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Formation of anion-vacancy clusters and nanocavities in thermochemically reduced MgO single crystals
| Content Provider | Semantic Scholar |
|---|---|
| Author | Monge, María Angeles Popov, A. I. Ballesteros, Carmen González, Roberto Chen, Yunle Kotomin, Eugene A. |
| Copyright Year | 2000 |
| Abstract | An MgO crystal was thermochemically reduced (TCR) under extreme reducing conditions such that the concentration of anion vacancies $(F$ centers) was exceptionally large, $6\ifmmode\times\else\texttimes\fi{}{10}^{18}{\mathrm{cm}}^{\ensuremath{-}3}.$ Optical absorption measurements demonstrate that in addition to F centers absorbing at $250\mathrm{nm},$ anion-vacancy clusters absorbing at $355,$ $406,$ $440,$ $480,$ and $975$ nm were observed. Upon thermal annealing in a reducing atmosphere, a broad extinction band at 345 nm with a full width at half maximum (FWHM) of 1.25 eV emerged. With further heat treatment the peak wavelength shifted toward 370 nm and the FWHM varied between $1.25$ and 2.25 eV. Transmission electron microscopy (TEM) showed that concomitantly there exist rectangular defects with typical dimensions of $3\mathrm{nm}.$ Microdiffraction, x-ray microanalysis, and high-resolution electron microscopy, in conjunction with Mie theory, indicate that these rectangular defects are nanocavities with their walls plated with magnesium. Therefore, both oxygen vacancies and magnesium-rich regions have been observed in a thermochemically reduced MgO crystal. |
| Starting Page | 9299 |
| Ending Page | 9304 |
| Page Count | 6 |
| File Format | PDF HTM / HTML |
| DOI | 10.1103/PhysRevB.62.9299 |
| Volume Number | 62 |
| Alternate Webpage(s) | http://teor.cfi.lu.lv/articles/popov/popov_P_71.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
