Composition-driven anionic disorder-order transformations triggered single-Eu²⁺-converted high-color-rendering white-light phosphors

Single-component, single-activator-converted high-color-rendering index (CRI) white-light phosphors have sparked much interest for phosphor-converted white light-emitting diodes. However, manipulating the distribution and locations of single activators to target desired sites in a given host lattice is still a challenge. Herein, we report the remote regulation of the distribution of Eu²⁺ ions by engineering and controlling the structural ordering in Sr₃(Ce_1−xLa_x)(PO₄)₃:0.05Eu²⁺ (SCLP:Eu²⁺) compound, which are designed by using two-color phosphors with different anionic structural ordering, viz., Sr₃Ce(PO₄)₃:Eu²⁺ (yellow) with disordered state of PO₄ tetrahedra, and Sr₃La(PO₄)₃:Eu²⁺ (blue) with ordered state of PO₄ tetrahedra. The successive substitution of Ce by La triggers a pronounced disorder-to-order structural transformation of PO₄ tetrahedra within SCLP:Eu²⁺ compounds and guides remotely the distribution of Eu²⁺ activators, which is demonstrated by a detailed analysis of synchrotron X-ray diffraction refinement, electron paramagnetic resonance spectra, electron spin-echo envelope modulation spectra, Raman spectra, nuclear magnetic resonance spectra and micro-cathodoluminescence spectrum. Benefitting from the controllable structural ordering transformation, as-prepared samples form a unique disorder-order crystal structure, exhibiting controllable microstructure acting on Eu²⁺ ions, tunable-color emissions including a high CRI (Ra = 90) white-light, increased structural rigidity and thermal stability. These interesting findings in the local structure-dependent luminescence properties demonstrate that structural ordering engineering may be an effective approach to regulate the migration of Eu²⁺ activators and improve the thermal stability of phosphors.