| |
[摘要]：High quality upconverting NaYF(4):Ln (Ln Yb, Er, Tm) crystal layers were successfully fabricated directly onto glass substrates at a relatively low temperature of 350 degrees C by a novel two-step flux coating method. First, mixed pastes of solute (NaF and YF(3)) and dopants (LnF(3)) were coated on glass substrates by simple bar-coating, and then flux pastes (NaNO(3) or NaNO(3)-NaF) were coated onto the dopant-containing solute layer. After the two-step coating, raw material-coated substrates were heated at 350 or 400 degrees C in an electric furnace. To remove the remaining flux, the crystal layers were washed with warm water. Finally, high quality, nanotextured NaYF(4):Ln crystal layers with good adhesion were directly grown onto the glass substrates. These crystal layers consisted of densely packed idiomorphic NaYF(4):Ln crystals. In particular, individual NaYF(4):Ln crystals were typically shaped as hexagonal prisms. The NaYF(4):Ln crystal phases depended strongly on the heating conditions, i.e., temperature and time. The NaNO(3) and NaNO(3)-NaF fluxes were effective for the growth of high-quality idiomorphic NaYF(4):Ln crystals. Additionally, the upconversion fluorescence properties of NaYF(4):Ln crystal layers were controlled by changing dopant types and ratios. The NaYF(4):10% Yb, 1% Er, NaYF(4):50% Yb, 1% Er, NaYF(4):20% Yb, 1% Tm and NaYbF(4):1% Er crystal layers emitted green, orange, blue and red fluorescences, respectively, under 980 nm laser irradiation. |
|
