A New Zero‐Field Paramagnetic Resonance Spectrometer
The construction of a new zero‐field paramagnetic resonance (ZFPMR) spectrometer is discussed. Spectrometer organization and construction details are presented for both resonant cavities and broadband traveling‐wave helices as sample holders. A new circuit diagram for a square wave magnetic field modulator with fast rise time is given. The performance of each kind of spectrometer is discussed with particular emphasis on investigation of paramagnetic rare earth ions with zero‐field splittings in diamagnetic host lattices.
Pressure effects on zero-field resonance. II. Gd3+ in various zircon structure compounds
A systematic investigation of the influence of hydrostatic pressure on the zero-field resonance of trivalent gadolinium has been made in a set of nine isomorphic crystals. The pressure coefficients of the rotational symmetric crystal field parameters (which are reliably determined by our experiment) do not only vary markedly in the absolute value with the compounds but also change sign. 
 
 
 
Die systematische Untersuchung des Einflusses von hydrostatischem Druck auf die Null-feldaufspaltung des dreiwertigen Gadoliniums wurde auf eine Serie von neun Kristallen gleicher Struktur ausgedehnt. Dabei fallt auf, das die Druckkoeffizienten der aus diesem Experiment zuverlassig bestimmbaren rotationssymmetrischen Kristallfeldparameter in den verschiedenen Verbindungen nicht nur dem Betrage nach stark variieren, sondern sogar Vorzeichenwechsel des Druckeffektes auftritt.
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.