Energy transfer mechanism from Gd3+ to Sm3+ in K3Gd(PO4)2:Sm3+ phosphor

Abstract

Undoped K3Gd(PO4)2 and trivalent samarium (0.5–2.5 mol%) doped K3Gd(PO4)2 phosphors were synthesized by the solid-state method. The phase formation, optical and luminescence properties were investigated by x-ray diffraction (XRD), diffuse reflectance (DR) spectroscopy, and photoluminescence (PL) spectroscopy. The fluorescence decay spectra of the obtained phosphors were also recorded to study the energy transfer from sensitizer (Gd3+) to activator (Sm3+). Energy transfer effects from sensitizer to activator caused by rare-earth ions were mainly observed in the obtained PL and lifetime spectra. The decay curves of K3Gd(PO4)2 phosphor with different Sm3+ ions concentrations were found to be non-exponential and the data is well fitted with the Inokuti–Hirayama (I–H) model. The energy transfer parameters such as critical distance for the transfer processes were determined. The Commission Internationale de l’Eclairage (CIE) chromatic coordinates and color-correlated temperature were also determined for the prepared phosphor.