Preparation and optical properties of Ho3+-doped YSZ single crystals

Single crystals of yttria-stabilized zirconia (YSZ) doped with different contents of holmium were prepared by the optical floating zone method, and their structures and phase composition were characterized by XRD and Raman spectroscopy. These showed that the metastable tetragonal phase was stabilized by the substitutions. Transmittance of each of the Ho3+-doped YSZ single crystals was larger than 85% in the visible region. Measurements of fluorescence spectra indicated a strong emission at a wavelength of 553.5 nm, and two weak emission peaks at 671 nm and 759 nm when the crystals were excited by light with a wavelength of 448 nm. The YSZ doped with 0.75 mol% of Ho2O3 had a relatively higher fluorescence intensity and possessed high color purity (99.7%) in the green region, indicating that it can be used to produce efficient green emission.