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Ferroelectric Transition of Sr 5 SmTi 3 Nb 7 O 30 Tungsten Bronze Ceramics Investigated Using Differential Scanning Calorimetry and Raman Scattering
Author(s) -
Zhu Xiao Li,
Chen Xiang Ming
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05286.x
Subject(s) - ferroelectricity , differential scanning calorimetry , materials science , phase transition , raman spectroscopy , analytical chemistry (journal) , tetragonal crystal system , dielectric , hysteresis , transition temperature , mineralogy , crystallography , chemistry , condensed matter physics , crystal structure , optics , thermodynamics , superconductivity , physics , optoelectronics , chromatography
Ferroelectric transition of Sr 5 SmTi 3 Nb 7 O 30 tetragonal tungsten bronze ceramics was investigated using dielectric characterization, differential scanning calorimetry ( DSC ), and the in situ Raman scattering. The first‐order ferroelectric transition was indicated around 200°C by the dielectric peak and the endothermic DSC peak on heating. The ferroelectric transition exhibited large thermal hysteresis and severe depression of the Curie–Weiss temperature ( T 0 ), where the transition peak did not show up on cooling in both the permittivity and DSC curves. The thermal hysteresis was attributed to the complex nature of the tungsten bronze structure. According to the DSC results, gradual recovery of the endothermic peak occurred after aging at 20°C, indicating the gradual stability of the ferroelectric phase after cooling from the high temperature paraelectric phase. Meanwhile, anomalies in the Raman spectra were also observed around 200°C, corresponding to the ferroelectric transition. Mechanism of the ferroelectric transition in Sr 5 SmTi 3 Nb 7 O 30 ceramics was discussed according to the variation of the external and internal Raman modes with increasing temperature.