Papers by Author: Lyubomir Aleksandrov

Abstract: Low melting glasses in the MoO3-Nd2O3-Bi2O3 system were obtained at slow (102 K/s) and high cooling rates (104-105 K/s). The amorphous state of the samples was proved by X-ray diffraction. Comparative analysis of the infrared spectra of the obtained glasses and other available molybdate spectral data was carried out. The structure of glasses with a high MoO3 content was found to consist of corner shared MoO6 units. The increasing of Nd2O3 and Bi2O3 lead to partial transformation of MoO6 to MoO4 units, due to breaking of Mo-O-Mo linkage.

Abstract: Novel low melting glasses in the MoO3-La2O3-Nd2O3 system were obtained at different cooling rates (102 K/s and 104-105 K/s). Characterization of the amorphous samples was made by differential thermal analysis (DTA) and X-ray absorption fine structure (XAFS) method. According to DTA data of the glass samples, the glass transition temperatures are at 325-330 0C, the crystallization started above 410 0C and the melting temperatures are at 660-720 0C. A structural model of glasses was suggested on the basis of XAFS and IR investigations. It was shown that the predominant structural units in the amorphous network of glasses containing 90 -80 mol% MoO3 are MoO6 groups. The appearance of MoO4 groups deteriorates the glass formation ability.