The Colours of Nickel in Glasses of Various Types and their Implications Concerning Glass Structure. Part II. Detailed Study of the Absorption Curves Given by Nickel in Glasses and Certain Sintered Masses

JSGT 1955 V39 T250-T286

In Part II the absorptions of the various glasses described in Part I are studied in detail; the three types of absorption spectra show that nickel can exist in three different states in glass. The absorptions, even in base glasses of identical composition, are not proportional to the nickel concentration. In considering the curves, therefore, attention has been paid to the positions and intensities of the centres of the various absorption bands and to the ways in which these are changed by changes in glass composition. The more important of these changes may be summarised as follows: (1) In the "Cabal" glasses containing equal proportions of nickel oxide, changes of composition which would render the structure more "open" cause an increase of intensity of bands 1 and 5 associated, usually, with a movement towards the longer wavelengths. Similar effects are shown by glasses of other types. (2) The borates and borosilicate glasses give transmission curves of the "green" type when the alkali content is high compared with the NiO content but less than would give an alkali/boric oxide ratio approaching  1: 3. (3) The "green" form gives place to the "brown" form within a short range of alkali contents when the alkali is increased beyond the proportion indicated in 2. (4) The" brown" form gives place to the" undulatory" form when the alkali content is further increased. (5) The "undulatory" form is given by binary alkali-silica glasses and by ternary glasses of the soda-lime-silica type, also by the alkali-silica sintered masses referred to in the text, provided that the alkali content is large compared with the NiO content. Additional experiments of a quantitative character are dealt with, and reference is made also to the effects of chilling certain glasses of "critical" compositions. Observations on various sintered masses are also described, but none of this additional experimental work can usefully be dealt with except in detail as in the paper. The ideas arising out of the detailed study of the absorptions of the various glasses and sintered masses are indicated, but their full development is dealt with in Part III.

H. Moore & H. Winkelmann