1. Structural and dielectric properties of the fluorite-type LaxCe1−xO2−δceramics
- Author
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Kundan Kumar, Sanjib Nayak, Kushal Singh, D. C. Joshi, Mir Motakabbir Alom, Anirban Chowdhury, and Subhash Thota
- Subjects
010302 applied physics ,Permittivity ,Materials science ,Acoustics and Ultrasonics ,Condensed matter physics ,Doping ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Variable-range hopping ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Charge carrier ,Grain boundary ,Ceramic ,0210 nano-technology - Abstract
High density (95–97%) La x () ceramics were tested for structural and dielectric properties. Dense microstructure and controlled phase-purity were obtained for all the -doped samples. A surprising three-fold increase was noticed in the frequency dependent dielectric permittivity behavior for the ceramic, associated with the space-charge polarization at grain boundaries or inhomogeneous microstructure of the ceramic. High resistivity (~108 Ωm) at room temperature was noticed for the ceramics (at 100 Hz). Hopping of electrons within the oxygen vacancies were noted as the main transport mechanism; strong localization of charge carriers were noticed at high frequencies. The temperature dependent ac-resistivity analysis (T) provides strong evidence for Mott's variable range hopping process of charge carriers, between the localized states with an average hopping length of RH of 3 nm and hopping energy of WH of 0.67 eV. Moreover, the effect of grains and grain boundaries on the correlation between ac-conductivity and angular-frequency ω has been discussed in detail.
- Published
- 2017
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