In-situ transmission electron microscopy at pressures above 1 bar and elevated temperatures

摘要: Recent developments using MEMS techniques to make nanoreactors [1] allow in-situ TEM experiments at very high gas pressures and elevated temperatures. For instance we have succeeded in performing (de)hydrogenation studies of palladium with up 4.5 bar [2]. imaging under these require a confinement the small area. In an environmental transmission electron microscope (ETEM) is completely filling sample holder area, resulting column least 10 mm if one targets resolution information, maximum pressure roughly mbar, depending course also on scattering potential molecules. nanoreactor length can be limited μm thus allowing 1000 times larger than e-TEM similar image resolution. To achieve such short has contain thin membranes that are airtight. Evidently, thinner better for resolution, but they too will not withstand difference Figure 1 shows tip fitted developed. The MEMS-based contains microheater, two electron-transparent windows inlet outlet. various O-rings leak-tight connections nanoreactor.. system was tested Pd temperatures between 20 300°C oxidation reduction 700°C. film consisted islands being 15 nm thick 50 500 wide. (see figure 2) studied diffraction mode showing reproducibly crystal lattice expansion shrinkage owing hydrogenation dehydrogenation, respectively. selected-area bright/dark-field modes individual particles followed. When thermally cycled, thermal hysteresis about 16 °C hydrogen absorption desorption observed 0.5 bar, agreement Siefert bulk samples. Importantly, 0.8 3.2 wide range beam intensities showed temperature affected by beam, this reliable fast method investigate storage materials providing information nanometer scale Oxidation 600°C occur different forms, intensity oxygen pressure. some cases front seen moving through particle. Reduction does room even atmosphere. Evidently instrumentation used other processes, like oxidation-reduction reactions semiconducting particles, corrosion metal surfaces. Also it combination analysis infrared spectroscopy scanning X-ray microscopy. talk examples given possibilities limitations discussed.