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

Yttria stabilized zirconia (YSZ) single crystals doped with Tm 2 O 3 , Ho 2 O 3 , and Yb 2 O 3 were prepared by the optical floating zone method in order to investigate the effects of varying the Tm 3+ , Ho 3+ , Yb 3+ 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 Tm 3+ following excitation with a 980 nm (1.33 eV) laser increased with Tm 3+ content reached a maximum in the crystal with 0.30 mol% Tm 2 O 3 , and then decreased with higher Tm 3+ 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 5 F 4 level of Ho 3+ to the 5 S 2 level decreases with increasing Tm 3+ concentration. This research also demonstrates that there was competition between Ho 3+ and Tm 3+ for the transfer of energy from excited Yb 3+ , and that there was also direct transfer of energy from Ho 3+ to Tm 3+ . 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.