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Porous platinum is a frequently used catalyst material in electrosynthesis and a robust broadband absorber in thermoelectrics. Pore size distribution and localization determine its properties by a large extent. However, the pore formation mechanism during the growth of the material remains unclear. In this work we elucidate the mechanism underlying electrochemical growth of nanoporous platinum layers and its control by ionic concentration and current density during electrolysis. The electrode kinetics and reduction steps of PtCl4 on platinum electrodes are investigated by cyclic voltammetry and impedance measurements. Cyclic voltammograms show three reduction steps: two steps relate to the platinum cation reduction, and one step relates to the hydrogen reduction. Hydrogen is not involved in the reduction of PtCl4, however it enables the formation of nanopores in the layers. These findings contribute to the understanding of electrochemical growth of nanoporous platinum layers in isopropanol with thickness of 100 nm to 500 nm. Porous platinum is a frequently used electrocatalyst and thermoelectric material, but the growth mechanism of nanopores in platinum layers is still not fully understood. Here, the authors show that hydrogen is not involved in the reduction process of PtCl4, however it enables the formation of nanopores.

In microstructural corrosion studies, knowledge on the initiation of corrosion on an nm-scale is lacking. In situ transmission electron microscope (TEM) studies can elucidate where/how the corrosion starts, provided that the proper corrosive conditions are present during the investigation. In wet corrosion studies with liquid cell nanoreactors (NRs), the liquid along the electron beam direction leads to strong scattering and therefore image blurring. Thus, a quick liquid removal or thickness control of the liquid layer is preferred. This can be done by the use of a Peltier element embedded in an NR. As a prelude to such in situ work, we demonstrate the local wetting of a TEM sample, by creating a temperature decrease of 10 ± 2°C on the membrane of an NR with planar Sb/BiSb thermoelectric materials for the Peltier element. TEM samples were prepared and loaded in an NR using a dual-beam focused ion beam scanning electron microscope. A mixture of water vapor and carrier gas was passed through a chamber, which holds the micro-electromechanical system Peltier device and resulted in quick formation of a water layer/droplets on the sample. The TEM analysis after repeated corrosion of the same sample (ex situ studies) shows the onset and progression of O2 and H2S corrosion of the AA2024-T3 alloy and cold-rolled HCT980X steel lamellae.

The sensitivity of planar multijunction thermal converters was significantly increased by filling the housing with noble gasses, preferably xenon or krypton. The performance was observed for almost two years, and no degradation of the sensitivity was found. Also, the frequency response of the ac–dc transfer difference remains unchanged at high frequencies and even improves below 40 Hz. Using the lowest at present manufacturable heater resistance of 90 $\Omega $ with the noble gas filling, ac–dc transfer at voltages down to almost 70 mV compared to about 100 mV in air becomes possible.

In microstructural corrosion studies, knowledge on the initiation of corrosion on an nm-scale is lacking. In situ transmission electron microscope (TEM) studies can elucidate where/how the corrosion starts, provided that the proper corrosive conditions are present during the investigation. In wet corrosion studies with liquid cell nanoreactors (NRs), the liquid along the electron beam direction leads to strong scattering and therefore image blurring. Thus, a quick liquid removal or thickness control of the liquid layer is preferred. This can be done by the use of a Peltier element embedded in an NR. As a prelude to such in situ work, we demonstrate the local wetting of a TEM sample, by creating a temperature decrease of 10 ± 2°C on the membrane of an NR with planar Sb/BiSb thermoelectric materials for the Peltier element. TEM samples were prepared and loaded in an NR using a dual-beam focused ion beam scanning electron microscope. A mixture of water vapor and carrier gas was passed through a chamber, which holds the micro-electromechanical system Peltier device and resulted in quick formation of a water layer/droplets on the sample. The TEM analysis after repeated corrosion of the same sample (ex situ studies) shows the onset and progression of O2 and H2S corrosion of the AA2024-T3 alloy and cold-rolled HCT980X steel lamellae.

The development of new application fields of microelectromechanical systems (MEMS) devices often implies a high degree of complexity and the integration of several functionalities within these devices. In this paper, thermoelectric planar thin-film microcoolers become more and more important due to their cooling and temperature stabilization ability, respectively, in MEMS devices. This paper reports on the investigation of the design, manufacturing, and characterization of a membrane-integrated thin-film thermoelectric cooling arrangement for active temperature control and precise local cooling of the sensitive region in a thin-film dew-point sensor. The sensor concept is based on the combination of a thermal sensor heater and a planar thin-film Peltier cooler, which are all arranged on a freestanding and thermally insulated membrane. To obtain a high performance concerning the maximum temperature decrease of the active-cooled membrane, a highly efficient thermoelectric materials combination of Sb and Bi0.87Sb0.13 was used for the fabrication of the in-plane Peltier configuration. For the first sensor setup, a temperature decrease of 10.6 K was achieved under atmospheric conditions at 293 K. In combination with an externally assembled two-stage Peltier cooler dew-point, temperature measurements down to 213 K (−60 °C) were performed in a climatic exposure test cabinet. [2014-0132]

An experimental setup is presented to measure and interpret the solid phase crystallization of amorphous silicon thin films on glass at very high temperatures of about 800 °C. Molybdenum-SiO(2)-silicon film stacks were irradiated by a diode laser with a well-shaped top hat profile. From the relevant thermal and optical parameters of the system the temperature evolution can be calculated accurately. A time evolution of the laser power was applied which leads to a temperature constant in time in the center of the sample. Such a process will allow the observation and interpretation of solid phase crystallization in terms of nucleation and growth in further work.