Studies on the Opto-Electronic Constants of Alkali-Halide Crystals

Authors: MAHMOUD A. SALEM

Abstract: In this presentation, the correlation between refractive index n of alkali-halide crystals and both energy band gap E_{g} and Pauling's electronegativity difference \Delta x have been studied. The following relations are proposed for estimating the refractive index n: n^2 + C = A / E_{g} ^{1 / 2} and n^2 + C = E / (\Delta x)^{0.425}, where A, C and E are numerical constants. In addition, an interrelation between the energy band gap E_{g} and electronegativity difference \Delta x has been also proposed. The proposed relation is E_g = 4.45 (\Delta x)^{0.85}. The estimated values of the refractive index are utilized to evaluate the electronic polarizability of alkali-halides by applying the Lorentz-Lorenz formula. The computed values of refractive index, energy gap and electronic polarizability are compared with those in literature.

Keywords: Refractive index, energy gap, electronegativity, electronic polarizability, alkali-halides.

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