Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

Abstract

A polycrystalline sample of ceramic oxide Ni 0.27 Cu 0.10 Zn 0.63 Fe 2 O 4 was prepared by the solid state reaction method. The sintered sample was well polished to remove any oxide layer formed during sintering and the two surfaces of the pellet were coated with a silver paste as a contact material. Among dielectric properties, complex dielectric constant (ε * = ε − jε ), loss tangent (tanδ) and ac conductivity (σ ac ) in the frequency range of 20 Hz to 2 MHz were analyzed in the temperature range of 303 to 498 K using a Wayne Kerr impedance analyzer (model No. 6500B). The experimental results indicate that ε , ε , tanδ and σ ac decrease with an increase in frequency and increase with increasing temperature. The transition temperature, as obtained from dispersion curve of ε , shifts towards higher temperature with an increase in frequency. The variation of dielectric properties with frequency and temperature shows the dispersion behavior which is explained in the light of Maxwell-Wagner type of interfacial polarization in accordance with the Koop's phenomenological theory. The frequency dependent conductivity results satisfy the Jonscher's power law, σ T (ω) = σ (o) + Aω n , and the results show the occurrence of two types of conduction process at elevated temperature: (i) low frequency conductivity, due to long-range ordering (frequency independent, region I), (ii) mid frequency conductivity at the grain boundaries (region II, dispersion) and (iii) high frequency conductivity at the grain interior due to the short-range hopping mechanism (frequency independent plateau, region III).

Dielectric, Conductivity and Modulus Properties of Au/ZnO/p-InP (MOS) Capacitor

“…This deals with the increase in orientation polarization, which leads to an increase in dielectric constant. [22][23][24][25][26][27][28][29][30][31][32][33] The mobility of charge carriers increases due to increased temperature. This case causes an increase in the dielectric loss.…”

“…Besides, the temperature-dependent σ ac is for the reason that the increase in thermally activated carrier mobility and thermal activation of hopping frequency. [27][28][29][30][31][32][33] Therefore, the current transport in the MOS capacitor may be the result of the hopping conduction of thermally activated electrons under ac field. Also, the frequencydependent σ ac is due to the polarization effects.…”

“…In addition, the ac conductivity may be analyzed by Arrhenius equation defined as follows 23,28,[38][39][40][41] I indicates the computed values of E a and σ 0 . While the E a value for Region 1 decreases with increase in the frequency, the E a value for Region 2 increases with the increase in temperature.…”

“…As the temperature increases in semiconductor devices, electrons in the valence band can jump to the conduction band. Besides, the temperature-dependent σ ac is for the reason that the increase in thermally activated carrier mobility and thermal activation of hopping frequency [27][28][29][30][31][32][33]. Therefore, the current transport in the MOS capacitor may be the result of the hopping conduction of thermally activated electrons under ac field.…”