Pyroelectric energy harvesting using low–TC (1–x)(Ba0.7Ca0.3)TiO3–xBa(Zr0.2Ti0.8)O3 bulk ceramics |
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| Authors: | Daisuke Ando Ken‐ichi Kakimoto |
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| Affiliation: | 1. Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya, Japan;2. Frontier Research Institute for Materials Science, Nagoya Institute of Technology, Nagoya, Japan |
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| Abstract: | Lead‐free ferroelectric ceramics (1–x)(Ba0.7Ca0.3)TiO3–xBa(Zr0.2Ti0.8)O3 (BCTZ100x) with x = 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, and 0.80 were evaluated for their pyroelectric energy harvesting performance, using the Olsen cycle. As the composition ratio x increased, the crystal phase changed to tetragonal, orthorhombic, rhombohedral, and cubic; the phase boundaries crossed each other in the vicinity of BCTZ70. The crossover phase transition behavior between first‐order and diffuse phase transition changed to only the diffusion phase transition with increasing x. A pinching effect occurred because an increase in dielectric constant was also observed. Energy densities ND of 229 mJ/cm3 and 256 mJ/cm3 for BCTZ50 and BCTZ80 were obtained, respectively, in temperature of 30°C‐100°C and an electric field of 0‐30 kV/cm. These ND values are over two times higher than that of soft–Pb(Ti,Zr)O3 (PZT), which exhibits piezoelectric performance equivalent to BCTZ50 at room temperature. Compared with soft–PZT, BCTZ50 and BCTZ80 exhibited larger ND values owing to their lower Curie temperatures (TC ~ 50°C‐110°C). We conclude that low–TC ferroelectrics are useful for pyroelectric energy conversion based on the Olsen cycle even if they are unsuitable for piezoelectric applications at high temperatures. |
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| Keywords: | energy harvesting ferroelectricity/ferroelectric materials lead‐free ceramics phase transition pyroelectricity |
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