Synthesis, physicochemical characterization and crystallographic twinning of Li2ZnSnS4

Li2ZnSnS4 is a new diamond-like semiconductor, which is of interest as a host structure for the creation of potentially interesting electronic, magnetic and photovoltaic materials. The compound was synthesized via traditional high-temperature solid-state methods and was predicted to adopt a wurtz-stannite structure with all atoms possessing tetrahedral environments. Initial analysis of single-crystal X-ray diffraction data indicated crystallographic disorder that upon closer examination violated basic chemical principles. The structure was subsequently re-evaluated and the apparent “disorder” problem was found to be the result of pseudo-merohedral twinning. The crystal structure was finally solved in the monoclinic space group Pn, which resulted in a chemically reasonable model. The refinement converged with R1=1.68% (for all data). Additional characterization of the sample, including diffuse reflectance, thermal analysis and second harmonic generation measurements, was also performed.