Oxygen ion conductivity studies of bismuth and bismuth-calcium co-doped ThO2
| Autor: | Rajamani Nagarajan, Aanchal Sethi, Sitharaman Uma |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Band gap Analytical chemistry chemistry.chemical_element 02 engineering and technology Conductivity 01 natural sciences Bismuth symbols.namesake 0103 physical sciences Materials Chemistry 010302 applied physics Dopant Rietveld refinement Process Chemistry and Technology Doping technology industry and agriculture 021001 nanoscience & nanotechnology Surfaces Coatings and Films Electronic Optical and Magnetic Materials chemistry Ceramics and Composites symbols Grain boundary 0210 nano-technology Raman spectroscopy |
| Zdroj: | Ceramics International. 47:21498-21508 |
| ISSN: | 0272-8842 |
| DOI: | 10.1016/j.ceramint.2021.04.161 |
| Popis: | A series of trivalent (Bi3+) doped and divalent (Ca2+) co-doped ThO2 samples i.e., Th0.50-xCaxBi0.50O2-δ (x = 0.00, 0.05, 0.10, 0.15 and 0.20) have been synthesized by citrate-nitrate solution combustion route and investigated in the context of oxygen ion conductivity and dielectric relaxation phenomena. The Rietveld refinement of the Powder X-ray diffraction data confirmed monophasic fluorite structures (S.G. Fm 3 ‾ m) for calcium concentrations up to 20 mol %. The optical band gap decreased with the increase in Ca2+ concentration up to 10 mol %. In contrast, the defect band's intensity in the Raman spectra increased due to oxygen vacancies on divalent addition. The quantitative aspect of oxygen vacancy and defect concentration was derived from Raman spectra. The crystallographic index application was further employed to interpret the optimum doping concentration to maximize oxide ion conductivity. Remarkably high oxide ion conductivity (~10−3 S/cm) was observed for Bi3+ doped (50 mol %), and Bi3+ (50 mol %)-Ca2+ (10 mol %) co-doped ThO2 samples at 773 K. The Nyquist plot exhibited grain contribution for low dopant levels. Both grain and grain boundary contribution were present in the higher dopant concentrations. Conductivity, dielectric, and modulus properties of doped and co-doped samples have been compared, from which 10 mol % of Ca2+-doping was identified to be the optimum concentration. |
| Databáze: | OpenAIRE |
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