The field-switching properties of NbO2/NbO or NbO2/(reduced NbO2) devices have been investigated. Under an applied electric field they switch from a high (≳10 kΩ) to a low (∼10 Ω) resistance in times shorter than 0.7 ns. For pulse durations of several ns, the current carrying capability is higher than 80 A. The switching mechanism appears to proceed in two stages: the field-assisted Poole-Frenkel mechanism for low applied field and thermal runaway. However, the unique switching properties of NbO2 could also be understood by a small poloron-conduction mechanism.

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The paramagnetic resonance spectrum of solid [Ag dipy2] S2O8 and its solution in nitric acid have been observed at 77°K. The frozen solution exhibits silver hyperfine and nitrogen superhyperfine structure. Due to a strong axial g anisotropy it is possible to determine the principal values of the hyperfine interaction tensors. With these values it is found that the hole in the silver d shell is highly delocalized. Wavefunctions for the unpaired electron are calculated on the basis of the experimental results. Exchange narrowing in the solid wipes out the hyperfine structure.

The paramagnetic resonance spectrum of (Agpy2)2+ in frozen nitric solution has been observed at 77°K. It exhibits silver hyperfine as well as superhyperfine structure, this latter due to interaction with two equivalent nitrogen nuclei. Due to a strong axial g anisotropy the principal values of the hyperfine and superhyperfine interaction tensors may be determined. Wavefunctions are calculated for the unpaired electron as well as its density in the metal ion and the ligands. The experimental values are consistent with the picture of a hole in the Ag d shell in an oblate tetragonal octahedron, which is partially transferred to an sp4 nitrogen hybrid. Coefficients for the wavefunctions are given and the ring C–N–C angle found in reasonable agreement with independently estimated values.

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