| Full text | |
| Author(s): |
Pontes, D. S. L.
[1]
;
Longo, E.
[1]
;
Pontes, F. M.
[2]
;
Pereira-da-Silva, Marcelo A.
[3, 4]
;
da Silva, J. H. D.
[5]
;
Chiquito, A. J.
[6]
;
Pizani, P. S.
[6]
Total Authors: 7
|
| Affiliation: | [1] Univ Estadual Paulista UNESP, Inst Chem, BR-14801970 Araraquara, SP - Brazil
[2] Univ Estadual Paulista UNESP, Dept Chem, BR-17033360 Bauru, SP - Brazil
[3] Ctr Univ Cent Paulista UNICEP, BR-13563470 Sao Carlos, SP - Brazil
[4] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560250 Sao Carlos, SP - Brazil
[5] Sao Paulo State Univ UNESP, Adv Mat Grp, Dept Phys, BR-17033360 Bauru, SP - Brazil
[6] Univ Fed Sao Carlos, Dept Phys, BR-13565905 Sao Carlos, SP - Brazil
Total Affiliations: 6
|
| Document type: | Journal article |
| Source: | Journal of Sol-Gel Science and Technology; v. 55, n. 2, p. 151-157, AUG 2010. |
| Web of Science Citations: | 2 |
| Abstract | |
Dielectric and Raman scattering experiments were performed on polycrystalline Pb(1-x-y)Ca(x)Sr(y)TiO(3) thin films as a function of temperature. Temperature-dependent dielectric measurements revealed a decreasing ferroelectric-to-paraelectric phase transition temperature and peak dielectric permittivity showed a broad phase transition near room temperature with increasing levels of CaO(12) and SrO(12) clusters. Therefore, for higher levels of substitution, the possible random position of the CaO(12) and SrO(12) clusters leads to a diffuse state. At 100 kHz, the ferroelectric-to-paraelectric phase transition temperatures were 633, 495 and 206 K for PCST90 (Pb(0.90)Ca(0.05)Sr(0.05)TiO(3)), PCST70 (Pb(0.70)Ca(0.15)Sr(0.15)TiO(3)) and PCST30 (Pb(0.30)Ca(0.35)Sr(0.35)TiO(3)) thin films, respectively. The evolution of the Raman spectra was also studied as a function of temperature. The temperature dependence of the E(1TO) soft mode frequencies was used to characterize the phase transition. Raman peaks were observed above the ferroelectric-to-paraelectric phase transition temperature, although all optical modes should be inactive in Raman scattering. The origin of these modes was interpreted as a breakdown of the local cubic symmetry by the random distribution of CaO(12) and SrO(12) clusters. (AU) | |