Tunable giant negative thermal expansion in Ti2O3-based polycrystalline materials

Abstract

Abstract Thermal expansion properties are investigated for Ti2O3-based sintered polycrystalline materials by controlling crystal lattice parameters and porous structures. Negative thermal expansion (NTE) is observed in a temperature range between room temperature and 593 K, and found to exceed ΔL/L = −0.7% at high temperatures, in spite of continuous increase of the unit cell volume. The temperature range for the significant NTE is successfully tuned by modifying electron-lattice-coupled phase-transition temperature. The magnitude of the NTE is enhanced upon introducing pores, indicating the importance of microstructural effect. These results demonstrate high potential of Ti2O3-based materials for practical applications.