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Keywords:

  • Energy transfer;
  • Luminescence;
  • Phosphors;
  • Yttrium;
  • Sol-gel processes;
  • Oxonitridosilicates

Abstract

Ce3+-, Tb3+-, and Dy3+-activated Y4Si2N2O7 phosphors have been prepared by the Pechini-type sol–gel method followed by ammonolysis of the precursors. The phase purity, morphology, crystallization condition, chemical composition, and thermal stability of the products have been studied carefully by X-ray diffraction (XRD), energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), fourier-transform infrared (FTIR), and thermogravimetry analysis (TGA) techniques. The photoluminescence (PL) and cathodoluminescence (CL) properties of Ce3+-, Tb3+-, and Dy3+-doped Y4Si2N2O7 phosphors were also investigated. The electronic structure of Y4Si2N2O7 has been investigated by density-functional theory methods. The calculations revealed that the nitrogen atom contributes more excited electrons than the O atom. The band gap has been calculated through the reflection spectrum of the Y4Si2N2O7 host. For Ce3+/Tb3+/Dy3+ singly doped Y4Si2N2O7 products, the phosphors give the typical emissions of the activators. The energy transfers from Ce3+ to Tb3+ and Dy3+ ions have been found and demonstrated through the PL spectra and luminescence decay times. The emission color of Y4Si2N2O7:Ce3+, Tb3+ and Y4Si2N2O7:Ce3+, Dy3+ samples can be tuned by energy transfer processes. Additionally, the temperature-dependent PL properties and the degradation property of CL under continuous electron bombardment of the as-synthesized phosphors prove that the Y4Si2N2O7 host has good stability. Therefore, the Y4Si2N2O7:Ce3+, Tb3+, Dy3+ phosphors could serve as a promising candidate for UV W-LEDs and FEDs.