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Preparation and Highly Enhanced Eelectrocaloric Effect in a Bimodal-Structured 0.9KNbO3-0.1BaTiO3 Solid Solution at Room Temperature
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Submitted:
16 June 2022
Posted:
17 June 2022
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Abstract
The bimodal grain-size distribution 0.9KNbO3-0.1BaTiO3 ceramics, with a typical perovskite structure in tetragonal phase at room temperature, were successfully prepared by an induced abnormal grain growth (IAGG) method at a relatively low sintering temperature. In this bimodal grain-sized distribution structure, the extra-large grains (about 10‒50 μm) were evolved from the micron-sized filler powders and the fine grains (about 0.05‒0.35 μm) were derived from the sol precursor matrix. The 0.9KNbO3-0.1BaTiO3 ceramics exhibit relaxor-like behavior with the diffused phase transition near room temperature, and confirmed by the existence of the polar nanodomain regions (PNRs) using the HRTEM images. The large room-temperature electrocaloric (EC) effect was found, characterized by an adiabatic temperature drop of 1.5 K, an isothermal entropy change of 2.48 J kg-1 K-1, and high EC strengths of ïDT/DEï = 1.50×10-6 KmV-1 and DS/DE = 2.48×10-6 Jmkg-1K-1V-1directly measured under E = 1.0 MV/m. These excellent ECEs demonstrate that this simple IAGG method is highly appreciated for synthesizing high-performance EC materials for efficient cooling devices.
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Subject: Chemistry and Materials Science - Other
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