AC, DC conduction and dielectric behaviour of solid and liquid phase sintered Al₂O₃-15 mol% V₂O₅ pellets

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• 作者：S. Seethalakshmi^a ; B. Subramanian^b ; Avi Bendavid^c ; A.K. Nanda Kumar^b ; ^{aknk27@yahoo.com}
• 关键词：Al2O3-V2O5 ; Mixed oxides ; Dielectrics ; Impedance spectroscopy ; Sintering
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：15 February 2017
• 年：2017
• 卷：43
• 期：3
• 页码：3202-3211
• 全文大小：2442 K
• 卷排序：43

文摘

Microstructural and dielectric characterization of porous Al2O3-V2O5 pellets sintered under both solid (600 °C) and liquid phase (850 °C) conditions are reported. The low temperature solid state sintering (SSS) leaves a very porous network of dense alumina particles surrounded by smaller facetted vanadia, whereas under liquid phase sintering (LPS), the V2O5 melts and recrystallizes over the relatively inert Al2O3, leading to a connected network structure. The ac conductivity and dielectric parameters of the pellets investigated from room temperature (RT) to 400 °C exhibited both universal dielectric (diffusive) behaviour at low frequencies and nearly constant loss (sub-diffusive) regimes at low temperatures. Activation energies calculated for dc/ac conduction at different frequencies suggests a composite conduction mechanism controlled by the Vanadia phase: at low frequencies, the calculated energies (Ea≈0.5 eV) compare with ionic diffusion of vanadium in V2O5, while at high frequencies and low temperatures an additional (Ea≤0.16 eV) polaronic hopping mechanism is seen. This cross-over frequency is significant for the LPS specimen indicating that the vanadia connected network assists conduction by providing a continuous (but disordered) diffusion route. Impedance and modulus spectral analysis show the presence of distributed time constants arising from electrodes, pore/matrix and phase interfaces and GBs.