Standard X-ray Diffraction Powder Patterns

D. E. Appleman, and D. Handworker. Latticeconstant errors are given only for data refined onthat program and are based on least squaresrefinement of the variance-covariance matrixderived from the unweighted A0 residuals.Published unit cell data in kX units wereconverted to angstrom units using the factor1.00202 as recommended by an internationalconference of crystallographers [4].The space groups are listed with both theSchoenflies and short Hermann-Mauguin symbolsas well as the space group numbers given in theInternational Tables for X-ray Crystallography[5],Orthorhombic cell dimensions are presentedaccording to the Dana convention [6] 6>a>c.The densities calculated from the NBS latticeconstants are expressed in grams per cubiccentimeter and are computed with atomic weightsbased on carbon 12 [7], and the Avogadro number(6.02252 X10 23 ).References[1] Index to the X-ray Powder Data File, AmericanSociety for Testing and Materials, 1916 Race Street.Philadelphia 3, Pa. (1962).[2] L. Alexander, H. P. Klug, and E. Kummer, Statisticalfactors affecting the intensity of x-rays diffracted bycrystalline powders, J. Appl. Phys. 19, No. 8,742-753 (1948).[3] E. R. Jette and F. Foote, Precision determination oflattice constants, J. Chem. Phys. 3, 605-616 (1935).[4] The conversion factor for kX units to angstrom units,J. Sci. Inst. 24,27 (1947).[5] International Tables for X-ray Crystallography, 1,1952.[6] Dana's System of Mineralogy, 1, 6 (1944).[7] International Union of Pure and Applied Chemistry,Chem. Eng. News, Nov. 20, 43 (1961).Aluminum 3:2 Silicate (mullite)* 3A12O3 • 2SiO2 (orthorhombic)Powder data cardsCardnumber6-025810-394Indexlines3.382. 203.413. 393.422.54SourceF. H. Cillery [1].H. Scholze [2] 1955.Additional published patterns. Norton [3]1925, Navias and Davey [4] 1925; Wyckoff,Grieg, and Bo wen [5] 1926; Mark and Rosbaud[6] 1926; Nahmias [7] 1933; Comeforo, Fischer,and Bradley [8] 1948; and Kurylenko [9] 1952.NBS sample. The sample of aluminum 3:2silicate was prepared at NBS by C. Bobbins.Gamma A1203 and SiO2-nR 2O were mechanicallymixed in stoichiometric proportions of 3A12 O3 to2SiO2-7iH2O. This mixture was pressed into pellets and fired at 1400 C and 1500 C with littlereaction, then remixed and fired in an open systemat 1700 C for 24 hr. Reaction was nearly complete. It was crushed, reground in an agatemortar and refired at 1725 C for 24 hr. Chemicalanalysis of the finished product showed 61.6 molepercent A12O3 and 38.4 mole percent SiO2 insteadof the beginning percentages of 60 and 40 in the3:2 mixture. Spectrographic analysis showed thefollowing major impurities: 0.01 to 0.1 percentiron, and 0.001 to 0.01 percent each of calcium,chromium, magnesium, manganese, nickel, titanium, and zirconium.*Some disagreement exists in the literature as to which ratio or ratios ofalumina to silica should be considered for mullite (3:2, 2:1, or both).This sample was prepared as 3:2 at the request of P. Schroth of the ArmcoSteel Corp. to be used as an identification, diffraction standard for mullitein refractory brick.The sample was colorless and optically positivewith the indices of refraction Na= 1.637, N$ =1.641, and N T =1.652.The ^-values of the othree strongest lines are:3.390, 3.428 and 2.206 A.Structural data. Sadanaga, Tokonami, andTakeuchi [10] in 1962 determined that mullitehas the space group Dlh-Pbam (No. 55). Wyckoff, Grieg, and Bowen [5] in 1926 determined thatmullite has 3/4(3Al2O 3-2SiO2 ) per unit cell. Several lattice constants have been converted fromkX to angstrom units for comparison with theNBS values.19261928193319521955196019621963Wyckoff, Grieg,and Bowen [5],Taylor [!!] . ...Nahmias [7]Kurylenko [9]___Scholze [2]_ ____Agrell and Smith[12].Sadanaga,Tokonami,and Takeuchi[10].National Bureauof Standardsat 25 C.*These values are for 2AliO8-SiOi.Lattice constantsaoA7. 527. 517. 547. 5807. 5377. 5582*7. 5837. 5456. 0004bA7. 687. 657. 677. 6897. 6717. 6878*7. 6817. 6898. 0005cA2. 862. 882. 902. 8952. 8782. 8843*2. 88542. 8842. 0002The density calculated from the NBS latticeconstants is 3.170 g/cm3 at 25 C.