Hizhnyi Y. Electronic structure and luminescence mechanisms of compounds with oxyanions and Mn+ cations (n = 1 - 4) in their composition

The dissertation presents systematic theoretical-calculated and experimental studies of the electronic structure and spectroscopic properties of a series of oxide compounds of different cationic composition and structure. The mechanisms of luminescence of a number of oxide crystals of different classes - tungstates, molybdates, phosphates and chromates - have been elucidated. It is established that low-energy bands in the excitation spectra of the intrinsic luminescence of AWO4 tungstate crystals (A = Pb, Cd, Zn) are formed by the mechanism of band-to-band transitions with the participation of tungstate groups. It was found that the excitation of the intrinsic luminescence of crystals of molybdates AMoO4 (Ca, Sr, Zn, Pb) and Li2MoO4 in the energy region of fundamental absorption occurs by band-to-band mechanism, through genetically bound electrons and holes that bind to excitons on the same molybdate groups MoO42-, where the excitation occurred. It is established that the luminescence components of BiPO4, K3Bi5(PO4)6 and K2Bi(PO4)(MoO4) crystals, which have maxima in the blue and violet regions of the spectrum, are formed by 3P1 → 1S0 radiative transitions in Bi3+ ions. It is shown that the adsorption of nanoparticles of the K2CrO4 crystal by carbon nanostructured materials results in an additional band of monomolecular luminescence in the region of 600–700 nm. Such a band is formed by radiative transitions in CrO42- chromate groups, which are part of K2CrO4 nanoparticles adsorbed on the surface of carbon nanostructures. Control of the presence of this band in the spectra can form the basis of the method of luminescent monitoring of the fact of such adsorption.