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| Amma E. L., Jeffrey G. A. Study of the Wurtzite-Type Compounds. V. Structure of Aluminum Oxycarbide, Al2OC; A Short-Range Wurtzite-Type Superstructure // J. Chem. Phys. - 1961. - 34(1). - 252-259. Al2OC has long-range disordered structure based on the wurtzite lattice and a short-range sqrt.(3)a, 2c superstructure. The long-range atomic parameters were determined from the single crystal sharp diffraction data with MoK radiation. The diffuse spectra, although very apparent on the single-crystal x-ray photographs, were inadequate to completely define the short-range structure; however, the general features of this structure could be inferred and some analogies made to known structures which are wholly or in part wurtzite-lattice superstructures. |
| Barczak,V. J. Optical and X-Ray Powder Diffraction Data Al4SiC4 // J. Am. Ceram. Soc. - 1961. - June. - 299. [no abstract] |
| Cox J. H., Pidgeon L. M. An Investigation of the Aluminum-Oxygen-Carbon System // Can. J. Chem. - 1963. - 41. - 671-683. A differential thermal analysis technique was used to study the carbothermic reduction of aluminum oxide at reduced pressures in the temperature range 1700 - 2000° K. The reduction was found to proceed through the intermediate oxycarbide Al4O4C, identified by previous workers, to the aluminum carbide. The Al4O4C and another oxycarbide, Al2OC, were formed by a direct solid-solid reaction, rather than by formation of a gaseous aluminum suboxide and subsequent reaction with carbon as has been postulated. The carbon monoxide pressures over the following reactions were measured: Al2O3 + 3C = Al2OC + 2CO 2Al2O3 + 3C = Al4O4C + 2CO Al4O4C + 6C = Al4C3 + 4CO. Heats and free energies of reaction were found standard heats and free energies of formation were calculated for Al2OC, Al4O4C, and Al4C3. The values for Al4C3 agreed with previously published results. The direct reaction Al2O3 + 3C = 2Al + 3CO did not occur. To account for aluminum produced at high temperatures, the reaction below was postulated: Al4O4C + Al4C3 = 8Al + 4CO. The calculated equilibrium pressure above this reaction agreed with experimental observations. |
| Cox J. H., Pidgeon L. M. The X-Ray Diffraction Patterns of Aluminum Carbide Al4C3 and Aluminum Oxycarbide Al4O4C // Can. J. Chem. - 1963. - 41. - 1414-1416. An X-ray investigation of the compounds aluminum carbide, Al4C3, and aluminum oxycarbide Al4O4C yielded data which differed from that in the A.S.T.M. files. The aluminum carbide pattern was similar in many ways to that calculated by Steckelberg and Schnorrenberg (Z. Physik. Chem., Sect. B., 27, 37 (1934)). Minor differences occured in the Al4O4C pattern. |
| Jeffrey G. A., Slaughter M. The Structure of Aluminum Tetroxycarbide // Acta Cryst. - 1963. - 16. - 177-184. Aluminum tetroxycarbide, Al4O4C, is a high temperature reaction product in the aluminum oxide carbide system. Its structure has been determined by single crystal analysis of three-dimensional CuK data. The structure was solved from the Patterson synthesis, and refined by differential Fourier synthesis methods. The structure is based on Al(O3C) tetrahedra which share corners and edges. The unusual feature of the structure is a chain of tetrahedra which are linked alternately by sharing edges and corners. The observed Al-O bond lengths range from 1.71 to 1.87 A, the Al-C from 1.91 to 1.98 A, with standard deviations of 0.01 A. There are two short non-bonded distances associated with the shared edge of the tetrahedra, Al ··· Al 2.63 A, and O ··· O 2.53 A. [PDF- 379kb] |
| Jeffrey G. A., Wu V. Y. The Structures of the Aluminium Carbonitrides // Acta Cryst. - 1963. - 16. - 559 - 566. Three new aluminum carbonitrides have been identified by single-crystal X-ray analysis. These are Al6C3N2, Al7C3N3, Al8C3N4. These compounds, together with AlN, Al4C3, and Al5C3N form two structurally related polytipic series based on hexagonal packing with similar basal spacings and different c axis periodicities. A complete three-dimensional crystal structure analysis is reported for the Al7C3N3 compound. |
| Jeffrey G. A., Wu V. Y. The Structures of the Aluminum Carbonitrides. II. // Acta Cryst. - 1966. - 20. - 538-547. The results of three-dimentional single-crystal structure analyses are reported for Al4C3, Al5C3N, Al6C3N2 and Al8C3N4. These structures, which with AlN and Al7C3N3 form a homologous series, have Al-Al first neighbour distances ranging from 2.56 to 3.33 A, Al-C distances from 1.87 to 2.30 A, and Al-N distances from 1.86 to 1.99 A. The carbon atoms are five- and six-coordinated to nearest neighbour aluminum atoms. The relationship of these structures to that of AlN, the B4 type, is discussed in terms of the inversion and shear of blocks of tetrahedral coordination polyhedra. An attempt is made to describe the electronic structure qualitatively in terms of metallic and covalent interatomic bonding. The structure of the disordered Al2OC is reinterpreted. |
| Jeitschko W., Nowotny H. Crystal Structure of Ti3SiC2, a New Type of Complex Carbide // Monatsh. Chem. - 1967. - 98(2). - 329-337. The crystal structure of Ti3SiC2 has been determined by means of single crystal photographs; the lattice parameters of the hexagonal cell were found to be: a=3.068, c=17.669 A and c/a=5.759. The titanium atoms occupy the positions 2a) and 4f) (zTi=0.135), silicon atoms 2b) and the carbon atoms 4f) (zC=0.5675) of space group P63/mmc. The crystal structure type belongs to the class of complex carbides having octahedral groups [Ti6C]. |
| Morfopoulos V. C. P. Analysis of the Thermodynamics of the Al-C-O System in the Temperature Range 1000 to 1800 K // Can. Metall. Q. - 1964. - 3(1). - 95-116. [no abstract] |
| Sawatani T., Sakata S. Dialuminum monooxycarbide existing in the band-like region of slightly pressed sheet steel // Tetsu To Hagane. - 1968. - 54(4). - 455-458. (Japanese). [no abstract] |
| Worrell W. L. Carbothermic Reduction of Alumina. A Thermodynamic Analysis // Can. Metall. Q. - 1965. - 4(1). - 87-95. Using new thermodynamic data for Al4C3, stability relationships in the Al-C-O system have been determined. A Pourbaix-Ellingham diagram has been constructed and is used to evaluate the equilibrium carbothermic-reduction process. The analysis indicates that liquid aluminum can never be obtained below 2100°K and that appreciable amounts of Al2O (g) are present in the vapor. An analysis is also made of an alternate reduction path in which aluminum vapor is produced by decomposition of aluminum carbide. The Al4O4C and Al2OC oxycarbide phases are considered to be metastable, but their possible influence on the equilibrium reduction process is briefly discussed. |
