Ca3AlN3 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one N(3), two equivalent N(1), and two equivalent N(2) atoms. In the second Ca site, Ca(2) is bonded in a 5-coordinate geometry to one N(3), two equivalent N(1), and two equivalent N(2) atoms. In the third Ca site, Ca(3) is bonded in a 5-coordinate geometry to one N(1), two equivalent N(2), and two equivalent N(3) atoms. Al(1) is bonded to one N(1), one N(2), and two equivalent N(3) atoms to form edge-sharing AlN4 tetrahedra. There are three inequivalent N sites. In the first N site, N(1) is bonded in a 6-coordinate geometry to one Ca(3), two equivalent Ca(1), two equivalent Ca(2), and one Al(1) atom. In the second N site, N(2) is bonded in a 7-coordinate geometry to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and one Al(1) atom. In the third N site, N(3) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), two equivalent Ca(3), and two equivalent Al(1) atoms.
Ca3AlN3 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one N(3), two equivalent N(1), and two equivalent N(2) atoms. The Ca(1)-N(3) bond length is 2.48 Å. There is one shorter (2.30 Å) and one longer (2.48 Å) Ca(1)-N(1) bond length. There is one shorter (2.52 Å) and one longer (2.79 Å) Ca(1)-N(2) bond length. In the second Ca site, Ca(2) is bonded in a 5-coordinate geometry to one N(3), two equivalent N(1), and two equivalent N(2) atoms. The Ca(2)-N(3) bond length is 2.43 Å. There is one shorter (2.56 Å) and one longer (2.85 Å) Ca(2)-N(1) bond length. There is one shorter (2.43 Å) and one longer (2.59 Å) Ca(2)-N(2) bond length. In the third Ca site, Ca(3) is bonded in a 5-coordinate geometry to one N(1), two equivalent N(2), and two equivalent N(3) atoms. The Ca(3)-N(1) bond length is 2.53 Å. There is one shorter (2.41 Å) and one longer (2.79 Å) Ca(3)-N(2) bond length. There is one shorter (2.36 Å) and one longer (2.73 Å) Ca(3)-N(3) bond length. Al(1) is bonded to one N(1), one N(2), and two equivalent N(3) atoms to form edge-sharing AlN4 tetrahedra. The Al(1)-N(1) bond length is 1.89 Å. The Al(1)-N(2) bond length is 1.90 Å. There is one shorter (1.92 Å) and one longer (1.95 Å) Al(1)-N(3) bond length. There are three inequivalent N sites. In the first N site, N(1) is bonded in a 6-coordinate geometry to one Ca(3), two equivalent Ca(1), two equivalent Ca(2), and one Al(1) atom. In the second N site, N(2) is bonded in a 7-coordinate geometry to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and one Al(1) atom. In the third N site, N(3) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), two equivalent Ca(3), and two equivalent Al(1) atoms.