High-temperature X-ray diffraction and Raman scattering studies of Ba-doped (Na0.5Bi0.5)TiO3 Pb-free piezoceramics |
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Authors: | Dibyaranjan Rout Kyoung-Seok Moon Jihoon Park Suk-Joong L Kang |
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Institution: | 1. Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea;2. School of Applied Sciences (Physics), KIIT University, Bhubaneswar 751 024, Odisha, India |
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Abstract: | The structural changes in (100 ? x)Na0.5Bi0.5TiO3–xBaTiO3 (0 ≤ x ≤ 10) ceramics were investigated as a function of composition and temperature by X-ray diffraction and Raman spectroscopy. As Ba concentration increases, the structure changed from rhombohedral to tetragonal (x ≥ 6.5) across a morphotropic phase boundary like phase coexistence at x ~ 5.5, which is further evidenced by phonon anomalies observed in composition-dependent Raman spectra. On heating, the disappearance of peak splits in {111} (x ≤ 5) and {200} (x ≥ 6.5) Bragg peaks and the changes in their 2θ-positions indicated temperature-driven structural changes: ferroelectric to antiferroelectric (≈Td, depolarization temperature) at 220 °C and antiferroelectric to paraelectric (rhombohedral to tetragonal) at 320 °C. In addition, Raman spectral analysis suggested that at elevated temperatures, two tetragonal phases with slightly different space groups coexisted at x ≥ 6.5 and most of the phase transition temperatures shifted towards left with increasing x. |
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Keywords: | Lead-free piezoelectric Phase transition Microstructure Raman spectroscopy |
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