International Journal of Physics

International Journal of Physics | Vol. 17, No. 1, January 2026 | pp. 1–8

DOI: 10.46882/2026/IJP/000189

Research Article

Title: High-Pressure Mechanical Attributes and Elastic Anisotropy Indices of Ultra-Incompressible Hafnium Tetraboride

Names of Authors: V. I. Morozov¹, I. R. Sokolov²

Authors’ Affiliations:
¹ Institute of High Pressure Physics, Russian Academy of Sciences, Troitsk, Russia
² Kapitza Institute for Physical Problems, Russian Academy of Sciences, Moscow, Russia

Abstract: Synthesizing ultra-hard, incompressible refractory configurations capable of resisting intense mechanical shearing and structural deformation under high stress is essential for advancing ballistic shielding and aerospace industrial tooling. This paper examines high-pressure mechanical attributes and quantifies elastic anisotropy indices in orthorhombic hafnium tetraboride (HfB4) up to hydrostatic loads of 150.0 GPa. We performed first-principles density functional theory computations incorporating generalized gradient approximations across systematically compressed lattice grids. At zero pressure, the calculated bulk modulus is B0 = 286.0 GPa, with an elastic pressure derivative coefficient of B0' = 4.14, matching experimental diamond anvil cell recordings within a tight 1.2% margin. The single-crystal elastic constants (C11, C22, C33, C44, C55, and C66) climb monotonically under compression, strictly satisfying all Born mechanical stability parameters across the complete pressure range. The directional compressibility curves reveal that the crystal c-axis displays exceptional stiffness due to short, covalent hafnium-boron bonds interlocking the structural rows. Electronic band-structure maps verify a high density of states at the Fermi boundary, indicating that HfB4 retains its metallic character under high stress.

Keywords: Hafnium tetraboride; density functional theory; elastic constants; high pressure; mechanical stability; directional compressibility

Manuscript Timeline: Received: October 12, 2025; Revised: November 24, 2025; Accepted: December 15, 2025; Published: January 15, 2026

Citation: Morozov, V. I., & Sokolov, I. R. (2026). High-Pressure Mechanical Attributes and Elastic Anisotropy Indices of Ultra-Incompressible Hafnium Tetraboride. International Journal of Physics, 17(1), 1–8.