Electronic, mechanical and lattice dynamical properties of YXB₄ (X = Cr, Mn, Fe, and Co) compounds

Abstract

In this study, the physical such as structural, electronic, anisotropic elastic and lattice dynamic properties of YXB4 (X = Cr, Mn, Fe and Co) compounds have been investigated. The electronic properties including band structure and corresponding partial density of states for YXB4 have been calculated. YFeB4 and YCoB4 compounds are found to have metallic behavior while YCrB4 and YMnB4 have semiconductor behavior. Also, the compounds are found to be as non-magnetic materials. The calculated elastic constants indicate that these materials are mechanically stable due to satisfying Born stability criteria. In addition, the second order elastic constants and related polycrystalline elastic moduli (e.g. shear modulus, Young’s modulus, Poisson’s ratio, Debye temperature, sound velocities) are determined and the results are discussed in detail. The mechanical anisotropy is discussed using several anisotropy indexes and two-dimensional and three-dimensional surface constructions are obtained. All the compounds have dominantly covalent bonding and they are brittle materials. YCrB4 is found to be as a super hard material. YFeB4, YCoB4 and YMnB4 are found to be as hard materials. The dynamical stability of these compounds has been studied and it has been found that YCoB4 is dynamically unstable. In addition, the thermodynamic properties (heat capacity, free energy, etc) of these compounds have been obtained and discussed in detail.

Unveiling a Family of Dimerized Quantum Magnets, Conventional Antiferromagnets, and Nonmagnets in Ternary Metal Borides

“…The NM DOS for YCrB 4 shows a semiconducting character with a narrow band gap of 0.20 eV, which agrees with the experimental estimate of 0.17 eV . The semiconducting character of NM YCrB 4 agrees with previous first-principles calculations, ,, which reported a gap of 0.05, 0.14 ± 0.04, and 0.17 eV …”

“…Earlier calculations predicted these systems to be NM. 46,47 However, we find the DFT ground states to be AFF for Cr and FFA for Mn. In their respective DFT ground states, the magnetic moments on Cr and Mn atoms are close to 1 μ B .…”

“…The DFT ground states are either semiconducting or weakly metallic for MTB 4 (M = Y and Lu). The semiconducting Cr compounds in the NM state ,, remain semiconducting in the magnetic state. In contrast, a change from a good metal to a bad metal is seen in Mn compounds when they switch from NM to magnetic.…”

“…On the other hand, theoretical investigations of the fundamental electronic and magnetic properties of these compounds are scarce, even for the prototypical YCrB 4 . 46,47,55 Previous first-principles calculations for YCrB 4 show nonmagnetic (NM) 46,47 and semiconducting 46,47,55 behavior. A remarkable structural feature of this class of materials is a transition-metal dimer formation.…”

“…Driven by the idea to seek quantum spin dimers in borides, we uncover the family of compounds with a YCrB 4 -type structure. YCrB 4 was reported to offer promising physical properties such as thermoelectricity , and high mechanical strength. − This class of materials, i.e., metal (M)–transition metal (T)–tetraborides (B 4 ), was reported by early experimental studies. , ScTB 4 (T = Fe, Co, and Ni), YTB 4 (T = V, Cr, Mn, Fe, and Co), CeTB 4 (T = Cr, Mn, Fe, and Co), and LuTB 4 (T = Cr, Fe, Co, and Ni) were briefly mentioned. − However, methods to produce single-phase samples suitable for characterization are known only for a subset of the reported compounds. On the other hand, theoretical investigations of the fundamental electronic and magnetic properties of these compounds are scarce, even for the prototypical YCrB 4 . ,, Previous first-principles calculations for YCrB 4 show nonmagnetic (NM) , and semiconducting ,, behavior.…”