@article{WintzheimerOppmannDoldetal.2019, author = {Wintzheimer, Susanne and Oppmann, Maximilian and Dold, Martin and Pannek, Carolin and Bauersfeld, Marie-Luise and Henfling, Michael and Trupp, Sabine and Schug, Benedikt and Mandel, Karl}, title = {Indicator Supraparticles for Smart Gasochromic Sensor Surfaces Reacting Ultrafast and Highly Sensitive}, series = {Particle \& Particle Systems Characterization}, volume = {36}, journal = {Particle \& Particle Systems Characterization}, number = {10}, doi = {10.1002/ppsc.201900254}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213671}, year = {2019}, abstract = {The detection of toxic gases, such as NH\(_{3}\) and CO, in the environment is of high interest in chemical, electronic, and automotive industry as even small amounts can display a health risk for workers. Sensors for the real-time monitoring of these gases should be simple, robust, reversible, highly sensitive, inexpensive and show a fast response. The indicator supraparticles presented herein can fulfill all of these requirements. They consist of silica nanoparticles, which are assembled to supraparticles upon spray-drying. Sensing molecules such as Reichardt's dye and a binuclear rhodium complex are loaded onto the microparticles to target NH\(_{3}\) and CO detection, respectively. The spray-drying technique affords high flexibility in primary nanoparticle size selection and thus, easy adjustment of the porosity and specific surface area of the obtained micrometer-sized supraparticles. This ultimately enables the fine-tuning of the sensor sensitivity and response. For the application of the indicator supraparticles in a gas detection device, they can be immobilized on a coating. Due to their microscale size, they are large enough to poke out of thin coating layers, thus guaranteeing their gas accessibility, while being small enough to be applicable to flexible substrates.}, language = {en} } @article{SzczerbaZukrowskiPrzybylskietal.2016, author = {Szczerba, Wojciech and Zukrowski, Jan and Przybylski, Marek and Sikora, Marcin and Safonova, Olga and Shmeliov, Aleksey and Nicolosi, Valeria and Schneider, Michael and Granath, Tim and Oppmann, Maximilian and Straßer, Marion and Mandel, Karl}, title = {Pushing up the magnetisation values for iron oxide nanoparticles via zinc doping: X-ray studies on the particle's sub-nano structure of different synthesis routes}, series = {Physical Chemistry Chemical Physics}, volume = {18}, journal = {Physical Chemistry Chemical Physics}, number = {36}, doi = {10.1039/c6cp04221j}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187390}, pages = {25221-25229}, year = {2016}, abstract = {The maximum magnetisation (saturation magnetisation) obtainable for iron oxide nanoparticles can be increased by doping the nanocrystals with non-magnetic elements such as zinc. Herein, we closely study how only slightly different synthesis approaches towards such doped nanoparticles strongly influence the resulting sub-nano/atomic structure. We compare two co-precipitation approaches, where we only vary the base (NaOH versus NH\(_3\)), and a thermal decomposition route. These methods are the most commonly applied ones for synthesising doped iron oxide nanoparticles. The measurable magnetisation change upon zinc doping is about the same for all systems. However, the sub-nano structure, which we studied with Mossbauer and X-ray absorption near edge spectroscopy, differs tremendously. We found evidence that a much more complex picture has to be drawn regarding what happens upon Zn doping compared to what textbooks tell us about the mechanism. Our work demonstrates that it is crucial to study the obtained structures very precisely when "playing'' with the atomic order in iron oxide nanocrystals.}, language = {en} }