Structural and Compositional Analyses of Spray Pyrolysis α‑Lanthanum Sulphide (α‑La2S3) Thin Films

Abstract

This article describes the frst syringe pump spray pyrolysis synthesis of orthorhombic lanthanum sesquisulfde (α-La2S3) thin flms. Two precursors lanthanum nitrate La(NO3)3.6H2O and thiourea (SC(NH2)2) were used to develop these rare earth chalcogenides in two diferent “[S]:[La]” ratios of 5 and 11. The flms were developed on glass and silicon substrates. The microstructure, chemical composition, and optical properties of the (α-La2S3) flms were thoroughly characterized using X-ray difraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), microanalysis, scanning electron microscopy (SEM), FTIR spectroscopy, and UV–Vis spectrometry. Microstructural analyses showed that both synthesized flms had α-La2S3 structure and were polycrystalline. The morphology, vibration intensities, and grain sizes of the flms are afected by the amount of sulfde present. The XPS results give a qualitative description of La and S as well as an indication of their potential chemical state. Measurements of particle-induced X-ray emission (PIXE) provide information on the stoichiometric ratios of the constituent components in α-La2S3. The optical bandgap was calculated to be 3.39 eV and 3.45 eV, respectively, for ratios 5 and 11 of the disulfde content.