where (h) indicates specifically which reflection was chosen for tabulation purposes. For each of our patterns, the reflection (h) will be the one with I = 100 since only copper radiation was used. Typically, at least 3 sets of reflections and 2 mountings of the mixture were used to obtain 6 or more values for the reference intensity ratio, I/I These values yielded, the tabulated average <I/I_>. From these data, the standard deviation, σ, was obtained from c Format of tables. The printing of the data has been computerized. Superimposed reflections are treated in one of two ways. If a d-spacing has only two possible indices, an M is added to the d-spacing which is repeated on the next line, but with the second index. However, if there are more than two possible indices, a plus sign is used in like manner. In both cases, the composite intensity is printed only once and aligned with the first reflection. The symbol "1L" in the intensity column is used to indicate "less than 1". UNITS In this publication the Ångström unit (1Å 100 pm) was selected for presentation of the dspacings and lattice parameters. This maintained consistency with (a) the earlier publications of Standard X-ray Diffraction Powder Patterns (Circular 539 and Monograph 25), (b) the publications of the International Union of Crystallography, and (c) the continuing publication of cards and search manuals of the PDF (now consisting of over 35,000 entries). The PDF search manuals are based on the d-spacings in Å of the 3 strongest lines. Consistent with the choice of the unit for length, the volume of the unit cell is expressed in 3 (13 1 x 10-30 m3). Densities are reported in g/cm3 (1 gm/cm3 = 103 kg/m3). ACKNOWLEDGMENTS = We would like to thank Carolyn Wingo of the JCPDS Associateship for her assistance, particularly for keyboarding the data and helping with the proofreading of this manuscript. Appreciation is also expressed to the Text Editing Facility of the National Measurement Laboratory of NBS for typing the manuscript. Alexander, L., Klug, H. P., and Kummer, E. (1948). J. Appl. Phys., 19, No. 8, 742. Crystal Data (1973). (3rd Ed. Published jointly by the U.S. Department of Commerce, National Bureau of Standards, Washington, D.C. 20234, and the Joint Committee on Powder Diffraction Standards, 1601 Park Lane, Swarthmore, PA 19081). Deslattes, R. D. and Henins, A. (1973). Phys. Rev. Deslattes, R. D., Henins, A., Bowman, H. A., Evans, H. T., Jr., Appleman, and Handwerker, D. S. Groth, P. (1908). Chemische Kristallographie II (Engelmann, Leipzig, Germany). Hartshorne, N. H. and Stuart, A. (1970). Crystals and the Polarizing Microscope (Edward Arnold and Co., London, 4th Ed.) Hubbard, C. R. and Smith, D. K. (1977). Advances in X-ray Analysis, (Plenum Publishing Corporation, 227 West 17th St., New York, NY 10011), 20, p. 27. Hubbard, C. R., Swanson, H. E., and Mauer, F. A. International Union of Pure and Applied Chemistry quest. Current prices will be quoted on re Palache, C., Berman, H., and Frondel, C. (1944). Standard Reference Material 640 (1974), Silicon Powder X-ray Diffraction Standard, obtainable from the National Bureau of Standards, Office of Standard Reference Materials, Washington, DC 20234. Current price will be quoted on request. Swanson, H. E., Morris, M. C., and Evans, E. H. (1966). Natl. Bur. Stand. U.S. Monogr. 25, Sec. 4, 3. Visser, J. W. and de Wolff, P. M. (1964). "Absolute Intensities," Report 641.109, Technisch Physische Dienst, Delft, Netherlands. Visser, J. W. (1969). J. Appl. Crystallogr. 2, 89. J. Appl. Crystallogr. 1, Wolff, de, P. M. (1968). 108. |