Materials Data on MgAs4 by Materials Project
MgAs4 crystallizes in the tetragonal P4_12_12 space group. The structure is three-dimensional. Mg2+ is bonded to six As+0.50- atoms to form MgAs6 octahedra that share corners with four equivalent MgAs6 octahedra and corners with fourteen AsMgAs3 tetrahedra. The corner-sharing octahedral tilt angles are 55°. There are a spread of Mg–As bond distances ranging from 2.75–2.97 Å. There are two inequivalent As+0.50- sites. In the first As+0.50- site, As+0.50- is bonded to one Mg2+ and three As+0.50- atoms to form distorted AsMgAs3 tetrahedra that share corners with five equivalent MgAs6 octahedra and corners with nine AsMgAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 52–78°. There are a spread of As–As bond distances ranging from 2.46–2.51 Å. In the second As+0.50- site, As+0.50- is bonded to two equivalent Mg2+ and two equivalent As+0.50- atoms to form distorted AsMg2As2 tetrahedra that share corners with two equivalent MgAs6 octahedra and corners with fourteen AsMgAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 66–71°.