Bekh I. Physical, chemical and emission properties of the systems, based on the scandium

Experimental researches, oriented on elucidation of the emission mechanism of scandate dispenser cathodes, and, in particular, on elucidation of the scandium role in this mechanism is the main goal of the dissertation. In this study the interaction of the components of activator of the Sc-Ba dispenser cathodes is examined by using the systems that simulate the surface of the cathodes. Physical properties and emission properties of the real Sc-Ba dispensed cathodes are studied. Physical model of working surface of the Sc-Ba dispensed cathodes is constructed, which allows to explain the behaviour of their I-V characteristics and to describe the role of the scandium in their emission mechanism. It is shown that interaction between the components of the cathodes activator in the systems, which simulate the surface of the cathodes, both at the room temperature and at the high temperature, results in formation of three-dimensional islands of these components. The I-V characteristics of the Sc-Ba dispenser cathodes in the space-charge region does not submit to the law of "3/2" and their complex analysis allows to talk about thermo-field mechanism of their emission. The role of the scandium in Sc-Ba dispenser cathodes is determined. It consists in the creation of conditions for increasing the field emission component in anodic current by increasing of the quantity and change of the shape of three-dimensional emitting centres of the activator. Another way of the scandium component influence on the field emission component of anodic current is creation of the condition for increasing the depth of the electric field penetration into the emitting centres on the cathode surface. It is shown that the presence of Sc affects strongly the absolute value of the emission current of the matrix of Si-tip field cathodes. Moreover, this influence can be positive or negative depending on the amount of Sc on the surface. The growth of the emission ability of Si-tip field cathodes in the presence of Sc is explained by the creationof a complex chemical compound on their surface on the basis of the oxides of scandium and silicon, which causes a decrease of the total work function of a specimen.