STRUCTURAL STATES OF NI(II) IN GLASSES AND GLASS-CERAMIC MATERIALS OF THE LITHIUM ALUMINUM SILICATE SYSTEM

Optical absorption spectra of Ni(II) have been investigated in glass-ceramic materials of the lithium-aluminium-silicate system at various phase transition stages. Four types of absorption spectra have been revealed. The Ni(II) absorption bands have been attributed based on the calculation of the energy level diagram. It has been shown that in the case of heat treatment at the initial stage of phase decomposition, there arise aluminium titanium nickel regions that decompose in subsequent heating into titanium phases and aluminium-nickel spinel microcrystals. In crystallizing the main phase, i.e. solid solutions of beta-eucryptite, Ni(II) is built into the structure of this phase replacing lithium isomorphously.