Effect of copper impurities on the absorption spectrum of thin films of superionic conductors MAg4I5 (M = K, Rb)

Abstract

The absorption spectra of thin films of the solid electrolytes MAg4I5 (M = K, Rb) doped with copper (0 ≤ x ≤ 0.15) are studied in the spectral range 2–6 eV at temperatures of 90 and 290 K. It is established that the critical Cu content reaches xcrit = 0.05. A decrease in the Cu content to x ≤ 0.05 leads to the formation of MAg4 − 4xCu4xI5 solid solutions, and the films remain spectrally stable. At x > 0.05, the films segregate into different phases: MAg4 − 4xCu4xI5, Ag1 − xCuxI, and M2AgI3.