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The superconductor YB6 has the second highest critical temperature Tc among the boride family MBn. We report measurements of the specific heat, resistivity, magnetic susceptibility, and thermal expansion from 2to300K, using a single crystal with Tc=7.2K. The superconducting gap is characteristic of medium-strong coupling. The specific heat, resistivity, and expansivity curves are deconvolved to yield approximations of the phonon density of states F(ω), the spectral electron-phonon scattering function αtr2F(ω), and the phonon density of states weighted by the frequency-dependent Grüneisen parameter γG(ω)F(ω), respectively. Lattice vibrations extend to high frequencies >100meV, but a dominant Einstein-like mode at ∼8meV, associated with the vibrations of yttrium ions in oversized boron cages, appears to provide most of the superconducting coupling and gives rise to an unusual temperature behavior of several observable quantities. A surface critical field Hc3 is also observed.

Resistivity and thermo-EMF are studied for lanthanum and cerium hexaboride alloys containing from 0.5% to 15% W, Ta, Re, or Hf. With increasing transition-metal concentration, resistivity first decreased sharply and then gradually increased. Addition of elements capable of raising the proportion of atoms with stable (d sub 0) and (d sub 5) configurations can markedly improve the thermoemission properties of rare-earth hexaborides., Trans. of Redkozemelnye Metally i ikh Soedineniya (sic) v70 p119-128 1970.

A discussion is given of the connection of the thermoemissive characteristics of transitional metals, their alloys and compounds with non-metals (boron, carbon, silicon and nitrogen) with the electronic structure of both the metal and non-metal. Dependences of the work function of metals, as well as of carbides, borides, nitrides and silicides, on the position of the elements in the periodic system are presented. Cases are considered of alloys of d-transitional metals, transitional metals with non-transitional (having outer s-and p-electrons), transitional metals with non-metals (boron, carbon, silicon, nitrogen). Proceeding from the results of the discussion, the conclusion may be drawn that the work function of the electrons substantially depends on the nature of filling of p - d electron states of metal atoms and on the degree of their stability. The value of the work function is, in addition, determined by the degree of non-filling of the electron states of transitional metals and ionization potential of the metalloid atom. The maximum values of the work function should belong to systems with completely or half filled stable states. The work function of electrons from metalloid refractory compounds is lowered as a result of a lesser degree of coupling of electrons with the cores of metal and metalloid atoms. This property in conjunction with the very high melting points permits creation of effective thermocathodes on their base. (Author), Unedited rough draft trans. of Ukrayinskyi Fizychnyi Zhurnal (USSR), v10 n6 p622-9 1965.

It is shown that the crystalline structure of the melted media of the binary boride (LaNa)B6 obtained by electrolysis corresponds to the type CaB6, the periods of the crystalline lattice increasing with an increase in sodium content. (Author), Unedited rough draft trans. of Zhurnal Prikladnoi Khimii (USSR) v37 n9 p1872-8 1964.