Papers by Author: Angelina Stoyanova

Abstract: α-Bi2Mo3O12 and β-Bi2Mo2O9 crystal phases have been synthesized by crystallization of a glass for a short time. Amorphous samples with the compositions corresponding to the alpha and beta bismuth molybdates have been obtained at high cooling rates (104-105 K/s). XRD, DTA and SEM studies were performed to examine the phase formation, thermal behavior of the glasses and the microstructure of obtained crystalline products. By scanning electron microscopy it was shown that the obtained bismuth molybdates consist of dense agglomerates, containing uniform distributed crystals with submicron size.

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.