Sub-micron-sized delafossite CuCrO₂ with different morphologies synthesized by nitrate–citric acid sol–gel route

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• 作者：SATISH BOLLOJU ; RADHAKRISHNAN SRINIVASAN
• 关键词：Delafossite ; semiconductors ; sol–gel ; morphology ; particle size.
• 刊名：Bulletin of Materials Science
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：40
• 期：1
• 页码：195-199
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Materials Science, general; Engineering, general;
• 出版者：Indian Academy of Sciences
• ISSN：0973-7669
• 卷排序：40

文摘

Currently, copper chromium oxide crystallizing in delafossite structure attracts huge research interest due to its versatile applications arising from its layered structure. In this work, delafossite CuCrO₂ was synthesized by sol–gel method from their respective hydrated nitrate salts with citric acid as a chelating agent. The phase formation temperature was found to be between 750 and 775∘C. At 750∘C, the partial formation of delafossite CuCrO₂ spheres with particle size in nano-regime was observed in the midst of platelets of spinel CuCr₂O₄. A green coloured powder with particle size 125–350 nm exhibiting distorted spheres was obtained at 775∘C. The increase in temperature has a profound impact on the particle size, morphology and the optical properties of CuCrO₂. The X-ray powder diffraction studies revealed the formation of 3R-CuCrO₂ phase (rhombohedral, space group R-3m) as a major product in the temperature range 775–1000∘C. The unit cell parameters were found to be a = b = 2.9711 Å and c = 17.0723 Å at 1000∘C. Scanning electron micrographs illustrated the different morphologies from spheres to hexagonal form via distorted spheres and cubes. The UV–Vis diffuse reflectance spectra measured for the powders exhibited semiconductor characteristics with an interesting size-related and temperature-dependent bandgap.