Nuclear magnetic resonance on oriented rare-earth nuclei in rare-earth hosts: Application to 160Tb.
We summarize the application of nuclear magnetic resonance of oriented nuclei to rare-earth impurities implanted in ferromagnetic crystals of heavy rare-earth hosts. The experimental aspects are treated in some detail; we present results obtained on $^{160}\mathrm{Tb}$$\mathrm{Tb}$, and give a formal description of the experiments. A discussion of extension to other, similar systems with applications in nuclear, solid-state, and low-temperature physics is given.
Measurements of spin, magnetic moment, and electric quadrupole moment of 41.5 h 188Ir.
The techniques of nuclear orientation and nuclear magnetic resonance on oriented nuclei were applied to /sup 188/Ir after recoil implantation into Fe and Ni. Combining the results of nuclear orientation and nuclear magnetic resonance on oriented nuclei, which are sensitive to the magnetic moment and the g factor, respectively, the spin of /sup 188/Ir was determined to be I = 1, in contradiction to I = 2 adopted previously. In addition, the splitting of the nuclear magnetic resonance on oriented nuclei resonance into two subresonances due to quadrupole interaction was observed, which proves again I = 1.
Stability of planar PEMFC in Printed Circuit Board technology
Abstract The use of planar PEMFCs in printed circuit board (PCB) technology with a thickness of less than 3.5 mm are presented. This planar design consists of an open cathode side which allows a completely passive, self-breathing operation of the fuel cell. Power densities of 100 mW/cm 2 at 500 mV with hydrogen as a fuel were achieved. A steady operation with this type of fuel cell was demonstrated over a week without any cell flooding. Since the electrical conducting elements of PCBs usually are made of copper, corrosion in the wet environment of a PEMFC is expected. Thus, a significant degradation in performance of fuel cells made of plain copper PCBs was seen in long-term operation. In order to avoid corrosion, the copper layer has to be coated. Fuel cells in PCB design with diverse coatings were tested in long-term operations up to 1000 h under load. Moreover, corrosion currents have been determined by the use of potentiodynamic scans. Promising coatings are electroplated Cr and Ni and a combination of Ni/Au.