Synthesis, characterization and photoluminescence properties of CaSiO3 : Dy3+ nanophosphors

Abstract

CaSiO3 : Dy3+ (1–5 mol. %) nanophosphors were synthesized by a simple low-temperature solution combustion method. Powder X-ray diffraction patterns revealed that the phosphors are crystalline and can be indexed to a monoclinic phase. Scanning electron micrographs exhibited faceted plates and angular crystals of different sizes with a porous nature. Photoluminescence properties of the Dy3+-doped CaSiO3 phosphors were observed and analyzed. Emission peaks at 483, 573 and 610 nm corresponding to Dy3+ were assigned as 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 transitions, respectively, and dominated by the Dy3+ 4F9/2 → 6H13/2 hyperfine transition. Experimental results revealed that the luminescence intensity was affected by both heat treatment and the concentration of Dy3+ (1–5 mol. %) in the CaSiO3 host. Optimal luminescence conditions were achieved when the concentration of Dy3+ was 2 mol. %. UV–visible absorption features an intense band at 240 nm, which corresponds to an O–Si ligand-to-metal charge transfer band in the group. The optical energy band gap for the undoped sample was found to be 5.45 eV, whereas in Dy3+-doped phosphors it varies in the range 5.49–5.65 eV. The optical energy gap widens with increase of Dy3+ ion dopant.