| Texto completo | |
| Autor(es): |
Mastelaro, V. R.
[1]
;
Mascarenhas, Y. P.
[1]
;
Neves, P. P.
[2]
;
Mir, M.
[2]
;
Doriguetto, A. C.
[2]
;
Michalowicz, A.
[3, 4]
;
Moscovici, J.
[3, 4]
;
Lente, M. H.
[5]
;
Eiras, J. A.
[5]
Número total de Autores: 9
|
| Afiliação do(s) autor(es): | [1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Paulo - Brazil
[2] Univ Fed Alfenas UNIFAL MG, Lab Cristalog, BR-37130000 Alfenas, MG - Brazil
[3] CNRS, Inst Chim & Mat Paris Est, F-94320 Thiais - France
[4] Univ Paris Est Creteil, F-94320 Thiais - France
[5] Univ Fed Sao Carlos UFSCar, Dept Fis, BR-13565670 Sao Paulo - Brazil
Número total de Afiliações: 5
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Applied Physics; v. 107, n. 11 JUN 1 2010. |
| Citações Web of Science: | 5 |
| Resumo | |
In this work, we investigated the temperature dependence of short and long-range ferroelectric ordering in Pb0.55La0.30TiO3 relaxor composition. High-resolution x-ray powder diffraction measurements revealed a clear spontaneous macroscopic cubic-to-tetragonal phase transition in the PLT relaxor sample at similar to 60 K below the maximum of the dielectric constant peak (T-m). Indeed, the x-ray diffraction (XRD) data showed that at 300 K (above T-m but below the Burns temperature, T-B) the long-range order structure corresponds to a macroscopic cubic symmetry, space group number 221 (Pm-3m), whereas the data collected at 20 K revealed a macroscopic tetragonal symmetry, space group number 99 (P4mm) with c/a=1.0078, that is comparable to that of a normal ferroelectric. These results show that for samples with tetragonal composition, the long-range ferroelectric order may be recovered spontaneously at cryogenics temperatures, in contrast to ferroelectric samples with rhombohedral symmetry. On the other hand, x-ray absorption spectroscopy investigations intriguingly revealed the existence of local tetragonal disorder around Ti atoms for temperatures far below T-m and above T-B, for which the sample presents macroscopic tetragonal and cubic symmetries, respectively. (C) 2010 American Institute of Physics. {[}doi: 10.1063/1.3431024] (AU) | |
| Processo FAPESP: | 00/09722-9 - Materiais ferroelétricos: fenomenologia, propriedades e caracterização |
| Beneficiário: | José Antonio Eiras |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |