Carbides magnetic susceptibility

Catalyst Production. Supported magnetite particles were produced on Grafoll (Union Carbide), a high surface area form of graphite. The nature of Grafoll and the reasons It is convenient to use In MCssbauer spectroscopy experiments eu e described elsewhere (25). Grafoll is also well suited for magnetic susceptibility experiments. 

The Group 4—6 carbides are thermodynamically very stable, exhibiting high heats of formation, great hardness, elevated melting points, and resistance to hydrolysis by weak acids. At the same time, these compounds have values of electrical conductivity, Hall coefficients, magnetic susceptibility, and heat capacity in the range of metals (7). 

Other formally divalent compounds are the hydrides, MH2 (page 186), and the sulfides, MS, e.g., the golden-yellow LaS. These sulfides have the NaCl-type structure and are metallic conductors they are best formulated as M3+(S2 )e. Similarly the carbides, MC2, which give acetylene on hydrolysis, are M3 + (C2 )e. The sulfides of Sm, Eu and Yb are, however, in the M2 + state according to their magnetic susceptibilities. 

In addition to the magnetic susceptibility, the electrical resistivity and the thermoelectric power at low temperatures for the RC,- and R2C-type carbides have been measured (Lallement 1968). The resultant magnetic and electrical data are shown in table 22. 

The results show that the magnetic susceptibility of these carbides agrees well with a Curie-Weiss law of the form X = Xq + (C/T — 0 ) above the temperature T. The only exception is samarium hypocarbide, for which a deviation from this law has been observed. This type of deviation also occurs in SmC2 and has been attributed to Van Vleck paramagnetism. 

Gusev, A. I., Rempel, A. A. (1984). A Study of the Atomic Ordering in the Niobium Carbide Using the Magnetic Susceptibility Method. Physica Status Solidi. A, Applied Research, 84,527—534. doi 10.1002/pssa.2210840223. 

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