Subject index

The structures of phosphorus-selenium glasses P_xPe_1?x with x=0 (pure selenium), 0.05, 0.15, 0.25, 0.40 and 0.50 have been investigated with neutron diffraction, extented, X-ray absorption fine structure measurements, and Raman and infrared spectroscopy. The behavior of the near-neighbor coordination at $\text{r～2.3}\text{A}\text{?}$ as a function of x suggests a picture in which P₄Se_n molecular units are linked together by Se atoms or chains. The diffraction patterns exhibit anomalous peaks at Q ～ 1.2Å which rise dramatically as P is added to the Se glass; these peaks can also be understood on a molecular picture. The Raman spectra at the larger P concentrations are characterized by series of relatively sharp peaks which also suggest molecular units and for x = 0.5 bear a close correspondence to the spectrum of crystalline P₄Se₃.