Optical Properties of Nanocrystalline Monoclinic Y2O3 Stabilized by Grain Size and Plastic Strain Effects via High-Pressure Torsion
| Autor: | Hoda Emami, Kaveh Edalati, Etsuo Akiba, Hadi Razavi-Khosroshahi, Zenji Horita, Masayoshi Fuji |
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| Rok vydání: | 2017 |
| Předmět: |
Phase transition
Photoluminescence Band gap chemistry.chemical_element 02 engineering and technology Yttrium 010402 general chemistry 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Nanocrystalline material Grain size 0104 chemical sciences Inorganic Chemistry Crystallography chemistry Physical and Theoretical Chemistry 0210 nano-technology Monoclinic crystal system |
| Zdroj: | Inorganic Chemistry. 56:2576-2580 |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/acs.inorgchem.6b02725 |
| Popis: | Yttrium oxide (yttria) with monoclinic structure exhibits unique optical properties; however, the monoclinic phase is thermodynamically stable only at pressures higher than ∼16 GPa. In this study, the effect of grain size and plastic strain on the stability of monoclinic phase is investigated by a high-pressure torsion (HPT) method. A cubic-to-monoclinic phase transition occurs at 6 GPa, which is ∼10 GPa below the theoretical transition pressure. Microstructure analysis shows that monoclinic phase forms in nanograins smaller than ∼22 nm and its fraction increases with plastic strain, while larger grains have a cubic structure. The band gap decreases and the photoluminescence features change from electric dipole to mainly magnetic dipole without significant decrease in the photoluminescence intensity after formation of the monoclinic phase. It is also suggested that monoclinic phase formation is due to the enhancement of effective internal pressure in nanograins. |
| Databáze: | OpenAIRE |
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