Electrical conductivity of a sitall

The electrical conductivity of a STsNK sitall, and the nature of the current flow in it, was studied. Such materials are used as high-temperature dielectrics in electrical and radio engineering. The conductivity of tablets of STsNK glass powder was clearly increased by heat treatment (5.5 x 10 exp(-12) and 4.9 x 10 exp(-11) for specimens before and after baking at 450 C, respectively). The temperature dependence of conductivity was analysed over the 200-500 K range; three characteristic regions of temperature dependence were seen: a high-temperature region, a low-temperature one, and a traditional region separating these, where in the function W(t) there is a characteristic inflexion, corresponding to reduction in the activation energy of the conductivity with fall in temperature. The reaction in activation energy factor at low temperatures is evidently associated with a consequent change in the conduction mechanism. The conductivity was shown to increase with increase in frequency of applied electric field (100 Hz to 10 MHz). The dielectric constant and loss tangent are almost independent of frequency. It was concluded that heat-treated STsNK sitall specimens have an ordered structure. 5 refs.