Enhanced Seebeck coefficient in Magnéli phase Ti6O11 ceramics through zinc volatilization induced defect and interface engineering

Magnéli phase Ti 6 O 11 ceramics were prepared by the solid-state reduction of TiO 2 with graphite. By adding zinc oxide during processing, dual energy-filtering systems comprising defect clusters and carbon layers were formed in the ceramics. The power factor showed a significant increase with the addition of zinc oxide during preparation. At 973 K, the sample with x = 0.03 exhibited a power factor of 380 μWm −1 K −2 , representing a 15% enhancement compared to the sample prepared without it. When sintered at 1400°C, the ceramic sample underwent gradual zinc volatilization, promoting the formation of defect cluster structures and carbon layers that filtered out low-energy electrons and consequently increased the absolute value of the Seebeck coefficient. Additionally, the zinc oxide acted as a fluxing agent, increasing the ceramic density by 4.5%, and the carrier mobility at 323 K was improved by 16%. The synergistic effect of the dual energy filtering mechanism and densification played important roles in the overall optimization of electrical transport performance in the materials. Finally, at 973 K, the sample with x = 0.03 achieved a thermoelectric figure of merit of 0.14, which was 12% higher than that of the sample without added zinc oxide.