SYSTEM
Ni0-A1203
465
X-RAY DIFFRACTION STUDIES I N T H E SYSTEM NiO-Al2Od W. 0. MILLIGAN
AND
L . MERTEN
Department of Chemistry, The Rice Institute, Ho~tston,Texas Received April 8 , 1046
In a previous report from this laboratory (4) it was observed that mixed gels of cupric and ferric oxides exhibited an unusual mutual protective action. Thus 90 t o 70 mole per cent of ferric oxide prevented or retarded the crystallization of cupric oxide in mixed gels precipitated and dried in air a t room temperature. At lower concentrations of ferric oxide, there was observed the x-radiogram of cupric oxide alone, the results indicating that the cupric oxide is retarding the crystallization of the ferric oxide. The observed mutual protective action persisted in samples aged under water a t 100°C. and in samples heated a t 1000°C. for 2 hr. The present paper reports the results of an attempt to determine whether the observed mutual protective action is specific for the system CuO-FezO3, or applies generally to dual systems of hydrous oxides. EXPERIMENTlL
Preparation of samples Mixtures of varying volumes of nickel nitrate solution (0.5 M with respect to N O ) and aluminum nitrate solution (0.5 M with respect to &Os) were precipitated with equivalent amounts of sodium hydroxide solution (approximately 3.5 M ) in a rapid-mixing device described elsewhere (6). The compositions of the mixtures of nickel and aluminum nitrate solutions were adjusted so that there was obtained a series of eleven hydrous oxides containing 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 mole per cent (anhydrous basis) of nickel oxide (NiO). The precipitated gels were washed with distilled water, using a centrifuge, until the supernatant liquid was free of nitrate ions, and filtered on a Buchner funnel. The resulting filter cakes were dried in air a t room temperature. Portions of the air-dried samples were heated for periods of 2 hr. at temperatures of 500", 700", and 1000°C. X-ray diflraction analysis X-ray diffractionpatterns were obtained for the samples described above, using chromium K, x-radiation. The KB x-radiation was removed by vanadium pentoxide filters. The results obtained for the samples heated a t 500°C.(figure l), 700°C. (figure 2), and 1000°C. (figure 3) are given in chart form. Reproductions of some of the x-ray diffraction negatives are given in figure 4. Presented before the Texas Regional Meeting of the American Chemical Society, held in Austin, Texas, December 7-8, 1915.
466
W. 0. MILLIGAN AND L. MERTEN DISCUSSION
The air-dried samples are essentially amorphous t o x-rays. The gel formed from pure nickel nitrate solution gives an x-radiogram consisting of broad bapds corresponding to Ni(OH)2 (1, 5 ) . It has been previously shown (7, 8) that alumina precipitated from the nitrate consists of yA1203. HzO crystals. The 5 0 1
3 0
0
10 20
I O'
30
1
I
60
.
40
50
50
40
60
30
70
20
80
1C
90
0
100
I
I
I
I
I
I
I
I
I
I
I
I
( Standard
Y-A1*03 1
I L
5.0
R
I 3.u
2.G
1 5
1.2
N t O - i t l ~ O 3 Gels H e a t e d 5 O O O C .
FIG. 1. X-ray diffraction patterns
amorphous character of the air-dr'ied gels in the Ni0-Al20s system indicates that each oxide mutually protects the other against crystallization at room temperature. In several of the gels there were observed some weak x-ray diffraction (7, S), which is known to form spontaneously lines corresponding to a-AlzOs .3Hz0 when an alumina gel is left in contact with alkali solution for a period of several
SYSTEN
467
NiQ-i11203
hours. The time required for the washing of the gels in the centrifuge was sufficient t o allow the occasional forniation of some a-A120a.3&0 crystals. The x-ray diffraction patterns (figure 1) of the gels heated at 500°C.show that each oxide retards or prevents the crystallization of the other. Samples containing from 0 to 20 mole per cent alumina show only the diffraction pattern of 5.0
!.
3.0
2.0
1.5
1.2
Mole % N i O A1203 ( S t a n d a r d NiO)
100
0
90
10
80
20
70
30
60
40
50
50
40
60
30
70
20
80
10
90
0
100
Standard
?'-A1203 5.0
1.
3.0
2.0
1.5
1.2
NiO-Al203 G e l s H e a t e d 700°C.
FIG.2. X-ray diffraction patterns
KiO. The lines become broader as the amount of alumina increases. The samples containing 30 to 50 mole per cent of alumina are amorphous t o x-rays, and samples containing 60 to 100 mole per cent alumina exhibit the diffraction pattern of yAbO3, which becomes progressively sharper as the nickel oxide content decreases.
'
468
W. 0. MILLIGAN AND L. MERTEN
Samples heated a t 700°C. are all crystalline, but the protective action persists since the diffraction lines are still quite broad. The x-radiograms (figure 3) of thegels heated a t 1000°C. show that,whileall the samples are crystalline, the lines are shifted in a regular manner. The results indicate solid-solution phenomena. In figure 5, compositions of the gels are 5.0
1.
3.0
1 5
2.0
1.2
Mole % NIO
A1203
(Standard N i O )
I
t
1
I
I
I L I
I 1.
100
0
90
10 20
30 40
I
I
I
I
I
I
50
50
40
60
70 80 90
100
I 5.0
1.
3.0
I 2.0
N i 0 - A l 2 O 3 6 e l s Heated
Standard 7-A1203
I
1.5
1.2
looooc-
FIG.3. X-ray diffraction patterns qlotted against interplanar spacings for the diffraction line where d/n = ca. 2.4 A. The results strongly support the view that a compound having the composition Ni0.Al2O3has been formed. The observed interplanar spacings agree with values previously reported in the literature (2,3) for nickel aluminate. It will be noted that both nickel oxide (NiO) and alumina form solid solutions with
SYSTEM
4G9
KiO-A.1203 Mole (j&
NO
A1203
100
0
90
10
80
20
70
30
60
40
50
50
40
eo
30
70
20
80
10
90
NiO-Al203 gels heated 1OOO'C.
Fro. 4 . X-ray diffraction patterns k! i C A 1203
2.4501
I
I
I
I
T
I
I
I
t
1
1
-1
N i C - A l 2 C 3 G e l s H e a t e d 1000°C.
FIG.5 . Solid solution in the system NiO-hl20a
the nickel aluminate. Formation of nickel aluminate is supported further by additional lines faintly visible in figure 4, but omitt8edfrom figure 3, since the extreme faintness of these lines on the x-radiograms from the 70, 60, and 40 per
470
KARL SOLLKER AND HARRY P. GREGOR
cent nickel oxide samples rendered dificult an accurate measurement of their positions . SUMMARY
The following is a brief summary of the results of this investigation: 1. Mixed dual gels of nickel and aluminum oxides precipitated and dried a t room temperature exhibit a mutual protective action against crystallization, in confirmation of similar result’s previously obtained in the system cupric oxideferric oxide. 2. The mutual protective a’ction js still pronounced in dual gels heated a.t 500-1000°C. 3. Equimolar mixtures of nickel and alum.inum- oxides react at 1000°C. to form nicltel aluminate, N O .AI2O3. 4. Kickel aluminate forms solid solutions with each cf the pure oxides. REFERENCES (1) CAIRNSA N D OTT:J. Am. Cliem. SOC.66, 527 (1933). (2) HOLGERSSON: Z. anorg. a.llgeni. Chem. 204, 378 (1032). (3) KRAUSEA X D THIEL: Z. anorg. allgem. Chem. 203, 120 (1032). (4) MILLIOAN A N D HOLIIES: J. Am. Chein. SOC.63, 149 (1941). (5) NATTA:Atti accncl. Lincei [61 2, 495 (1026). (6) WEISER A N D MILLICAN:J . Phys. Chem. 40, 1075 (1936). (7) WEISER A N D MILLIGAN: Chem. Rev. 26, 7 (1939). (8) WEISERAP;D MILLICAN: Adrances i n Colloid Science, Vol. I, p. 228. lishers, Inc., New York City (1042).
11
Interscience gub-
THE ELECTROCHEMISTRY OF PERMSELECTIVE COLLODIOK M E R I B R A S E S . I
R.LTESTUDIES
O N THE ESTABLlSHMENT
OF THE COMCEiVTRATION
POTENTIAL ACROSS V L k R I O c S TYPESO F PERMSELECTIVE
COLLODION MEMBRANES KARL SOLLNER A N D HARRY P. GREGORl Department o j Physiology, Cniversity of dfinnesota, Minneapolis, Alinneso!a Received M a y 28, 1946
I In a preceding paper (4) improved and reproducible methods of preparation of various types of (elect,ronegative) permselective collodion membkanes were described. In addition to data on their water content, these memhranes were characterized by (a) the “characteristic concentration potential” (‘5), i.e., the potential of the chain 0.1 6f IW1 I membrane 10.01 Af K C I ; ( b ) the diffusion potential or “bi-ionic potential” (B.I.P.) across the membrane i f the chain 0.1 llf IiCl 1 membrane 1 0.1 64 LiC1; and (c) the electrical resistance ilf the mem-
* Present address: Polytechnic
Institute of Brooklyn, Brooklyn, New York.
