Fabrication of Li2O-Al2O3-SiO2 glass-ceramic ferrules by precision drawing of crystallized preforms.

In this paper, we describe the fabrication of Li2O-Al2O3-SiO2 (LAS) crystallized preforms with suitable drawing formability, and the characteristics of drawn LAS glass-ceramic capillaries. It was found that addition of K2O to the LAS glasses reduces crystallinity of the crystallized preforms and forms low-viscosity glass matrices. It was confirmed that, by using a parallel plate viscometer, such crystallized preforms show suitable viscosity for drawing below the melting temperatures of the crystalline phase. We also proved that the addition of K2O is effective in stabilizing the preforms by preferential precipitation of stable β-spodumene solid solution (s.s.), which is essential in preventing the deposition of coarse surface crystals during the drawing. The LAS glass-ceramic capillaries drawn from the crystallized preform containing 50 mass% β-spodumene s.s. showed a dimensional accuracy within sub-micrometers. It was confirmed that the glass-ceramic capillaries have a low thermal expansion coefficient (25 × 10-7/K) and excellent mechanical and chemical durability, making them promising candidate components of fiber-optic devices. [ABSTRACT FROM AUTHOR]