Trivalent zirconium and hafnium ions in yttria-based transparent ceramics
Electron paramagnetic resonance spectra of transparent yttria-based ceramics with zirconium and hafnium additives contain signals with close parameters due to paramagnetic Zr3+ and Hf3+ ions, which have similar ground-state electron configurations of [Kr]4d1 and [Xe]5d1, respectively.
Optical Transparency and Local Electronic Structure of Yb-Doped Y2O3 Ceramics with Tetravalent Additives
The results of optical transmission and X-ray core-level spectra measurements of Yb:Y2O3 ceramics with different tetravalent sintering additives (ZrO2, CeO2 and HfO2) fabricated from nanopowders (produced by the laser ablation method) and then annealed at 1400 ℃ in air for 2 h are presented. It is found that the transmission values for ZrO2- and HfO2-doped ceramics at the lasing wavelengths are higher than those of CeO2-doped samples. The X-ray photoelectron spectra (XPS) O 1s spectra show that the relative intensity of oxygen defect peak detected for 3Yb:Y2O3 + 5CeO2 ceramics decreases substantially and consistently compared to that of 5Yb:Y2O3 + 5HfO2 and 3Yb:Y2O3 + 5ZrO2 samples. This can be attributed to a more complete filling of oxygen vacancies due to annealing-induced oxygen diffusion into the highly defective sintered ceramics. The measurements of XPS Ce 3d spectra showed that the insufficiently complete filling of the oxygen vacancies in the 3Yb:Y2O3 + 5CeO2 compound is due to the appreciable presence of trivalent cerium ions.
Continuous-wave and mode-locked laser operations based on Yb 3+ :(YGd 2 )Sc 2 (GaAl 2 )O 12 disordered ceramic
Yb3+:(YGd 2 )Sc 2 (GaAl 2 )O 12 disordered ceramic has been fabricated. 2.9-W average power with an optical-to-optical efficiency of 44% was achieved in a continuous-wave operation. 112-fs pulse duration with 860-mW average power was also achieved in a mode-locked operation.