Crystallization of Glasses Containing K2O, PbO, BaO, Al2O3, B2O3, and TiO2

Abstract

The objective of this work was to obtain glass-ceramics from stable glasses, with a composition of barium, lead, and potassium titanate phases, for use as semiconductors. For this purpose, the glass-ceramic technique was used to control crystal growth and obtain a fine-grained microstructure. Various glasses containing K2O, PbO, BaO, Al2O3, B2O3, and TiO2 were prepared using a melt-quenching method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed a single amorphous phase of all samples. Infrared spectra confirmed the presence of B-O bonds stretching vibrations of (B3O6)3− boroxol rings and BO3 triangles, as well as Ti-O stretching vibrations of (TiO6/2) and (AlO6/2) octahedral units. Thermal analyses confirmed the presence of one or more crystallization peaks in the range of 700 to 744 °C. On this base, they were heat-treated to promote crystal growth. XRD and SEM detected Ba4Ti12O27, Ti7O13, and BaTiO3 phases, homogeneously distributed throughout the material with fine crystallite size. In addition, crystallized glasses’ (glass-ceramics) properties were determined; the density values were 2.8–3.55 g/cm3; the chemical resistance to acidic and basic media was low; and the band-gap values were in the range of 2.88 to 3.05 eV. These results suggest that crystallized glasses may have application in photocatalysis.

Reformulation of bone china body for the reduction of pyroplastic deformation

“…To make a quantitative phase analysis, a baseline was drawn from the beginning of the diffractogram to the end to limit the area of each peak. The area of crystalline phase was calculated using the number of counts multiplied by the angle 2 θ 33 . The amount of glassy phase was calculated by the difference of the crystalline phase area from the total area of all peaks.…”

“…The area of crystalline phase was calculated using the number of counts multiplied by the angle 2θ. 33 The amount of glassy phase was calculated by the difference of the crystalline phase area from the total area of all peaks. In addition, the percentage of each of the identified crystalline phases was determined using the X'Pert HighScore Plus Software.…”

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“…On the other hand, glass ceramics are crystalline materials obtained when a glass of specific compositions is mixed with a small amount of crystallization agent, such as TiO 2 or CaF 2 or ZrO 2 or other titanate phases, such as BaTiO 3 , PbTiO 3 , and subjected to devitrification heat treatment. The properties of the resulting glass ceramics were controlled through the chemical compositions of the ingredients, devitrification heat treatment sequence and cooling rate [5][6][7][8][9][10]. However, many glasses are stable against crystallization; therefore, the choice of specified compositions is important in order to create glass ceramics.…”