Tunable giant negative thermal expansion in Ti₂O₃-based polycrystalline materials

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.

Biaxial negative thermal expansion in Zn[N(CN)2]2

“…In addition, the NTE properties of some anisotropic materials are improved after sintering into bulk, such as Ca 2 RuO 4 , 16 Zn 1.6 Mg 0.4 P 2 O 7 , 17 and Ti 2 O 3 -based polycrystalline materials. 18 It is found that the flexibility of the crystal structure and transverse vibrations of the bridged atoms govern the NTE behavior in framework structure materials.…”

Systematic Study on the Role of the Third Zn-Site Element in Zn₂₋<i>_x</i>Mg<i>_x</i>P₂O₇ Showing Giant Negative Thermal Expansion

“…In sintered bodies of Cu 2 V 2 O 7 4) and its analogues, 5) ¢eucryptite, 17) and Ca 2 RuO 4 , 18,19) the dilatometric NTE exceeds the crystallographic NTE because of these effects. For Ti 2 O 3 , 20,21) despite the positive crystallographic thermal expansion, these effects can render the dilatometric thermal expansion negative. Therefore, we examined the microstructural effects in this material as well, which revealed that these effects were less pronounced.…”

Structural phase transition and negative thermal expansion in Cu 1.8 Zn0.2V2–x P x O7 solid solutions

“…21,22) Recently, it has also been reported in Ti 2 O 3 . 23,24) The microstructural effect has attracted a great deal of attention as a promising mechanism for producing NTE. In the case of the microstructural effect, the NTE performance of the bulk body can be strongly affected by the degree of sintering, in principle.…”