Excitation induced tunable emission from yellow to red in ZnO:Eu3+, Na+ nanophosphors

Wurtzite structured ZnO:Eu³⁺,Na⁺ nanophosphors were synthesized by chemical precipitation method at a temperature of 60 °C. The nanophosphor formation was confirmed by transmission electron microscopy (TEM). Phase and structural parameters were evaluated using x-ray diffraction (XRD) and optical characterization was done by diffuse reflectance spectroscopy (DRS) and photoluminescence (PL). Photoluminescence study reveals the emission from various transition levels of Eu³⁺ as well as from the host material and tunable yellow to red emission was observed on varying the excitation energy. Even though the particle size of ZnO:Na⁺, Eu³⁺ phosphor falls in the nanoregime, no considerable increase in bandgap was observed due to the band tailing effect.