通電加圧焼結により作製したTiO2-TiN 系焼結体の結晶相と熱電特性

概要

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TiO2 - based compacts were fabricated by Spark Plasma sintering using starting powder mixtures of TiO2 and TiN. Here, the TiN mol fraction, m mol%, was varied as m = 0, 1, 3, 5, 8, 10, 12, and 20. The phases of the compacts were found to be a rutile phase for m = 0 and 1, whereas those to be a defective phase, TiO1.93, for m = 3, and Magneli phases, TinO2n−1 (n = 5, 6, 7, 8, 9, 10), for m = 5 through 20. The electrical conductivity, σ, reached the maximum value of 6.6 × 104 Sm−1 at 50 °C for the compact with m = 12. The Seebeck coefficient were found to be negative for all the compacts, and the maximum of the absolute value was recorded to be 760 µVK−1 at 50 °C for m = 0. The minimum value of thermal conductivity, κ, was found to be 2.2 Wm−1K−1 at 50 °C for m = 5 and 8. The dimensionless figure of merit, ZT, was found to increase with temperature, reaching the maximum of 0.24 at 800 °C for m = 10.