Synthesis And Optical Properties Of Gd³⁺?Sc³⁺-doped NaErF₄:Yb/Polystyrene Nanocomposites

Rare earth ion-doped upconverting nanomaterials have attracted increasing attention because of their ability to absorb and convert near-infrared low-energy excitations into visible high-energy emissions.Nanocomposites prepared by polymerization of upconversion nanocrystals with polymer materials have potentially good application prospects in the fields of in vivo imaging,solid-state lasers,three-dimensional display and so on.NaErF₄:Yb upconversion nanocrystals with unique red emissions separately doped with different concentrations of Gd³⁺ and Sc³⁺ ions are prepared via a facile hydrothermal route.The effects of different rare earth ions on the crystal phase,morphology,sizes and upconversion luminescence of NaErF₄:Yb nanocrystals are investigated.While doped with 25 mol% Gd³⁺ and 10 mol% Sc³⁺ ions of NaErF₄:Yb system exhibit the strongest upconversion emission intensity and the largest R/G ratio because of the partly release of inversion symmetry and the crystal field distortion.The fluorescence quenching phenomenon suppresses upconversion luminescence by further increasing the dopant content.Meanwhile,the energy transfer mechanism between Yb³⁺ and Er³⁺ is investigated under the excitation of 980 nm diode laser.NaErF₄:Yb,Gd upconverted nanocrystals are synthesized by hydrothermal method at different temperatures.The effect of Gd³⁺ on the upconversion nanocrystals at different reaction temperatures of 140°C and 190°C is discussed.The crystal phase,morphology,and size of NaErF₄ nanocrystals are rational controlled.And morphology-dependent upconversion luminescence properties are realized.The well crystallized NaErF₄:Yb,Gd nanorods at 190°C have the strongest red light emission,and the upconverting photon excitation and energy transfer mechanism of NaErF₄:Yb,Gd system are investigated simultaneously.NaEF₄:Yb /polystyrene?PS?nanocomposites are prepared by in situ polymerization of styrene with NaErF₄:30%Yb/10%Sc nanoparticles and NaErF₄:30%Yb/25%Gd nanorods in different proportions respectively.Doping upconversion nanocrystals results in a slight increase in the thermal stability.In addition,the luminescence intensity of the composites is increasing with the increase of the amount of nanocrystalline,which makes the nanocomposites have good application value in the field of display devices.