Transparent athermal glass-ceramics in Li_2O-Al_2O_3-SiO_2 system

摘要

An attempt has been conducted to develop multicomponent transparent glass-ceramics which have athermal property better than silica glass. Transparent Li_2O-Al_2O_3-SiO_2 (LAS) glass-ceramics with small thermal expansion coefficient was chosen as a candidate. Athermal property of the glass-ceramics was improved by the independent control of temperature coefficients of electronic polarizability (φ) and thermal expansion coefficient (α), both of which govern the temperature coefficient of optical path length. It was found that α and φ of the LAS glass-ceramics were controllable by the additives and crystallization conditions. The doping of B_2O_3 and the crystallization under a hydrostatic pressure of 196 MPa were very effective to reduce φ without a remarkable increase in α. It was deduced that the reduction in φ by the crystallization under 196 MPa resulted from the inhibition of the precipitation of β-spodumene solid solution. The relative temperature coefficients of optical path length of B_2O_3-doped glass-ceramic crystallized under 196 MPa was 11.7 x 10~(-6)/℃, which was slightly larger than that of silica glass. Nevertheless, the α value of this glass-ceramic was smaller than that of silica glass.