Shape controllable synthesis and enhanced upconversion photoluminescence of β-NaGdF4:Yb3+, Er3+ nanocrystals by introducing Mg2+ |
(color online) (a) XRD patterns of β-NaGdF4:20-mol% Yb3+, 2-mol% Er3+, x mol% Mg2+ (x = 0, 40, 50, 60, and 70) nanoparticles and (b) amplified XRD patterns of the main diffraction peaks. |