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The double perovskites AA′ MnWO 6 (AA′ = Ba 2 , SrBa, Sr 2 , SrCa and Ca 2 ) have been prepared as pure powders by a conventional solid-state reaction process. Stoichiometric amounts of BaCO 3 , SrCO 3 , CaCO 3 , MnO and WO 3 were mixed, ground and calcined in a nitrogen atmosphere. The materials have been studied by X-ray and neutron powder diffraction (NPD), and magnetization measurements. NPD and magnetization measurements have been carried out at different temperatures in order to correlate their structural and magnetic properties. Susceptibility- Temperature (χ-T) curves were measured between 2K and 200K in field cooled (FC) and zero-field-cooled (ZFC) modes with an applied field (H) up to 3T. Rietveld analysis of NPD data shows that the samples were B-site ordered perovskites with different types of lattice distortions. Magnetisation measurements at low temperatures indicate the antiferromagnetic ordering of magnetic moments. [ABSTRACT FROM AUTHOR]

Describes a second-harmonic Gunn diode oscillator with a rectangular waveguide resonator for the fundamental frequency. Results of testing in a 50 gigahertz frequency range; Frequency decrease when a static magnetic field is applied.

The application of the self-consistent field methods to the calculation of the asymmetrical stripline characteristic impedance has been investigated. A criterion for iteration procedure is proposed and numerical data for large variety of the strip thickness and width are presented. For some particular cases, where is possible comparison with the results of other authors, the data obtained for the impedance are in good agreement. [ABSTRACT FROM AUTHOR]