Preparation and characterization of nanocrystalline ZrO2:Yb3+,Er3+ up-conversion phosphors.

Nanocrystalline up-converting phosphors with zirconium oxide (ZrO(2)) as the host lattice were prepared with combustion and sol-gel methods. Impurities were analyzed with Fourier transform infrared (FT-IR) spectroscopy. Yb(3+) absorption was studied in the wave number region 10,000-11,500 cm(-1) at room temperature and at 10 K. The whole-blood absorption was measured in the region 9100-41,600 cm(-1) at room temperature. Up-conversion luminescence was excited at room temperature with an IR-laser at 977 nm. The up-conversion luminescence spectra showed red (650-685 nm) and green emission (520-560 nm) due to the (4)F(9/2) --> (4)I(15/2) and ((2)H(11/2), (4)S(3/2)) --> (4)I(15/2) transitions of Er(3+), respectively. The materials prepared with combustion synthesis were found to yield the most efficient up-conversion intensity and the longest luminescence decay.