Structural analysis of AgxCu1−xI (0.75⩽x<1.00) in the superionic phase using solid 63Cu NMR and X-ray diffraction methods

Two types of 63Cu NMR signals and X-ray diffraction patterns of AgxCu1−xI (0.75⩽x<1.00) were observed in the γ-phase (zincblende) to α-phase (body-centered cubic) transition. The high-field signal of 63Cu NMR in the α-phase structure is considered to be due to the positive Cu ion mainly in the octahedral 6(b) position and partially in the tetrahedral 12(d) position, by comparison with the Cu chemical shielding calculations of three types of trigonal 24(h) CuI32−, tetrahedral 12(d) CuI43−, and octahedral 6(b) CuI65− complexes using the ab initio GAUSSIAN 94 program with a double-ζ basis set. The Ag and Cu chemical shieldings of the metal complexes are explained mainly by the paramagnetic term.