Crystal growth in zinc borosilicate glasses

TitleCrystal growth in zinc borosilicate glasses
Publication TypeJournal Article
Year of Publication2016
AuthorsKullberg ATG, Lopes AAS, Veiga JPB, Monteiro RCC
JournalJournal of Crystal Growth
KeywordsBorosilicate glass, Crystal growth, Crystal morphologies, Crystallite size, Differential thermal analysis, Glass ceramics, Glass compositions, Growth from melts, Heat treatment, Heat treatment conditions, Melt quenching techniques, Scanning electron microscopy, Specific heat, Thermoanalysis, Transparent nanocomposites, Ultraviolet visible spectroscopy, UV-vis spectroscopy, X ray diffraction, Zinc, Zinc borosilicate glass, Zinc compounds, Zinc oxide

Glass samples with a molar composition (64+x)ZnO-(16-x)B2O3-20SiO2, where x=0 or 1, were successfully synthesized using a melt-quenching technique. Based on differential thermal analysis data, the produced glass samples were submitted to controlled heat-treatments at selected temperatures (610, 615 and 620°C) during various times ranging from 8 to 30h. The crystallization of willemite (Zn2SiO4) within the glass matrix was confirmed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Under specific heat-treatment conditions, transparent nanocomposite glass-ceramics were obtained, as confirmed by UV-vis spectroscopy. The influence of temperature, holding time and glass composition on crystal growth was investigated. The mean crystallite size was determined by image analysis on SEM micrographs. The results indicated an increase on the crystallite size and density with time and temperature. The change of crystallite size with time for the heat-treatments at 615 and 620°C depended on the glass composition. Under fixed heat-treatment conditions, the crystallite density was comparatively higher for the glass composition with higher ZnO content. © 2016.