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 ⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_11/2 transitions, respectively, and dominated by the Dy^{3+ 4}F_9/2 → ⁶H_13/2 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.

Keywords:

• phosphor
• X-ray diffraction
• scanning electron microscopy
• FTIR spectra
• optical absorption
• photoluminescence

Acknowledgements

One of the authors (H.N.) thanks UGC for awarding a minor research project and Dr S.C. Sharma, Vice-Chancellor, Tumkur University, for constant support and encouragement. Dr R.P.S. Chakradhar thanks Dr H.S. Maiti, Director, CGCRI, and Dr Ranjan Sen, Head, GTL Lab, CGCRI for their constant support and encouragement.