Electronic polarizabilities of ions in doubly refracting crystals

A method is described for determining electronic polarizabilities of ions in doubly refracting ionic crystals solely from crystal data. An expression for computing polarizabilities by a least-squares fit can be derived. Such a method is used to obtain values for the polarizability of cations for the sodium D line in ų: Na⁺ 1.7, K⁺ 11.6, Rb⁺ 19.1, TI⁺ 48.7, Ca²⁺ 5.2, Sr²⁺ 11.1, Ba²⁺ 23.2, Pb²⁺ 38.3. Evidence is given of decreasing polarizability of the O^2- ion in aragonite-type carbonates with decreasing cation sizes.