The present work is devoted to the search for new electrode materials for lowtemperature thermionic energy converters (TECs). As shown, the carbon nanostructures (СNS) adding to pure powdered titanium in an amount of 3-9% wt. and their subsequent mechanical mixing leads to the formation of composites that acquire new qualities that were not present in any of their original pure constituents. Thus, the significant changes in the mechanical and electrical characteristics of composites are observed. For example, the electrical conductivity is changed up to 2 orders in initial state of composites as well as its maximum values after samples' compaction are increased (1.6-5 times) in comparison with both the pure Ti powder and the pure thermally extended graphite (TEG) in corresponding compression states. Such changes are caused by the presence of contacts between the metal particles and the CNS in the metal-nanocarbon composites and, accordingly, the possibility of the transition of free charges, including hot charges, from the metal to the CNS.

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The specific electrical conductivity (σ) of mechanical mixture consisting of particles LaNi 5 and multi-walled carbon nanotubes was studied under compression. Founded that the conductivity of mechanical mixture with micro particles LaNi 5 (diameter 28 ± 6 mkm) and 51 wt. % CNT is executed to the order of magnitude σ of CNT. Growth mechanism of specific electrical conductivity of mechanical mixture LaNi 5 with CNTs is due the process of ordering and the transfer electrons from the metal to CNTs. At this concentration, the mechanism of electron transfer from the metal particles to the CNT is most optimal.

A study of the electrical conductivity of mechanical mixture of both the carbon nanotubes (CNTs) (with work function of 4.7 eV) and the Cu and Al metal microparticles (with lower work functions of 4.2 and 4.0 eV, respectively) under compression is provided. As shown, the electrical conductivity of the Al and Cu powders is essentially increased with addition of the CNTs (up to 30 wt.%). The electrical conductivity dependence on the density of a powder mixture of Al with CNTs is characterized by a deep minimum observed at the concentration of 9.6 wt.% CNTs. This feature is a result of the electrons' localization in the Al 2 O 3 film formed on a sample surface. A number of factors, in particular, a shift of the Fermi level of the CNTs deep into the valence band, explain the sharp decrease in the electrical conductivity of the Al CNTs composite, unlike the Cu-based composite.

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