光学ガラスの分極率の温度係数について

抄録

The temperature coefficient of refractive index dn/dTand that of volume expansion β have been measured by an interferometric procedure designed to determine the coefficients simultaneously, with one sample. The temperature coefficient of electronic polarizability φ has been calculated from dn/dTand β. At first, φ is expressed as the sum of the contributions of each glass component, φ_i. Secondly, φ_i is expressed as follows: φ_i=β_i·γ_i, where β_iis the thermal expansion coefficient of cation-oxygen distance and γ_iis the change in electronic polarizability due to the change in interionic distance. φ_i decreases as the ionic field strength of cation, z/a² increases, which is the same tendency as that of β_i·γ_icalculated from φ_iand β_i, gradually increases as z/a² increases. This means that φ_iis mainly determined by the elongation of interionic distance, and it also suggests that the deformation of the electron cloud of oxygen ion caused by the change in interionic distance becomes larger, as the electronic polarizing power of cation increases.