Cooperative and charge transfer luminescence in Yb3+ -doped yttrium aluminum perovskite (YAlO3)

YAlO3 (YAP) crystals with different Yb3+ concentration have been grown by Czochralski method and cooperative fluorescence of Yb3+ ions in YAP crystal was studied under 940-nm infrared (IR) LD excitation at room temperature. The Yb concentration dependence of absorption intensity of IR and charge transfer bands exhibit different features. The green emission band in the region of 480-520nm was assigned to the cooperative deexcitation of two Yb3+ ions. The remaining upconverted emission bands containing various sharp peaks associated with impurity ions were observed and discussed. Charge transfer luminescence of heavily doped 20at% Yb:YAP is strongly temperature dependent and no concentration quenching of the charge transfer luminescence was found through the investigation of different Yb levels samples. (c) 2006 Elsevier B.V. All rights reserved.

Hot-pressed translucent aluminum oxynitride (AlON) ceramics

AlON with a composition of Al23O27N5 was prepared by hot pressing at temperatures lower than 1900°C. The microstructures and final properties, including both mechanical properties and optical properties, of the sintered specimens were studied. The results showed that sintering temperature had a great influence on the densification of specimens and could lead to very different properties, especially the optical transmittance and the maximum infrared transmission.