X‐ray Study of Boric Oxide‐silica Glass*

Abstract

X-ray diffraction patterns have been made of four samples of boric oxide-silica glass (15, 30, 45, and 60% SO2) and of Pyrex-brand chemical resistant glass. Radial distribution curves for the 5 samples were obtained by the usual Fourier analysis method. The results lead to a picture of boric oxide-silica glass in which each silicon is tetrahedrally surrounded by 4 oxygens, each boron is triangularly surrounded by 3 oxygens, and each oxygen is bonded between 2 cations. In Pyrex-brand chemical resistant glass, part of the borons are probably in tetrahedral coordination. The softening of silica glass by the addition of boric oxide results from replacing in the random network fourfold coordinated silicon by threefold coordinated boron. The low expansion coefficient of vitreous silica, contrasted with the higher expansion of crystalline silica, is explained by the impossibility of cooperative maneuvers in the random network of glassy silica.

Ultra-dense (Bi, V, B)-oxide-added zircon ceramics fabricated by liquid-phase assisted spark plasma sintering (SPS)

“…Furthermore, a small amount of amorphous silica as the zircon decomposition product may also affect the lowering of the ceramics' thermal expansion coefficient. The effect here, however, is diminutive [54] since the little phase composition in the bulk ceramics, as reported in the previous passage. It is worth noting that zircon-reidite transformation [55], [56] is not observed in this work.…”

Boroxol rings in SiO2–B2O3 glasses: Influence on low-temperature thermal properties

“…Perhaps part of the relative neglect of binary SiO 2 -B 2 O 3 glasses originates in their hygroscopic character and in the difficulty to synthesize them from end member components that form glasses at so widely different temperatures. In macroscopically homogenous SiO 2 -B 2 O 3 glasses, the presence of the respective SiO 4 tetrahedra and BO 3 triangles of the oxide end members was nonetheless early established through X-ray diffraction experiments [6,7]. Boroxol rings have also been observed, with relative abundances that decrease with increasing temperatures [8].…”

Synthesis of High Quality Few Layer Graphene Sheets in Large Quantities by Radio Frequency Chemical Vapor Deposition

“…The X-ray diffraction (XRD) technique was used to analyze the crystallinity and estimate the number of layers in the graphene nanosheets. The size of crystallite was evaluated from the width of the diffraction peaks using the Scherrer equation (K= 0.9) [27]. The intense peak positions at C (002) and C (100), which are typical features for graphite, are identified in this graphene XRD pattern [26].…”