Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10155481 | Journal of the European Ceramic Society | 2018 | 10 Pages |
Abstract
The influence of different substitutional mechanisms on the electrocaloric effect of a lead-free SrBi2(Nb0.2Ta0.8)2O9 Aurivillius phase was studied for application in electrocaloric cooling systems. The A-site substitution with barium efficiently reduced the temperature of maximum permittivity from about 300â°C to 100â°C. The A-site substitution induced phenomena that are typical of strong relaxor ferroelectrics such as significant broadening of the permittivity peak and an increase in its frequency dispersion and with a depolarization temperature below room temperature. These features directly influenced the electrocaloric effect. A direct measurement system, based on a modified-differential scanning calorimeter, was used to analyze the EC effect of the dense (Sr0.5Ba0.5)Bi2(Nb0.2Ta0.8)2O9 ceramics. In accordance with the relaxor characteristics, the EC effect was found to increase continuously over a broad temperature range above the room temperature. This was attributed to the alignment of field induced polar nanodomains. Directions for optimization towards a high-performing EC ceramic were identified.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Anna-Karin Axelsson, Florian Le Goupil, Matjaz Valant, Neil McN. Alford,