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The far-infrared spectra of five mixed ferrites in the range 200 t o 640 cm-I are reported. Four bands are observed. The high frequency band (vl) and low frequency band (v2) are assigned to the tetrahedral and octahedral complexes, respectively. A small band (v3) around v2 is observed and its intensity increases with divalent octahedral metal ion concentration. This band is assigned to the octahedral divalent metal-oxygen ion complexes. The lowest band observed for the highest concentration of cobalt is attributed to the lattice vibrations of the system. Die Ferninfrarot-Spektren von funf Mischferriten im Bereich 200 bis 640 cm-l werden mitgeteilt. Vier Banden werden beobachtet. Die hochfrequente Bande (vl) und die niederfrequente Bande (vy) werden den'tetraedrischen bzw. oktaedrischen Komplexen zugeordnet. Eine schwache Bande (v,) bei v, wird beobachtet, deren Intensitat mit der Konzentration divalenter oktaedrischer Metallionen zunimmt. Diese Bande wird den oktaedrischen divalenten Metall-Sauerstoff-Komplexen zugeordnet. Die niedrigste Bande, die fur die hochste Kobaltkonzentration beobachtet wird, wird den Gitterschwingungen des Systems zugeschrieben.

Using dielectric spectroscopy, some organic liquids consisting of mainly alkylhalides and acetic acid esters, have been studied over a wide frequency (106 to 10−3 Hz) and temperatures (down to 77 K). Measurements have also been made in the true liquid state at four microwave frequencies of 33, 22.4, 10, and 5.4 GHz in the temperature range 303–363 K. The high-temperature data reveals a significant contribution from the intramolecular (end- or side-group) rotation. The data corresponding to the supercooled state reveals a secondary (β) process in addition to the primary (α) process. The magnitude of the β process is found to be relatively large in systems which have greater contribution from the intramolecular process to the overall polarization at room temperature. The activation energies together with the side/end-group dependence of the magnitude of the β process suggest that the intramolecular process, though very much hindered during the process of supercooling, may survive to some extent in the glassy state to be realized as the β process. Our study suggests that the origin of the β process in these glasses may not be intermolecular in nature.

The electrical conductivity of some nickel-inc ferrites is studied as a function of temperature. The ferrites with iron in excess show n-type conduction and those with iron in deficiency show p-type conduction. Seebeck coefficient, X-ray analysis, and saturation magnetisation are also carried out to discuss the conductivity of these ferrites.Es wird die elektrische Leitfihigkeit einiger Nickel-Zinkferrite als Funktion der Temperatur gemessen. Ferrite mit EisenfiberschuD zeigen n-Leitfihigkeit, solche mit Eisenmangel p-Leitfiihigkeit. Untersuchungen des Seebeckkoeffizienten, der SLttigungsmagnetisiernng sowie Riintgenanalysis werden durchgefiihrt, um die Leitfiihigkeit dieser Ferrite zu diskutieren.

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