Characterization of tin selenides synthesized by high-energy milling
Tin selenides SnSeX (x=1,2) were synthesized from tin and selenium powder precursors by high-energy milling in the planetary ball mill Pulverisette 6 (Fritsch, Germany). The orthorhombic tin selenide SnSe and the hexagonal tin diselenide SnSe2 phases were formed after 4 min and 5 min of milling, respectively. Specific surface area of both selenides increased with increasing time of mechanochemical synthesis. The particle size distribution analysis demonstrated that the synthesized products contain agglomerated selenide particles consisting of numerous idiomorphic tin selenide crystals, measuring from 2 to more than 100 nm in diameter, which were also documented by TEM. UV-Vis spectrophotometry confirmed that tin selenide particles do not behave as quantum dots.
Semiconducting tin selenide thin films prepared by heating Se–Sn layers
Deposition of Se thin films of 80–350 nm in thickness from a chemical bath at a deposition yield of more than 95% is reported. These films are utilized to prepare SnSe and SnSe2 thin films either by heating a vacuum deposited Sn thin film in close contact with the Se thin film at 200 °C in a nitrogen atmosphere for 1 h or by heating a Se–Sn stack in air at 400 °C for about 5 min. By controlling individual film thicknesses and the conditions of heating, SnSe2 or composite films of SnSe2 and SnSe are formed. An optical band gap of 1–1.27 eV, electrical conductivity of 0.01–0.2 Ω−1 cm−1 and the photoconductivity of these materials fulfil the basic requirements for their integration into photovoltaic structures.
Mechanochemical synthesis of metal sulphide nanoparticles
Abstract The synthesis of ZnS, CdS and Ce 2 S 3 nanoparticles by mechanochemical reaction has been reviewed. During mechanical milling, solid-state displacement reactions between the respective metal chloride and alkali sulphide or alkaline earth sulphide were induced in a steady-state manner, leading to the formation of metal sulphide nanoparticles. A simple washing process to remove the chloride by-product yielded separated particles of ZnS, CdS and Ce 2 S 3 of ~8 nm, ~4 nm and ~20 nm, respectively. The resulting particles and crystallite sizes were dependent on the milling conditions, starting materials and the presence of a diluent. Structural change with decreasing particle size was observed for CdS and Ce 2 S 3 .