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Title:Donor doping of K0.5Na0.5NbO3 ceramics with strontium and its implications to grain size, phase composition and crystal structure
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)
Files:.pdf Manuscript_text.pdf (2,11 MB)
MD5: 05AAFFCB68669180CA908AD20748DF25
Work type:Not categorized
Typology:1.01 - Original Scientific Article
Organization:UNG - University of Nova Gorica
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.
Keywords:perovskite, potassium sodium niobate, donor doping, cation vacancies
Publication version:Author Accepted Manuscript
Year of publishing:2017
Number of pages:10
PID:20.500.12556/RUNG-2910-ee364ff8-64b4-3eb0-bca3-845b475de141 New window
COBISS.SI-ID:4638715 New window
DOI:10.1016/j.jeurceramsoc.2016.12.053 New window
Publication date in RUNG:17.01.2017
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Record is a part of a journal

Title:Journal of the European Ceramic Society
Year of publishing:2017


License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:16.01.2017