Fabrication, microstructure, and optical properties of nanocrystallinectransparent LAST glass ceramics containing CeO_2

摘要

In the present research, the effect of CeO_2 dopant on the fabrication of transparent lithium aluminosilicate titanate (LAST) glass ceramics was investigated. Nanocrystalline (3-quartz solid solution (s.s.) was observed to be the main phase crystallized in this system. Comparable refractive indices of the glassy matrix and P-quartz s.s., as well as the incorporation of very fine grains size were determined as the main reasons for retaining the transparency of the glass ceramics. CeO_2 was introduced as a suitable optical agent, playing a role as a network modifier in the glass ceramics, because it does not accelerate the growth process and retards the extended growth of crystals. Optical investigations indicate that the Fermi energy level, direct and indirect band gaps, and Urbach energy decrease with increasing nanocrystal content in the glassy matrix of specimens, which can be related to the expansion of conduction band, the enhancement of ionic bonds in the crystal lattice, and the enhancement of structural arrangement degree, respectively.