White-light emitting Ca2MgSi2O7:Dy3+ nanopowders: Structural, spectroscopic investigations and advanced forensic applications

In the present report a sequence of Dy3+ (1-9 mol%) incorporated Ca2MgSi2O7 nanopowders (NPs) are prepared through green combustion technique by means of Aloe vera gel as fuel. Powder X-ray diffraction (PXRD) patterns are studied in order to authorize the phase transparency of the fabricated samples. The PXRD profiles displayed that the fabricated samples have single-phase tetragonal structure with no change in the diffraction profiles with the addition of the Dy 3+ ions. Diffuse reflectance spectroscopy (DRS) studies are carried out to evaluate the energy band gap values of the fabricated powders (3.52-3.68 eV). The morphological features are studied by utilizing the scanning electron microscopy (SEM) images. The images revealed that the fabricated NPs are in dumb-bell shape in nature. A detailed study on the photoluminescence (PL) is carried out. The decrease in the PL intensity is detected after 5 mol % of the dopant ion incorporation, which is associated to the concentration quenching phenomena. Three prominent emission peaks centered at 480 (F-4(9/2 )-> H-6(15/2)), 578 (E-4(9/2) -> H-6(13/2)) and 666 nm (F-4(9/2) -> H-6(11/2)) are detected under 352 nm (H-6(15/2 )-> P-6(7/2)) excitation wavelength. In order to study the photometric characteristics, the color diagrams viz. CIE and CCT are estimated. From the CIE diagram it is noticed that the color coordinates fall in the white region with coordinates approximately (0.33, 0.33). 6328 K is the average CCT value observed in the present case and indicates that the fabricated NPs are useful for the cool white light emitting diode (wLED) applications. Further, the prepared powders are also used to visualize the latent fingerprint (LFP) on aluminium foil surface. It is noticed that the clear ridge features are observed under normal light without any difficulties. These results indicated that the prepared NPs can be effectively employed in the field of wLEDs and forensic applications.