Tunable luminescence and energy transfer mechanism of Ca2Sb2O7:Dy3+ host sensitized single phase cool white light emitting phosphor.

Tunable white light-emitting Ca (2-x) Sb 2 O 7 :xDy3+ phosphors were synthesized via high temperature solid-state reaction method. The crystal structure, morphology, luminescence characteristics, and energy transfer mechanism of the phosphors were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HR-TEM), UV–Visible spectroscopy, photoluminescence (PL) spectroscopy, and Fluorescence lifetime analysis. The XRD, EDS, and TEM analysis confirmed the phase purity and orthorhombic weberite structure of the samples with an average particle size in the range of 0.2 to 0.3 ​μm. Under ultraviolet (UV) excitation of 330/351 ​nm, the prepared phosphors exhibit characteristic emission bands of Dy3+ ions along with the blue emission band of the host. The broad band peaking at 440 ​nm corresponds to Sb5+ to O2− transition of host and the peaks at 477, 575, and 670 ​nm originates from 4F 9/2 ​→ ​6H 15/2 , 4F 9/2 ​→ ​6H 13/2 and 4 F 9/2 ​→ ​6H 11/2 transitions of Dy3+ ions respectively. There exists efficient energy transfer from Ca 2 Sb 2 O 7 host to Dy3+ ions and the energy transfer efficiency increases with an increase in Dy3+ ion concentration. Using Dexter's theory, the mechanism of energy transfer was found to be dipole-quadrupole interaction and the energy transfer process is explained in detail. The decay lifetime of Dy3+ ions was estimated to be in the microsecond range. The critical distance for concentration quenching is determined to be 13.807 ​Å and the dominant mechanism is dipole-dipole interaction. The calculated Commission International de L'Eclairng (CIE) coordinates and correlated color temperature (CCT) values imply that the emission color can be tuned from blue (0.144, 0.097) to near-white (0.296, 0.292) in the cool CCT region. The results suggest that Dy3+ doped Ca 2 Sb 2 O 7 phosphor is a potential candidate for solid-state lighting and display fields. [Display omitted] • Ca (2-x) Sb 2 O 7 :xDy3+ phosphors with orthorhombic weberite structure were synthesized via solid-state reaction method. • Photoluminescence spectra exhibit characteristic emission bands of Dy3+ ions along with blue emission band of the host. • Efficient energy transfer exists between host and Dy3+ ions via electric dipole-quadrupole interaction. • The emission color of the phosphors can be tuned from blue (0.144, 0.097) to near-white (0.296, 0.292). • The decay lifetime of the Dy3+ ions were found to be in the microsecond range in Ca 2 Sb 2 O 7 host. [ABSTRACT FROM AUTHOR]