Thorium electrical resistivity

The phase diagram between Th and ThC was studied by metallographic and X-ray techniques and by measurements of the electrical resistivity in quenched and slowly-cooled Th-C alloys. The a-p transformation temperature of thorium increased gradually with carbon content up to 2.3 at% C, and rapidly thereafter. Extrapolation to zero carbon content gave Ttrs(Th, cr) = (1633 + 10) K. 

The electrical resistivity of thorium rods containing 80-200 ppm of carbort, by weight, (plus 8-50 ppm N and 50-190 ppm O) were measrrred from room temperatrrre to 1973 K, and the a-p transformation temperatures irtferred from discontinrrities in the resulting curves. Extrapolation of the measurements to zero carbon content indicates Tte = (1623 + 10) K for pure thorium. These results, showing that carbon raises the transformation temperature, are consistent with the phase bormdaries estabhshed at much higher carbon contents. 

The exploding wire technique was used to measure some physical properties of Th(cr) and Th(l) up to the vicinity of the thorium boiling point ca. 5000 K). The main details of the paper concern the volume expansion and electrical resistivity, which are reported as a function of enthalpy, since no temperatures were measured. This restricts their usefulness for current purposes, since the enthalpy of thorium is not known above 3400 K. However, the results did show relatively distinct breaks at the a to p and melting transformations, from which the authors deduced transition enthalpies of 3.5 and 13.9 kJ-mor in excellent agreement with existing data. 

Chiotti, P., Dooley, G. J., Effect of carbon on the electrical resistivity and allotropic transformation of thorium, J. Nucl. Mater., 23, (1967), 45-54. Cited on pages 83,503. 

Fig. 15. The electrical resistivity of the light actinide metals from thorium to curium (from Fournier and Troc 1985).

Fused salts Molybdenum has excellent resistance to a wide range of fused salts and has been used in the fused salt electrolysis of magnesium, platinum, thorium and uranium. In the production of pure magnesium, molybdenum is used to couple graphite electrodes electrically. Molybdenum cathodes are... 

The thermal conductivity of thorium metal is given in Table 6.7. The electrical conductivity of thorium metal is very dependent on its impurity content. Chiotti [C3] found that at room temperature the resistivity of thorium metal containing 0.2 w/o (weight percent) carbon was 37 X 10 fl cm, and that of metal containing 0.03 w/o carbon was 18 X 10 fi cm. An extrapolated value for carbon-free thorium metal is 13 to 15 X 10 f2 cm. The temperature coefficient of resistivity is 3.6 to 4.0 X 10 per °C. 

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