 kHz are respectively, found to be 4198 and 0.04. Figure 3 displays the variation of " 0 and tan with temperature at different frequencies.…”