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http://hdl.handle.net/1843/57561| Type: | Artigo de Periódico |
| Title: | High-temperature antiferroelectric and ferroelectric phase transitions in phase pure LaTaO4 |
| Authors: | Yuslin González-Abreu Kisla Prislen Félix Siqueira Franklin Massami Matinaga Roberto Luiz Moreira Anderson Dias |
| Abstract: | Phase-pure LaTaO4 ceramics was prepared by solid-state reaction. Dielectric spectroscopic data as well as differential scanning calorimetric experiments showed the existence of a sequence two high-temperature first-order structural phase transitions. The first phase transition occurs above 160 °C (on heating), from the monoclinic P21/c space group at room temperature to the polar orthorhombic Cmc21 group, exhibiting a very large thermal hysteresis probably linked to the reconstructive nature of the structural transition. The second transition occurs around 225 °C to the orthorhombic Cmcm space group, with a small thermal hysteresis. Vibrational Raman spectroscopic analyses confirmed these two sequential phase transitions, as well as the thermal hysteresis observed for both first-order transitions in repeated heating and cooling cycles. The existence of a strong monoclinic distortion at room temperature could be related to the presence of defects (oxygen vacancies) in LaTaO4 ceramics, after sintering. Dielectric spectroscopy showed a strong influence of the electric conductivity on the dielectric response with activation energy of dc component of conductivity (0.62 eV) compatible with the presence of oxygen vacancies. Far-infrared data confirmed that the extra modes observed in the Raman spectra are forbidden bands, which were activated by defects into the structure. |
| Subject: | Cristais ferroeletricos Material cerâmico Espectros vibracionais Dielétricos Transformações de fase (Física estatística) Raman, Espectroscopia de |
| language: | eng |
| metadata.dc.publisher.country: | Brasil |
| Publisher: | Universidade Federal de Minas Gerais |
| Publisher Initials: | UFMG |
| metadata.dc.publisher.department: | ICX - DEPARTAMENTO DE FÍSICA ICX - DEPARTAMENTO DE QUÍMICA |
| Rights: | Acesso Restrito |
| metadata.dc.identifier.doi: | https://doi.org/10.1016/j.ceramint.2016.10.128 |
| URI: | http://hdl.handle.net/1843/57561 |
| Issue Date: | 2017 |
| metadata.dc.url.externa: | https://www.sciencedirect.com/science/article/pii/S0272884216318971 |
| metadata.dc.relation.ispartof: | Ceramics International |
| Appears in Collections: | Artigo de Periódico |
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