Simultaneously optimizing fluorescent and paramagnetic properties of bifunctional NaGdF4:Yb3+/Er3+ nanocrystals by crystal field tuning

Abstract Here, we show the simultaneous enhancement of fluorescent and paramagnetic properties in bifunctional NaGdF 4 :Yb 3+ /Er 3+ nanocrystals by crystal field tuning. The energy level splitting calculation indicates, that lanthanide ionic pairs La 3+ /Lu 3+ introduced into the NaGdF 4 host can modify the crystal field around emitters (e.g., Er 3+ and Tm 3+ ) and sensitizers (e.g., Yb 3+ ) that result in the broadening of crystal field splitting of energy levels and the abundant multi-site distribution of upconversion luminescence. The optimization of the paramagnetic properties in NaGdF 4 doped with emitters and sensitizers is ascribed to the lowering of anti-ferromagnetic coupling.