Electron Paramagnetic Resonance study of hopping in CCTO mixed with TiO₂

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• 作者：L. Vivas^a ; G.E. Delgado^d ; P. Leret^b ; J.F. Ferná ; ndez^b ; J.L. Costa-Krä ; mer^c ; P. Silva^a ; ^{pejosi@gmail.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Electron paramagnetic resonance ; Polaron hopping ; Linewidth ; CCTO ; TiO2
• 刊名：Journal of Alloys and Compounds
• 出版年：2017
• 出版时间：25 January 2017
• 年：2017
• 卷：692
• 期：Complete
• 页码：212-218
• 全文大小：1125 K

文摘

Electron Paramagnetic Resonance (EPR) is used to study the transport properties in CaCu₃Ti₄O₁₂(CCTO) and its mixtures with TiO₂. The temperature dependence of the peak to peak linewidth of the EPR spectra in the temperature range 430 ≤ T ≤ 660 K, is studied for the powders of CCTO, 5% CCTO + 95% TiO₂ and 1% CCTO + 99% TiO₂. All the samples show a behavior predicted by the Small Polaron Hopping model. This behavior is studied as a function of the TiO₂ content, finding an activation energy that decreases with increasing TiO₂ concentration. We found that two mechanisms govern the conductivity in these system one, intrinsic to the CCTO, via oxygen vacancies and the other one, which improve the conductivity, related to the polarizability of the Ti-ions at the surface of the grains and mediated by the oxygen vacancies at the surface of the CCTO.