| Full text | |
| Author(s): |
Silva, Jr., P. S.
[1]
;
Diaz, J. C. C. A.
[1]
;
Florencio, O.
[1]
;
Venet, M.
[1]
;
M'Peko, J. C.
[2]
Total Authors: 5
|
| Affiliation: | [1] Univ Fed Sao Carlos, Dept Phys, BR-13565905 Sao Carlos, SP - Brazil
[2] Univ Sao Paulo, Sao Carlos Inst Phys, BR-13566590 Sao Carlos, SP - Brazil
Total Affiliations: 2
|
| Document type: | Journal article |
| Source: | ARCHIVES OF METALLURGY AND MATERIALS; v. 61, n. 1, p. 17-20, MAR 2016. |
| Web of Science Citations: | 11 |
| Abstract | |
In this work, the syntheses and characterization by mechanical and dielectric spectroscopies of (1-x)Bi0.5Na0.5TiO3-xBaTiO3 (BNT-100xBT), with x = 0.05, 0.06 and 0.07, lead-free piezoelectric ceramics is reported. Ceramic samples of BNT-BT have been prepared by mixed-oxide method and then conventionally sintered. X-ray diffraction patterns of sintered samples, indicated for BNT-7BT the presence of tetragonal (P4mm) complex perovskite structure, whereas for BNT-5BT and BNT-6BT the samples exhibit a mixture of tetragonal (P4mm) and rhombohedral (R3c) crystalline phases, which reveal the presence of a morphotropic phase boundary (MPB) in the BNT-BT system. Measurements of internal friction, Q(-1), and the storage modulus, E', as a function of temperature at various frequencies were carried out in a Dynamic Mechanical Analyzer (DMA), in the temperature range from 0 degrees C to 600 degrees C. Dielectric profiles are recorded in the frequency range from 1kHz to 100kHz and the temperature range from room temperature to 475 degrees C. Mechanical loss spectra obtained for investigated compositions of BNT-BT samples showed different frequency-independent anomalies. Two main anomalies for BNT-5BT and BNT-6BT, observed around 100 degrees C and 430 degrees C were associated with the ferroelectric-antiferroelectric and antiferroelectric-paraelectric phase transitions, respectively. The results obtained from mechanical loss measurements were supported by dielectric relaxation spectra. For BNT-7BT, outside the MPB, four different frequency-independent processes were observed. (AU) | |
| FAPESP's process: | 12/08457-7 - Study of the phase transitions of the lead-free piezoceramics by mechanical spectroscopy |
| Grantee: | Paulo Sergio da Silva Junior |
| Support Opportunities: | Regular Research Grants |