Journal
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
Volume 41, Issue 2, Pages 1288-1298Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.jeurceramsoc.2020.10.016
Keywords
(K,Na)NbO3; BaTiO3 Positron annihilation spectroscopy; Dielectric properties; Point defects
Categories
Funding
- National Council of Scientific and Technical Research (CONICET) (Argentina) [PIP0432]
- National Agency for Scientific and Technological Promotion (ANPCyT) (Argentina) [PICT 2015-1832]
- Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA) (Argentina) [801/2018]
- Secretaria de Ciencia, Arte y Tecnologia -UNCPBA (Argentina) [03/C284/2017]
- National University of Mar del Plata (UNMdP) (Argentina) [15/G527]
- MINECO (Spain) [MAT2017-86450-C4-1-R]
- MINECO - European Social Fund [RyC-201518626]
- 2018 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation
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The study investigates the induced changes in the vacancy-like defect structure and dielectric properties of K0.5Na0.5NbO3 ceramics by adding various amounts of BaTiO3. Structural evolution was monitored using X-ray diffraction and Raman spectroscopy, with positron annihilation lifetime spectroscopy used to identify defect structures at a sub-nanometric scale. The discussion also highlights lattice symmetry changes and defects formed due to ion replacements in the KNN-based ceramics.
A study on the induced changes in the vacancy-like defect structure and the dielectric properties of K0.5Na0.5NbO3 ceramics by the addition of different amounts, between 0% and 7%, of BaTiO3 is presented. The samples were prepared by a mechanochemically activated solid-state reaction method. The structural evolution due to the orthorhombic to the tetragonal phase transition of the KNN doped samples was followed using X-ray diffraction and Raman spectroscopy. The use of positron annihilation lifetime spectroscopy allowed to identify the defect structure at sub-nanometric scale and the nature of the vacancy-like defects generated by the phase transition. The obtained results are discussed considering the lattice symmetry change and the defects structure formed due to the replacement of alkaline and niobium ions by barium and titanium ones. Additionally, changes in the dielectric properties are discussed in terms of the structural modifications of the different KNN-based ceramics involving different kinds of vacancy-like defects.
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