Color‐Tunable Eu3+, Eu2+‐Activated CaSiO3 Nano Phosphor Extract from Agricultural‐Recycling‐Food‐Waste Materials for Display Applications

Abstract

A series of Eu3+ and Eu2+ doped wollastonite is produced with a modified sol–gel technique using agricultural‐food waste materials. Rice husk ash (RHA) and eggshell (ES) are used as an usher for silica and calcium oxide, appropriately, at different concentrations (0.0, 0.2, 0.4, 0.6, 0.8, and 1 mol%). Most investigations have documented photoluminescence (PL) from Eu3+ ions caused by electronic transitions between 4f levels (5D0 → 7FJ) but there is limited information on emissions from Eu2+ ions. Fourier transform infrared (FTIR) spectra and X‐ray diffraction (XRD) studies reveal that varying amounts of europium ions do not have any effect on the structure of the host. PL spectra display that europium ions exist in both trivalent and divalent forms. A valence change from Eu3+ to Eu2+ ion is investigated using luminescence measurements. As‐prepared Eu3+ activated β‐wollastonite emitted as red and reduction atmosphere using argon gas produced Eu2+ activated phosphor gives off blue light. X‐Ray photoelectron spectroscopy reveals that throughout the processing of the samples, Eu3+ cations are partially reduced to Eu2+ cations in argon gas atmosphere. These findings prove the feasibility of fabricating white light‐emitting diodes (white‐LEDs) for three‐band type (RGB) phosphors utilizing only one host crystal.

Keywords

• egg shell
• luminescence
• nanophosphor
• rice husk
• w-LED