Optical Properties of Yttria-Stabilized Zirconia Single-Crystals Doped with Terbium Oxide

A series of yttria-stabilized zirconia single-crystals doped with 0.000–0.250 mol% Tb4O7was prepared by the optical floating-zone method. As shown by XRD and Raman spectroscopy, all of the crystals had a cubic-phase structure. These were initially orange–yellow in color, which is indicative of the presence of Tb4+ions, but they then became colorless after being annealed in a H2/Ar atmosphere as a result of the reduction of Tb4+to Tb3+. The absorption spectra of the unannealed samples show both the 4f8→4f75d1transition of Tb3+ions and the Tb4+charge-transfer band. In addition, the transmittance of the crystals was increased by annealing. Under irradiation with 300 nm of light, all of the single-crystal samples showed seven emission peaks in the visible region, corresponding to the decay from the5D3,4excited state of Tb3+to the7FJ(J = 6–0) states. The most intense emission was at 544 nm, which corresponds to the typical strong green emission from the5D4→7F5transition in Tb3+ions.Keywords:yttria-stabilized zirconia;Tb4O7-doped;annealed in H2/Ar atmosphere;optical properties;optical floating-zone method