| 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: | ID Hreščak, Jitka, Institut Jozef Stefan (Author)
ID Dražić, Goran, Institut Jozef Stefan (Author)
ID Deluca, Marco, Montanuniversitaet Leoben, Leoben, Austria (Author)
ID Arčon, Iztok, Univerza v Novi Gorici (Author)
ID Kodre, Alojz, Univderza v Ljubljani (Author)
ID Dapiaggi, M., University of Milan, Milano, Italy (Author)
ID Rojac, Tadej, Institut Jozef Stefan (Author)
ID Malič, Barbara, Institut Jozef Stefan (Author)
ID Benčan, Andreja, Institut Jozef Stefan (Author) |
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| Files: |  Manuscript_text.pdf (2,11 MB)
MD5: 05AAFFCB68669180CA908AD20748DF25
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| Language: | English |
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| Work type: | Not categorized |
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| Typology: | 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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| Publication version: | Author Accepted Manuscript |
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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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| PID: | 20.500.12556/RUNG-2910-ee364ff8-64b4-3eb0-bca3-845b475de141  |
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| COBISS.SI-ID: | 4638715 |
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| DOI: | 10.1016/j.jeurceramsoc.2016.12.053 |
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| NUK URN: | URN:SI:UNG:REP:K6AF7WGV |
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| Publication date in RUNG: | 17.01.2017 |
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| Views: | 5723 |
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| Downloads: | 329 |
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