Daniel M. Giaquinta

X-ray powder structure of Sr2CeO4: A new luminescent material discovered by combinatorial chemistry

Abstract A new luminescent inorganic oxide with the composition Sr 2 CeO 4 has been discovered using combinatorial chemical methodologies. A combinatorial library consisting of more than 25 000 chemically distinct compositions was prepared by an automated thin film physical vapor deposition method. The lead compound responsible for the luminescence in the Sr–Ce–O region of the library was prepared in bulk quantity for structural investigation. The three-dimensional structure of the compound was solved ab initio from X-ray powder diffraction data and refined by the Rietveld method. The structure consists of one-dimensional chains of edge-sharing CeO 6 octahedra that are linked together by Sr 2+ ions. A bulk sample prepared with the same elemental composition as above but heated for a shorter time was analyzed for the presence and amount of different phases formed in the initial stages of the reaction. The results show that this sample consists of SrCO 3 , CeO 2 , SrCeO 3 , and Sr 2 CeO 4 . Upon prolonged heating the former three phases convert to the final product, Sr 2 CeO 4 .

Kombinatorische Parallelsynthese und Hochgeschwindigkeitsrasterung von Heterogenkatalysator-Bibliotheken

Weniger als eine Minute war notig, um die katalytische Aktivitat und die Selektivitat eines Elements in einer kombinatorischen Bibliothek aus ternaren Rh-Pd-Pt-Cu-Legierungen zu bestimmen. Damit genugten zwei Stunden fast, um eine Bibliothek aus 136 Elementen zu uberprufen. Die Bibliotheken enthielten die Elemente (ca. 2–4 μg Material jeweils) in zweidimensionaler Anordnung und wurden mit Dunnschichttechniken synthetisiert. Zur Analyse wurden sie unter Einsatz von Rastertechniken, die mit Massenspektrometrie gekoppelt waren (siehe Bild), vermessen.