Preparation, upconversion luminescence, and solid-state NMR studies of water-soluble hexagonal NaScF4:Yb/Er microcrystals

Water-soluble hexagonal NaScF 4 :Yb/Er upconversion microcrystals (UCMCs) were synthesized using the hydrothermal method . The upconversion photoluminescence properties of NaScF 4 :xYb/2%Er microcrystals (x = 4–20%) were characterized under a 980-nm-wavelength laser excitation. The dependence of red/green (R/G) ratio on the concentration of Yb 3+ ions was investigated. The local environments of dopant ions (Yb 3+ , Er 3+ ) in NaScF 4 were studied using multiple solid-state nuclear magnetic resonance (NMR) techniques. The 19 F single pulse and 19 F{ 23 Na} and 19 F{ 45 Sc} rotational echo double resonance (REDOR) techniques proved that the dopant rare-earth ions (Yb 3+ , Er 3+ ) preferred to substitute Na + rather than Sc 3+ ions. Such solid-state NMR techniques provide a novel approach to study new phosphors.