ABSORPTION SPECTRAL PROPERTIES OF CU2-POTASSIUM SULFATE( IONS IN SODIUM)

This short note reports the results concerning electron paramagnetic r esonance (EPR) and optical absorption spectra of Cu2+ ions doped in so dium potassium sulphate both at 300K and 77K. The Cu2+ ion impurity ha s been well characterized in various hydrated double sulphates [1-9]. Sodium potassium sulphate, NaKSO4 (here onwards referred as SPS) has b een the subject of many investigations for the past several years [10- 14]. However, there is no information in literature on the EPR and opt ical absorption spectra of Cu2+ ions in this crystal. Therefore, the a uthors have undertaken the present work with a view to understand the site symmetry of the ion in the host lattice. The grown crystal of SPS is colourless and transparent. Aphthitalite, a sodium potassium sulph ate mineral, could be prepared easily in the laboratory from an aqueou s solution and also from the fused melts of various sodium and potassi um sulphate proportions [15]. Earlier several authors have done a deta iled investigation on the crystal structure. Bellanca [16] has confirm ed the structure of SPS that was earlier reported by Gossner [17] and who also explained that the NaKSO4 has a hexagonal unit which is alike to those of compounds LiKSO4 and Al2BaO4 with the chosen space group D-3d(3) (<P(3)over bar m1>). Crystals of SPS doped with Cu2+ ions were grown by slow evaporation at room temperature from an aqueous solutio n containing equimolar weights of sodium sulphate and potassium sulpha te to which 0.05 mole % of copper sulphate was added as an impurity. T he grown crystals were clear and blue in colour.