Relaxor behaviour and phase transition of perovskite ferroelectrics-type complex oxides (1–x)Na0.5Bi0.5TiO3–xCaTiO3 system
Abstract Polycrystalline powders of (1–x)Na0.5Bi0.5TiO3–xCaTiO3 ((1–x)NBT–xCT, 0 ≤ x ≤ 0.55) have been synthesized by solid state route. The effects of simultaneous substitution of Na+/Bi3+ at A-site in NBT on structural and dielectric properties were investigated. X-ray diffraction analysis reveale...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Tsinghua University Press
2018-03-01
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| Series: | Journal of Advanced Ceramics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/s40145-018-0264-6 |
| Summary: | Abstract Polycrystalline powders of (1–x)Na0.5Bi0.5TiO3–xCaTiO3 ((1–x)NBT–xCT, 0 ≤ x ≤ 0.55) have been synthesized by solid state route. The effects of simultaneous substitution of Na+/Bi3+ at A-site in NBT on structural and dielectric properties were investigated. X-ray diffraction analysis revealed the phase transition from rhombohedral structure (x = 0) to orthorhombic structure (x ≥ 0.15). A distinct behaviour in dielectric properties was obtained, where for x = 0, a normal ferroelectric behaviour was observed, whereas for x ≥ 0.15, a broad dielectric anomaly was revealed such that the maximum temperature (T m) strongly depended on the frequency and shifted towards low temperature with CT. The dielectric dispersion indicated a relaxor behaviour revealed by the degree of diffuseness and modelled via Vogel–Fulcher relation. The study highlighted the relaxor behaviour as a function of frequency and proved the transformation from a relaxor high-frequency dependence to a paraelectric phase at temperature T s. The distinct variation of the Raman spectra at room temperature was correlated with X-ray diffraction results and proved the already mentioned transition. On heating (-193–500 °C), the Raman spectra confirmed the structural stability (Pnma) of the materials. The phonon behaviour for x = 0.15 was discussed in terms of the appearance of polar nanoregions (PNRs) into a non-polar orthorhombic matrix responsible of the relaxor behaviour. For x = 0.20, unchanged phonon behaviour confirmed the variation in dielectric behaviour where the solids transformed from a relaxor to a paraelectric state without structural phase transition. |
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| ISSN: | 2226-4108 2227-8508 |