Xu, S. W.Wang, R. P.Luther-Davies, B.Kovalskiy, A.Miller, A. C.Jain, H.2015-10-222015-10-220021-8979http://hdl.handle.net/1885/16032We have measured high-resolution x-ray photoelectron spectra of Ge xAsySe1-x-y glasses with a mean coordination number (MCN) from 2.2 to 2.78. The valence band spectra showed that a number of Se–Se–Se trimers can be found in Se-rich samples, whilst multiband features induced by phase separation can be observed in extremely Se-poor samples. When the Ge, As, and Se 3d spectra were decomposed into several doublets, which correspond, respectively, to different chemical environments, the perfect AsSe₃/₂ pyramidal and GeSe₄/₂ tetrahedral structures in Se-rich samples gradually evolved into defect structures, including As–As and Ge–Ge homopolar bonds, with increasing Ge and As concentrations. Two transition-like features were found at MCN = 2.5 and 2.64–2.72 that correspond first to the disappearance of Se-chains in the glass network and, subsequently, destruction of the perfect GeSe₄/₂ tetrahedral structures, respectively.This research was supported by Australian Research Council through its Centres of Excellence, and Discovery Programs. R.P.W acknowledges support from U.S. National Science Foundation through International Materials Institute for New Functionality in Glass and the Australian Academy of Sciences through its Scientific Visits to North America program.http://www.sherpa.ac.uk/romeo/issn/0021-8979..."Publishers version/PDF may be used on author's personal website, institutional website or institutional repository" from SHERPA/RoMEO site (as at 22/10/15). Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics and may be found at https://doi.org/10.1063/1.48673972014-02-2810.1063/1.48673972015-12-10