International Journal of Physics | Vol. 9, No. 5, May 2018 | pp. 33–40
DOI: 10.46882/2018/IJP/000097
Research Article
Title: High-Pressure Elastic Moduli and Mechanical Stability of Ultra-Incompressible Molybdenum Tetraboride
Names of Authors: V. I. Morozov¹, I. R. Sokolov²
Authors’ Affiliations: ¹Institute of High Pressure Physics, Russian Academy of Sciences, Troitsk, Russia; ²Kapitza Institute for Physical Problems, Russian Academy of Sciences, Moscow, Russia
Abstract: Designing ultra-incompressible structural materials capable of withstanding extreme mechanical stress is vital for industrial tooling and high-pressure research components. This paper examines the high-pressure elastic moduli and structural stability of orthorhombic molybdenum tetraboride (MoB4) up to hydrostatic pressures of 140.0 GPa. We performed first-principles density functional theory computations within the generalized gradient approximation framework. At zero pressure, the calculated bulk modulus is B0 = 312.0 GPa, with an elastic derivative value of B0' = 4.18. These results match experimental diamond anvil cell measurements within a 1.5% margin. The single-crystal elastic constants (C11, C22, C33, C44, C55, and C66) increase monotonically under compression, satisfying all Born mechanical stability conditions across the tested pressure range. The directional compressibility curves reveal that the crystal c-axis is significantly stiffer than the a-axis and b-axis, which is due to short, covalent molybdenum-boron bonds aligned along the plane. The electronic structure calculations show a high density of states at the Fermi level, indicating that MoB4 retains its metallic character under high pressure. These precise elastic profiles confirm the potential of transition metal borides as viable alternatives to diamond-based superhard materials.
Keywords: Molybdenum tetraboride; density functional theory; elastic constants; high pressure; mechanical stability; directional compressibility
Manuscript Timeline: Received: January 20, 2018; Revised: March 05, 2018; Accepted: April 02, 2018; Published: May 11, 2018
Citation: Morozov, V. I., & Sokolov, I. R. (2018). High-Pressure Elastic Moduli and Mechanical Stability of Ultra-Incompressible Molybdenum Tetraboride. International Journal of Physics, 9(5), 33–40.
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