Tailoring defects to boost Eu3 + emission in MgGeO3 phosphors

Owing to the centrosymmetric 4fn configuration of rare-earth ions, their electric-dipole 4f–4f transitions are parity-forbidden, resulting in low oscillator strengths and poor excitation efficiency. To overcome this limitation, in this work, we propose a synergistic defect-engineering strategy by introducing magnesium vacancies (VMg″) into MgGeO3:Eu3+ and systematically investigate their regulatory role in enhancing luminescence performance and the underlying microscopic mechanisms. Mg vacancies induce significant local lattice distortions around Eu3+ sites, breaking inversion symmetry and lifting the parity-forbidden nature of the electric-dipole 5D0→7F2 transition, thereby intrinsically enhancing the radiative transition probability and resulting in approximately threefold increases in both emission intensity and fluorescence lifetime. This work not only elucidates a general mechanism for synergistically tuning luminescence properties via cation-vacancy engineering but also substantially fills the research gap in Eu3+-doped Ge-based oxide systems, providing new insights for the rational design of high-efficiency and high-stability rare-earth luminescent materials.