The Colours of Nickel in Glasses of Various Types and their Implications Concerning Glass Structure. Part I. The Types of Absorption Spectra Given by Nickel in Glass

JSGT 1955 V39 T215-T249

The colours given by nickel in glass differ greatly from the colours of nickel oxide and salts of nickel, and present an interesting subject for investigation. In the experimental work described in Part I, a study has been made of the colours given by nickel in binary alkali-silica glasses and ternary glasses of the soda–lime–silica type, in borates and borosilicate glasses, and also in non-silica, non-alkali glasses consisting of CaO, B₂O₃ and Al₂O₃, developed by Sir Herbert Jackson between 1917 and 1919, to which he gave the name "Cabal" glasses. The compositions of these various types of glasses were varied by altering the alkali contents, by altering the proportions of B₂O₃ and SiO₂ in the borosilicate glasses, and in other ways.

The transmission curves of the resulting glasses were obtained over the wavelength range from about 300 to 2300 µm. These curves could be divided into three types characterised by the presence or absence of six main absorption bands which are referred to in the paper as bands 1–6. The Cabal glasses give the simplest type of curve, with only three absorption bands, Nos. 1, 5 and 6, and are of a brown colour. Borates and borosilicates containing alkali less than some fairly definite proportion have four absorption bands, Nos. 1, 3, 5 and 6, and the visual colour is green. Binary alkali silicates and ternary silicates of the alkali-lime-silica type give absorptions corresponding with bands 1, 2, 4, 5 and 6. The visual colours of the silicate glasses depend on the relative intensities of bands 1 and 2, and on their precise positions in the spectrum. For example, soda glasses are brown to the eye and potash glasses are blue or blue-violet, though their absorptions are of closely corresponding types. For convenience, the three types of transmission are referred to as of the "brown," "green" and "undulatory" forms; they indicate that nickel can exist in three different states in glass, corresponding with different configurations which depend on the composition of the glass and on the structure imposed by the composition.

H. Moore & H. Winkelmann