Stability of 41 metal–boron systems at 0GPa and 30GPa from first principles

Abstract

A multitude of observed boron-based materials have outstanding superconducting, mechanical, and refractory properties. Yet, the structure, the composition, and the very existence of some reported metal boride (M-B) compounds have been a subject of extensive debate. This density functional theory work seeks to set a baseline for current understanding of known metal boride phases as well as to identify new synthesizable candidates. We have generated a database of over 12,000 binary M-B entries for pressures of 0 and 30 GPa producing the largest scan of compositions and systems in this materials class. The 175 selected crystal structures include both observed prototypes and new ones found with our evolutionary ground state search. The metals considered are: Al, and Zr. Based on the formation energy calculated at zero pressure and temperature 4 new M-B phases or structures have been predicted, while a number of previously reported compounds have been shown to be unstable. At 30 GPa, changes in the convex hulls are expected to occur in 18 out of 41 M-B systems, which is used to indicate regions of the periodic table (for metal borides) that require further investigation from the community. Analysis of the collected information has revealed a nearly linear relationship between the magnetic moment per atom and the metal content for all the Fe-B, Co-B, and Ni-B structures within 0.15 eV/atom of the stability tie line. Both GGA-PBE and LDA-PW functionals were used to provide an understanding of the systematic error introduced by the choice of the exchange-correlation functional.arXiv:1310.4157v2 [cond-mat.mtrl-sci]

Enthalpies of Formation of Transition Metal Diborides: A First Principles Study

“…Indeed, Kolmogorov et al [39] found that in the case of FeB 2 an orthorhombic structure, oP12, is more stable than the other structures. The results presented in Table 2 are in agreement with the results published by Van der Geest and Kolmogorov [14]. The discrepancies observed with the experimental investigations have already been discussed by these authors.…”

“…The characteristics of the structures considered in the present work are given in Table 1 [5][6][7][8][9][10][11][12][13]. [14]. Indeed, these authors have recently investigated a large number of binary boron alloys.…”

Synthesis of a predicted layered LiB via cold compression

“…Unexpectedly, our frozen phonon calculations 39,40 revealed that the family of Li 2n B 1D m phases across a large composition range becomes dynamically unstable under moderate pressures, a behavior not recognized in previous ab initio studies 17,[27][28][29][30]47,48 . Construction of most stable derived structures is a known challenge due to the possibility of multiple local minima with similar energies/enthalpies 43,49,50 .…”

Peierls distortion, magnetism, and high hardness of manganese tetraboride

“…While the present paper was under review, the same structure was proposed as the ground state structure for MnB 4 based on theoretical calculations [34] and determined experimentally [35] for normal-pressure synthesized MnB 4 crystals.…”