Calcium zinc oxysulfide: Newfound polytypes for potential optoelectronic applications

CaZnOS has attracted significant scientific interest, particularly for its layered structure, advanced properties, outstanding doping ability, and structure-property relationships. The CaZnOS compound has been synthesized through high-temperature experiments and characterized by X-ray powder diffraction (XRPD). The crystal structure of CaZnOS exhibits non-centrosymmetric hexagonal symmetry with the space group P6₃mc. The spectrum of possible CaZnOS polytypes has been investigated, predicting structural configurations that differ from those previously proposed or observed in CaZnOS, encompassing bulk crystal forms, nanostructures, or junction-based architectures. All computations were conducted from first principles utilizing density functional theory (DFT) and five different functionals (LDA−PZ, GGA−PBE, B3LYP, PBE0, and HSE06). Recently developed algorithms were used for structure prediction, and the predicted CaZnOS polytypes were investigated for their stability, electronic, and vibrational properties. Consequently, numerous potential stable and metastable CaZnOS polytypes have been identified, opening new possibilities for the synthesis of innovative materials with improved properties.