Revealing Anti‐Thermal Quenching Broadband Cyan‐Green Emission in Oxonitridoaluminosilicate Phosphors Induced by Anion Ordering Substitution

ABSTRACT

For a long time, the potential of regulating anion ordering in the first coordination shell of Eu ²⁺ to tune its luminescence properties has remained largely unexplored. In this work, exploiting the (in)compatibility of N in nitridosilicates and O in oxosilicates, we systematically achieved N/O ordering regulation in BaSi ₆ N ₈ O through coupled [AlO]‐for‐[SiN] substitution. Neutron diffraction and X‐ray diffraction data revealed ordered [AlO] substitution at Si2/N1 sites together with Ba ²⁺ vacancies and partial O substitution at N3 sites in [Al2N ₃ O] for the structure of Ba _{1‐ y} Al _x Si _{6‐ x} N _{8‐ x ‐2 y} O _{1+ x +2 y} (0.72 ≤ x ≤ 1.86, 0.05 ≤ y ≤ 0.09). Combined structural analysis and DFT calculations show that ordered substitution induces lattice stress along the Al‐N bond direction, splitting Ba coordination environments into [BaN ₂ (N/O) ₄ ] and [BaN ₆ (N/O) ₂ ]. The former causes spectral broadening, whereas the latter generates a new blue emission band, together producing single‐phase broadband cyan‐green emission. The substitution negligibly affects the intrinsic structural rigidity of the host lattice. Meanwhile, Ba ²⁺ vacancies introduce deep defect energy levels, ultimately giving rise to anti‐thermal quenching behavior. These findings establish N/O ordering regulation as an effective strategy for designing thermally robust white‐light‐emitting oxynitride phosphors.