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Phase Transition from Weak Ferroelectricity to Incipient Ferroelectricity in Li2Sr(Nb1–x Ta x )2O7
Pseudo Ruddlesden–Popper-type Li2SrNb2O7 undergoes a phase transition between paraelectric and weak ferroelectric phases at T c (=217 K), whereas Ta-counterpart Li2SrTa2O7 stays paraelectric though its room temperature structure is identical to that of Li2SrNb2O7. In the present study, the ferroelec...
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Published in: | Chemistry of materials 2020-01, Vol.32 (2), p.744-750 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | eng ; jpn |
Online Access: | Get full text |
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Summary: | Pseudo Ruddlesden–Popper-type Li2SrNb2O7 undergoes a phase transition between paraelectric and weak ferroelectric phases at T c (=217 K), whereas Ta-counterpart Li2SrTa2O7 stays paraelectric though its room temperature structure is identical to that of Li2SrNb2O7. In the present study, the ferroelectric phase transition of Li2Sr(Nb1–x Ta x )2O7 is investigated as a function of Ta-concentration x. As the Ta-concentration x increases, T c is found to decrease monotonously, leading to the disappearance of the ferroelectricity at x = 0.4. This phase-transition suppression with increasing x in Li2Sr(Nb1–x Ta x )2O7 is supported by first-principles calculations, showing that the soft mode in Li2SrNb2O7 or the increase of x in Li2Sr(Nb1–x Ta x )2O7 enhances their bonding states. In the composition of x = 0.4, dielectric permittivity gradually increases on cooling to become independent of temperature around 0 K, indicating an incipient ferroelectricity of the system. Empirical analyses suggest existence of a quantum paraelectric state in a composition range of 0.3 < x < 0.4. The present study provides a novel playground to investigate a quantum para/ferroelectricity in layered-perovskite-type compounds. |
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ISSN: | 0897-4756 1520-5002 |
DOI: | 10.1021/acs.chemmater.9b04022 |