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Heat capacities of some dilute alloys
Physica 28 181-183
Du Chatenier, F. J. De Nobel, J. 1962
LETTER
TO THE
Heat capacities
EDITOR
of some dilute alloys
In a previous publicationi), specific heats of some dilute alloys of manganese in silver and copper at low temperatures were reported. Afterwards measurements were performed on other dilute alloys (concentrations up to 1 at. %) of the first row of transition elements in silver, copper, zinc and aluminium. Although this program has not yet been finished, it seems worthwhile to give the results without considering theoretical aspects. As the guiding principle for the measurements and the choice of the alloys, we accepted a diagram given by Fried ela), in which the alloys which are expected to show correlation effects are indicated. In this diagram (table I) we marked the alloys for which we found an anomaly in the specific heat. We also marked the alloys for which anomalies in the specific heat or the electrical resistance were reported by other investigators. TABLE
I
Occurrence of anomalies in the resistance and the heat capacity of alloys. Friedel expects correlation effects above the heavy line in the diagram.
;
Au
Cr
+
Mll
+
~
Ag
~
l
+
Cu
0
?
.
+
(
Mg
/
/
+
0
03).
Zn
+
A6)
___-
+
Al
A
.-
A?
A
A
I Fe
+04).
+
+
As) I
co
+
+
Ni
?
?
+ -
resistance resistance
l
specific specific
0 A A ?
05)
?
A
shows an anomaly shows no anomaly heat heat
no specific
anomaly anomaly
heat
observed observed
by us by other
investigators
anomaly
observed
by us
no specific heat anomaly dubious anomalv.
observed
by others
-
181 -
F. 1. DU CHATENIER
182 From
our results
anomaly
for cobalt
was of the same
AND
in copper,
kind
1. DE NOBEL
no conclusion
as e.g. that
could
observed
be obtained
for manganese
whether
in copper.
tht Tht
mJ mole-K
1c
4
0:
Fig.
1. Molar
heat capacity
3
experimental
ii __-
US. temperature points points
experimental theoretical
curves
II
of pure Au, Ag and Cu. y characterizes the electronic part lattice
~
%y;
Au
I
99.9999
’
0.740
Ag
1
99.9999
1
0.682
Cu
of Mn in Cu.
1.0 at. o/0 Mn 0.135 at. o/0 Mn
for 0~ = 0.0238”K.
TABLE The heat capacities
for two alloys
for Cu for Cu -
1 ,io,
0.721
and 8~ the
part of the heat capacity.
1
1
“d$
/
oy
(
Od$)
)
w..)
165.2
165.2
167.0
169.8
226.2
221.1
211.8
212.”
338.9
338.9
323.2
307.8
HEAT CAPACITIES
OF SOME DILUTE
ALLOYS
183
change in specific heat could as well be a simple change in the electronic part of the specific heat. Recent results of C r a n e and 2 i m m e r m a n 5) for higher concentrations of cobalt show anomalies due to correlation effects. As for the aluminium alloys a small shift in the superconductivity transition point, but no other anomalies were observed. This is in agreement with results found by Martin 7) for Al-Mn alloys. In order to get a reference, especially in the region between 4°K and 30”K, measurements were carried out on pure gold, silver and copper from 1°K up to 30°K. The results are given in table II. Miedema and one of us (du Ch.) measured the specific heat of some Cu-Mn alloys below 1“K. The experimental procedure which involves adiabatic demagnetization and continuously cooling down of the sample has been described elsewhere Q). The shape of the anomaly in the specific heat vs. temperature curve has been predicted by several investigators (e.g. Marshall 9)). No exact conclusion could be obtained by us because of the steep rise of the specific heat that can be interpreted in terms of the interaction of the electronic and nuclear moments of the manganese ions. The interaction energy can be represented by E = --AS. I where (for the Mn++ ion) S = 5/Z and I = 5/Z. At temperatures high compared with the splitting parameter 0~ = 5A/Zk, the heat capacity anomaly has a tail given by C = (35/12) R(84/T)Q. The measurements have been plotted in fig. 1 on a logarithmic scale. This figure has been completed with results obtained at higher temperatures. The splitting parameter is 0~ = 0.0238”K corresponding to A = 0.0067 cm- 1. It is interesting to note that one usually finds higher values for these h.f.s. constants e.g. Cooke and EdmondslQ) found for manganous fluoride A = 0.0092 cm-i and Tin k ham ii) for small amounts of manganese in a zinc fluoride crystal A = 0.0096 cm-l. Details about our measurements will be published in this journal. This investigation is a part of the research program of the “Stichting voor Fundamenteel Onderzoek der Materie (F.O.M.)” and was made possible by financial support from the “Nederlandse Organisatie voor Zuiver Wetenschappelijk Onderzoek (Z.W.O.)” and the “Nederlandse Centrale Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (T.N.O.)“. Received 16-12-61 F. J. DU CHATENIER J. DE NOBEL Kamerlingh Onnes Laboratorium Leiden, Nederland
REFERENCES 1) De Nobel, J. and DuChatenier, F. J., Commun. Kamerlingh Onnes Lab., Leiden, NO. 317~; Physica 25 (1959) 969. 2) Blandin, A. and Friedel, J., J. Phys. Rad. 20 (1959) 160. 3) Zimmerman, J. E. and Hoare, F. E., J. Phys. Chem. Solids 17 (1960) 52. 4) Martin, D. L. and Franck, J. P., Proc. 7th. Int. Conf. on Low Temperature Physics (University of Toronto Press, Toronto 1960) p. 262. 5) Crane, L. T. and Zimmerman, J. E., Phys. Rev. 123 (1961) 113. 6) Logan, J. K., Clement, J. R. and Jeffers, H. R., Phys. Rev. 105 (1957) 1435. 7) Martin, D. L., not yet published. 8) Haseda, T. and Miedema, A. R., Commun. No. 329~; Physica 27 (1961) 908. 9) Marshall, W., Phys. Rev. 118 (1960) 1519. 10) Cooke, A. H. and Edmonds, D. T., Proc. phys. Sot. 71 (1958) 517. 11) Tinkham, M., Proc. roy. Sot. A 236 (1956) 535.
Du Chatenier, F. J. De Nobel, J. 1962
LETTER
TO THE
Heat capacities
EDITOR
of some dilute alloys
In a previous publicationi), specific heats of some dilute alloys of manganese in silver and copper at low temperatures were reported. Afterwards measurements were performed on other dilute alloys (concentrations up to 1 at. %) of the first row of transition elements in silver, copper, zinc and aluminium. Although this program has not yet been finished, it seems worthwhile to give the results without considering theoretical aspects. As the guiding principle for the measurements and the choice of the alloys, we accepted a diagram given by Fried ela), in which the alloys which are expected to show correlation effects are indicated. In this diagram (table I) we marked the alloys for which we found an anomaly in the specific heat. We also marked the alloys for which anomalies in the specific heat or the electrical resistance were reported by other investigators. TABLE
I
Occurrence of anomalies in the resistance and the heat capacity of alloys. Friedel expects correlation effects above the heavy line in the diagram.
;
Au
Cr
+
Mll
+
~
Ag
~
l
+
Cu
0
?
.
+
(
Mg
/
/
+
0
03).
Zn
+
A6)
___-
+
Al
A
.-
A?
A
A
I Fe
+04).
+
+
As) I
co
+
+
Ni
?
?
+ -
resistance resistance
l
specific specific
0 A A ?
05)
?
A
shows an anomaly shows no anomaly heat heat
no specific
anomaly anomaly
heat
observed observed
by us by other
investigators
anomaly
observed
by us
no specific heat anomaly dubious anomalv.
observed
by others
-
181 -
F. 1. DU CHATENIER
182 From
our results
anomaly
for cobalt
was of the same
AND
in copper,
kind
1. DE NOBEL
no conclusion
as e.g. that
could
observed
be obtained
for manganese
whether
in copper.
tht Tht
mJ mole-K
1c
4
0:
Fig.
1. Molar
heat capacity
3
experimental
ii __-
US. temperature points points
experimental theoretical
curves
II
of pure Au, Ag and Cu. y characterizes the electronic part lattice
~
%y;
Au
I
99.9999
’
0.740
Ag
1
99.9999
1
0.682
Cu
of Mn in Cu.
1.0 at. o/0 Mn 0.135 at. o/0 Mn
for 0~ = 0.0238”K.
TABLE The heat capacities
for two alloys
for Cu for Cu -
1 ,io,
0.721
and 8~ the
part of the heat capacity.
1
1
“d$
/
oy
(
Od$)
)
w..)
165.2
165.2
167.0
169.8
226.2
221.1
211.8
212.”
338.9
338.9
323.2
307.8
HEAT CAPACITIES
OF SOME DILUTE
ALLOYS
183
change in specific heat could as well be a simple change in the electronic part of the specific heat. Recent results of C r a n e and 2 i m m e r m a n 5) for higher concentrations of cobalt show anomalies due to correlation effects. As for the aluminium alloys a small shift in the superconductivity transition point, but no other anomalies were observed. This is in agreement with results found by Martin 7) for Al-Mn alloys. In order to get a reference, especially in the region between 4°K and 30”K, measurements were carried out on pure gold, silver and copper from 1°K up to 30°K. The results are given in table II. Miedema and one of us (du Ch.) measured the specific heat of some Cu-Mn alloys below 1“K. The experimental procedure which involves adiabatic demagnetization and continuously cooling down of the sample has been described elsewhere Q). The shape of the anomaly in the specific heat vs. temperature curve has been predicted by several investigators (e.g. Marshall 9)). No exact conclusion could be obtained by us because of the steep rise of the specific heat that can be interpreted in terms of the interaction of the electronic and nuclear moments of the manganese ions. The interaction energy can be represented by E = --AS. I where (for the Mn++ ion) S = 5/Z and I = 5/Z. At temperatures high compared with the splitting parameter 0~ = 5A/Zk, the heat capacity anomaly has a tail given by C = (35/12) R(84/T)Q. The measurements have been plotted in fig. 1 on a logarithmic scale. This figure has been completed with results obtained at higher temperatures. The splitting parameter is 0~ = 0.0238”K corresponding to A = 0.0067 cm- 1. It is interesting to note that one usually finds higher values for these h.f.s. constants e.g. Cooke and EdmondslQ) found for manganous fluoride A = 0.0092 cm-i and Tin k ham ii) for small amounts of manganese in a zinc fluoride crystal A = 0.0096 cm-l. Details about our measurements will be published in this journal. This investigation is a part of the research program of the “Stichting voor Fundamenteel Onderzoek der Materie (F.O.M.)” and was made possible by financial support from the “Nederlandse Organisatie voor Zuiver Wetenschappelijk Onderzoek (Z.W.O.)” and the “Nederlandse Centrale Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (T.N.O.)“. Received 16-12-61 F. J. DU CHATENIER J. DE NOBEL Kamerlingh Onnes Laboratorium Leiden, Nederland
REFERENCES 1) De Nobel, J. and DuChatenier, F. J., Commun. Kamerlingh Onnes Lab., Leiden, NO. 317~; Physica 25 (1959) 969. 2) Blandin, A. and Friedel, J., J. Phys. Rad. 20 (1959) 160. 3) Zimmerman, J. E. and Hoare, F. E., J. Phys. Chem. Solids 17 (1960) 52. 4) Martin, D. L. and Franck, J. P., Proc. 7th. Int. Conf. on Low Temperature Physics (University of Toronto Press, Toronto 1960) p. 262. 5) Crane, L. T. and Zimmerman, J. E., Phys. Rev. 123 (1961) 113. 6) Logan, J. K., Clement, J. R. and Jeffers, H. R., Phys. Rev. 105 (1957) 1435. 7) Martin, D. L., not yet published. 8) Haseda, T. and Miedema, A. R., Commun. No. 329~; Physica 27 (1961) 908. 9) Marshall, W., Phys. Rev. 118 (1960) 1519. 10) Cooke, A. H. and Edmonds, D. T., Proc. phys. Sot. 71 (1958) 517. 11) Tinkham, M., Proc. roy. Sot. A 236 (1956) 535.