Density functional study on Ag8-xCuxI8 (0≤x≤8).

Ab-initio calculations are performed to investigate the effect of defects on structural, electronic and optical properties of Ag 8-x Cu x I 8 (0 ≤x ≤ 8). Initially AgI geometrically optimized and Ag atoms are replaced successively by Cu atoms. AgI is thermodynamically most stable, it exhibits low defect formation energy and fast ion conduction. The forbidden energy gap successively decreases with x. There is higher Ag+ ions formation than Cu+ ions. In the optical study, by increasing x, peaks of imaginary and real dielectric functions are shifted towards lower frequency regions, with Ag/Cu defects, there is slight shifting towards higher energy region, gradual increase in refractive index, and the reflectivity peaks are shifted towards higher energy. [ABSTRACT FROM AUTHOR]