Synthesis of a δ-SnS Polymorph by Electrodeposition

A new SnS polymorph (δ-SnS) has been obtained by cathodic electrodeposition on SnO 2:F glass electrodes from warm (50−90 °C) acidic solutions with tartaric acid. Characterizations of the as-deposited films by energy dispersive spectroscopy confirm a 1:1 Sn/S chemistry, X-ray diffraction shows that δ-SnS has a primitive orthorhombic symmetry, and UV/vis spectroscopy shows a direct optical band gap of 1.05 eV. The structure was converted to the α-SnS phase (reduced a and c lattice constants, direct optical transition of 1.2 eV) following argon annealing above 270 °C. Scanning electron microscopy images indicate pseudomorphic replacement of plate-like nanoparticles after annealing.