The Physical Properties of Glasses. Part III. The Density of Borate Glasses
JSGT 1946 V30 T173-T191
The theory, given in an earlier communication, which sets out the way in which the density of silicate glasses is a function of their composition is extended to borate, borosilicate and boroaluminate glasses. It is shown that in these three cases there is an accumulation region (where the O− ions provided by the metallic oxides present are taken up as 'the result of the formation of tetrahedral instead of triangular oxygen configurations round the B3+ ions) and a destruction region (where the O− ions are taken up by the breaking of linkages, a process discussed in detail earlier). For the boroaluminates a crystalline region (where at least two phases are formed, of which at least one is crystalline) occurs as well. It is shown that the destruction regions are all characterised by constant values of χ in the new density formula discussed in Paper II of this series. Methods are given for calculating χ for the several glasses investigated, and the values so obtained are shown to be in satisfactory agreement with those derived by experiment.
J. M. Stevels
