Synthesis And Luminescent Properties Of Sr₂CeO₄: M Phosphors

The search for phosphors started more than 100 years ago and applications have been developed extensively in the fields of luminescence, display and detection. The green and red emissions are produced by the f-f transitions of Tb³⁺ and Eu³⁺, the relevant phosphors have been commercialized. But comparable commercial materials for the blue emission are still lacking. In 1998, a new rare-earth luminescent material Sr₂CeO₄, possessing one-dimensional chains of edge-sharing CeO₆ octahedron, was synthesized successfully and identified through combinatorial technique by Dinelson et al. Its luminescence is originated from charge-transfer transition (CTT). This phosphor emits blue-white fluorescence by excitation through the X-ray, cathode ray and ultraviolet ray. It is well known that the search for blue phosphors is of particular importance because of the limited number of stable blue luminescent materials available. Therefore, Sr₂CeO₄ has good potential for application as a blue phosphor in lamps and field emission displays, etc.In our present work, the Sr₂CeO₄ phosphors with good photoluminescence were synthesized successfully through combustion method, sol-gel method and sol-gel auto-combustion method. TG-DTA, XRD, SEM and photoluminescence spectra were used to investigate the decomposition process of the precursor, and the formation process of Sr₂CeO₄, microstructure and luminescent properties. The results show that the pure orthombic Sr₂CeO₄ phosphors can be obtained under proper conditions. Excitation spectumn is a wide band in the range of 200～400nm with two peaks. Emission spectrum is a broad band too. It is located in the range of 400～600nm with one peak. It is interesting that the position of the peaks show some differencese when Sr₂CeO₄ phosphors were obtainted by different methods.For Sr₂CeO₄ phosphors synthesized by the combustion process, the two excitation peaks are located at 298nm and 350nm respectively; the former is stronger than the latter. When stearic acid is used as fuel, the main emission peak is at 470nm. Meanwhile it is found that the...