INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1953
compositions of the gas phase coexisting with liquid reported by Purcell and Cheesman (9) were interpolated to 40” F. and were taken into account in the preparation of this diagram. I
I
I
I
I
I
819
NOMENCLATURE
b
= specific gas constant
M * = average molecular weight = pressGre, pounds per siuare inch absolute = universal gas constant
I
= absolute temperature,
O
R.
= specific volume, cubic feet per pound
= compressibility factor
I 1500 U
z
LITERATURE CITED
:: 12so
Baume, G., and Robert, M., Compt. rend., 169, 967 (1919). Briner, E., Biedermann, H., and Rothen, A., Helu. Chim. Acta,
3 vi
5
8, 923 (1925); J. chirn. phys., 23, 157 (1926).
1000
Epstein, D. A,, and Cirkova, L. A,, J . Appl. Chem., (Russia) 12,
n
14 (1939).
vi
n
5
2
”
Golding, B. H., and Sage, B. H., IND.ENG.CHEM.,43, 160
750
(1951).
Johnston, H. L., and Giauque, W. F., J . Am. Chem. Soc., 51, 3194 (1929).
SO0
Johnston, H. L., and Weimer, H. R., Ibid., 56, 625 (1934). Kobe, K. A., and Pennington, P. E., Petmleum Refiner, 29, 129
d
m
”
(1950).
250
Mittasch, A., Kuss, E., and Schlueter, H., 2. anorg. u. allgem. Chem., 159, 1 (1926). I
I 075 WEIGHT
I 080
I
I
I
OB5 090 085 NITROGEN DIOXIDE
Purcell, R. H., and Cheesman, G. H., J . Chem. SOC. (London),
I
1932, 826.
ID0
Reamer, H. H., and Sage, B. H., IND.ENG.CHEM.,44, 185
FRACTION
(1952).
Figure 8. Pressure-Composition Diagram for Higher Temperatures
Sage, B. H., and Lacey, W. N., Trans. Am. Inst. Mining Met. Engrs., 136, 136 (1940).
Scheffer, F. E. C., and Treub, J. P., 2. physilc. Chem., 81, 308 (1913).
Figure 8 depicts the pressure-composition relations for the higher temperatures. The behavior is much simpler for temperatures above 100’ F. and the data may be interpolated with but small uncertainty. Table I11 records the properties of the coexisting liquid and gas phases as a function of pressure and temperature. The information recorded in this tabulation was obtained by graphical interpolation of the volumetric measurements available.
Schlinger, W. G., and Sage, B. H., IND.ENG.CHEW,42, 2158 (1950).
Selleck, F. T., Reamer, H. H., and Sage, B. H., Washington, D. C., Am. Doc. Inst., Doc. 3844 (1952). Smith, L. B., and Keyes, F. G., Proc. Am. Acad. Arts and Sci.. 69, 285 (1934).
Verhoek, F. H., and Daniels, F., J . A m . Chem. SOC.,53, 1250 (1931).
Whittaker, A. G., Sprague, R. W., Skolnik, S., and Smith, G. B. L., Ibid., 74, 4794 (1952). Wichera, E., Ibid., 72, 1431 (1951). Wittorf, N. V., 2.anorg. Chem., 41, 85 (1904).
ACKNOWLEDGMENT
This investigation was supported by the Office of Naval Research. L. T. Carmichael and G. N. Richter contributed to the experimental program and Virginia Berry assisted in the preparation of the data in a form suitable for publication. The Naval Ordnance Test Station, Inyokern, Calif., made available the nitrogen dioxide used in this program. W. N. Lacey reviewed the manuscript.
RECEIVED for review November 18, 1952. ACCEPTED December 23, 1952. For supplemental information on “Experimental iMeasurements of the Volumetric and Phase Behavior of Mixtures of Nitric Oxide and Nitrogen Dioxide,” order Document 3844 from the American Documentation I n s t i t u t e , c/o Library of Congress, Washington 25, D. C., remitting $1.75 for microfilm (images 1inchhighon standard 35-mm. motion picture film) or $2.5Oforphotostats readable without optical aid.
Polymorphs of Alumina and Gallia RUSTUM ROY, V. G. HILL,
AND
E. F. OSBORN
School of Mineral Industries, The Pennsylvania State College, State College, Pa.
I
N RECENTLY published papers (3, 6), the authors have presented data on the structure, composition, and stability relationships among polymorphs of alumina, gallia, and their hydrates. Subsequent to the completion of this work, a paper by Foster and Stumpf (8) having a bearing on this subject appeared. These authors, and their colleagues (7), have maintained that alumina can be prepared in several distinct structural modifications. The position has been ably summarized by Rooksby (5). Others ( 1 , 4), however, have recognized only two forms of alumina, the cubic defect-spinel structure, y-alumina, and the stable hexagonal, a-alumina (corundum). The confusion regarding alumina polymorphs and the contradictory evidence which has been
published are due in part to the fact that the particular “anhydrous” phase obtained in a process depends on the nature of the hydrated starting material and on the temperature and time of heat treatment. Furthermore, these phases are poorly crystallized and even their x-ray diffraction patterns (the chief criterion for their characterization) are not unambiguous. Approaching this problem by a study of solid solution structures wherein gallium and aluminum occupy equivalent positions, additional evidence has been obtained in support of the existence of the theta and kappa structures. In their recent paper, Foster and Stumpf (I demonstrated ) that their form of alumina, called &alumina, was analogous to the
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
820
TABLEI. COMPARISON 100% GanOa d I/Io 4 72 3.68 2.965 2.955 2,833 2.678 2.555 2.41 2.347 2.108 1.982 1,876 1.601 1.441(d)
0.06 0.03 0.82 0.61 0.95 0.22 1.00 0.37 0.64 0.18 0.32 0.23 0.34 0.90
OF INTERPLANAR AXD
100% GanOa“ d I/Ia
2.80
0.90
2 53
0.80
1.44
1.00
Vol. 45, No. 4
SPACINGS O F 6-GALLIASTRUCTURE SOLID SOLUTIONS O-ALUNINA (A.) 75% GazOa d I/Io
40% GanOa d I/Io
B-AInOan d
4.67 3.66 2.935(d)
0.07 0.15 1.00
4.61 3,605 2.88(d)
0 07 0 15 1 00
5.25 4.55 3.56 2.87
2:si7
0.95 0.3 0.9 0.3 0.35 0.15 0.15 0.15 0.15 0.50
2:771 2.610 2.498 2.358 2,296 2.058 1.940 1.829 1.571 1.425 1.409
0 ’95 0 3 0 95 0 55 0 6 0 3 0 3 0 2 0 30 0 3 0 7
2.74 2.58 2.45 2.325 2.26 2.03 1.92 1.81 1.55 1.41 1,395
2.660 2.535 2.398 2.332 2.087 1.970 1.866 1,591 1.433 ( d )
...
D a t a from Stuinpf et al. ( 7 ) . S = strong, M S = moderately strong, 31 = moderate, W = weak, V W
=
TABLE11. stable form of gallia, p-gallia. Using entireIy different methods (3, e), the present authors have prepared a series of solid solutions between alumina and gallia having the p-gallia structure. In Table I are compared d-spacings for representative members of this series to show the regular shift in spacings with composition change. The 8-alumina structure is thus seen to be without question the end member of this solid solution series and therefore a definite alumina polymorph having the p-gallia structure. In Table I1 are compared d-spacings listed by Stumpf et ul, (‘i‘for ),their so-called alumina with those of a series of solid solutions ranging from 100% gallia to 5% gallia-95% alumina, which the authors had designated ( 3 ) as e-gallia solid solutions. It is clear that K-alumina and E-gallia are definite and characteristic polymorphs with the same structure. The agreement of the data for the 5 % gallia composition with those for ~-alumina is striking, particularly in view o i the fact that these mate-
There exists in the literature considerable confusion with regard to the naming of the anhydrous and hydrated alumina phases and it is desirable that a standard nomenclature be adopted for alumina and gallia structures. The authors suggest that a-&O3 and a-Ga203refer to phases with the corhndum structure, and y-AI2Oaand y-Ga203to phases with the cubic defect spinel structure. The term p-Ga203 has clear precedence over 8-AI203. Moreover, the former is a stable phase obtainable in single crystals and its precise structure will be known. Unfortunately, however, the term p-Al2O, which would logically be used rather than 8-Ah03, is entrenched in the literature as a designation for another compound. In this dilemma, 8A1203 should be retained for the alumina phase having the p-Ga203 structure, possibly with the parenthetical addition “with the /3-Ga20s structure.” Inasmuch as ~-Alg03 has historical precedence over e-Ga203,this alumina structure and the structurally similar series of Al203-Cag03 solid solutions should preferably be referred to as the kappa series. In view of the definite structural and genetic relationships existing between 0r-&o3and diaspore on the one hand, and among y-A1203, gibbsite, and boehmite on the other, and considering common usage, the following alumina hydrate designations are preferred: gibbsite = -y-A1103.3H20, boehmite = y-&03.H20, diaspore = aA1203.H~O. As the genetic relationships of bayerite are not known, confusion will be avoided if this phase is designated by name, or as AI20~.3H2O,bayerite.
d 6.42 4.67 3.24 3.17 2.926 2.693 2.528 2.434 2.328 2.23 2.22 2.17 1.96 191 1.83 1.706 1.55 1.52 1.494 1.452
I/IQ 0.4 0.4 VW 0.26 0.50 1.00 0.40 0.60 0.64 0.03 0 10 v TV 0.12 0.04 0.04 0.24 0.64
VW
r/ro
W h?
vw MS
...
MS
w
XIS M XI
A1S
h1Ts’
w
hl hI
S
veiy weak.
SPACINGS O F E-GALLIA SOLID SOLUTIOKS 4SD K-L\LUXIN.~ ( A . )
IIiTERP1,SKiSR
d
1/10
d
3.10 2.84 2.61 2.44 2.36
0.2 0.5 0.6 0.3 0.5
3.05 2.81 2.58 2.43 2.33
2.14 2.01 1.89 1.86 1.77 1.66
0.6
2.12 2.10 1.88 1.83 1.74 1.64
... ..,
...
... ...
VW 0.1
vw vw ...
0.3
...
...
...
...
I/Io
0.3 0.8 1.0 0.2 0.2
... , . ,
0.8
VW 0.4 VTT‘
0.2 0.8
... I . .
d
1/10
6.2 4,52 4.2 3.06 2.81 2.69 2.43 2.34 2.28 2.18 2,125 2.07 1.88 1.835 1.755 1,646 1.55 1.495 1.440 1 396
1:438 0 . 6 1:455 1.0 1.391 0 . 5 1.410 0.6 a Values froin Stumpf et al. ( 7 ) . S = strong, hlS = moderately strong, XI = moderate, TT = weak, VW = very weak. 0.48 0.40
rials are not well crystallized, and JTere prepared by entirely different methods in the two cases, and different x-ray techniques were used in obtaining the data. I t is no longer possible to explain the K-alumina pattern as a mixture of phases, and this must also be added to the list of definite polymorphs of alumina. COSCLUSIONS
A gallia structure corresponding to K-alumina definitely exists. Furthermore, a complete series of solid solutions, with a regular shift of d-spacings, exists between the alumina and gallia end members of the kappa series, and a solid solution from 100% gallia to 40% gallia content for the theta series. This evidence confirma the existence of @-aluminaand alumina as individual distinct structural polymorphs of alumina. LITERATURE CITED (1) Errin, Guy, Jr., Acta C ~ y s t .5, , 103 (1952). (2) Foster, L. M., arid Stumpf, H. C., J . Am. Chem. SOC.,73, 1590
(1951). (3) Hili, V. G., Roy, Rustum, and Osborn, E. F., J . Am. Ceram. Soc., 35, 135 (1952). (4) Jeilinek, M. H., and Fankuchen. I., IND.Exc. CHEM., 37, 158 ’
(1945).
(5) Rooksby, 1%.P., “X-Ray Idertificatioll and Structures of Citty Minerals,” Chap. X, London, Mineralogical Society, 1951. (6) Roy, Rustum, Rill, V. G., and Osborn, E. F., J . ilnz. Chem. SOC., 74, 719 (1952). (7) Stumpf, H. C., Russell, A. S.,Sewsome, J. TT., and Tucker, 42, 1998 (1950). C. M., IKD.ENG.CHEM?., RECEIVED €or review June 2, 1962.
ACCEPTEDDecember 8, 1952.
