Gallery of pictures from 2010
The picture shows the contact angle analyzer OCA 20 from the company Data Physics with the heating chamber TC 400, which allows measurements under well defined gas atmosphere and a temperature up to 400 °C. The contact angle analyzer is the first instrument aquired within the project “Electrochemistry for detection of mobility” (Kompetenzverbund Süd) funded by the BMBF. Herewith it is possible to measure the adhesion properties of nonstoichiometric compounds as a function of the composition. Picture Submitted by A. Rein
The image shows a cross section of about 2 µm photoresist and 200 nm gold deposited on a silicon substrate. This is an inspection of a photolithography process for micro structured gold electrodes via scanning electron microscopy. The resist areas covered by a mask during light exposure were removed in a solvent. Depending on the process parameters the shown resist undercut profile can be prepared, which provides a non-conform gold coating (i. e. the resist walls stay uncoated). During the wet chemical lift-off process the resist starts to dissolve at these areas.The small inlet shows a top view of the gold electrodes after lift-off. Picure submitted from P. Hartmann
The picture shows the coating of aluminum foil with electrode slurry. The slurry contains active material, conducting agent and binder. The manufactured electrodes are used in “halfcell” tests for lithium batteries where the electrode characteristics are measured. Picture submitted by S. Diegelmann
The picture shows the participants of the WG-seminar of the workgroup of Prof. Janek in front of the location of the seminar in Liensfeld (Schleswig-Holstein, Germany). The owners of the guest and seminar house "Hof am Wege"with their dog can also be seen at the right side of the front row in the picture.
The SEM picture shows a platinum electrode on YSZ. The platinum is grown up (111) orientated on the YSZ(111) single crystal. Because of the uniform dewetting the electrode has a large, easy to determin length of the three phase boundary, which can be changed by the production parameters. Ssmiley-like structures are visible with a little fantasy. Picture submitted by H.Pöpke
The right part of the picture is an optical image of a sample surface. On the left are three stacked SIMS image scans of the same sample area (500 µm X 500 µm). Dark colors (red to black) show areas of less signal intensities and bright colors (yellow to white) show areas of higher signal intensities. The surface structures can be seen in the total ion image (on the bottom of the left column, TI). The same can be seen in the distribution of Strontium (Sr) and Magnesium (Mg). Picture submitted by S. Steinmüller
Electrolytes based on ionic liquids for lithium-ion batteries are in great demand, especially because of their greater safety due to their very low vapour pressure. Before we are able to use ionic liquids as electrolytes however, their conductivity, especially the lithium ion conductivity, must be enhanced. To do this, we first analyse the conductivity of the pure ionic liquid with different concentrations of conducting salt. The results hopefully enable us to modify the system and to create a well performing electrolyte this way. The figure shows Arrhenius plots of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with different concentrations of lithium bis(trifluoromethylsulfonyl)imide as the conducting salt. The variation from linearity is described by the Vogel-Fulcher-Tammann law. With increased LiTFSI concentration the viscosity increases leading to an increased curvature of the data in the Arrhenius plot. Picture submitted by N.Krawczyk
Materials with tailored porosity can be prepared by templating methods. The left image shows a SiO2 (SiO2) material, consisting of fused spherical particles. A carbon replica (C) can be obtained as follows: (1) Infiltration of the SiO2-Material by a carbon precursor (e.g. sucrose solution), (2) Carbonization and (3) template removal by acid treatment. The pore size of the carbon replica corresponds to the particle size of the silica template. This principle can be also used to prepare porous materials on the nanometer scale. Picture submitted by B. Jache and P. Adelhelm
The SEM images show microstructured platinum electrodes on Yttria-stabilized zirconia (YSZ) substrates. Because of the topography of the electrode (and the materials properties) platinum appears in light grey and YSZ in dark grey. Using photolithography it is possible to prepare different structures in the micrometer scale. Firstly, a negative of the desired structure is made out of the photoresist on the YSZ substrate. Secondly, this substrate is coated with platinum by pulsed laser deposition (PLD). In the last step the photoresist is removed. In the case of platinum/YSZ electrodes the structuring is used to obtain a well defined three phase boundary length in order to attain better understanding of the oxygen exchange kinetics via electrochemical measurements. Pictures submitted by J. Neumeier and C. Bachmann
In the context of the conference of electrochemistry "Electrochemistry 2010: From Microscopic Understanding to Global Impact" in Bochum was the poster "In-Situ Electrochemical Deposition of Metals in a High Resolution Scanning Electron Microscope" by Dipl. Chem Rabea Dippel awarded with one of three Metrohm Autolab poster prizes. The Metrohm company awards every two years on the German Conference of Electrochemistry (GDCh, DBG, Dechema etc.) highly endowed poster prizes for the best scientific poster. Ms. Dippel (2nd from the left) investigates as a part of her doctoral thesis, the deposition of lithium on different ionic conductors, which can be measured by using a microprober module in a high-resolution scanning electron microscope (smaller picture on the left). Picture submitted by K. Sann
In situ secondary ion mass spectrometry (SIMS) is used to investigate the diffusion of different ions out of lanthanum strontium manganese oxide (LSM) as a function of the applied potential with high lateral resolution in the 0.1 µm range. LSM is used as a cathode material in solid oxide fuel cells (SOFCs). Manganese, strontium and lanthanum show a voltage-dependent segregation onto or away from the electrolyte (yttria stabilized zirconium oxide (YSZ)). This process is exemplarily shown in the upper picture by the secondary ion images of manganese. Brighter colors indicate higher ion intensities in the examined area. Both the applied potential and the polarization time are shown in the arrows above the images. These in situ measurements are offer valuable mechanistic information on the oxygen reduction and transport during fuel cell operation. The image size is 500 µm times 500 µm. Picture submitted by M. Falk
Cerium dioxide (CeO2) is characterized by mixed ionic and electronic conduction at elevated temperatures, thus ionic and electronic conduction occur in parallel. Ionic charge transport proceeds through double positively charged oxygen vacancies. Electronic charge transport is related to a polaronic jump process of electrons between Ceria ions. The figure shows typical impedance spectra of Ceria single crystals measured in air. The equivalent circuit corresponds to a parallel RC-circuit. R is attributed to the bulk transport and C reflects the geometric capacity of the sample. When temperature rises the semicircles become smaller, and the resistance decreases. Since charge transport is an activated process in ceria, it shows an exponential dependence from temperature. Applications for Ceria based materials are heterogeneous catalysis, sensors and SOFCs. Picture submitted by J.-P. Eufinger
