- Email: [email protected]
The preparation and properties of a hydrous ruthenium oxide
JOURNAL OF THE LESS-COMMON METALS
460
THE PREPARATION AND PROPERTIES A HYDROUS RUTHENIUM OXIDE
OF
C. J, I
Nickel
Company
(Mond.) Limited, Development Loxdosz (Great Britain)
and Research
Department.
J. P. REDFERN Inorganic Research Laboratories, Chew&ivy Department, London (Great Britain)
Battersea College
ofTechnology,
(Revised version received March I rth, 1962)
SUMMARY The preparation of a hydrous ruthenium oxide empirical formula RuOzHzO has been assigned. haviour has been studied. The kinetics of the evaluated for the reaction : Ru02H20 --f RuOz + and the anhydrous oxide (below r,~oo”C) show preliminary infra-red and X-ray studies yielded
is described to which the Its thermogravimetric bedecomposition have been HzO. The hydrous material catalytic properties. Some little positive information.
INTRODUCTION
Several oxides of ruthenium have been reportedibut only the tetroxides and the dioxiderT+9 have been well characterised. In the case of hydrated and hydrous ruthenium oxides, the situation is even less well defined. W~~HLER~ obtained a hydrated ruthenium dioxide of the composition Ru02(0H& while CHARONNATIO claimed to have obtained Ru(OH)a by the oxidation of Ru(OH)s by air. ANDERSON AND MCCONNELL~I stated that the end-product of the hydrolysis of Ru(IV) in nitric acid was Ru(OH)d. (H20)~ while CONNICK AND HURLEY~~ prepared RuO~zH20 by acidifying an alkaline solution of a ruthenate. They showed that, after washing and drying for three hours at 140°C the X-ray pattern was not that of RuOx. When heated to 700°C in a stream of dry oxygen the weight loss was 22% (theoretical requires 20.0%) and the X-ray pattern corresponded to Ru0~ During the course of studying methods for the recovery of ruthenium from the tetroxide it was discovered that, on reacting molten ruthenium tetroxide with hydrogen, a black precipitate was formed 13. The nature of the reaction suggests that the compound is probably a hydrous oxide of ruthenium. The preparation, the assignment of an empirical formula, thermogravimetric, preliminary infra-red and X-ray studies are reported. * Present address: John I,aing Research and Development Herts. (Great Britain).
Limited, Manor Way, Boreham Wood,
J. Less-Covnmon Metals, 4 (1962) 460-465
EXPERIMENTAL
Preparation h convenient quantity of material was prepared by reacting a mixture of 50 g ruthenium tetroxide and 60 ml water with hydrogen at 00 p.s.i. and 45-5o’C in a glass pressure vessel* from which all the air was displaced by hydrogen before assembl!.. The reaction mixture was maintained at 35-50°C by means of a water-bath and the pressure vessel shaken to achieve maximum mixing of the contents. (Ruthenium tetroxide is a highly reactive material, consequently, n-hen working with this c-ompound, the operator should protect himself by wearing gloves and safety spectack~s, and carrv out manipulations behind a safetv screen ant1 in a fume-cupboard lvitlr toughened glass windows.) The reaction was allowed to proceed for five hours; the apparatus \z’as tlismantl~d and the product filtered on a No. 3 porosity sinteretl-glass filter funnel, wash~l with hot water to remo\.e residual tetrosicle and finally dried to constant weight at xoocC.
The compound, dried to constant weight, was annlysccl for ruthenium b!. ignition under hydrogen and weighing as elemental ruthenium. The weight loss between IOO” and 550°C was determined using a thermobalance. (On exposure to air in the crucible at room temperature the compound adsorbed moisture. As the temperature \vas raised this was lost around 75” and upwards. If the heating was stopped at this point, on cooling the compound readsorbed moisture. Abo\*e IIO’C the loss of water was not reversible.)
Results
obtained
on various batches
were as follows :
In order to establish that the weight loss was attributable to water vapour only, the sample, previously dried to constant weight at IOO’C, was heated in a stream of argon to rjo”C.
Ko other gas besides water vapour was detected.
The weight loss of the compound on heating in air was studied using a Stanton Thermobalnnce (Model HT-D) which was programmed for a linear temperature rise from room temperature to 1,400’C over periods of four, eight and twelve hours. l’rixfired recrpstallised alumina crucibles were used throughout. The plot of rate of weight loss against temperature is given in Fig. I. At temperatures exceeding 1,300°C a further weight loss becomes apparent. This corresponds to the oxidation of the dioxide and its volatilisation as the tetroxicleiJ. If the temperature is maintained at 1,400”C complete weight loss is observed. Otlaev studies X-ray
powder
diagrams
of various
samples
of the compound
heated
at certain
C. J. KEATTCH, J. I?. REDFERN
462
fixed temperatures were taken with a 9.0 cm Unicam Powder Camera using Cu KLX radiation with a nickel filter. The results are recorded in Table1 together with details of the colour of the material and a qualitative indication of its catalytic properties (as measured by the compound’s ability to decompose 300 vol. hydrogen peroxide).
3C
I
,
2i
z E
2c
10
3 t t:
3
15
fC
OE
Fig. I. Differential thermogravimetric cm-ve of a hydrous ruthenium oxide. Weight of sample: 222.4 mg. Rate of heating I [GO/h. I&-fired recrystallised alumina crucible. Chart speed 12 in.jh. TABLE X-RAY
DIFFRACTION
X-my
PATTERNS
AND
OTHER
PROPERTIES
pattevn
110
Black
No discernable pattern-material amorphous to X-rays
587 740 895
Black Black Black
Pattern of RuOa with diffuse diffraction 1 lines
Blue
Sharp pattern of crystalline RuOs
1x20
I
* As revealed by the decomposition
Strongly catalytic
Ru02HsO
Strongly catalytic Strongly catalytic Strongly catalytic Negligibly
of 300 volume:
RuOp RuOz RuOz
catalytic
RuOz
hydrogen peroxide
Moisture is avidly adsorbed by the material and the extent to which this occurs is dependent on the conditions; for example, in the presence of de-aerated water and under an atmosphere of nitrogen at ZO’C, the uptake of water, from the vapour, is about 4% by weight. Such moisture is lost when the material is maintained at a temperature of IOO’C for two hours, constant weight being achieved. Infra-red studies were made with a Grubb-Parsons Spectrophotometer in the region J.
Less-Co~~o~~
Mefals,
4 (1962) 460-465
HYDROUS RI.THEKIUM OxIDE of 5-7 p and 2.594 p. The Nujol countered
in obtaining
Mull technique
any useful information
was employed.
$)3 Difficulty
from these studies possibly
was CIP due to the
extreme difficulty in grinding the material sufficiently fine to make a satisfactor! mull. However, the dehydrated compound which had been heated at Aoo”C, the hydrous oxicle dried to constant weight at IOO’C and the compound which was allo\v~tl to stand in contact with saturated water vapour for some 24 h at room temperature were examined. For the hydrous oxide no water bands as such were discerned but only a slight flattening in the region 5.8M.3 ,u when compared with the dehydratytl material. The compound which had been in contact v;ith water vapour showed a \.t:ry weak band between
5.8-6.5
p with a maximum
at 6.x ,u. Sothing
was observctl
in
the 2.5-4 ,u region.
The experimental results suggest that the compound has an empirical formula RuOzHzO, and that it adsorbs moisture reversibly. From the rate of weight loss curvt’ (Fig. I) it is not easy to distinguish between the moisture which the compound has adsorbed on exposure to air in the thermobalance and the actual loss of bonded water. It will be seen, however, that water is lost below 10o“C. The kinetics of decomposition of the compound were examined by the method of FREEMAN AND C~RKOIL~~ who derived the equation :
where
E* = the activation I 7‘
energy of the reaction
= the kinetic order of the reaction : the absolute temperature
X = the general gas constant and W, = W, - W, where W, is the weight and W the total weight loss up to time t. A plot of
loss at the completion
of the reaction
dzo
‘4 log WV
a@iinSt
_I(T-1) ~--~ .1 log II’,
should result in a linear plot having a slope of -E*/2.3K and an intercept corrcspontling to X. The results are given in Fig. 2. The derived points fall into two distinct classes A and R. The random scatter of points (A) are derived from the weight loss occurring below IOO’C. A scatter of points is sometimes observed for the very early stages of a decomposition due perhaps to a rather long induction period and to the difficulty of accurately assessing a slow weight loss. However, the scatter is somewhat greater than that normally encountered and may possibly be due to the driving off of the
C. J. KEATTCH,
464 reversibly bonded
adsorbed water.
this region. water
The
The
according
moisture
as well as the actual
FREEMAN-CARROLL
remaining
points
equation
This rising
of the loss of the
not be expected line
and apply
to apply
in
to the loss of
to the reaction:
is a single
chemical
By
process
calculation,
portion
commencement would
(B) lie on a straight
RuOzHzO(s)
applicable.
J. P. REDFERN
of the rate
+ RuOz(s) + HzO(g)
and the FREEMAN-CARROLL
the activation of weight
energy
loss curve)
I
treatment
for the reaction is 21.5 kcal/gmole
is therefore
(derived
from
the
and the reaction
0
05
10 102
15
-A CT-‘)
20
0 K-l
4 log WY
Fig. 2. Kinetics of the reaction RuOzHzO(s) has a kinetic evidenced
order
of the displaced
water
If the material
lack
of X-ray that
a non-ordered diffraction
a single
may
it would
indicate
structure
obtained
after
is difficult
is possibly
that
heating
have
behaviour is being hydroxy
shown
that
pattern
mixtures
thermogravimetrically.
the compound
involving
as is
adsorption
to show a complicated
AND NEHRING~~
compound
to achieve
due to the strong
productre.
be expected
show additive
amorphous
cross-linked
patterns
of dehydration
2. This
WIEDEMANN oxalates
pattern
stage
upon the decomposition
Thus
and magnesium
therefore,
final
tail in Fig.
were a mixture
of decomposition. nickel
of 2. The
by the skew
+ RuOz(s) + HsO(g).
is amorphous.
investigated or Hz0
to the various
intermediate
J. Less-Common
Metals,
It is likely,
which
bridgingls.
of The
may
have
The diffuse temperatures
4 (1962) 460-465
HYDROUS
RUTHENIUM
465
OXIDE
indicate the growth of a crystalline form of RuOz, and the sharpening of the lines after heating to I,IZO’C probably indicate growth of crystalline size. The catalytic activity must presumably be ascribed to a large surface area, associated with the fine grain-size. ACKNOWLEDGEMENT
One of us (C.J.K.) wishes to thank The International Nickel Company (Mond.) Limited for permission to publish this paper, and both authors are indebted to Mr. H. C. ANGE of The International Nickel Company (Mond.) L imited, for the X-ray diffraction photographs and to Dr. G. M. LGKASZEWSKI (Rattersea College of Technology) for helpful discussions. REFERENOES 1 C. E. CLAUS, .4nn. Chew
L.iebigs, =,9 (1846)
214,
,ai\.GUTBIER AND F. "RANsoHoF&,Z. anorg. Chem.,'45(19og) 243. 0 c‘.E. CLAUS, BuEI. acad. xi. St.Peter&, I (1860) 9j'. f,II.DEBRXY AND X. JOLY, Cow@. rewd., 106 (1888) IOO. 7 F. KRAUSS AND G. SCKRBDER, Z. avzwg. C.&em.,176 (1928) 385. 8 1,.WT'SHLER et &.,Z. ayzorg. Chem., 139 (1924) 205. 9 S. AOYAMA, Z. axorg.Chem., 138 (1924) 249. 1’) R. CHARONNAT, /Inn. chim. etphys., 16 (1931) 13. 11 J. S. ANDERSON AND J. D. M. MCCOKNELL,]. Inorg. and Nucl. Chem., I (1955) 371. 12 R. E. CONNICK AND C. R. HURLEY,]. Anr. Chem.Soc., 74 (1952) 5olr. '3 British Patent Appl., 27573/60. 1.1 I”. F. CAMPBELL. M. H. ORTNER AND C. 1. ANDERSON. AnaI.Chesn.. ?? ir961\ 58. 1: E. S. FREEMAN AND B. CARROLL, J. Phy;. Chem., 62 (1958) 394. “- ’ . ’ .’ 1s~W. E. GARNER. Chemistry of the S&d State. Butterworths Sci. Publ.. London. 1455. D. 21% I _... 1 17 H. G. ~~IEDE~I~~NN ANI) 5. ~JEHRING,~. atzorg. Ckem., 304 (1960) 137. 18 G. II%.LUKASZEWSKI AND J. P. REDFERN, ?iatuv~,190 (1961) Raj. J. Lxss-Common
Metals,
4 (rgfjr) 460-465
460
THE PREPARATION AND PROPERTIES A HYDROUS RUTHENIUM OXIDE
OF
C. J, I
Nickel
Company
(Mond.) Limited, Development Loxdosz (Great Britain)
and Research
Department.
J. P. REDFERN Inorganic Research Laboratories, Chew&ivy Department, London (Great Britain)
Battersea College
ofTechnology,
(Revised version received March I rth, 1962)
SUMMARY The preparation of a hydrous ruthenium oxide empirical formula RuOzHzO has been assigned. haviour has been studied. The kinetics of the evaluated for the reaction : Ru02H20 --f RuOz + and the anhydrous oxide (below r,~oo”C) show preliminary infra-red and X-ray studies yielded
is described to which the Its thermogravimetric bedecomposition have been HzO. The hydrous material catalytic properties. Some little positive information.
INTRODUCTION
Several oxides of ruthenium have been reportedibut only the tetroxides and the dioxiderT+9 have been well characterised. In the case of hydrated and hydrous ruthenium oxides, the situation is even less well defined. W~~HLER~ obtained a hydrated ruthenium dioxide of the composition Ru02(0H& while CHARONNATIO claimed to have obtained Ru(OH)a by the oxidation of Ru(OH)s by air. ANDERSON AND MCCONNELL~I stated that the end-product of the hydrolysis of Ru(IV) in nitric acid was Ru(OH)d. (H20)~ while CONNICK AND HURLEY~~ prepared RuO~zH20 by acidifying an alkaline solution of a ruthenate. They showed that, after washing and drying for three hours at 140°C the X-ray pattern was not that of RuOx. When heated to 700°C in a stream of dry oxygen the weight loss was 22% (theoretical requires 20.0%) and the X-ray pattern corresponded to Ru0~ During the course of studying methods for the recovery of ruthenium from the tetroxide it was discovered that, on reacting molten ruthenium tetroxide with hydrogen, a black precipitate was formed 13. The nature of the reaction suggests that the compound is probably a hydrous oxide of ruthenium. The preparation, the assignment of an empirical formula, thermogravimetric, preliminary infra-red and X-ray studies are reported. * Present address: John I,aing Research and Development Herts. (Great Britain).
Limited, Manor Way, Boreham Wood,
J. Less-Covnmon Metals, 4 (1962) 460-465
EXPERIMENTAL
Preparation h convenient quantity of material was prepared by reacting a mixture of 50 g ruthenium tetroxide and 60 ml water with hydrogen at 00 p.s.i. and 45-5o’C in a glass pressure vessel* from which all the air was displaced by hydrogen before assembl!.. The reaction mixture was maintained at 35-50°C by means of a water-bath and the pressure vessel shaken to achieve maximum mixing of the contents. (Ruthenium tetroxide is a highly reactive material, consequently, n-hen working with this c-ompound, the operator should protect himself by wearing gloves and safety spectack~s, and carrv out manipulations behind a safetv screen ant1 in a fume-cupboard lvitlr toughened glass windows.) The reaction was allowed to proceed for five hours; the apparatus \z’as tlismantl~d and the product filtered on a No. 3 porosity sinteretl-glass filter funnel, wash~l with hot water to remo\.e residual tetrosicle and finally dried to constant weight at xoocC.
The compound, dried to constant weight, was annlysccl for ruthenium b!. ignition under hydrogen and weighing as elemental ruthenium. The weight loss between IOO” and 550°C was determined using a thermobalance. (On exposure to air in the crucible at room temperature the compound adsorbed moisture. As the temperature \vas raised this was lost around 75” and upwards. If the heating was stopped at this point, on cooling the compound readsorbed moisture. Abo\*e IIO’C the loss of water was not reversible.)
Results
obtained
on various batches
were as follows :
In order to establish that the weight loss was attributable to water vapour only, the sample, previously dried to constant weight at IOO’C, was heated in a stream of argon to rjo”C.
Ko other gas besides water vapour was detected.
The weight loss of the compound on heating in air was studied using a Stanton Thermobalnnce (Model HT-D) which was programmed for a linear temperature rise from room temperature to 1,400’C over periods of four, eight and twelve hours. l’rixfired recrpstallised alumina crucibles were used throughout. The plot of rate of weight loss against temperature is given in Fig. I. At temperatures exceeding 1,300°C a further weight loss becomes apparent. This corresponds to the oxidation of the dioxide and its volatilisation as the tetroxicleiJ. If the temperature is maintained at 1,400”C complete weight loss is observed. Otlaev studies X-ray
powder
diagrams
of various
samples
of the compound
heated
at certain
C. J. KEATTCH, J. I?. REDFERN
462
fixed temperatures were taken with a 9.0 cm Unicam Powder Camera using Cu KLX radiation with a nickel filter. The results are recorded in Table1 together with details of the colour of the material and a qualitative indication of its catalytic properties (as measured by the compound’s ability to decompose 300 vol. hydrogen peroxide).
3C
I
,
2i
z E
2c
10
3 t t:
3
15
fC
OE
Fig. I. Differential thermogravimetric cm-ve of a hydrous ruthenium oxide. Weight of sample: 222.4 mg. Rate of heating I [GO/h. I&-fired recrystallised alumina crucible. Chart speed 12 in.jh. TABLE X-RAY
DIFFRACTION
X-my
PATTERNS
AND
OTHER
PROPERTIES
pattevn
110
Black
No discernable pattern-material amorphous to X-rays
587 740 895
Black Black Black
Pattern of RuOa with diffuse diffraction 1 lines
Blue
Sharp pattern of crystalline RuOs
1x20
I
* As revealed by the decomposition
Strongly catalytic
Ru02HsO
Strongly catalytic Strongly catalytic Strongly catalytic Negligibly
of 300 volume:
RuOp RuOz RuOz
catalytic
RuOz
hydrogen peroxide
Moisture is avidly adsorbed by the material and the extent to which this occurs is dependent on the conditions; for example, in the presence of de-aerated water and under an atmosphere of nitrogen at ZO’C, the uptake of water, from the vapour, is about 4% by weight. Such moisture is lost when the material is maintained at a temperature of IOO’C for two hours, constant weight being achieved. Infra-red studies were made with a Grubb-Parsons Spectrophotometer in the region J.
Less-Co~~o~~
Mefals,
4 (1962) 460-465
HYDROUS RI.THEKIUM OxIDE of 5-7 p and 2.594 p. The Nujol countered
in obtaining
Mull technique
any useful information
was employed.
$)3 Difficulty
from these studies possibly
was CIP due to the
extreme difficulty in grinding the material sufficiently fine to make a satisfactor! mull. However, the dehydrated compound which had been heated at Aoo”C, the hydrous oxicle dried to constant weight at IOO’C and the compound which was allo\v~tl to stand in contact with saturated water vapour for some 24 h at room temperature were examined. For the hydrous oxide no water bands as such were discerned but only a slight flattening in the region 5.8M.3 ,u when compared with the dehydratytl material. The compound which had been in contact v;ith water vapour showed a \.t:ry weak band between
5.8-6.5
p with a maximum
at 6.x ,u. Sothing
was observctl
in
the 2.5-4 ,u region.
The experimental results suggest that the compound has an empirical formula RuOzHzO, and that it adsorbs moisture reversibly. From the rate of weight loss curvt’ (Fig. I) it is not easy to distinguish between the moisture which the compound has adsorbed on exposure to air in the thermobalance and the actual loss of bonded water. It will be seen, however, that water is lost below 10o“C. The kinetics of decomposition of the compound were examined by the method of FREEMAN AND C~RKOIL~~ who derived the equation :
where
E* = the activation I 7‘
energy of the reaction
= the kinetic order of the reaction : the absolute temperature
X = the general gas constant and W, = W, - W, where W, is the weight and W the total weight loss up to time t. A plot of
loss at the completion
of the reaction
dzo
‘4 log WV
a@iinSt
_I(T-1) ~--~ .1 log II’,
should result in a linear plot having a slope of -E*/2.3K and an intercept corrcspontling to X. The results are given in Fig. 2. The derived points fall into two distinct classes A and R. The random scatter of points (A) are derived from the weight loss occurring below IOO’C. A scatter of points is sometimes observed for the very early stages of a decomposition due perhaps to a rather long induction period and to the difficulty of accurately assessing a slow weight loss. However, the scatter is somewhat greater than that normally encountered and may possibly be due to the driving off of the
C. J. KEATTCH,
464 reversibly bonded
adsorbed water.
this region. water
The
The
according
moisture
as well as the actual
FREEMAN-CARROLL
remaining
points
equation
This rising
of the loss of the
not be expected line
and apply
to apply
in
to the loss of
to the reaction:
is a single
chemical
By
process
calculation,
portion
commencement would
(B) lie on a straight
RuOzHzO(s)
applicable.
J. P. REDFERN
of the rate
+ RuOz(s) + HzO(g)
and the FREEMAN-CARROLL
the activation of weight
energy
loss curve)
I
treatment
for the reaction is 21.5 kcal/gmole
is therefore
(derived
from
the
and the reaction
0
05
10 102
15
-A CT-‘)
20
0 K-l
4 log WY
Fig. 2. Kinetics of the reaction RuOzHzO(s) has a kinetic evidenced
order
of the displaced
water
If the material
lack
of X-ray that
a non-ordered diffraction
a single
may
it would
indicate
structure
obtained
after
is difficult
is possibly
that
heating
have
behaviour is being hydroxy
shown
that
pattern
mixtures
thermogravimetrically.
the compound
involving
as is
adsorption
to show a complicated
AND NEHRING~~
compound
to achieve
due to the strong
productre.
be expected
show additive
amorphous
cross-linked
patterns
of dehydration
2. This
WIEDEMANN oxalates
pattern
stage
upon the decomposition
Thus
and magnesium
therefore,
final
tail in Fig.
were a mixture
of decomposition. nickel
of 2. The
by the skew
+ RuOz(s) + HsO(g).
is amorphous.
investigated or Hz0
to the various
intermediate
J. Less-Common
Metals,
It is likely,
which
bridgingls.
of The
may
have
The diffuse temperatures
4 (1962) 460-465
HYDROUS
RUTHENIUM
465
OXIDE
indicate the growth of a crystalline form of RuOz, and the sharpening of the lines after heating to I,IZO’C probably indicate growth of crystalline size. The catalytic activity must presumably be ascribed to a large surface area, associated with the fine grain-size. ACKNOWLEDGEMENT
One of us (C.J.K.) wishes to thank The International Nickel Company (Mond.) Limited for permission to publish this paper, and both authors are indebted to Mr. H. C. ANGE of The International Nickel Company (Mond.) L imited, for the X-ray diffraction photographs and to Dr. G. M. LGKASZEWSKI (Rattersea College of Technology) for helpful discussions. REFERENOES 1 C. E. CLAUS, .4nn. Chew
L.iebigs, =,9 (1846)
214,
,ai\.GUTBIER AND F. "RANsoHoF&,Z. anorg. Chem.,'45(19og) 243. 0 c‘.E. CLAUS, BuEI. acad. xi. St.Peter&, I (1860) 9j'. f,II.DEBRXY AND X. JOLY, Cow@. rewd., 106 (1888) IOO. 7 F. KRAUSS AND G. SCKRBDER, Z. avzwg. C.&em.,176 (1928) 385. 8 1,.WT'SHLER et &.,Z. ayzorg. Chem., 139 (1924) 205. 9 S. AOYAMA, Z. axorg.Chem., 138 (1924) 249. 1’) R. CHARONNAT, /Inn. chim. etphys., 16 (1931) 13. 11 J. S. ANDERSON AND J. D. M. MCCOKNELL,]. Inorg. and Nucl. Chem., I (1955) 371. 12 R. E. CONNICK AND C. R. HURLEY,]. Anr. Chem.Soc., 74 (1952) 5olr. '3 British Patent Appl., 27573/60. 1.1 I”. F. CAMPBELL. M. H. ORTNER AND C. 1. ANDERSON. AnaI.Chesn.. ?? ir961\ 58. 1: E. S. FREEMAN AND B. CARROLL, J. Phy;. Chem., 62 (1958) 394. “- ’ . ’ .’ 1s~W. E. GARNER. Chemistry of the S&d State. Butterworths Sci. Publ.. London. 1455. D. 21% I _... 1 17 H. G. ~~IEDE~I~~NN ANI) 5. ~JEHRING,~. atzorg. Ckem., 304 (1960) 137. 18 G. II%.LUKASZEWSKI AND J. P. REDFERN, ?iatuv~,190 (1961) Raj. J. Lxss-Common
Metals,
4 (rgfjr) 460-465