Optical Properties of Hexagonal ZnS Single Crystals

Abstract

The optical transmission of hexagonal zinc sulfide crystals has been measured in the spectral range from 0.32 to 15 μ. From the spacing of interference maxima, the dependence of index of refraction on wavelength has been determined. Measurements of the effects of temperature from 20°C to 120°C and of pressure up to 1700 atmos on the width of the forbidden energy band indicate an increase in band gap of 9×${10}^{-6\mathrm{}}$ ev/atmos with pressure and a decrease of 7×${10}^{-4\mathrm{}}$ ${\mathrm{e}\mathrm{v}/\mathit{C}}^0$ with temperature for both ordinary and extraordinary rays. Approximately one-fifth of the shift with temperature is the result of dilatation of the lattice. The origin of the larger portion of the shift is discussed.