Single crystals of Ho2O3-doped Y2O3 stabilized ZrO2 (YSZ) with different Y2O3 and Ho2O3 contents were grown by the optical floating zone method. XRD and Raman spectra were measured and showed that crystal samples all had tetragonal structures. Measurements of positron annihilation lifetime spectra indicated that the increase in Y2O3 concentration led to the increases of defects and mean positron lifetime, which enhanced the scattering of light and reduced the luminous intensity and the quantum yield (QY) of the crystal. Under the excitation at 446 nm, photoluminescence (PL) spectra of Ho2O3-doped YSZ crystals showed emission peaks at 540, 551, 670, and 757 nm corresponding to Ho3+ transitions from 5S2, 5F4, 5F5, and 5I4 excited states to the 5I8 ground state, respectively. At low Ho2O3-doped concentrations (0.10–0.50 mol%), the overall emission intensity increased with Ho2O3 contents, reached the maximum value at 0.50 mol%, then decreased with higher Ho2O3 contents, probably as a result of increased non-radiative relaxation caused by increased interactions between Ho3+ ions. Quenching of the PL occurred at Ho2O3 concentrations > 0.5 mol% and due to the electric dipole–dipole interaction. The calculated chromaticity coordinates (CIE) were approximately (0.307, 0.683) and the color purity achieved 99.6%. The results showed that Ho2O3: YSZ crystals were suitable for green light-emitting devices.

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Transparent single crystals of (ZrO2)92(Y2O3)8-x(Nd2O3)x ( x=0.30, 0.50, 0.75, 1.00, 1.25, 1.50) were prepared by the optical floating zone method, and shown by XRD to have a cubic phase structure....

Large-size and high-quality stable ZrO 2 single crystals containing x mol % Yb 2 O 3 (x = 7, 8, 9, 10) (denoted as xYbSZ), and 8YbSZ crystals doped with 0.5 mol % Er 2 O 3 were grown by the optical floating zone (OFZ) method. Yb 3+ was indicated by XRD and Raman spectroscopy to have successfully entered into the ZrO 2 lattice, which was stabilized in the cubic phase when the concentration of Yb 2 O 3 was ≥8 mol %. Er 3+ successfully entered the 8YbSZ lattice, and its spectral absorption intensity was enhanced compared to Er 3+ in the corresponding yttria-stabilized zirconia (8YSZ), thus demonstrating that the Yb 3+ ion has an excellent sensitizing effect on the up-conversion luminescence of Er 3+ . Fluorescence decay curves show that the up-conversion luminescence excited state lifetime of Er 3+ is significantly enhanced in 8YbSZ compared to 8YSZ. Thus, these results demonstrate that Yb 3+ ions not only successfully stabilize ZrO 2 in the cubic phase structure but also maintain their role as an up-conversion luminescence sensitizer for Er 3+ ions.

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