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High-Temperature Modifications of Thorium Dicarbide

  • P. K. Gantzel (a1), S. Langer (a1), N. L. Baldwin (a1) and F. L. Kester (a1)


Thermal analyses of samples of thorium dicarbide in equilibrium with graphite show arrests which indicate phase transitions at 1427 ± 21°C arid 1481 ± 28°C. These thermal effects have been observed on heating and cooling both in standard thermal analysis and in differential thermal analysis using graphite as a reference material. The microstructure of thorium dicarbide samples shows the characteristic “herringbone” pattern of a material which has undergone a martensitic-type transition.

A high-temperature X-ray investigation has revealed that the observed thermal arrests correspond to erystallographic transformations. The monodinic modification found at room temperature is stable to 1427°C, at which temperature a tetragonal modification with a 0 = 4.235 ± 0.002Å and c 0 = 5.408 ± 0.002Å is formed. At 1481°C, the tetragonal is transformed to cubic with a 0 = 5.809 ± 0.002 Å. The best agreement between observed and calculated intensities has been obtained with C-C units of 1.5-Å assumed bond length in space groups P42/mmc and Pa3 for the tetragonal and cubic modifications, respectively.



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1. Wilhelm, H. A. and Chiotti, P., “Thorium-Carbon System,” Trans. Am. Soc. Metals 42:12951310, 1950.
2. Langer, S., et al., Proceedings of the International Conference on Compounds of Potential Interest in Nuclear Technology, University of Colorado, August 3-5, 1964 (to be published).
3. Vogcl, R. E. and Kempter, C. P., A Mathematical Technique for the Precision Determination of Lattice Constants, Los Alamos Scientific Laboratory Report LA-2317, 1959.
4. Smith, D. K., A Fortran Program for Calculating X-Ray Powder Diffraction Patterns, University of California Radiation Laboratory Report UCRL-7196, 1963.
5. Gantzel, P. K. and Baldwin, N. L., “Powder Indexing and Lattice Constants for ThCa,” Acta Cryst. 17:772773, 1964.
6. Wilson, W. E., “High-Temperature X-Ray Diffraction Investigations of the Uranium-Carbon System,” J. Am. Ceram. Soc. 43:7781, 1960.
7. Langer, S., Baldwin, N. L., and Gantzel, P. K., “Solid Solutions of Uranium and Thorium Dicarbide” (to be published).
8. Hunt, E. B. and Rundle, R. E., “The Structure of Thorium Dicarbide by X-Ray and Neutron Diffraction” J. Am. Chem. Soc. 73:4777-478: 1, 1951.
9. Austin, A. E., “Carbon Positions in Uranium Carbides,” Acta Cryst. 12:159161, 1959.
10. Atoji, M. arid Medrud, R. C., “Structures of Calcium Dicarbide and Uranium Dicarbide by Neutron Diffraction,” J. Chem. Phys. 31:332337, 1959.
11. Bredig, M. A., “The High-Temperature Cubic Phases of Uranium and Lanthanum Dicarbides,” J. Am. Ceram. Soc 43: 493, 1960.
12. Chang, R., “A Diffus ionless UC3 (Cubic) to UC a (Tetragonal) Transformation,” Acta Cryst. 14:10971098, 1961.


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