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The heat capacity of uranium mononitride
JOURNAL
OF NUCLEAR
MATERIALS
THE
HEAT
42 (1972)233-234.0 NORTH-HOLLAND
CAPACITY
OF URANIUM
E. H. P. CORDFUNKE
md
PUBLISHING
CO., AMSTERDAM
MONONITRIDE
R. P. MXIS
Reactor Centrum Nederland, Petten, The Netherlands Received
10 August
The high temperature heat capacity of uranium mononitride has been measured by Speidel and Keller i), by Harrington 3), and more recently by Takahashi et a1.3). The first mentioned two sets of measurements show a considerable disagreement with each other, being about 7 y. at 1000 K. Takahashi et al., using a laser flash method instead of drop calorimetry, in turn arrived at a different set of measurements. The situation thus appears t,o be rabher chaotic. However, Takahashi et al. referred to our unpublished results which appear to be in close agreement with their measurements. For this reason, we give here the full details of our measurements. Uranium mononitride was prepared by heating uranium sesquinitride (in turn prepared from the elements via uraniumhydride) at about 1400 “C in a stream of purified argon. The chemical analyses, performed by the analytical group, are listed in table 1. The oxygen is present partly as a surface contaminant in the form of UO3, and partly as UO in solid solution with UN as determined by the limit of its solubility (5 at %). No correction presence of oxygen has been made.
for the
TABLE 1 Analysis
of the UN
Element
total
Heat content measurements were made in a diphenyl ether calorimeter of the type described by Giguere et a1.4) and (for ice) by Ginnings et al.‘)). The UN-sample (11.9977 g) was encapsulated in a sealed quartz ampoule (2.2402 g) so that the heat content of the sample is about 84% of the total at all temperaTABLE
2 mononitride
v
386.8
1054
397.8
1171
433.2
1610
434.1
1614
463.5
1961
485.4
2251
508.6
2554
513.0
2622
531.1
2889
546.4
3034
589.3
3643
617.5
3981
618.8
3989
638.1
4275
654.3
4459
658.5
4502
677.9
4743
701.3
5074
sample
Amount
tures. For details of the measurements the reader is referred to a article 3). The apparatus has been with the standard substance Al3O3’). Temperature calibrated thermocouples. Weights 3). Corrections were made for the small difference between the calorimeter temperature and the
present (wt %)
U
94.52
N
5.34
0 Al
0.35
Fe
0.045
C
0.045
Si of other impurities
1971
0.015
0.020 0.020 233
E.
234
16
H.
A
Takohashi.et
.
Speidel
P.
CORDFUNKE
R.
P.
MUIS
1
al.
and Keller
0
Harrington
-_
Westrum and Barber present work
o
AND
8
6
0
100
200
300
400
500
600
700
, ‘K
temperature
Fig.
1.
Included
Mean
heat capacity
are data calculated
of uranium
mononitride
standard reference temperature, 298.15 K, using the C&-values at 298.15 K. Heat contents formulae were calculated with an Eleotrologica X-8 computer, using a least squares programme after eliminating two constants with AHma = 0 and C, (298) from low-temperature heat capacity measurements. The difference between the experimental values and the computed data is less than O,5o/o for all measurement. Heat contents of the UN-sample are listed in table 2. The results can be summarized by: HT-H298.15= 0.9516
11.51
x 105 T-l-3891
T+
(cal.mole-l.deg
K-1)
from smoothed functions given by Takahashi Harrington 2) and We&rum and Barber 9).
1.581
x 10-s
!Z’z-i-
(Cal/mole; 298-700
The present results are plotted as mean heat capacities in fig. 1, together with those of the previous investigations. It is evident that our values agree with those of Takahashi et al. The two sets of measurements differ with the older values. In fig. 1, results of the low-temperature heat
of temperature)
Speidel and Keller 1,.
capacity data, by Westrum and Barber 9) are included. Since there is a smooth continuity between the low-temperature data and our high-temperature measurements, it is concluded that the heat capacity of UN is now known over a wide range of temperatures. References 1) E. 0. Speidel and D. L. Keller, BMI-report 2)
(1963) L. C. Harrington,
3)
Y. Takahashi, T. Mukaibo,
K).
as a function et al.*),
4)
CNLM-report
M. Murabayashi, 5. Nuol. Mater.
4461 Y.
1633
(1963)
Akimoto
38 (1971)
and
303
P. A. Giguerre, B. G. Morisette and A. W. Olmos, Can. J. Chem. 33 (1955)
657
5)
D. C. Ginnings and R. J. Corruccini, J. Res. Nat.
6)
Bur. Stand. 38 (1947) 583 E. H. P. Cordfunke, to be published
7)
A. C. Macleod, Trans. Faraday Soe. 63 (1967) 300
8)
A.
9)
Sot. 84 (1962) 4175 E. F. Westrum, Jr. J.
E. Cameron
Chem.
Phys.
and E. Wichers, and
45 (1966)
J. Am.
Carolyn 635
M.
Cbem. Barber,
OF NUCLEAR
MATERIALS
THE
HEAT
42 (1972)233-234.0 NORTH-HOLLAND
CAPACITY
OF URANIUM
E. H. P. CORDFUNKE
md
PUBLISHING
CO., AMSTERDAM
MONONITRIDE
R. P. MXIS
Reactor Centrum Nederland, Petten, The Netherlands Received
10 August
The high temperature heat capacity of uranium mononitride has been measured by Speidel and Keller i), by Harrington 3), and more recently by Takahashi et a1.3). The first mentioned two sets of measurements show a considerable disagreement with each other, being about 7 y. at 1000 K. Takahashi et al., using a laser flash method instead of drop calorimetry, in turn arrived at a different set of measurements. The situation thus appears t,o be rabher chaotic. However, Takahashi et al. referred to our unpublished results which appear to be in close agreement with their measurements. For this reason, we give here the full details of our measurements. Uranium mononitride was prepared by heating uranium sesquinitride (in turn prepared from the elements via uraniumhydride) at about 1400 “C in a stream of purified argon. The chemical analyses, performed by the analytical group, are listed in table 1. The oxygen is present partly as a surface contaminant in the form of UO3, and partly as UO in solid solution with UN as determined by the limit of its solubility (5 at %). No correction presence of oxygen has been made.
for the
TABLE 1 Analysis
of the UN
Element
total
Heat content measurements were made in a diphenyl ether calorimeter of the type described by Giguere et a1.4) and (for ice) by Ginnings et al.‘)). The UN-sample (11.9977 g) was encapsulated in a sealed quartz ampoule (2.2402 g) so that the heat content of the sample is about 84% of the total at all temperaTABLE
2 mononitride
v
386.8
1054
397.8
1171
433.2
1610
434.1
1614
463.5
1961
485.4
2251
508.6
2554
513.0
2622
531.1
2889
546.4
3034
589.3
3643
617.5
3981
618.8
3989
638.1
4275
654.3
4459
658.5
4502
677.9
4743
701.3
5074
sample
Amount
tures. For details of the measurements the reader is referred to a article 3). The apparatus has been with the standard substance Al3O3’). Temperature calibrated thermocouples. Weights 3). Corrections were made for the small difference between the calorimeter temperature and the
present (wt %)
U
94.52
N
5.34
0 Al
0.35
Fe
0.045
C
0.045
Si of other impurities
1971
0.015
0.020 0.020 233
E.
234
16
H.
A
Takohashi.et
.
Speidel
P.
CORDFUNKE
R.
P.
MUIS
1
al.
and Keller
0
Harrington
-_
Westrum and Barber present work
o
AND
8
6
0
100
200
300
400
500
600
700
, ‘K
temperature
Fig.
1.
Included
Mean
heat capacity
are data calculated
of uranium
mononitride
standard reference temperature, 298.15 K, using the C&-values at 298.15 K. Heat contents formulae were calculated with an Eleotrologica X-8 computer, using a least squares programme after eliminating two constants with AHma = 0 and C, (298) from low-temperature heat capacity measurements. The difference between the experimental values and the computed data is less than O,5o/o for all measurement. Heat contents of the UN-sample are listed in table 2. The results can be summarized by: HT-H298.15= 0.9516
11.51
x 105 T-l-3891
T+
(cal.mole-l.deg
K-1)
from smoothed functions given by Takahashi Harrington 2) and We&rum and Barber 9).
1.581
x 10-s
!Z’z-i-
(Cal/mole; 298-700
The present results are plotted as mean heat capacities in fig. 1, together with those of the previous investigations. It is evident that our values agree with those of Takahashi et al. The two sets of measurements differ with the older values. In fig. 1, results of the low-temperature heat
of temperature)
Speidel and Keller 1,.
capacity data, by Westrum and Barber 9) are included. Since there is a smooth continuity between the low-temperature data and our high-temperature measurements, it is concluded that the heat capacity of UN is now known over a wide range of temperatures. References 1) E. 0. Speidel and D. L. Keller, BMI-report 2)
(1963) L. C. Harrington,
3)
Y. Takahashi, T. Mukaibo,
K).
as a function et al.*),
4)
CNLM-report
M. Murabayashi, 5. Nuol. Mater.
4461 Y.
1633
(1963)
Akimoto
38 (1971)
and
303
P. A. Giguerre, B. G. Morisette and A. W. Olmos, Can. J. Chem. 33 (1955)
657
5)
D. C. Ginnings and R. J. Corruccini, J. Res. Nat.
6)
Bur. Stand. 38 (1947) 583 E. H. P. Cordfunke, to be published
7)
A. C. Macleod, Trans. Faraday Soe. 63 (1967) 300
8)
A.
9)
Sot. 84 (1962) 4175 E. F. Westrum, Jr. J.
E. Cameron
Chem.
Phys.
and E. Wichers, and
45 (1966)
J. Am.
Carolyn 635
M.
Cbem. Barber,