Luminescence of Eu-doped langanite nanopowders synthesized by a citrate sol–gel method

• Published in: Journal of alloys and compounds 2010-10, Vol.507 (2), p.470-474
• Main Authors: Georgescu, S., Voiculescu, A.M., Toma, O., Nastase, S., Matei, C., Osiac, M.
• Format: Article
• Language: English
• Subjects: Annealing; Citrates; Color centers; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Eu 3; Exact sciences and technology; Langanite; Luminescence; Nanocomposites; Nanocrystals and nanoparticles; Nanomaterials; Nanopowder; Nanostructure; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Sol gel process; Sol–gel
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.07.206

▶ For annealing temperatures up to 800 °C, only the langanite phase is observed. ▶ For annealing temperatures above 800 °C, part of the langanite transforms in LaGaO 3. ▶ The red color of the LGN powder intensifies with increasing annealing temperature. ▶ Best efficiency of the emission obtained for the sample treated at 700 °C. ▶ Lifetime of 5 D 0 is in the millisecond range, regardless the annealing temperature. Eu-doped langanite nanopowders were prepared by a citrate sol–gel method and annealed in air at various temperatures between 700 °C and 1000 °C. For annealing temperatures up to 800 °C, only the langanite phase is observed. For higher annealing temperatures, part of the langanite powder transforms in perovskite (LaGaO 3), as evidenced in both XRD and luminescence spectra. Regardless the annealing temperature, the lifetime of 5 D 0 remains close to 1 ms. The reddish color of the powders due to color centers associated to oxygen defects intensifies with increasing annealing temperature. The best efficiency of the Eu-langanite nanopowders was obtained for the sample annealed at 700 °C (∼60% of the efficiency of the bulk material).