Characterization of interactive up-conversion luminescence mechanisms in Tm3+/Ho3+/Yb3+ doped yttria stabilized zirconia single crystals

Abstract Yttria stabilized zirconia (YSZ) single crystals doped with Tm2O3, Ho2O3, and Yb2O3 were prepared by the optical floating zone method in order to investigate the effects of varying the Tm3+, Ho3+, Yb3+ contents on the luminescence properties. All samples were shown by powder X-ray diffractometry (XRD) to be in the cubic phase at room temperature with good crystallinity, and the optical bandwidth of about 4.63 eV indicates their suitability for the development of luminescence products. The blue emission peaks from Tm3+ following excitation with a 980 nm (1.33 eV) laser increased with Tm3+ content reached a maximum in the crystal with 0.30 mol% Tm2O3, and then decreased with higher Tm3+ concentrations as a result of quenching caused by electric dipole interactions. The ratio of the integral intensities of the green emission peaks at 2.42 eV (539 nm) and 2.36 eV (552 nm) indicate that the probability of the non-radiative transition from the 5F4 level of Ho3+ to the 5S2 level decreases with increasing Tm3+ concentration. This research also demonstrates that there was competition between Ho3+ and Tm3+ for the transfer of energy from excited Yb3+, and that there was also direct transfer of energy from Ho3+ to Tm3+. Thus, in YSZ doped with a combination of rare earth ions, the luminescence properties are determined by a combination of energy transfer processes between the different types of rare earth ions, as well as those for the individual ions, and thus presents an opportunity for fine tuning emissions from such crystals to produce a new generation of materials with intense luminescence properties.