NUCLEATION AND CRYSTALLIZATION OF A LITHIUM ALUMINOSILICATE GLASS

An aluminosilicate glass of composition 61SiO(2) . 6Al(2)O(3) . 10MgO . 6ZnO . 12Li(2)O . 5TiO(2) (mol%) has been prepared by a melting proc ess and investigated as far as crystallization is concerned. Glass-cer amic is easily obtained because glass shows a high tendency to crystal lize starting from 700 degrees C. The crystalline phases evolve with t emperature, showing the aluminosilicates to be the main phase up to 10 50 degrees C, followed by metasilicates and silicates, some of which h ave lower melting points. The titanates of Mg and Zn develop from the phase-separated glass, soon after T-g, and grow to form nucleation cen ters for the other crystalline phases. The evolution from phase-separa ted glass to glass-ceramic has been followed by many thermal, diffract ometric, spectroscopic, and microscopic techniques.