Growth of single crystals of bismuth sulpho iodide in gel

Abstract

Single crystals of bismuth sulpho iodide have been grown in sodium silicate gel at room temperature by diffusing suitable reactants. In the first batch of experiments 3 to 7 g solution of BiCl3 was diffused into the gel containing 10 to 15% KI. Platelets of dimensions upto 5 mm were obtained in a period of 30 days. When thiourea of concentration 5 to 10% was used as the inner reactant and 2 to 4g of BiI3 dissolved in 50% HI was used as the outer reactant, thin needles of BiSI were obtained. Larger thick needles of BiSI were also obtained when thiourea was used as the inner reactant and solutions of Bi2O3 and BiI3 were used as the outer reactants. Similarly in the next batch of experiments H2S was used as the inner reactant instead of thiourea and the same outer reactants were diffused. Platelets of dimensions 5 to 8 mm in size were obtained. The effects due to gel density, concentration of the reactants and the neutral gel on nucleation are also discussed.