Fresnoite: A new ferroelectric mineral
| Autor: | D. J. Arbogast, Panos Photinos, S. C. Abrahams, R. M. Nielson, M. C. Foster |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 85:2299-2303 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.369541 |
| Popis: | Fresnoite, Ba2TiOSi2O7, has been predicted structurally to be a new ferroelectric. Detection of both ac and dc dielectric hysteresis verifies the prediction. The spontaneous polarization Ps estimated from the hysteresis at 1.2 MV m−1 ac is ∼0.2 C m−2 at 295 K, comparable with the minimum Ps observed in one-dimensional ferroelectrics. A reproducible calorimetric anomaly with entropy change 0.19(3) J mol−1 K−1 at 433(2) K in polycrystalline material coincides with a small dielectric and pyroelectric anomaly previously reported in single crystals; an entropy change ∼0.2 J mol−1 K−1 at 810(5) K also accompanies a dielectric anomaly observable in ceramic samples at 805(5) K. Both calorimetric anomalies are ∼60 K wide. Observation of dielectric hysteresis at 875 K shows that neither anomaly corresponds to the Curie temperature; both are likely associated with small changes in atomic position, not with symmetry changes. Melting onset in fresnoite is 1703(1) K with undercooling as deep as 435 K. |
| Databáze: | OpenAIRE |
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