Luminescence and photometric characterization of K+ compensated CaMoO4:Dy3+ nanophosphors

Abstract

A series of CaMoO4 phosphors doped with trivalent dysprosium (Dy(3+)) and codoped with potassium (K(+)) ions were prepared by hydrothermal method. The nanostructures of the as-synthesized phosphors were investigated by X-ray diffraction (XRD). The results reveal that the obtained powder phosphors are single-phase scheelite structure with tetragonal symmetry and the crystallite size is in the range of 10-60 nm. The emission spectra show a bright yellow emission at 576 nm and blue emission at 487 nm. As a charge compensator, K(+) ions were incorporated into CaMoO4:Dy(3+) phosphors, which enhance the PL intensities depending on the doping concentration of K(+). The CIE parameters such as colour coordinates, colour correlated temperature and luminous efficacy of radiation were calculated using spectral energy distribution functions and McCamy's empirical formula. Photometric characterization indicates the suitability of K(+) compensated CaMoO4:Dy(3+) phosphor for white LED applications.

Emerging cool white light emission from Dy3+ doped single phase alkaline earth niobate phosphors for indoor lighting applications

“…The possible non-radiative channels explained in Fig. 8 41,45,53 Further, the luminescence intensity ratio of yellow to blue (Y/B) is essential for white-light emission. The calculated (Y/B) ratio for the optimized excitation wavelength of 386 nm was found to be close to unity for all doping concentrations.…”

“…25 These color coordinates are calculated from the PL emission spectra using x(λ), ȳ(λ) and z(λ) color matching functions defined in the CIE 1931. For a specified power spectral density P(λ), the degree of stimulation required to match the color of P(λ) is given by three equations:…”

Enhanced luminous efficiency in Pr3+ activated Ca0.5La(MoO4)2 red phosphor with blue excitation for WLED applications

“…The photometric parameters are calculated by the spectrophotometric method using spectral energy distribution of CIE diagram. Dutta et al [48] reported that the tristimulus values X, Y, and Z can be estimated by the following equations, Table 1, which show an enhancement of x, y values in CIE diagram. All the color coordinates were extremely close to that of NSTC standard red color.…”

Synthesis of CaMoO4 hierarchical structures via a simple slow-release co-precipitation method

“…Traditional synthetic methods, such as microemulsion method [11], solid-state reaction [12], solvent/hydrothermal method [13], and microwave-assisted synthesis [14] etc., are often employed to prepare the luminescent materials. For example, CaMoO 4 thin films were obtained through complex polymerization method and annealed at high temperatures [15], while CaMoO 4 nanorods were also successfully fabricated via microwave irradiation assisted chelating agent method [16].…”

“…However, these methods are inevitable to take some harsh reaction conditions, such as high temperature, special equipment or organic compound, which throw the practical application into a dilemma. Up to now, the co-precipitation method [18] has been widely used to synthesize meso-nano materials because of simple equipment, short time period and handy operation [13].…”