High‐Temperature Transport Property of In 2− x Ce x O ₃ (0 ≤  x  ≤ 0.10) Fine Grained Ceramics

Using the spark plasma sintering process In 2 −x Ce x O 3 (0 ≤ x ≤ 0.10) fine grained ceramics have been synthesized. Our results indicate that all the In 2 O 3 ‐based ceramic samples show good electrical conductivity and high thermoelectric power factor. In comparison with pure In 2 O 3 bulks or doped samples with grain size above 1 μm, the 100–300 nm fine grain In 2 O 3 ‐based ceramics exhibit much lower thermal conductivities (1.9–2.5 W·(m·K) −1 at 1173 K), demonstrating a remarkable cooperative tuning effect imposed by grain size reduction and nano‐clusters formation. The maximum figure of merit ZT value is optimized up to ~0.47 at 1223 K for In 1.92 Ce 0.08 O 3 sample, which makes them promising candidates for thermoelectric applications.