ABSTRACT
Manganese doped ZnO/Zn2SiO4 (MZS) composite phosphors were successfully prepared by conventional solid state reaction method. The structural and optical properties of as-prepared samples were analysed by means of XRD, SEM, PLE and PL. The result shows that the samples consist of both ZnO and ZnSiO4 phases which confirms the composite phosphor. The strain acting on the phosphor is found to be in the range of 0.0040-0.0058 for different concentration of Mn(2+) doping. The doping of Mn(2+) significantly influences the optical properties of phosphor. Under 266 nm laser excitation samples show green emission (â¼530 nm) and with 355 nm laser excitation blue emission (â¼441 nm) is shown. The enhancement of luminescence intensity is achieved with Mn(2+) doping up to an optimum concentration (10 at.%) and then decreases. On 266 nm excitation, blue emission intensity decreases with Mn(2+) doping. This composite phosphor shows both blue and green emission under different excitations.
Subject(s)
Luminescent Agents/chemistry , Manganese/chemistry , Silicon Compounds/chemistry , Zinc Oxide/chemistry , Luminescence , Luminescent Agents/chemical synthesis , Silicon Compounds/chemical synthesis , X-Ray Diffraction , Zinc Oxide/chemical synthesisABSTRACT
Eu(3+) co-doped ZnO/Zn2SiO4:Mn(2+) composites were synthesized via conventional solid state reaction route and were characterized by X-ray diffraction (XRD) scanning electron microscopy (SEM) and Fourier transform infra-red (FTIR) techniques. XRD studies reveal the presence of both ZnO and Zn2SiO4 phases. Photoluminescence properties of the samples were studied using 266 Nd-YAG laser excitations. Emission bands observed at ~400 nm are ascribed to ZnO phosphor. The green emission bands at 530 nm is associated with the presence of Mn(2+) ion, while orange (~583) and red (615 nm) bands are supposed to be due to the presence of Eu(3+) doped Zn2SiO4 phosphor. Energy transfer from power dependence of the sample for electric dipole transition (615 nm) was studied under 532 nm excitation by varying the power from 0.1 to 4.5 W. The estimated colour correlated temperature (CCT) values are found to be ~4875 and 4458 K under 266 nm and 532 nm laser (0.5 W) excitations. These values are close to those of tubular fluorescent or cool white/daylight compact fluorescent (CFL) (~5000 K) lamps. The present composite phosphor may have potential application in display devices.
