Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-27T03:50:02.236Z Has data issue: false hasContentIssue false
  • English
  • Français

High-Temperature Modifications of Thorium Dicarbide

Published online by Cambridge University Press:  06 March 2019

P. K. Gantzel ,
S. Langer ,
N. L. Baldwin  and
F. L. Kester
P. K. Gantzel
Affiliation:
General Atomic Division of General Dynamics Corporation San Diego, California
S. Langer
Affiliation:
General Atomic Division of General Dynamics Corporation San Diego, California
N. L. Baldwin
Affiliation:
General Atomic Division of General Dynamics Corporation San Diego, California
F. L. Kester
Affiliation:
General Atomic Division of General Dynamics Corporation San Diego, California
Get access

Abstract

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 a0 = 4.235 ± 0.002Å and c0 = 5.408 ± 0.002Å is formed. At 1481°C, the tetragonal is transformed to cubic with a0 = 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.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 8: Thirteenth Annual Conference on Applications of X-ray Analysis, August 12-14, 1964 , 1964 , pp. 78 - 85
Copyright
Copyright © International Centre for Diffraction Data 1964

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Wilhelm, H. A. and Chiotti, P., “Thorium-Carbon System,” Trans. Am. Soc. Metals 42:1295–1310, 1950.Google Scholar
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).Google Scholar
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.Google Scholar
4. Smith, D. K., A Fortran Program for Calculating X-Ray Powder Diffraction Patterns, University of California Radiation Laboratory Report UCRL-7196, 1963.Google Scholar
5. Gantzel, P. K. and Baldwin, N. L., “Powder Indexing and Lattice Constants for ThCa,” Acta Cryst. 17:772–773, 1964.Google Scholar
6. Wilson, W. E., “High-Temperature X-Ray Diffraction Investigations of the Uranium-Carbon System,” J. Am. Ceram. Soc. 43:77–81, 1960.Google Scholar
7. Langer, S., Baldwin, N. L., and Gantzel, P. K., “Solid Solutions of Uranium and Thorium Dicarbide” (to be published).Google Scholar
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.Google Scholar
9. Austin, A. E., “Carbon Positions in Uranium Carbides,” Acta Cryst. 12:159–161, 1959.Google Scholar
10. Atoji, M. arid Medrud, R. C., “Structures of Calcium Dicarbide and Uranium Dicarbide by Neutron Diffraction,” J. Chem. Phys. 31:332–337, 1959.Google Scholar
11. Bredig, M. A., “The High-Temperature Cubic Phases of Uranium and Lanthanum Dicarbides,” J. Am. Ceram. Soc 43: 493, 1960.Google Scholar
12. Chang, R., “A Diffus ionless UC3 (Cubic) to UC a (Tetragonal) Transformation,” Acta Cryst. 14:1097–1098, 1961.Google Scholar