Growth, structure, thermal, electrical and optical properties of potassium aluminum sulfate dodecahydrate (potash alum) single crystal

Abstract

Single crystal of potassium aluminum sulfate dodecahydrate (potash alum) was grown by the slow evaporation technique of supersaturated aqueous solution at room temperature. The obtained crystal was characterized by using powder X-ray diffraction, DSC, TGA, electrical conductivity, optical transmittance and optical reflectance measurements. Structural and thermal analyses were performed on potash alum crystal. The electrical conductivity of potash alum as electrolyte sample was 1.894 × 10−6 S/cm. The optical transition and optical band gap energy of potash alum crystal were studied for the first time. Direct and indirect optical band gap energies were 5.75 and 4.50 eV respectively. Extinction coefficient, refractive index, real and imaginary dielectric constants and optical conductivity were calculated for potash alum crystal at a range of photon energies between 1.4 and 6.2 eV. Normal dispersion parameters of potash alum crystal were calculated for the first time.