Ba3Sr3Np2 crystallizes in the tetragonal P-4m2 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted body-centered cubic geometry to four equivalent Sr(1) and four equivalent Np(1) atoms. In the second Ba site, Ba(2) is bonded in a distorted body-centered cubic geometry to four equivalent Sr(1) and four equivalent Np(1) atoms. In the third Ba site, Ba(3) is bonded in a distorted body-centered cubic geometry to four equivalent Sr(1) and four equivalent Np(1) atoms. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted body-centered cubic geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), and two equivalent Sr(2) atoms. In the second Sr site, Sr(2) is bonded to four equivalent Sr(1) and four equivalent Np(1) atoms to form distorted edge-sharing SrSr4Np4 tetrahedra. Np(1) is bonded in a body-centered cubic geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), and two equivalent Sr(2) atoms.
Ba3Sr3Np2 crystallizes in the tetragonal P-4m2 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted body-centered cubic geometry to four equivalent Sr(1) and four equivalent Np(1) atoms. All Ba(1)-Sr(1) bond lengths are 3.97 Å. All Ba(1)-Np(1) bond lengths are 3.97 Å. In the second Ba site, Ba(2) is bonded in a distorted body-centered cubic geometry to four equivalent Sr(1) and four equivalent Np(1) atoms. All Ba(2)-Sr(1) bond lengths are 3.97 Å. All Ba(2)-Np(1) bond lengths are 3.97 Å. In the third Ba site, Ba(3) is bonded in a distorted body-centered cubic geometry to four equivalent Sr(1) and four equivalent Np(1) atoms. All Ba(3)-Sr(1) bond lengths are 3.96 Å. All Ba(3)-Np(1) bond lengths are 3.96 Å. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted body-centered cubic geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), and two equivalent Sr(2) atoms. Both Sr(1)-Sr(2) bond lengths are 3.96 Å. In the second Sr site, Sr(2) is bonded to four equivalent Sr(1) and four equivalent Np(1) atoms to form distorted edge-sharing SrSr4Np4 tetrahedra. All Sr(2)-Np(1) bond lengths are 3.96 Å. Np(1) is bonded in a body-centered cubic geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), and two equivalent Sr(2) atoms.