2. Techniques for Structural Investigations (Theory and Experimental)

In order to investigate the structure and electronic behavior of chalcogenide materials, commonly used techniques include XRD (X-ray diffraction), SEM (scanning electron microscopy), and XAFS (X-ray absorption fine structure). XRD can determine the crystal’s structure. It requires the material under investigation to be a crystal or in crystallite form to render a diffraction pattern. For the case of non-crystalline or amorphous materials, the XRD pattern exhibits a broad halo. Modern XRD facility is capable of providing cif (crystal information file) files which include the lattice parameters, atomic position and space group symmetry of the crystal. These cif files can then be treated as input files for the ab initio calculations as mentioned in the following sections. SEM examines the morphology of samples. XAFS spectra, including XANES and EXAFS, probe into the local environment of atomic species and are widely obtained in synchrotron facilities.