Change in the permittivity, the dielectric loss and the resistance of tgs caused by the loss of tgs-fragments in ultra-high-vacuum

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Abstract
TGS was observed in a UHV-apparatus over a time period of nearly one hundred days. The individual desorbed TGS-fragments were measured continuously with a Partial-Pressure-Analyzer. In this way it was possible to evaluate the pumped partial pressure components as a function of time, and also to obtain some knowledge of the number of pumped TGS-fragments per unit cell. A great influence was observed on the characteristic dielectric properties of TGS above the Curie-Temperature. The temperature dependence and the maximum value of the permittivity, as well as the dielectric loss and the electrical resistivity were influenced. We can understand the measurements with the assumption of a nonferroelectric surface layer, covering the whole crystal. The thickness of this surface layer is approximately proportional to the number of pumped NH2-radicals.