Thermal stability and local atomic structure of (Na0.5K0.5)NbO3 doped BaTiO3 ceramics |
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| Affiliation: | 1. SPECIFIC – College of Engineering, Swansea University, Baglan Bay Innovation & Knowledge Centre, Central Avenue, Baglan, Port Talbot SA12 7AX, United Kingdom;2. University of Bath – Department of Chemistry, 1 South 1.20, Bath BA27AY, United Kingdom;1. School of Materials Science and Engineering, University of Jinan, Jinan 250022, China;2. Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, China;1. INFLPR – National Institute for Laser, Plasma and Radiation Physics, Laser Department, Bvd. Atomistilor, Nr. 409, 077125 Măgurele (Ilfov), Bucharest, Romania;2. EaStCHEM Research School of Chemistry, University of St Andrews, North Haugh, St Andrews, KY16 9ST Fife, Scotland, United Kingdom;1. School of Chemistry, Biology and Material Engineering, Suzhou University of Science and Technology, Suzhou 215009, China;2. Shanxi Province Key Laboratory of Functional Nanocomposites, North University of China, Taiyuan 030051, China;1. Unité de recherche de Nanomatériaux et Environnement (UR15ES01), IPEIT, Université de Tunis, 2 Rue Jawaher Lel Nahru, 1089 Montfleury, Tunisia;2. Faculté des Sciences de Tunis, Université Tunis El Manar, 2092 El Manar, Tunis, Tunisia;1. Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar 201314, Uttar Pradesh, India;2. Department of Condensed Matter Physics and Material Sciences S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, India;3. Nanotechnology and Integrated Bioengineering Centre (NIBEC), University of Ulster at Jordanstown, Shore Road, Newtownabbey BT37 0QB, United Kingdom;4. Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar 201314, Uttar Pradesh, India |
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| Abstract: | Dielectric properties of x(Na0.5K0.5)NbO3–(1−x)BaTiO3 (x=0.00 and 0.06) specimens were investigated in terms of changes in local atomic structure, according to the phase transition by elevating the overall temperature. A 0.06(Na0.5K0.5)NbO3–0.94BaTiO3 (NKN–BT) specimen exhibited enhanced temperature stability along with an increased dielectric constant. The degree of reduction in tetragonality (c/a) at the Curie temperature was smaller in NKN–BT compared to that in pure BaTiO3, as calculated by Rietveld refinement. From a comparison of the pre-edge region in the Ti K-edge, it was determined that the off-center displacement of the Ti atom was also raised to 13.4% through NKN substitution, with a change in local orientation from the [001] to the [111] directions. The substitution by NKN, which has a different ionic radius and electrical charge compared with BaTiO3, causes structural distortion of the TiO6 octahedra in the NKN–BT lattice, resulting in local polarization. These structural changes lead to the temperature stability of the dielectric constant and an overall improvement in the electrical properties of BaTiO3. |
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| Keywords: | Dielectric properties Thermal properties Phase transition Lattice distortion |
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