Structure stability, mechanical properties and thermal conductivity of the new hexagonal ternary phase Ti₂InB₂ under pressure

ABSTRACT

Recently, Wang et al. [Nat. Commun. 10 (2019) 2284] report a new compound, Ti₂InB₂, a stable boron-based ternary phase in the Ti-In-B system. This predicted compound is successfully synthesised using a solid-state reaction route and its space group is confirmed as $P\overline{6}m2$ (No. 187). In this work, the structural stability, mechanical properties, and thermal conductivity of the new hexagonal ternary phase Ti₂InB₂ under pressure up to 100 GPa have been carried out with first-principles calculations based on density functional theory. Our calculated lattice parameters in the ground state are consistent well with the theoretical prediction data. The calculations of elastic constants and phonon dispersion curves indicate that Ti₂InB₂ is mechanically and dynamically stable at least up to 100 GPa. Moreover, the pressure dependent elastic properties, such as bulk modulus B, shear modulus G, transverse sound velocity v_t, longitudinal sound velocity v_l, and Debye temperature Θ, are successfully obtained. It is found that Ti₂InB₂ behave in brittle manner under pressure up to 100 GPa. Meanwhile, the anisotropy of the directional linear compressibility and the Young’s modulus under pressure are also analysed for the first time. Finally, the minimum thermal conductivity of Ti₂InB₂ under different pressures are further evaluated by using both Clark’s model and Cahill’s model. The results show that Ti₂InB₂ exhibits relatively low thermal conductivity in the ground state and is suitable to be used as thermal insulating materials.

KEYWORDS:

• Ti₂InB₂
• mechanical properties
• thermal conductivity
• high pressure

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant numbers 11904282, 11805151, and 11405127], the Doctoral Scientific Research Foundation of Xi’an University of Science and Technology [grant number 2018QDJ029].