ZnO – Yb$_2$O$_3$ composite optical ceramics: Synthesis, structure and spectral-luminescent properties
Résumé
Zinc oxide optical ceramics containing 0 – 2 wt% ytterbium are prepared by
uniaxial hot pressing of commercial oxides at 1150 and 1180 °C. The ceramics have the
main crystalline phase of hexagonal wurtzite-type ZnO. Ytterbium ions do not enter the
ZnO crystals but form a cubic sesquioxide phase of Yb2O3 located at the ZnO grain
boundaries. Yb acts as an inhibitor for the ZnO grain growth. The ceramics exhibit
transmittance up to 60% in the visible. Their transmission in the infrared is determined
by the free charge carrier absorption. The Yb3+ ions are found in C2 and C3i sites in Yb2O3
crystals. Under X-ray excitation, the ceramics exhibit intense luminescence bands in the
blue (near-band-edge emission) and green (defect emission) whose positions, intensities
and decay times depend on the Yb content. Yb2O3 causes a redistribution of luminescence
intensity in favor of the near-band-edge emission and fastens the emission decay.
Domaines
Optique [physics.optics]
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