Xiaoting Chen,Lehui Liu,Yisheng Huang,Feifei Yuan,Lizhen Zhang,Zhoubin Lin
In this article, a series of Dy x Ca 3 Gd 2-x (BO 3 ) 4 (x = 0.02–0.2) polycrystalline compounds were synthesized by solid-state reaction to select the optimum concentration for single crystal growth, after then a 6.36 at.% Dy 3+ :Ca 3 Gd 2 (BO 3 ) 4 (Dy:CGB) single crystal with a disordered structure was successfully grown by the Czochralski method . The spectroscopic properties and Judd-Ofelt analyses of the crystal were carried out. Focusing on the absorption cross-section at 453 nm corresponding to the emission bands of InGaN laser diodes, the Dy:CGB crystal has a comparatively large value of 0.95 × 10 -21 cm 2 with a full width at half maximum (FWHM) of 10.2 nm. The yellow light emission cross-section at 576 nm is 2.2 × 10 -21 cm 2 with a FWHM of 14.0 nm. The Judd-Ofelt parameters Ω 2 , Ω 4 and Ω 6 were obtained to be 2.79 × 10 -20 cm 2 , 2.10 × 10 -20 cm 2 and 2.28 × 10 -20 cm 2 , respectively. The fluorescence lifetime of 4 F 9/2 → 6 H 13/2 transition was measured to be 0.26 ms. These results reveal that the Dy:CGB crystal is a promising yellow laser candidate.
Peng Zhang,Wenxia Wu,Limin Wu,Yazhao Wang,Shengdi Ta,Zeyu Cheng,Shoulei Xu,Bernard Albert Goodman,Wen Deng
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. Nd3+ entered into the crystal structure during crystal growth, and the lattice parameters and cell volume increased with increasing Nd2O3 concentration as Nd3+ replaced the smaller Y3+. A series of absorption peaks involving transitions from the Nd3+ ground state (4I9/2) were observed in the UV-vis-NIR absorption spectra. Under excitation with yellow light at 589 nm, up-conversion luminescence spectra showed three distinct emission peaks, corresponding to the 4D5/2 → 4I9/2 (334 nm), 4D3/2 → 4I9/2 (363 nm) and 2P1/2 → 4I9/2 (442 nm) transitions. The maximum intensity of the emission spectra was with 0.75 mol% Nd2O3, and higher concentrations resulted in quenching through electric dipole–quadrupole interactions. From analysis of the absorption and emission spectra using the Judd–Ofelt theory, values for the strength parameters Ωt (t = 2, 4, 6) and radiative transition properties were obtained for the (ZrO2)92(Y2O3)7.25(Nd2O3)0.75 single crystal. These showed Ω4> Ω2> Ω6, with the large Ω2 value indicating a highly covalent interaction and asymmetric local environment for Nd3+. The spectroscopic quality factor (χ) and radiative properties, such as the transition probability, radiation lifetime and branching ratio, indicate that this sample is a potential material for near-UV up-conversion luminescence and laser output.
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