Infrared Quantitative Analysis Data. CS-143 ... - ACS Publications

first reported by Becker and Ebert. (1), who found a. NaCl-type lattice. ... The X-Ray Powder Data. File contains a CbC data card (2-1031) which lists...
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194.

Niobium Monocarbide

E. K. STORMS, N. H. KRIKORIAN, and C. P. KEMPTER California, 10s Alamos, N. M.

Los Alamos Scientific Laboratory, University of

by tumbling and then fired in a graphite crucible a t about 2300" C. for 3 hours. The resulting sintered plug was pulverized to -325 mesh and rereacted a t 2200' C. for 3 hours. The sample was again pulverized to -325 mesh, and a portion heated a t 1860' C. for 65 hours under a vacuum of 7 X 1 0 9 mm. Hg. Three separate analyses (6) were made for niobium, two for total carbon, and two for free carbon; these gave, respectively, an average of 87.00, 13.04, and 1.87%. The resultant empirical formula is NbCD.093. X-ray diffraction studies were carried out on a Norelco unit with a 114.59mm. Debye-Schemer camera. The 16hour exposure was made a t 25' C. using nickel-filtered copper radiation.

HE crystal structure of NbC was Tfirst reported by Becker and Ebert ( I ) , who found a NaC1-type lattice. Since then the lattice parameter has been determined by several workers (9-4, 6 ) . The X-Ray Powder Data File contains a CbC data card (2-1031) which lists approximate interplanar spacings and rough intensities with no Miller indices assigned. There is also a NbC/NbrCs data card (5-0658) which lists data for a cubic (close-packed) lattice with a lattice constant of 4.449 A. Neither card has analytical data.

A mixture of -325mesh AUC graphite and Fansteel niobium was prepared

Table 1.

The DebyeScherrer data are shown in Table I. The relative intensities (peak background) are visual estimates. The lattice constant and its standard deviation were determined on an IBM 704 computer using the method of Vogel and Kempter ('7). The last two doublets were measured three times by four readers; the systematic errors in Aao/5 were aasumed directly proportional to tan +, where + is the complement of the Bragg angle. The lattice constant (with the lowest standard deviation) obtained was u, = 4.47085 & 0.00009 A. a t 25' C.; correcting for refraction

X-Ray Powder Diffraction Data for NbC 0.993

Miller Indices 111

Relative Intensity 100

200

d, A.

2.575 2.231 1.580 1.348 1.290 1.118 1.026 0.9999 0.91% 0.8605 0.7904

100

220 311

95 95 40 30

222 400

331

50

70 80

420

422 511,333 440

+

!K) 50

+

in copper radiation, this value becomes 4.47095 A. The standard deviation expresses only the precision of the measurement, not the accuracy. The theoretical density (for 4 NbC 0.998 per unit cell) is 7.79 grams per cc. and the Nb-C bond distance for coordination number 6 is 2.2355 A. ACKNOWLEDGMENT

The authors thank Mary Jane Jorgensen and L. A. Wahman for reading the x-ray films, and C. G.Heasley for chemical analysis of the material. LITERATURE CITED

(1) Becker, K., Ebert, F., 2. Physik 31, 268 (1925). (2) Brauer, G., Renner, H., Wernt-t, J., 2.a w g . allgem. cha. 277,249 (1954). (3) Elliott, R. P., Armour Research Foundation, Re t ARF-2120-4 (1959). Nadler, M. R., J . (4) Kempter, C. Chem. Phys. 32, 1477 (1960). (5) Kriege, 0. H., L o s Alamos Scientific Lab., Rept. LA-2306 (l959). (6) Storms, E. K., Krikormn, N. H., J . Phys. Chem. 63, 1747 (1959). (7) Vogel, R. E., Kempter, C. P., Loa Alamos Scientific Lab., Rept. LA-2317 (1959). CRYSTALLOGRAPHIC data for publication in this section should be sent to W. C. McCrone, 501 East 32nrl St., Chicago 16,

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Determinution of Dihydmrytrenzenes

Cs-14

D. E. WCHOLSON, Humblo Oil & w i n g Co., Boybwa, Tax.

NO.

Name

Roop.

%

Formula

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Length

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Concn.

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Instrument: Perkin-Elmer Model 21, NaCi prism Somple Pham: Solution in N,N-dimethylformamide

i

0-100 0-100

I

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j

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13.35~10.290 1.0 10.054~ 1.0

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10.351

ANALYTICAL CHEMISTRY

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P o i n t X Successive o p p r o x A

Relotive AbrorbancerAnalyfical Matrix:

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0.207 a.0401

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1 2

3 Material Purify:

12.001 0.1805 0.0692 0.0193 99 $%, minimum.

13.35~ 0.0499 0.1950 0.0600

10.35p 0.000 0.000 0.1535