Spectral and surface investigations of Mn²⁺ doped SrZnO₂ nanocrystalline phosphors

A yellow light-emitting SrZnO₂:Mn²⁺ nanophosphor was synthesized through a combustion process using metal nitrates as precursors and urea as fuel. The nanocrystals have sizes ranging from 25 to 30 nm. X-ray diffraction, transmission electron microscopy, photoluminescence (PL) and cathodoluminescence spectra were utilized to characterize the present samples. Crystallographically the occupancy of cations in SrZnO₂ has been explained. Under the UV and the electron-beam excitation, the SrZnO₂:Mn²⁺ nanoparticle shows a yellow emission due to the characteristic transition of the Mn²⁺ (⁴T₁ → ⁶A₁). To study oxygen-related defects and the surface chemical composition, the X-ray photoelectron spectroscopy technique was used. Surface chemical study suggests that oxygen vacancies may be generated by surface shrinkage due to the size reduction. For post-combustion annealing at 900 °C, the PL intensity of the nanopowders was increased due to better crystallinity and improved activity of the recombination centers.