Replication of wood into biomorphous nanocrystalline Y2O3:Eu3+ phosphor materials

• Published in: Wood science and technology 2010-11, Vol.44 (4), p.547-560
• Main Authors: Van Opdenbosch, Daniel, Kostova, Mariya H., Gruber, Sabine, Krolikowski, Sebastian, Greil, Peter, Zollfrank, Cordt
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Cathodoluminescence; Cell walls; Ceramics; Chelating agents; Chelation; Citric acid; Composites; Crystallites; Crystals; Electric dipoles; Electron micrographs; Europium; Fluorescence; Glass; Life Sciences; Machines; Magnetic dipoles; Manufacturing; Natural Materials; Nitric acid; Optical properties; Original; Phosphors; Photoluminescence; Photons; Processes; Replication; Roasting; Sol-gel processes; Spectroscopy; Struts; Vacuum; Wood Science & Technology; X ray powder diffraction; Yttrium oxide
• ISSN: 0043-7719; 1432-5225
• DOI: 10.1007/s00226-010-0375-x

Biomorphous Eu 3+ -doped Y 2 O 3 was fabricated by replication of wood templates using vacuum-assisted infiltration of a water-based sol–gel mixture and subsequent calcination at 750°C. The precursor sols were prepared from (Y 0.95 Eu 0.05 ) 2 O 3 dissolved in 10 vol% nitric acid and adding citric acid as the chelating agent. X-ray powder diffraction analyses and Rietveld refinements confirmed that the calcined samples were solely composed of bixbyite Y 2 O 3 :Eu 3+ phase with a mean crystallite size of 16 nm. Scanning electron micrographs and cathodoluminescence imaging showed that the cellular preform anatomy was retained and that the original wood cell walls were completely transformed into phosphor struts with pore sizes ranging from 5 to 20 μm. The optical properties of the biomorphous phosphor materials were analyzed by photoluminescence spectroscopy and assigned to the characteristic Eu 3+ (4f 6  → 4f 6 ) electric dipole or magnetic dipole transitions. From fluorescence lifetime measurements, the mean lifetime was calculated as 1.62 ms.