20.500.12556/RUNG-2910-ee364ff8-64b4-3eb0-bca3-845b475de141
Donor doping of K0.5Na0.5NbO3 ceramics with strontium and its implications to grain size, phase composition and crystal structure
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.
perovskite
potassium sodium niobate
donor doping
cation vacancies
true
true
false
Angleški jezik
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2017-01-16 11:32:33
2017-01-17 06:38:06
2023-06-09 03:19:23
0000-00-00 00:00:00
2017
0
0
10
37
2017
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PostprintKoncna
NiDoloceno
NiDoloceno
0000-00-00
0000-00-00
0000-00-00
4638715
10.1016/j.jeurceramsoc.2016.12.053
URN:SI:UNG:REP:K6AF7WGV
Manuscript_text.pdf
Manuscript_text.pdf
1
05AAFFCB68669180CA908AD20748DF25
54032e0843afcd318afc4dde339f7d1cf21ac22698d73cfd9489c6cf56d0bd9e
28626a6a-05ce-11ee-9c48-5ef991fed68f
https://repozitorij.ung.si/Dokument.php?lang=slv&id=5192
Univerza v Novi Gorici
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