Preparation and Upconversion Luminescence of Three-Dimensionally Ordered Macroporous ZrO2: Er3+, Yb3+.

The three-dimensionally ordered macroporous (3DOM) ZrO2: Er3+, Yb3+ materials were successfully synthesized by the sol–gel method combined with a polystyrene latex sphere templating technique, and their morphologies, surface physicochemical properties, and upconversion photoluminescence (UC-PL) properties were studied. The results indicate that the materials exhibited both porosity and strong UC-PL under the excitation of a 978 nm diode laser. In comparison with the nonporous samples, the relative intensity of the red (4F9/2-4I15/2) to the green (4S3/2/2H11/2-4I15/2) emission decreased visibly because of the decreased nonradiative relaxation in the 3DOM materials. It was also observed that the relative intensity of the green emission to the red emission increased significantly with the increasing excitation power. An indirect three-photon populating process occurred for the green emission as the excitation power and Yb3+ concentration was high enough. [ABSTRACT FROM AUTHOR]