resumo
Synthesis of chlorine-free, rare earth oxide aerogels from the lanthanide series was achieved using a modified epoxide-assisted sol-gel method. An ethanolic solution of the hydrated metal nitrate, propylene oxide, and ammonium carbonate was found to gel upon heating to 333K. Critical point drying of the wet gel in CO2 yielded monolithic aerogels. Most of the aerogels were amorphous as-prepared, but became nano-crystalline after calcination at 923K in air. The aerogels had high surface areas (up to 150m(2)/g), low densities (40-225mg/cm(3)), and were photoluminescent. [GRAPHICS] HighlightsRare earth oxide aerogels were prepared by epoxide-assisted sol-gel route.Rare earth oxide aerogels are monolithic, chlorine-free, and possess large surface areas.Calcination at 923K results in nano-crystalline aerogels, with particles less than 25nm in diameter.Characterization of these aerogels includes photoluminescence spectroscopy, Rietveld refinements, and electron microscopy.
palavras-chave
X-RAY-DIFFRACTION; POWDER NEUTRON-DIFFRACTION; CRYSTAL-STRUCTURE; MAGNETIC-SUSCEPTIBILITY; PRASEODYMIUM OXIDE; SINGLE-CRYSTALS; A-FORM; B-TYPE; ELECTRON-DIFFRACTION; LATTICE-PARAMETERS
categoria
Materials Science
autores
Worsley, MA; Ilsemann, J; Gesing, TM; Zielasek, V; Nelson, AJ; Ferreira, RAS; Carlos, LD; Gash, AE; Baumer, M
nossos autores
Luís Carlos
Professor Catedrático
Maria Rute de Amorim e Sá Ferreira André
Professor Catedráticoagradecimentos
We like to thank the German Science Foundation (DFG) for financial support in the scientific large instrument program under the project number INST144/435-1FUGG. JI and MB gratefully acknowledge funding by the DFG through the graduate school 1860 Micro-, meso-and macroporous nonmetallic Materials: Fundamentals and Applications. This work is partially developed in the scope of the projects CICECO-Aveiro Institute of Materials (UID/CTM/50011/2013) financed by national funds through the Fundacao para a Ciencia e a Tecnologia/Ministerio da Educacao e Ciencia (FCT/MEC) and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. We acknowledge the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (Bremen, Germany) for the provision of access to their TEM facility and Karsten Thiel for assistance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, through LDRD awards 13-LW-099 and 16-ERD-051.