The Influence of Partial Isomorphic Substitution on Electronic and Optical Parameters of ABSO4 Group Crystals

P.A. Shchepanskyia,b, V.M. Gaba c, V.Yo. Stadnyk a, M.Ya. Rudysha,b, R.S. Brezvin a and M. Piasecki b aFaculty of Physics, Ivan Franko National University of Lviv, 8 Kyrylo-and-Mefodii Str., UA-79005 Lviv, Ukraine bInstitute of Physics, Jan Dlugosz Academy, Armii Krajowej 13/15, PL-42201, Czestochowa, Poland cNational University "Lviv Politechnic", 5 Mitropolit Andrei Str., UA-79013 Lviv, Ukraine

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First principles calculations of band energy, density of states and dielectric function of K1.75(NH4)0.25SO4 single crystals in Pnma structure is performed in the framework of density functional theory. In order to describe the exchange-correlation interaction the general gradient approximation and local density approximation are used. Character and genesis of main energy bands of the crystal are discussed and comparison with data set for K2SO4 isomorphic crystal performed. The influence of partial isomorphic substitution K→ NH4 found itself mainly in altering the bottom of conduction band and decrease of band gap value. From the dielectric functions dependences, the refractive indices dispersion and absorption coefficient spectra are deduced. Obtained refractive indices satisfactorily agree with experimental data in the visible spectrum region.

DOI: 10.12693/APhysPolA.133.781 PACS numbers: 71.20.-b, 77.84.-s, 77.84.Bw