UV absorption of RbAg4I5-RE (Sm,Yb) thin-film systems

UV spectra of samples prepared by vacuum deposition of Sm and Yb thin films on 100-200-nm thick films of the RbAg4I5 solid electrolyte (SE) at 300-350 K contain strong absorption bands peaking at about 4.3 and 5.0 eV. After d eposition of similar to 5 nm of Sm, the ionic conductivity sigma of the sam ples decreases from sigma(0) to approximate to 0.9 sigma(0), and the SE lat tice parameter, from 11.24 to approximate to 11.15 Angstrom, with the x-ray reflection halfwidth increasing from 0.5 to 0.8 degrees. Further growth of Sm concentration in the samples changes the x-ray diffraction pattern, the absorption at 4.3 and 5.0 eV increases, a new absorption edge forms at 3.8 eV, and s decreases down to similar to 10(-2) sigma(0). It is conjectured that the strong UV absorption bands in heavily defected silver halides of t he RbAg4I5-Sm(Yb) system is genetically related to the 4d(10)-->4d(9)5s ele ctronic transitions in free Ag+ ions. (C) 1999 American Institute of Physic s. [S1063-7834(99)00702-9].