Increase of Co solubility with decreasing grain size in ZnO
Nanograined (grain size 10 nm) ZnO films with various Co contents (0–52 at.% Co) were synthesized by a novel liquid ceramics method. The solubility limit for Co was determined at 550 °C. The lattice parameter c of the ZnO-based solid solution with würzite structure ceases to grow at 33 at.% Co. The...
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Published in | Acta materialia Vol. 56; no. 20; pp. 6246 - 6256 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ltd
01.12.2008
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Subjects | |
Online Access | Get full text |
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Summary: | Nanograined (grain size 10
nm) ZnO films with various Co contents (0–52
at.% Co) were synthesized by a novel liquid ceramics method. The solubility limit for Co was determined at 550
°C. The lattice parameter
c of the ZnO-based solid solution with würzite structure ceases to grow at 33
at.% Co. The peaks of the second phase (Co
2O
3 or with cubic lattice) become visible in the X-ray diffraction spectra at 40
at.% Co. The same second phase appears in the bulk ZnO already at 2
at.% Co [Bates CH, White WB, Roy R. J Inorg Nucl Chem 1966;28:397]. A few years ago it was predicted theoretically that ZnO could become ferromagnetic at room temperature and above by doping with Co and other transition metals. Recently published papers on the structure and magnetic behaviour of Co-doped ZnO allowed us to obtain the size dependence of Co solubility in ZnO for the polycrystals and small single-crystalline particles. The overall Co solubility drastically increases with decreasing grain size. The quantitative estimation leads to the conclusion that, close to the bulk solubility limit, the thickness of a Co-enriched layer is several monolayers in grain boundaries and at least two monolayers in the free surfaces. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 1359-6454 1873-2453 |
DOI: | 10.1016/j.actamat.2008.08.032 |