A nonlinear current-voltage characteristic gives rise to a DC voltage proportional to the deviation from Ohm's law when microwave radiation of frequency omega and its second harmonic 2 omega are applied to a sample. The principles of this method and the microwave apparatus are described in detail and the advantages of this method are discussed. As an example, some results on NbSe3 in the temperature range between 4.2 and 300K are presented.

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We report shortly the observation of visible cathodoluminescence (CL) from micropowders of Eu-doped cubic boron nitride synthesized under high-pressure/high-temperature conditions and also annealed in a vacuum in the temperature range from 400 to 1100 °C. The multiplet of lines due to the intra-4f transitions on the Eu 3+ ion is detected in spectral region from 580 to 740 nm. The fact that the main line of the multiplet has the highest intensity, and the removed degeneracy of the 7 F 1 and 7 F 2 electronic levels represented by the second and third bands of the multiplet allow the conclusion that the red luminescence is due to the Eu 2 O 3 inclusions in the monoclinic form (probably, as nano particles) incorporated into the cBN grains.

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