For three types of colloidal magnetic nanocrystals, we
demonstrate
that postsynthetic cation exchange enables tuning of the nanocrystal’s
magnetic properties and achieving characteristics not obtainable by
conventional synthetic routes. While the cation exchange procedure,
performed in solution phase approach, was restricted so far to chalcogenide
based semiconductor nanocrystals, here ferrite-based nanocrystals
were subjected to a Fe2+ to Co2+ cation exchange
procedure. This allows tracing of the compositional modifications
by systematic and detailed magnetic characterization. In homogeneous
magnetite nanocrystals and in gold/magnetite core shell nanocrystals
the cation exchange increases the coercivity field, the remanence
magnetization, as well as the superparamagnetic blocking temperature.
For core/shell nanoheterostructures a selective doping of either the
shell or predominantly of the core with Co2+ is demonstrated.
By applying the cation exchange to FeO/CoFe2O4 core/shell nanocrystals the Neél temperature of the core
material is increased and exchange-bias effects are enhanced so that
vertical shifts of the hysteresis loops are obtained which are superior
to those in any other system.
We present the first realization of printed capacitive touch buttons and touch pads integrated into the organic coatings on sheet steel. The properties of coated sheet steel relevant for printing are discussed and compared with substrates, commonly used for printed electronics. Different designs and read-out methods for capacitive buttons on sheet steel have been screen printed and their sensitivity in dependence on design parameters is rated. Index Terms-Organic coating, embedded transducer, embedded sensor, conductive substrate, capacitive button, rough surface, substrates for printed electronics.
This work reports on the hysteresis behavior and an initial baseline drift of printed strain gauges embedded in organic coating layers on sheet steel that we recently introduced. We subsequently investigated the performance over an extended period of time, which revealed interesting and partially unexpected material properties of printed strain gauges made from silver and carbon. Both silver-and carbon-based strain gauges show a hysteresis behavior of the gauge factor and non-negligible nonlinear characteristics. Furthermore, the carbon-based sensors show a strong initial base line drift within the first 50-100 cycles. All three effects, namely hysteresis, nonlinear gauge factor and initial base line drift, are confirmed within their respective standard deviations.
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