FORMATION OF SEMICONDUCTOR STATE IN OXYSULFOSTIBNITES RSbS₂O WITH R = Dy, Ho, Er

The features of the formation of the semiconducting state in oxysulfostibnites of the rare earth metals DySbS₂O, HoSbS₂O and ErSbS₂O are investigated. Theoretical calculations performed using the GGA+U method, taking into account electronic correlations in the 4f-shell of rare earth elements. It is demonstrated that three compounds DySbS₂O, HoSbS₂O and ErSbS₂O are semiconductors with a small direct gap of 0.06, 0.10 and 0.09 eV for DySbS₂O, HoSbS₂O and ErSbS₂O, respectively, at a high- symmety point X. For the first time, it was found that for the formation of a band gap in oxysulfostibnites of rare earth metals, it is important both to optimize the crystal structure and to take into account the spin-orbit interaction. Oxysulfostibnites of rare earth metals, like their layered structural analogues oxysulfides, due to their properties can find wide application in biomedicine, photoluminescence and other fields.