Quaternary borides

The electronic stracture of quaternary borides of the type RETBC was presented and discussed recently in a review-type paper. Theoretical calculations, predictions, and syntheses of were also presented for BN analogues of fiillerenes (fiilborenes) and BN nanotubes. ... 

Since the manuscript of this chapter was written quite a number of papers have been published dealing with the physical properties of ternary and quaternary boride systems containing rare earth elements and platinum metals. It was the original intention of this manuscript to only cover the structural properties and the phase equilibria in ternary and higher order boride systems. However, for a detailed discussion of the interesting and unusual, puzzling low temperature behavior of these alloys the reader is referred to the excellent review articles by Maple et al. (1982), Fischer and Maple (1982) and more recently by Maple (1983a, b,c). 

The use of quaternary ammonium salts has a long history in both aqueous and nonaqueous electrochemistry. In fact, quaternary ammonium salts of te-traphenyl borides are important in the theory of individual ion conductivities, since it is presumed that such large ions will not undergo ion pairing, even in... 

Superconductivity in the multiphase quaternary borocarbide system Y-Ni-B-C has been recently reported [141,142], Earlier work on valence fluctuations in ternary borides RENiaB were studied and in the case of YNi4B, a weak but reproducible signal of superconductivity at Tc of 12 K was observed. This is the first report or discovery of a ternary superconducting phase of the elements Y, Ni and B with a high Tc value (Fig. 12.27). 

Before the present work, insufficient data were available in the literature for phase equilibria of systems based on Ti-B. There is a large body of data in literature on the properties of titanium-boride materials, but there is no systematic information regarding the specific role(s) of candidate alloying elements. Thus, the present effort was undertaken to explore the role of alloying additions through the study of phase equilibria and alloy properties, as well as their interrelation, from the binary Ti-B system to the Ti-rich portions of ternaries Ti-Al-B and Ti-B-X, further to quaternaries Ti-10 at.% Al-B-X (where X = Si, Ge, Sn, Zr, V, or Nb) and to some multi-component alloys. 

Taking into account that the volume content, size, distribution and properties of the reinforcing boride phase practically do not change with the alloying studied here, the strengthening of the ternary and quaternary eutectic alloys should be attributed practically in full to solid- solution strengthening of the titanium alloy matrix. 

U.S. Bureau of Mines Bull. 672, 674, and 677. Bulletins 672 and 674 cover the elements, binary oxides and binary halides in a very complete fashion. Bulletin 677, summarizes the values from Bulletins 672 and 674, and adds a modest selection of tables for arsenides, antimonides, borides, carbides, carbonates, hydrides, nitrides, phosphides, selenides, silicates, silicides, sulfates, sulfides and tellurides. The coverage of these added compound types, however, is far from complete for example, there are no tables for PbS04, SnS04, GaS and Li2S. The only ternary compounds included are the carbonates, sulfates and silicates, and no quaternary compounds are listed except for a limited number of hydrated compounds. Only brief references are given to the data sources, without attempt to explain the choice between conflicting values. 

Boron behaves in rare-earth ternary nitrides as a particular element in the sense that it is able to form both BN3 units similar to BO3 units found in borates, and B-B pairs as in borides. Quaternary boro-nitrides analogous to boro-carbides will be discussed in section 3.4.3.4. 

Quaternary boro-nitrides. The well-known magnetic properties of R2T14B ternary borides (T=transition metal) are typified by the neodymium iron compound Nd[2Fei4B, discovered in 1983. Several studies aimed at introducing interstitial nitrogen in the composition of such permanent-magnet materials in order to improve their characteristics, in particular the Curie temperature. 

---