| Title: | Donor doping of K0.5Na0.5NbO3 ceramics with strontium and its implications to grain size, phase composition and crystal structure |
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| Authors: | Hreščak, Jitka (Author)
Dražić, Goran (Author)
Deluca, Marco (Author)
Arčon, Iztok (Author)
Kodre, Alojz (Author)
Dapiaggi, M. (Author)
Rojac, Tadej (Author)
Malič, Barbara (Author)
Benčan, Andreja (Author) |
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| Files: |  Manuscript_text.pdf (2,11 MB)
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| Language: | English |
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| Work type: | Not categorized (r6) |
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| Tipology: | 1.01 - Original Scientific Article |
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| Organization: | UNG - University of Nova Gorica |
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| Abstract: | In this study, the particular effects of A-site donor doping in a lead-free piezoceramic material K0.5Na0.5NbO3 (KNN) doped with Sr2+, i.e., the crystal-structure change, the secondary-phase formation and the grain-size decrease, were investigated. The already-reported causes of these effects upon doping KNN were critically discussed and a mechanism of the effects’ formation was suggested and experimentally supported with advanced analytical methods. Extended X-ray absorption fine structure (EXAFS) analyses proved that the Sr occupies the perovskite A-sublattice, and locally modifies the KNN monoclinic structure to cubic. With the help of Sr K-edge EXAFS and wavelength-dispersive X-ray spectroscopy, the Sr was found to be homogenously distributed in the KNN perovskite lattice with 0.5, 1 and 2% Sr and no Sr segregation on the nano level was found in any of the studied samples with transmission electron microscopy. Introducing Sr into the A-sublattice, as well as accounting for the charge-compensating A-site vacancies in the starting composition, causes increasing lattice disorder and microstrain, as determined from a Rietveld refinement of the synchrotron X-ray diffraction data. Above 2% Sr the system segregates the A-site vacancies in a secondary phase in order to release the chemical pressure, as revealed by Raman spectroscopy. All these effects result in an increasing number of low-angle grain boundaries that limit the grain growth and finally lead to a significant grain-size decrease. |
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| Keywords: | perovskite, potassium sodium niobate, donor doping, cation vacancies |
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| Year of publishing: | 2017 |
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| Number of pages: | 10 |
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| Numbering: | 37 |
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| COBISS_ID: | 4638715  |
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| URN: | URN:SI:UNG:REP:K6AF7WGV |
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| DOI: | 10.1016/j.jeurceramsoc.2016.12.053 |
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| License: | 
This work is available under this license: Creative Commons Attribution Non-Commercial No Derivatives 4.0 International |
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| Views: | 3935 |
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| Downloads: | 299 |
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| Metadata: |     |
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| Categories: | Document is not linked to any category. |
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