| Full text | |
| Author(s): |
Total Authors: 3
|
| Affiliation: | [1] Univ Sao Paulo, Inst Fis Sao Carlos, Grp Crescimento Cristais & Mat Ceram, BR-13560970 Sao Paulo - Brazil
[2] Univ Colorado, Dept Mech Engn, Boulder, CO 80309 - USA
Total Affiliations: 2
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| Document type: | Journal article |
| Source: | Journal of the American Ceramic Society; v. 96, n. 12, p. 3760-3767, DEC 2013. |
| Web of Science Citations: | 39 |
| Abstract | |
The defect chemistry-modulated dielectric properties of dense yttria-doped zirconia ceramics prepared by conventional sintering (at 1350 degrees C-1500 degrees C) and electric field-assisted flash sintering (55V/cm at 900 degrees C) were studied by impedance spectroscopy. While the bulk dielectric properties from both sets of samples showed only small and insignificant changes in conductivity and permittivity, respectively, a huge increase of these properties was measured for the grain boundaries in the flash sintered specimens. A close analysis of these results suggests that flash sintering reduced grain-boundary thickness (by about 30%), while increasing the concentration of oxygen vacancies near these interfaces (by about 49%). The underlying mechanism proposed is electric field-assisted generation and accommodation of defects in the space-charge layers adjacent to the grain surface. The changes in measured permittivity are attributed to the boundary thickness effect on capacitance, while conductivity involved variations in its defect density-dependent intrinsic value, accounting for changes also observed in grain-boundary relaxation frequencies. Therefore, in terms of modifications to the specific dielectric properties of these materials, the overall consequence of flash sintering was to considerably lower the semi-blocking character of the grain boundaries. (AU) | |
| FAPESP's process: | 12/06448-0 - Correlation between (di)electrical properties and (micro)structural characteristics in PTCR-type Ba1-x(RE)xTiO3 thermistor materials |
| Grantee: | Jean-Claude Mpeko |
| Support Opportunities: | Scholarships abroad - Research |