Application of spectroscopy and positron annihilation methods in studies of the gel-glasses materials

The results of optical spectroscopy (absorption and emission) and positron annihilation investigations of glasses are presented and discussed. The alcoholic sol-gel method was adapted for the incorporation of Ln(III) into silica gel network and the resulting gels were prepared with chlorides of selected lanthanides (cerium, praseodymium, europium, ytterbium) and with or without some addition of ethylene glycol. During the sol-gel process, a new type of compound with general formula of C12H24Cl3O12Pr2, 3(Cl) was crystallized. Its crystal structure was determined by X-ray diffraction studies what helps understanding the silica network structure. Measurements of absorption, emission and emission excitation spectra were carried out at 4 and 293 K. The optical properties of gels were compared with the spectroscopic data Of C12H24Cl3O12Pr2, 3(Cl) single crystal. The experimental results of positron annihilation investigations were correlated with those from optical spectroscopy. (c) 2007 Elsevier B.V All rights reserved.