  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, Ag, Au, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Hf, Hg, Ir, K, La, Li, Mg,
Mn, Mo, Na, Nb, Ni, Os, Pd, Pt, Rb, Re, Rh, Ru, Sc, Sr, Ta, Tc, Ti, V, W, Y,
Zn, 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.
