Structure and dielectric properties of Na0.5Bi0.5TiO3-CaTiO3 solid solutions

Birks, E.; Dunce, M.; Ignatāns, Reinis; Kuzmin, Alexei; Plaude, A.; Antonova, M.; Kundziņš, K.; Sternberg, A.

doi:10.1063/1.4942221

Cited by 33 publications

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References 18 publications

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“…Moreover, Du et al [49] demonstrated that this system is susceptible to orthorhombic distortion for x ≥ 0.14 and the MPB was found to lie around 0.08 ≤ x < 0.14. On the contrary, Birks et al [50] reported the structural properties of poled and unpoled conditions of (1-x)NBT-xCT assuming the coexistence of rhombohedral and orthorhombic phases. Despite the various studies of NBT-CT system, the structure of these materials and its link to the obtained physical properties are still not understood and under investigation due to mutual contradicting results.…”

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Relaxor behaviour and phase transition of perovskite ferroelectrics-type complex oxides (1–x)Na0.5Bi0.5TiO3–xCaTiO3 system

2018

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Polycrystalline powders of (1-x)Na 0.5 Bi 0.5 TiO 3 -xCaTiO 3 ((1-x)NBT-xCT, 0 ≤ x ≤ 0.55) have been synthesized by solid state route. The effects of simultaneous substitution of Na + /Bi 3+ 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 ℃), 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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Relaxor behaviour and phase transition of perovskite ferroelectrics-type complex oxides (1–x)Na0.5Bi0.5TiO3–xCaTiO3 system

2018

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“…Obviously, the different behavior indicates different states of the poled and the depoled sample even in the temperature range, where the poled state is destroyed. A different behavior was observed also for the temperature and frequency dependences of dielectric permittivity [37].…”

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confidence: 89%

“…For the total calculated T(T), this temperature is shifted in the direction of high temperatures due to contribution of d 2 /dT ( Figure 7). Since nature of the electric field-induced polarization is rather complicated in the temperature range between T d and T m , where relaxor properties continuously diminish and diffused phase transition to orthorhombic phase is approached upon increasing of temperature [37], it is hard to comment such coincidence at the moment.…”

Section: Resultsmentioning

confidence: 99%

“…Nature of polarization in the depoled state of NBT is different compared to the poled state, as it should be considered as a relaxor state [37], consisting of polar nanoregions (PNR) of rhombohedral structure, embedded in the nonpolar matrix. It means that, besides the induced polarization, P i (E) contains other relevant contributions, such as reorientation and breathing of PNR [45].…”

Section: Resultsmentioning

confidence: 99%

“…Poled and depoled states in NBT are essentially different. While the poled NBT is in the ferroelectric state with symmetry R3c [35], the depoled state can be apparently characterized only by coexistence of phases with different symmetry and corresponds to behavior of relaxor ferroelectrics [36,37]. Since the critical electric field (E c ) between the relaxor and the ferroelectric states in NBT is high and a phase transition occurs in a narrow electric field range (inset on the left in Figure 1), both states are well separated, which makes such a comparison reasonable.…”

Section: Introductionmentioning

confidence: 99%

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Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3

Birks

Dunce

Peräntie

et al. 2017

Journal of Applied Physics

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Direct and indirect studies of electrocaloric effect were performed in poled and depoled Na 0.5 Bi 0.5 TiO 3 . For this purpose polarization and electrocaloric effect temperature change measurements were made at different electric field pulses as a function of temperature. Applicability of the widely-used indirect electrocaloric effect determination method, using the Maxwell relation, was critically analyzed with respect to the reliable direct measurements.Quantitative differences were observed between the results obtained by both approaches in case of the poled Na 0.5 Bi 0.5 TiO 3 sample. These differences can be explained by the temperature-dependent concentration of domains oriented in the direction of the applied electric field. Whereas in the depoled Na 0.5 Bi 0.5 TiO 3 , which is characterized by electric field dependence of polar nanoregions embedded in a nonpolar matrix, the Maxwell relation is not applicable at all, as it is indicated by the obtained results. Possible mechanisms which could be responsible for the electrocaloric effect in the relaxor state were considered. The results of this study are used to evaluate the numerous results obtained and published by other authors, using the Maxwell relation to indirectly determine electrocaloric effect. The reason of the negative electrocaloric effect values, obtained in such a way and widely discussed in literature in case of Na 0.5 Bi 0.5 TiO 3 , have been explained in this study.

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Progress on Emerging Ferroelectric Materials for Energy Harvesting, Storage and Conversion

Wei

Domingo

Sun

et al. 2022

Advanced Energy Materials

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Since the discovery of Rochelle salt a century ago, ferroelectric materials have been investigated extensively due to their robust responses to electric, mechanical, thermal, magnetic, and optical fields. These features give rise to a series of ferroelectric‐based modern device applications such as piezoelectric transducers, memories, infrared detectors, nonlinear optical devices, etc. On the way to broaden the material systems, for example, from three to two dimensions, new phenomena of topological polarity, improper ferroelectricity, magnetoelectric effects, and domain wall nanoelectronics bear the hope for next‐generation electronic devices. In the meantime, ferroelectric research has been aggressively extended to more diverse applications such as solar cells, water splitting, and CO2 reduction. In this review, the most recent research progress on newly emerging ferroelectric states and phenomena in insulators, ionic conductors, and metals are summarized, which have been used for energy storage, energy harvesting, and electrochemical energy conversion. Along with the intricate coupling between polarization, coordination, defect, and spin state, the exploration of transient ferroelectric behavior, ionic migration, polarization switching dynamics, and topological ferroelectricity, sets up the physical foundation ferroelectric energy research. Accordingly, the progress in understanding of ferroelectric physics is expected to provide insightful guidance on the design of advanced energy materials.

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Structure and dielectric properties of Na0.5Bi0.5TiO3-CaTiO3 solid solutions

Cited by 33 publications

References 18 publications

Relaxor behaviour and phase transition of perovskite ferroelectrics-type complex oxides (1–x)Na0.5Bi0.5TiO3–xCaTiO3 system

Relaxor behaviour and phase transition of perovskite ferroelectrics-type complex oxides (1–x)Na0.5Bi0.5TiO3–xCaTiO3 system

Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3

Progress on Emerging Ferroelectric Materials for Energy Harvesting, Storage and Conversion

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