DETERMINATION OF SULFUR-COMPOUNDS IN THE SOL-GEL PROCESSING OF GES2 BY POTENTIOMETRIC TITRATION

The potentiometric titration method was used for quantitative determin ation of germanium sulfide and germanium mercaptide evolved during the sol-gel processing of GeS2 from germanium ethoxide and H2S. The titra tions were performed in 2-propanol or in a 50-50 vol.% mixture of 2-pr opanol and toluene. The ion selective Ag/Ag2S electrode was used for e quivalence point detection. Study of the Nernst equation shows that co mplexes were formed at the electrode surface. However, the titration e quivalence point volume clearly demonstrates the formation of Ag2S and Ge(SAg)(n). In order to explain this discrepancy, a new electrode rea ction mechanism is suggested and a modified Ag/Ag2S electrode potentia l equation is proposed. (C) 1998 Elsevier Science Ltd. All rights rese rved.