Structural, morphological, and optical characteristics of Gd<sub>2</sub>Si<sub>2</sub>O<sub>7</sub>:Dy<sup>3+</sup> nanophosphors for WLEDs
Isha Gupta, Devender Singh, Pawan Kumar, Sitender Singh, Shri Bhagwan, Vinod Kumar
Abstract
Abstract Yellowish‐white light‐emitting Gd 2‐x Si 2 O 7 :xDy 3+ (x = 1–5 mol%) nanophosphors were prepared using a solution combustion synthesis method. Fluorescence spectrophotometry and X‐ray diffraction measurements were performed to scrutinize the optical performances and phase recognition of the designated nanophosphors. The outcomes specified that the prepared phosphors were crystallized into a triclinic phase with a P‐1 space group. As the concentration of Dy 3+ ions was increased, the unit‐cell volume decrease proportionally due to the replacement of large‐sized Gd 3+ by small‐sized Dy 3+ ions. Under ultraviolet excitation at 349 nm, emission spectra consisted 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 was examined by considering the ratio of yellow‐to‐blue emission intensity. The observed critical distance (R c ) value was ~20.56 Å (≫5 Å), which signified that energy transfer primarily occurred due to multipolar interaction. The obtained coordinates were close to the white region of the Commission Internationale de l'Éclairage chromaticity diagram, which marked a significant milestone in the development of white light‐emitting diodes.