BiCuTeO is a potential thermoelectric material owing to its low thermal conductivity and high carrier concentration. However, the thermoelectric performance of BiCuTeO is still below average and has much scope for improvement. In this study, we manipulated the nominal oxygen content in BiCuTeO and synthesized BiCuTeOx (x = 0.94–1.06) bulks by a solid-state reaction and pelletized them by a cold-press method. The power factor was enhanced by varying the nominal oxygen deficiency due to the increased Seebeck coefficient. The thermal conductivity was also reduced due to the decrease in lattice thermal conductivity owing to the small grain size generated by the optimal nominal oxygen content. Consequently, the ZT value was enhanced by ∼11% at 523 K for stoichiometric BiCuTeO0.94 compared to BiCuTeO. Thus, optimal oxygen manipulation in BiCuTeO can enhance the thermoelectric performance. This study can be applied to developing oxides with high thermoelectric performances.

Barium strontium titanate (Ba0.7Sr0.3TiO3, BST) ceramics prepared by a reaction-sintering process were investigated. The mixture of raw materials of stoichiometric Ba0.7Sr0.3TiO3 was pressed and sintered into ceramics without any calcination stage involved. Perovskite BST ceramics were obtained after sintered at 1330–1370°C for 2–6 h. For 6 h soak time, a density value 5.68g/cm3 (99.8% of the theoretic value) was obtained at 1350°C sintering. Grains of sizes between 2μm and 15μm were formed after 1330–1370°C sintering for 2–6 h. A diffused ferroelectric-paraelectric transition was observed in pellets sintered at 1330°C for 2 h and disappeared at a longer soak time or a higher sintering temperature.

Synthesis of (Pb0.45Ca0.55)(Fe0.5Nb0.5)1-yTiyO3 (y=0 and 0.1; PCFN and PCFNT) ceramics by a reaction-sintering process was investigated. The mixture of raw materials was pressed and sintered into ceramics without any calcination stage involved. The density 5.88g/cm3 (91.6% of the theoretical value) is reached at 1270°C for 2 h soak time in PCFN. Densification increased as B-site was substituted by 10% Ti and a density value 6.21g/cm3 (98.1% of theoretical value) was obtained after 2 h sintering at 1270°C. Grains are of 4.6–19.3μm in PCFN and 2.5–16.5μm in PCFNT at 1150–1270°C. Grain growth was retarded as the B-site was substituted by 10% Ti in PCFN ceramics.