JAHN-TELLER TYPE SELF-TRAPPING OF HOLES IN MIXED-CRYSTALS AGBR1-XCLX

Electron spin resonance study shows that holes in Cl-rich AgBr1-xClx mixed crystals are self-trapped as the Ag2 + complexes having Br ligand ions, (AgBrCl5)4-, (AgBr2Cl4)4- I, II and (AgBr4Cl2)4- besides (AgCl6)4-. The complexes (AgBr2Cl4)4- II and (AgBr4Cl2)4- which have two and four Br ligand ions in the same plane respectively have the tetragonal symmetry due to the crystalline field created by Br ions and the Jahn-Teller effect. The anisotropy in g values for these complexes is, however, reduced somewhat compared with that expected by the static Jahn-Teller effect. The decay temperatures of the complexes (AgCl6)4- and (AgBrCl5)4- are decreased with the increase of the concentration of Br ions. This fact is discussed with the theory of optical-phonon-assisted hopping. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.