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X‐RAY STUDY OF BORIC OXIDE‐SILICA GLASS *
Author(s) -
Biscoe J.,
Robinson C. S.,
Warren B. E.
Publication year - 1939
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1939.tb19448.x
Subject(s) - boron , boric acid , oxide , silicon , materials science , borosilicate glass , boron oxide , borate glass , mineralogy , chemical engineering , inorganic chemistry , analytical chemistry (journal) , composite material , chemistry , metallurgy , chromatography , organic chemistry , engineering
A bstract X‐ray diffraction patterns have been made of four samples of boric oxide‐silica glass (15, 30, 45, and 60% SiO 2 ) 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 tetra‐hedrally 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.