Phase transition from hexagonal LnF(3) (Ln = La, Ce, Pr) to cubic Ln(0.8)M(0.2)F(2.8) (M = Ca, Sr, Ba) nanocrystals with enhanced upconversion induced by alkaline-earth doping

Complete phase transition from hexagonal LnF(3) (Ln(3+) = La3+, Ce3+, Pr3+) to monodisperse ultrasmall (similar to 7 nm) cubic Ln(0.8)M(0.2)F(2.8) (M2+ = Ca2+, Sr2+, Ba2+) disordered solid solution nanocubes was successfully achieved through alkaline-earth doping, which induced great intensification of the near-infrared to visible upconversion emissions of the optically active rare earth ions.