Structural Engineering of Impregnated Matrix-Type Cathodes

Abstract

Targeted research efforts focusing on the properties and structure of impregnated cathodes (IC) have been monitored. The data are summarized in terms of scale structural hierarchy in inorganic materials to develop principles for controlling their formation in the design of high-emissive and life ICs. The performance of impregnated ICs of different types is modeled using the materials science triad ‘chemical composition ↔ structure ↔ properties’ and the concept of structural hierarchical levels in ICs. Basic structural levels of ICs are determined: electronic, nanostructured, mesoscopic, microscopic, and macroscopic. Their structural elements are analyzed: electrons, emitter layer, film coating, skeleton, and emissive substance, and cathodic construction. It is found out that the electronic level is the key one in view of the hierarchy of IC structural levels; its effectiveness depends on the nanocrystalline, mesoscopic, and microscopic levels. Principles of structural engineering are developed for the design of high-emission and long-lived ICs and for control of their formation at nanostructured and microscopic levels by variation in their chemical composition and structure.