Time schedule by speaker > Cabral Aluisio

The knowledge of the dominant crystallization mechanism and the corresponding structure of a given glass ceramic is highly required, since most of the applications of those materials depend on these characteristics. In this paper, a CaO-SrO-B2O3-SiO2 glass composition was prepared by melting/quenching. In the next, bulk glass samples were heat-treated in a tubular furnace at temperatures above Tg for different periods of time (Tg » 680oC). The evolution of the crystalline phases formed after crystallization at 850oC for a wide time interval (20h – 382h) was investigated by X-ray diffraction (XRD). Using Raman Confocal Microscopy, the Raman spectra of the partially crystallized glass samples were collected at room temperature, at a wavelength range between 200 and 1200 cm-1. From the SEM micrographs, well-separated crystals were found in the surface (dendritic) as well as in the volume (spherulithic), with well-distinctive crystal growth rates. In addition, as demonstrated by the Raman spectra, these crystals belong to the same crystalline phase.