Dysprosium site occupancy in SrZnO2 nanophosphors probed through XANES

Abstract

Doping-assisted lattice site engineering is widely practiced to obtain a tailor made response, which subsequently poses a need for an efficient probe of the local electronic structure of the system. This study presents a detailed analysis of the local electronic structure around the host cations (Zn²⁺ and Sr²⁺) and dopant (Dy³⁺) through combined experimental and simulated X-ray absorption near edge structure. The real space full multiple scattering-based simulations of the Zn K-edge are done by substituting Dy at cationic sites in the second coordination shell around Zn, in various combinations along with and/or without oxygen vacancies in the system. The results revealed that Dy tends to substitute the less symmetric Sr²⁺ site at low doping concentration, whereas it starts substituting the relatively more symmetric Zn²⁺ lattice site with an increase in doping concentration, consequently affirming the origin of cold white emission upon charge transfer in the system (Manju, M. Jain, P. Vashishtha, G. Gupta, A. Sharma, S. O. Won, A. Vij and A. Thakur, J. Phys.: Condens. Matter, 2020, 33, 035703). The effect of Zn site occupancy is seen as bifurcation of the single peaked Dy L₃ absorption edge, which is usually reported as the sole indication of the existence of a mixed valence state. Thus, the combined analyses decipher the effect of lattice site occupancy on the local electronic structure of host as well as dopant atoms.