Altering of the Electric and Magnetic Dipole Transition Probability of Eu³⁺ in YPO₄ Lattice by Codoping of K⁺ Ion: Potential Materials for Imaging and Heating

Abstract

Aqueous, dispersible, luminescent YPO4:Eu3+-K+ and hybrid magnetic-luminescent Fe3O4@YPO4:Eu3+-K+ nanoparticles are prepared at an optimum temperature with a simple synthesis route. The shape of YPO4:Eu3+-K+ nanoparticles is found to be nanorods. Photoluminescence spectrum of a sample upon excitation at 395 nm shows the characteristic peaks of Eu3+ such as magnetic–dipole transition (5D0 → 7F1) at 592 nm, the electric–dipole transition (5D0 → 7F2) at 615 nm, and electric–dipole transition (5D0 → 7F4) at 695 nm. Luminescence intensity increases with K+ doping. Interestingly, their luminescence intensities are almost the same. This could be explained by the polarizability effect of the PO4 3– group and K+ upon emission of Eu3+. This high intensity at 695 nm will be useful in bioimaging since this wavelength falls in biological window I. This hybrid material shows a hyperthermia temperature under an AC magnetic field, making this material a potential candidate for cancer therapy.

Eu3+ Site Distribution and Local Distortion of Photoluminescent Ca3WO6:(Eu3+, K+) Double Perovskites as High‐Color‐Purity Red Phosphors

“…Conversely, MDs are not affected by inversion operations, which means the MD transition probability between 4 f N electronic states is typically weak but not always zero. [ 44 , 45 , 46 ] The 5 D 0 ‐ 7 F 1 transition of the Eu 3+ ion represents a purely MD nature and contributes to the orange‐colored PL. According to the Judd‐Ofelt theory, [ 17 , 18 ] rare‐earth ions experience crystal fields due to coordination anions, and the odd components of these crystal fields affect the wavefunctions of 4 f N electronic states.…”