@article{PrimusRitschelSigueenzaetal.2014, author = {Primus, Philipp-Alexander and Ritschel, Thomas and Sigueenza, Pilar Y. and Cauqui, Miguel Angel and Hernandez-Garrido, Juan Carlos and Kumke, Michael Uwe}, title = {High-resolution spectroscopy of europium-doped ceria as a tool to correlate structure and catalytic activity}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {118}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {40}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/jp505467r}, pages = {23349 -- 23360}, year = {2014}, abstract = {Site-selective emission spectra of Eu3+-doped CeO2 nanoparticles up to the D-5(0) - F-7(5) transition were recorded under cryogenic conditions to identify the local structure around the Eu3+ dopants in ceria. It is found that pretreatment conditions are crucial for the redistribution of dopants from a broad variety of environments to six well-defined lattice sites. The influence of the dopant and the host structure on the catalytic activity was investigated. A relationship between structure and reactivity is discussed. It is shown that oxygen transport is most efficient in particles with a pronounced amorphous character.}, language = {en} } @misc{MondalBehrensMatthesetal.2014, author = {Mondal, Suvendu Sekhar and Behrens, Karsten and Matthes, Philipp R. and Sch{\"o}nfeld, Fabian and Nitsch, J{\"o}rn and Steffen, Andreas and Primus, Philipp-Alexander and Kumke, Michael Uwe and M{\"u}ller-Buschbaum, Klaus and Holdt, Hans-J{\"u}rgen}, title = {White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-79953}, pages = {4623 -- 4631}, year = {2014}, abstract = {Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a-d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+.}, language = {en} }