Structural, morphological and optical characteristics of Gd 2 Si 2 O 7 :Dy 3+ nanophosphors for WLEDs.

Yellowish-white light-emitting Gd 2-x Si 2 O 7 :xDy 3+ (x = 1-5 mol %) nanophosphors were prepared via the solution combustion synthesis (SCS) method. Fluorescence spectrophotometry and X-ray diffraction (XRD) measurements were performed to scrutinize the optical performances and phase recognition of the designated nanophosphors. The outcomes specified that the prepared phosphors are crystallized into a triclinic phase with a P-1 space group. As the concentration of Dy 3+ ions increase, the unit cell volume decreases proportionally due to the replacement of large-sized Gd 3+ by small-sized Dy 3+ ions. Under UV excitation at 349 nm, emission spectra consist of two pronounced emission lines at ~482 nm (blue line), ~578 nm (yellow line), and a relatively weaker emission at ~670 nm (red line) due to 4 F 9/2 → 6 H 15/2 , 4 F 9/2 → 6 H 13/2 , and 4 F 9/2 → 6 H 11/2 intraconfigurational transitions of Dy 3+ ions, respectively. The evidence about the site symmetry around Dy 3+ ions is examined by considering the ratio of yellow-to-blue (Y/B) emission intensity. The observed critical distance (R c ) value is ~20.56 Å (>> 5 Å), which signifies that energy transfer primarily occurs due to multipolar interaction. The obtained coordinates are close to the white region of the CIE chromaticity diagram, which marks a significant milestone in the development of white light-emitting devices (WLEDs).