Borides ternary compounds

Figure 2. Formation of ternary borides and phase equilibria within ternary boride systems of the type M-M-B or M-Y-B (M = metal, Y = honmetal). , complete isothermal section established B, part of a diagram only. Numbers in the lower part of each square correspond to the refs, to the ternary section. The number of ternary compounds observed is indicated in the right upper corner of each square.

Low-temperature solvents are not readily available for many refractory compounds and semiconductors of interest. Molten salt electrolysis is utilized in many instances, as for the synthesis and deposition of elemental materials such as Al, Si, and also a wide variety of binary and ternary compounds such as borides, carbides, silicides, phosphides, arsenides, and sulfides, and the semiconductors SiC, GaAs, and GaP and InP [16], A few available reports regarding the metal chalcogenides examined in this chapter will be addressed in the respective sections. Let us note here that halide fluxes provide a good reaction medium for the crystal growth of refractory compounds. A wide spectrum of alkali and alkaline earth halides provides... 

Binary and Ternary Compounds with Elements of Groups II, III, and V. 2f-ray electron spectroscopy has been used to probe the electronic structures of tungsten borides, nitrides and also some carbides and oxides. Enthalpies of formation AH°298.i5 the tungsten borides WB and W2B have been determined by fluorine calorimetry and are — 66.5 and — 68.2 kJ mol respectively. The theoretical possibilities of preparing M02B, a-MoB, MO2B5, WjB, a-WB, and W2B5 by chemical vapour deposition is discussed and MoXj (X = B or Be) have been prepared and examined by X-ray methods. ... 

Mo2lrB2 type structure and the stabilizing influence of small amounts of oxygen is discussed. The ternary compounds YMoB, YWB, and CeMoB3 have been isolated and the complex borides UMB (M = Mo or W) prepared which are isotypic with ThMoB. ... 

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. 

It is very often difficult to establish the existence and composition of borides owing to one or more of the following reasons. The great reactivity of boron toward, for instance, the crucible material leads to the occurrence of impurities in the products. The impurities are often said to stabilize a structure type, while in reality a ternary compound has been formed although unintentionally. It is also difficult to analyze chemically or by microprobe the boron content owing to low accuracy of the methods. Indeed, in many cases a single-crystal-structure determination is, together with complementary structural information obtained by other... 

The isothermal section of Sc-Ni-B at 800°C has been established by Stepanchikova and Kuz ma (1981). The occurrence of an earlier known ternary compound, Sc3Ni2oB6 has been confirmed and four new ternary borides have been added (table 14). Zavalii et al. (1988) used a single crystal investigation for the refinement of the composition of the ScNi4B4 compound reported by Stepanchikova and Kuz ma. According to the results of... 

While most of the binary carbides and nitrides considered above form unlimited homogeneous solid solutions, some other 5 and p elements (B, Be, Al, Mg, etc.) have only a low solubility in these phases. As their content in carbides and nitrides increases, ternary compounds with very specific crystal structures are formed which were reviewed by Alyamovsky et al (1981) and Goldschmidt (1967). It is well known (see Samsonov, Serebryakov and Neronov (1975)) that B or transition metal borides do not form unlimited solid solutions, when interacting with MX phases (X = C, N) and single-phase TiNjBj, compounds exist over a narrow composition range for example, when z + y = 0.62-0.94, y < 0.03 (see Alyamovsky, Zainulin and Shveikin (1976)). As the B/N ratio increases. 

Fig. 1. Existence of ternary borides and phase equilibria in ternary boride systems of the type R-M-B. (R = rare earth element, M = element as indicated, B = boron). complete isothermal section has been established, Q1 partial isothermal section established. The numbers in the squares correspond to the number of ternary compounds observed for each particular elemental combination.

Johnston, D.C. and H.F. Braun, 1982, Systematics of superconductivity in ternary compounds, in Superconductivity in Ternary Compounds, Vol. 2, eds. 0. Fischer and M.B. Maple (Springer, Berlin). Maple, M.B., 1981, Superconductivity and magnetism of rare earth rhodium boride compounds, in Ternary Superconductors, Proc. Intern. Conf. on Ternary Superconductors, Lake Geneva, WI, USA (1980), eds. G.K. Shenoy, B.D. Dunlap and F.Y. Fradin (North-Holland, Amsterdam) pp. 131-139. Shelton, R.N. and D.C. Johnston, 1978, Pressure dependencies of the superconducting and magnetic critical temperatures of ternary rhodium borides, in High Pressure and Low Temperature Physics, eds. C.W. Chu and J.A. Wollam (Plenum, New York) pp. 409-417. 

Gschneidner and Verkade (1974). For nickel borides see Y-Ni-B. From lattice parameter changes the mutual solubilities of binary compounds were found to be insignificant. Six ternary compounds were observed from both the as-cast and heat treated alloys (table 3). 

Phase equilibria in the Ce-V-B system at 800°C (fig. 17) were established by X-ray analysis of 40 arc melted and subsequently heat treated (in evacuated silica tubes, 800°C, 800 h) alloys (Mikhalenko and Bilensh, 1979). Starting materials were of 99.9 min. purity. Solid solubilities of binary compounds were negligible and no ternary compounds were found to exist. The vanadium borides observed V2B3 (UjSij-type), VB (CrB-type), VjB (VsB -type), V3B4 (TajB4-type), VjB, (VjBj-type) and VB2 with AlBj-type are in good accordance with a recent critical assessment of the V-B binary by Spear et al. (1981). 

Mutual solid solubility of Y and Cr borides was found to be small. Ternary phase equilibria are characterized by one ternary compound YCrB4. The crystal structure... 

Maple, M.B., H.C. Hamaker and L.D. Woolf, 1982, Superconductivity, magnetism and their mutual interaction in ternary rare earth rhodium borides and some ternary rare earth transition metal stannides, in Superconductivity in Ternary Compounds n. Topics in Current Physics, Vol. 34 (Springer, Berlin) pp. 99-141. 

All the unary and binary phases are presented in Table 2. No stable ternary compound was foimd in the system. During crystallization of amorphous alloy Fe7oCrioB2o, a tetragonal 74 Fe2Cr4Bg ternary boride was identified, which transformed to anoflier Wmcm FeeCr2B4 at further heating [2005San]. 

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