This paper describes the preparation of a transparent glass-ceramic from the SiO 2-K 2 O-ZnO-Al 2 O 3-TiO 2 system containing a single crystalline phase, gahnite (ZnAl 2 O 4). TiO 2 was used as a nucleating agent for the heat-induced...
moreThis paper describes the preparation of a transparent glass-ceramic from the SiO 2-K 2 O-ZnO-Al 2 O 3-TiO 2 system containing a single crystalline phase, gahnite (ZnAl 2 O 4). TiO 2 was used as a nucleating agent for the heat-induced precipitation of gahnite crystals of 5-10 nm. The evolution of the ZnAl 2 O 4 spinel structure through the gradual formation of Al-O bonds was examined by infrared spec-troscopy. The dark brown color of the transparent precursor glass and glass-ceramic was eliminated using CeO 2. The increase in transparency of the CeO 2-doped glass and glass-ceramics was demonstrated by UV-visible absorption spec-troscopy. EPR measurements confirmed the presence of Ce 3+ ions, indicating that CeO 2 was effective in eliminating the brown color introduced by Ti 3+ ions via oxidation to Ti +4. The hardness of the glass-ceramic was 30% higher than that of the as-prepared glasses. This work offers key guidelines to produce hard, transparent glass-ceramics which may be potential candidates for a variety of technological applications, such as armor and display panels. K E Y W O R D S
