Electron magnetic resonance and optical properties of Ga2-2xIn2xO3 solid solutions

Oxygen deficient Ga2-2xIn2xO3 (0 less than or equal to x less than or equal to 0.5) solid solutions are investigated by means of optical absorption, f luorescence spectroscopies and electron spin resonance of conduction electr ons. Optical spectroscopies show a decrease of the band gap when x increase s. Electron spin resonance demonstrates that this phenomenon can be correla ted to a progressive participation of indium orbitals in the conduction ban d edge, The predominant contribution of In-Ss orbitals is responsible for a strong nuclear dynamic polarization, leading to the largest nuclear field B-n = 1.4 mT ever produced at high temperatures and low magnetic fields, fo r the composition with x = 0.3. However, the expected bistability of the el ectron magnetic resonance resulting from this nuclear polarization is relat ively small, most probably due to a disorder in the distribution of gallium and indium among the crystallographic sites. This disorder and the presenc e of Fe3+ impurities is responsible for the variable magnetic properties of these compounds. (C) 1999 Elsevier Science Ltd. All rights reserved.