Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (9)
- Deutsch (2)
- Französisch (1)
Schlagworte
- Corrosion (3)
- Dissipation (2)
- Friction (2)
- Nanoparticle (2)
- 3D Calibration (1)
- 3D Kalibrierung (1)
- AFM (1)
- Anticorrosion (1)
- Antimony clusters (1)
- Corrosion costs (1)
- Corrosion protection (1)
- Coûts de la corrosion (1)
- Diastolic dysfunction (1)
- DySEM (1)
- Electrochemical noise (1)
- FIB patterning (1)
- Hardness Indenter (1)
- Heart failure (1)
- Lipids (1)
- Liver X receptor (1)
- Manipulation (1)
- Metal fluorides (1)
- Modal analysis (1)
- Nanolithography (1)
- Nanomarker (1)
- Nuclear receptor (1)
- Preventive strategies (1)
- Protection (1)
- Rastermikroskopie (1)
- Round-robin (1)
- SPM (1)
- Sol-gel synthesis (1)
- Stratégies deprévention (1)
- Structured cantilever (1)
- Synchrotron radiation (1)
- X-ray photoelectron spectroscopy (1)
Organisationseinheit der BAM
The fluorolytic sol–gel synthesis is applied with the intention to obtain two different types of core–shell nanoparticles, namely, SrF2–CaF2 and CaF2–SrF2. In two separate fluorination steps for core and shell formation, the corresponding metal lactates are reacted with anhydrous HF in ethylene glycol. Scanning transmission electron microscopy (STEM) and dynamic light scattering (DLS) confirm the formation of particles with mean dimensions between 6.4 and 11.5 nm. The overall chemical composition of the particles during the different reaction steps is monitored by quantitative Al Kα excitation X-ray photoelectron spectroscopy (XPS). Here, the formation of stoichiometric metal fluorides (MF2) is confirmed, both for the core and the final core–shell particles. Furthermore, an in-depth analysis by synchrotron radiation XPS (SR-XPS) with tunable excitation energy is performed to confirm the core–Shell character of the nanoparticles. Additionally, Ca2p/Sr3d XPS intensity ratio in-Depth profiles are simulated using the software Simulation of Electron Spectra for Surface Analysis (SESSA). In principle, core–shell like particle morphologies are formed but without a sharp interface between calcium and strontium containing phases.
Surprisingly, the in-depth chemical distribution of the two types of nanoparticles is equal within the error of the experiment. Both comprise a SrF2-rich core domain and CaF2-rich shell domain with an intermixing zone between them. Consequently, the internal morphology of the final nanoparticles seems to be independent from the synthesis chronology.
Sixteen laboratories have performed electrochemical noise (EN) measurements based on two systems. The first uses a series of dummy cells consisting of a 'star' arrangement of resistors in order to validate the EN measurement equipment and determine its baseline noise performance, while the second system, based on a previous round-robin in the literature, examines the corrosion of aluminium in three environments. All participants used the same measurement protocol and the data reporting and analysis were performed with automatic procedures to avoid errors. The measurement instruments used in the various laboratories include commercial general-purpose potentiostats and custom-built EN systems. The measurements on dummy cells have demonstrated that few systems are capable of achieving instrument noise levels comparable to the thermal noise of the resistors, because of its low level. However, it is of greater concern that some of the instruments exhibited significant artefacts in the measured data, mostly because of the absence of anti-aliasing filters in the equipment or because the way it is used. The measurements on the aluminium samples involve a much higher source noise level during pitting corrosion, and most (though not all) instruments were able to make reliable measurements. However, during passivation, the low level of noise could be measured by very few systems. The round-robin testing has clearly shown that improvements are necessary in the choice of EN measurement equipment and settings and in the way to validate EN data measured. The results emphasise the need to validate measurement systems by using dummy cells and the need to check systematically that the noise of the electrochemical cell to be measured is significantly higher than the instrument noise measured with dummy cells of similar impedance.