Co3−δO4 paracrystal: 3D assembly of nanosize defect clusters in spinel lattice |
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Authors: | Wen-Hsu Lee |
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Institution: | Institute of Materials Science and Engineering, National Sun Yat-sen University, 80424 Kaohsiung, Taiwan, ROC |
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Abstract: | Paracrystalline array of defect clusters ca. five times the lattice spacing of the average Co3−δO4 spinel structure occurred more or less in a relaxed manner when the sintered Co1−xO polycrystals were air-quenched below the Co1−xO/Co3−δO4 transition temperature to activate oxy-precipitation of cube-like Co3−δO4 at dislocations. The same paracrystalline spacing was obtained for Co3−δO4 when formed via oxidizing/sintering the Co1−xO powders at 800°C in air, suggesting a nearly constant δ value for Co3−δO4 in the T-PO2 conditions encountered. The extra cobalt vacancies and Co3+ interstitials, as a result of δ value, may form additional 4:1-derived defect clusters for further paracrystalline distribution in the spinel lattice. The nanosize defect clusters self-assembled by columbic interactions and lattice relaxation in ionic crystal may have potential applications as step-wise sensor of oxygen partial pressure at high temperatures. |
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Keywords: | Co3&minus δO4 Spinel Defect cluster Paracrystal TEM |
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