Investigation on lanthanum sensitized CaZrO 3 blue nanophosphors for white LED applications

In present study, CaZrO3 nanophosphors with different lanthanum (0.5, 1.0, 1.5, 2.0 and 2.5.) concentrations were prepared by employing polyvinyl alcohol as chelating agent through sol-gel method. To study the structural and optical properties, the samples were characterized by X-ray diffractometer (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscope (TEM) and Photoluminescence (PL) spectrophotometers. The XRD results revealed that the samples were well crystallized and the average crystallite sizes were calculated. The average crystallite size value was in good agreement with the value obtained from TEM analysis. The EDS of FESEM was confirmed the existence of La in the prepared samples. From the photoluminescence spectrum, La sensitized samples exhibit three bands 402 nm, 438 nm and 463 nm in visible range when excited with 260 nm. As the La proportion increases, the intensity of bands 438 nm and 463 nm decreased whereas band at 402 nm remained stable. The TRPL spectra illustrate lifetime of the samples. The corresponding CIE co-ordinates of La sensitized CaZrO3 were calculated.