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,
f'.;
Ill.
~
Determinution of Dihydmrytrenzenes
Cs-14
D. E. WCHOLSON, Humblo Oil & w i n g Co., Boybwa, Tax.
NO.
Name
Roop.
%
Formula
:;r
__.__-
I
-1-
Resorcinol
1722
"p:
Length
Av
11.0112.00p
HydroCSHSOZ 0-100 quinone
/Catecho'I 1
1
Concn.
Cell Windows: Hac1 Abtorbanca Measunmenl: Calculation:
~~
eHeOz
-l
3
Slit (mm) AX or
Xorv
Instrument: Perkin-Elmer Model 21, NaCi prism Somple Pham: Solution in N,N-dimethylformamide
i
0-100 0-100
I
~
j
f1.5
1
13.35~10.290 1.0 10.054~ 1.0
fl.O
'
10.351
ANALYTICAL CHEMISTRY
~
Inverse m a t r i r G r a p h i c a l
CompanentlX
~
~
P o i n t X Successive o p p r o x A
Relotive AbrorbancerAnalyfical Matrix:
- -l
I
I -__ 1-I CsHsOz
0.207 a.0401
Base line-
:A% j :::
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
