Hydrothermal preparation of PbS crystals and shape evolution

In the current paper, we successfully prepared lead sulfide (PbS) microcrystals with various shapes in a simple aqueous system using the hydrothermal synthesis route. Experimental results indicated that the change of the molar ratio of Pb2+/S2O32− could significantly influence the morphology of the product while keeping the other experimental conditions constant: with the decrease of the molar ratio of Pb2+/S2O32− from 1:1 to 1:4, the shape of the products varied from tri-prism, cube to magic-square structure. Changing the reaction temperature had big effect on the shape of the product: flower-shaped product was obtained at 80 °C and cube-shaped products were produced at 120 °C. When the reaction time varied, the shapes of the as-obtained PbS crystals also changed. At the same time, SEM observations showed that the counter-anions for Pb2+ could influence the shape of the product: Pb(NO3)2 being used as lead ion sources, most flower-shaped and few cubic PbS crystals were produced; while PbSO4 as lead ion source, the PbS cubes were obtained. An evolution process was described based on experimental facts.