A new single-component KCaY(PO4)2:Dy3+, Eu3+ nanosized phosphor with high color-rendering index and excellent thermal resistance for warm-white NUV-LED

Abstract

In this study, novel KCaY(PO₄)₂:Dy³⁺, Eu³⁺ (KCYP:Dy³⁺, Eu³⁺) nanophosphor has been successfully prepared by a facile solution-combustion route. The crystal structure, morphological and microstructural features, and photoluminescence (PL) properties of KCYP:Dy³⁺, Eu³⁺ nanophosphor, as well as its thermal properties, have been studied. Investigations based on XRD, FTIR and Raman verify the formation of single-phased and well-crystallized KCYP:Dy³⁺, Eu³⁺. SEM and TEM observations reveal that the KCYP:Dy³⁺, Eu³⁺ nanophosphor displays uniform spherical morphology with an average particle size of about 47 nm. The optimal concentrations of Dy³⁺ and Eu³⁺ ions in KCYP were determined to be 3 mol% and 7 mol%, respectively. Under near-ultraviolet (NUV) excitation, individual Dy³⁺- or Eu³⁺-doped samples exhibit characteristic PL emissions in their respective regions. As for the Dy³⁺, Eu³⁺ co-doped KCYP, energy transfer has been confirmed happening from Dy³⁺ to Eu³⁺ via an electric dipole–dipole interaction, and the critical distance (R_c) was calculated to be 17.07 Å. Our experiments reveal that it is easy to produce warm white or tunable emissions by regulating the Eu³⁺ content. Moreover, the single-component KCYP:3%Dy³⁺, 7%Eu³⁺ nanosized phosphor has a very low correlated color temperature (2766 K) and a high color-rendering index (R_a = 81.6). The quenching temperature (T_0.5) of the KCYP:Dy³⁺, Eu³⁺ nanophosphor was found to be higher than 220 °C, indicating its superior thermal resistance. Consequent three rounds of the heating–cooling cycle experiments demonstrate no occurrence of thermal degradation. These findings suggest that this nanophosphor is a promising candidate for application in NUV-pumped glareless warm-white LED.