Pb 2+ and Ce 3+ Doped SrZnO 2 : New Blue Luminescent Phosphors
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0916-DD02-08
Pb2+ and Ce3+ Doped SrZnO2: New Blue Luminescent Phosphors Alp Manavbasi, and Jeffrey C LaCombe Materials Engineering, University of Nevada Reno, Reno, NV, 89557 ABSTRACT Two new blue emitting phosphors, SrZnO2:Pb2+ and Ce3+ were synthesized by adipic acid and sucrose templated sol-gel routes, respectively. The resulting phosphor particles were fine, nanocrystalline and pure. The optimum activator concentrations were found to be 1 mol% Pb2+ and 12 mol% Ce3+. Two excitation bands centered at 283 and 317 nm, plus a weak shoulder at 275 nm were observed for Pb2+ doped samples, however only one broad excitation band with a maximum at 294 nm was observed for Ce3+ doped samples fired at 1000 °C for 2h. The emission spectra of SrZnO2:Pb2+ showed a very broad band extending from 374 to 615 nm with a 1 S0 transition on the Pb2+ ions allowed by maximum at ~455 nm which was ascribed to the 3P1 the strong spin-orbit (SO) coupling. Similarly, SrZnO2:Ce3+ showed a broad emission band extending from 374 to 609 nm and centered at 467 nm. This broad emission was attributed to the 5d1 4f1 transition of Ce3+ ions. The lower level 2F5/2 of the 4f1 is populated but the level 2F7/2 is almost empty at room temperature where all measurements were taken. The luminescence properties of Ce3+, K+ co-doped SrZnO2 revealed that the characteristic band locations remained the same and the ratio of emission to excitation intensities were constant. X-ray diffraction patterns showed that the SrZnO2 phase started to form at 900 °C (after 2 hrs), and the singlephase SrZnO2 obtained at 1000 ºC. SEM micrographs of both phosphors have a rounded and filled morphology for individual particles with an approximate diameter of 50-250 nm. Dynamic light scattering studies revealed that average particle size is around 1 m for both phosphors.
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INTRODUCTION Phosphor materials have been under development for more than a century and applications have been progressively developed, mainly for use in display and lighting systems [1]. These luminescent materials are mostly crystalline in nature and are also called optical transducers because of converting a specific energy into electromagnetic radiation in the visible and/or infrared radiation [2]. In the last two decades, great efforts have been dedicated to improve the performance of oxide based luminescent materials because mixed oxide compounds are resistant to high-density electron irradiation, while maintaining their stability and luminescent efficiency [3]. Therefore, they are often selected as the optimal candidate in plasma display panel (PDP) and field emission display (FED) devices. In addition to designing better electronics, developing new materials and improving manufacturing processes are required to improve the overall efficiency of these devices [4]. In recent years, a new host lattice material, SrZnO2, has yielded yellow emission after codoping with Ba2+ and Mn2+ [5] and green emission after doping with Tb3+ [6].Activating SrZnO2 with other rare earth and/or transition metals can
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