Abstract
ABSTRACT
The powders of La0.3(Ca1−xAx)0.55Cu3Ti4O12 (A = Sr, 0 ≤ x < 0.8, A = Mg, 0 ≤ x ≤ 0.1) with cubic Perovskite like structure were synthesized at 1323 K in air via a polymerized complex route. Lattice constants a of the dense (≥ 97 %) ceramics, fabricated in air using a hot-pressing (1273 K/3.60 × 103 s/50 MPa), increased and decreased with increasing x for the ceramics (A = Sr) and (A = Mg), respectively, On the other hand, the electrical conductivities σe decreased and increased with increasing x and temperature, respectively. Their negative Seebeck coefficients S had the maximum values of ca. −560 µV·K−1 for the ceramics (A = Sr at x = 0.8: Sr0.8) and −515 µV·K−1 for Mg0.02, showing the behavior that the absolute S values decreased and increased slightly with increasing temperature and x, respectively. Their power factor S2σe had the maximum values at Sr0.2 and Mg0.05. Thermal conductivities λ for the ceramics (x = 0.0, Sr0.2 and Mg0.1) were measured from 300 to 1073 K in air; lower λ were attained for Mg0.1 in comparison with others. Their dimensionless figure of merit ZT reached ~4.0 × 10−3 at 1073 K. These results indicated that La0.3(Ca0.8Mg0.05)0.55Cu3Ti4O12 could be a candidate of the host materials of the new hybrid-type thermoelectric element.
