Growth and optical absorption of single crystals of nickel sulfate hexahydrate

Abstract

The crystalline alpha-hexahydrate of nickel sulfate was obtained by growing crystals from solution by utilizing Holden's Rotary Crystallizer within the temperature limits of 35 deg C and 50 deg C. The crystals were then cut in two different directions, one in parallel with and the other perpendicular to the optic axis, and polished on abrasive papers and powders to a thickness of 2.53 + 0.01 mm. The dichroism was then studied with Perkin-Elmer Spectrophotometers in ultraviolet, visible, and infrared regions. The ranges of wavelength under study are from 190 to 700 millimicrons in UV-VIS region and from 2.5 to 40 microns in IR region. It is found that in the IR region, the material has nearly total absorption, and in the UV-VIS region the material has total absorption in the wavelength ranges of 190 to 195 millimicrons, 350 to 430 millimicrons, and 590 to 700 millimicrons, while the maximum transmittance occurs at 310 millimicrons and 490 millimicrons. It is also found that there is neither a detectable linear dichroism existing in the alpha-hexahydrate of nickel sulfate crystals within the UV, VIS, and IR wavelength regions, nor a shift in the edge of the absorption bands with regard to changes in the crystallographic direction.