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Knight shifts of 31P in the paramagnetic state of the UP-US solid solutions
Volume
28A.
number
2
PHYSICS
KNIGHT
SHIFTS
OF
OF THE
31P
LETTERS
IN THE
UP-US
4 November
PARAMAGNETIC
SOLID
SOLUTIONS
1968
STATE *
M. KUZNIETZ, G. A. Argonne
National Laboratory, Received
Argonne
3 September
I Illinois,
USA
1968
Knight shifts of 31P were measured in the paramagnetic state of UP-US solid solutions. For all compositions K = K, axM, lK,/ cc K, and (Y = 4.0 i- 0.5 (cgs). In the uniform conduction-electronpolarization model J,f = -(2.4 I 0.4) eV is obtained.
Knight shift (K) results for 3lP in the UPlXSX at 300, 232 and 1920K are given in table 1. K increases with the decrease of temperature and with the increase of X, the sulfur concentration. By the use of the molar susceptibility ( xM) data of Allbutt and Junkison [6] (not studied for UPO.8&33), a linear dependence of K on XM is found, K = K. + ‘YxM with IK,l s-
Knight shift measurements have been reported for 3lP in the paramagnetic state of all uranium phosphides (UP, U3P4, and UP2) [l-4]. This letter reports the extension of these measurements to the paramagnetic state of the UP1 _XSX system. UP and US show a complete miscibility. UP is antiferromagnetic and US is ferromagnetic. The UP-US solid solutions have the NaCl-type structure and are good conductors of electricity (p = 200 E.152 -cm at room temperature) [5]. The UP-US solid solutions were prepared by mixing the desired amounts of the UP and US components, pelletizing, and homogenizing in vacuum for three hours at 1800°C. Approximately 1 g of fine powders (- 250 mesh) were used for the NMR measurements. * This work was performed under the auspices United States Atomic Energy Commission.
The temperature
dependence
ff = Jsf Ke k’J -
where J,f is the s-f exchange constant, is the Land6 factor, PB is the Bohr magneton, NA is gJ
of the
of the 31 P Knight
Table 1 shift in the paramagnetic
Magnetic
ordering
$
(OK)
state
of the UP1__$x
system.
K x lo4
TN, TCIP Composition
1)/2gJPB2NA ,
300°K
232OK
192oK
antiferromagnetic
125
200 * 3
270 I 3
330 + 10
upo.95so.05
antiferromagnetic
122
205 + 3
279 + 3
360 f 11
upo.90so.10
antiferromagnetic
102
212 i- 5
302 i 5
372 f 11 410 + 2ott
UP
UPo.afiSo.15
antiferromagnetic
95
220 f 6
322 i 5
up0.i’5s0.25
ferromagnetic
102
232 i 6
355 f 8
520 f 30 XT
up0.67s0.33
ferromagnetic
118
245 -t 6
380 f 20 I$
610 i 503f
UPo.5oSo.50
ferromagnetic
150
266 + 6
345 -I 20 $$
770 f- 65 XX
1 Data obtained in a recent neutron diffraction study [12]. are too wide for CW detection; K determined
I$ NMR lines
122
The ordering refers by pulsed NMR.
to the region
below
TN or TC.
Volume
28A.
” so-
",SO-
x E 3
number
2
PHYSICS
F-If% 0 . h s 0 .
L 0 0.05 0.10 0.1, O.LI 0.*0
I
P
-
s, D lA
z 3
00
tween the uranium ions, with the number of conduction electrons per uranium atom (2) varying from about one in UP to about two in US. This variation is expected to be manifested in the RKKY sums which appear in the RKKY analysis of cy 1111. However, the non-dependence of N on X (or .Z), or the non-oscillatory character of o, indicates that a simple RKKY model is inadequate to describe the Knight shift results in the UP1 _XSX system.
1.
5
I
I
IO
15
I
2. 3.
20
x,x Idkpr, Fig. 1. The dependence the molar susceptibility (with the temperature
November 1968
References
0,
I
4
We wish to thank Dr. G. H. Lander for helpful comments on this letter.
+
40-
20-
LETTERS
of the Knight shift of 31P on in the UP-US solid solutions as an implicit variable).
the Avogadro number, and K, is the Knight shift in the isostructural diamagnetic compound. By using Ke of 31P in ThP [9] + (4.4 f 0.2) x 10-4 and assuming U+4 ions and 5f2 configuration @J = 0.8) [lo], a value of J,f = -(2.4 f 0.4) eV is obtained similar to the value of Jones [2] for U3P4. J,f is negative, as in the lanthanide compounds, but one order of magnitude larger, probably due to the larger extent of the 5f electronic functions. The model proposed to account for the magnetic properties of UP and US and their solid solutions [ lo] suggests RKKY-type interactions be-
4. 5.
6.
7.
8. 9.
10.
11. 12.
B.A. Scott, K. A. Gingerich and R. A. Bernheim. Phys. Rev. 159 (1967) 387. E. D. Jones, Phys. Letters 25A (1967) 111. K. R. K. Easwaran. V. U. S. Rao. R. Vijayaraghavan and V. R. K. Rao. Phys. Letters 25A (1967) 683. F. Friedman, J. Grunzweig and M. Kuznietz, Ph.vs. Letters 25A (1967) 690. Y. Baskin and P. D. Shalek. Proc. Int. Symp. on Compounds of Interest in Nuclear Reactor Technology (Boulder, Colorado. 1965) pp. 457-461; a a paper on the UP-US system has been submitted to J. Am. Ceram. Sot. M. A. Allhutt and A. R. Junkison. Chemistry Division. Harnell. United Kingdom. Report AERE R5465 (1967). M. Kuznietz. submitted to Phys. Rev. W. B. Lewis. S. W. Rabideau. N. H. Krikorian and W. G. Witteman, Phys. Rev. 170 (1968) 455. M.Kuznietz. J. Chem. Phys.. to be published. J. Grunzweig and M. Kuznietz. J. Appl. Phys. 39 J.Grunzweig. M.Kuznietz and F.Friedman. Phys. Rev. 173 (1968) 562. K. H. Buschow, J. F. Fast, A.M. Van Diepen and H. W. De Wijn. Phvs. Stat. Sol. 24 (1967) 714. M. Kuznietz. G. H. Lander and Y. Baskin, to be published.
123
28A.
number
2
PHYSICS
KNIGHT
SHIFTS
OF
OF THE
31P
LETTERS
IN THE
UP-US
4 November
PARAMAGNETIC
SOLID
SOLUTIONS
1968
STATE *
M. KUZNIETZ, G. A. Argonne
National Laboratory, Received
Argonne
3 September
I Illinois,
USA
1968
Knight shifts of 31P were measured in the paramagnetic state of UP-US solid solutions. For all compositions K = K, axM, lK,/ cc K, and (Y = 4.0 i- 0.5 (cgs). In the uniform conduction-electronpolarization model J,f = -(2.4 I 0.4) eV is obtained.
Knight shift (K) results for 3lP in the UPlXSX at 300, 232 and 1920K are given in table 1. K increases with the decrease of temperature and with the increase of X, the sulfur concentration. By the use of the molar susceptibility ( xM) data of Allbutt and Junkison [6] (not studied for UPO.8&33), a linear dependence of K on XM is found, K = K. + ‘YxM with IK,l s-
Knight shift measurements have been reported for 3lP in the paramagnetic state of all uranium phosphides (UP, U3P4, and UP2) [l-4]. This letter reports the extension of these measurements to the paramagnetic state of the UP1 _XSX system. UP and US show a complete miscibility. UP is antiferromagnetic and US is ferromagnetic. The UP-US solid solutions have the NaCl-type structure and are good conductors of electricity (p = 200 E.152 -cm at room temperature) [5]. The UP-US solid solutions were prepared by mixing the desired amounts of the UP and US components, pelletizing, and homogenizing in vacuum for three hours at 1800°C. Approximately 1 g of fine powders (- 250 mesh) were used for the NMR measurements. * This work was performed under the auspices United States Atomic Energy Commission.
The temperature
dependence
ff = Jsf Ke k’J -
where J,f is the s-f exchange constant, is the Land6 factor, PB is the Bohr magneton, NA is gJ
of the
of the 31 P Knight
Table 1 shift in the paramagnetic
Magnetic
ordering
$
(OK)
state
of the UP1__$x
system.
K x lo4
TN, TCIP Composition
1)/2gJPB2NA ,
300°K
232OK
192oK
antiferromagnetic
125
200 * 3
270 I 3
330 + 10
upo.95so.05
antiferromagnetic
122
205 + 3
279 + 3
360 f 11
upo.90so.10
antiferromagnetic
102
212 i- 5
302 i 5
372 f 11 410 + 2ott
UP
UPo.afiSo.15
antiferromagnetic
95
220 f 6
322 i 5
up0.i’5s0.25
ferromagnetic
102
232 i 6
355 f 8
520 f 30 XT
up0.67s0.33
ferromagnetic
118
245 -t 6
380 f 20 I$
610 i 503f
UPo.5oSo.50
ferromagnetic
150
266 + 6
345 -I 20 $$
770 f- 65 XX
1 Data obtained in a recent neutron diffraction study [12]. are too wide for CW detection; K determined
I$ NMR lines
122
The ordering refers by pulsed NMR.
to the region
below
TN or TC.
Volume
28A.
” so-
",SO-
x E 3
number
2
PHYSICS
F-If% 0 . h s 0 .
L 0 0.05 0.10 0.1, O.LI 0.*0
I
P
-
s, D lA
z 3
00
tween the uranium ions, with the number of conduction electrons per uranium atom (2) varying from about one in UP to about two in US. This variation is expected to be manifested in the RKKY sums which appear in the RKKY analysis of cy 1111. However, the non-dependence of N on X (or .Z), or the non-oscillatory character of o, indicates that a simple RKKY model is inadequate to describe the Knight shift results in the UP1 _XSX system.
1.
5
I
I
IO
15
I
2. 3.
20
x,x Idkpr, Fig. 1. The dependence the molar susceptibility (with the temperature
November 1968
References
0,
I
4
We wish to thank Dr. G. H. Lander for helpful comments on this letter.
+
40-
20-
LETTERS
of the Knight shift of 31P on in the UP-US solid solutions as an implicit variable).
the Avogadro number, and K, is the Knight shift in the isostructural diamagnetic compound. By using Ke of 31P in ThP [9] + (4.4 f 0.2) x 10-4 and assuming U+4 ions and 5f2 configuration @J = 0.8) [lo], a value of J,f = -(2.4 f 0.4) eV is obtained similar to the value of Jones [2] for U3P4. J,f is negative, as in the lanthanide compounds, but one order of magnitude larger, probably due to the larger extent of the 5f electronic functions. The model proposed to account for the magnetic properties of UP and US and their solid solutions [ lo] suggests RKKY-type interactions be-
4. 5.
6.
7.
8. 9.
10.
11. 12.
B.A. Scott, K. A. Gingerich and R. A. Bernheim. Phys. Rev. 159 (1967) 387. E. D. Jones, Phys. Letters 25A (1967) 111. K. R. K. Easwaran. V. U. S. Rao. R. Vijayaraghavan and V. R. K. Rao. Phys. Letters 25A (1967) 683. F. Friedman, J. Grunzweig and M. Kuznietz, Ph.vs. Letters 25A (1967) 690. Y. Baskin and P. D. Shalek. Proc. Int. Symp. on Compounds of Interest in Nuclear Reactor Technology (Boulder, Colorado. 1965) pp. 457-461; a a paper on the UP-US system has been submitted to J. Am. Ceram. Sot. M. A. Allhutt and A. R. Junkison. Chemistry Division. Harnell. United Kingdom. Report AERE R5465 (1967). M. Kuznietz. submitted to Phys. Rev. W. B. Lewis. S. W. Rabideau. N. H. Krikorian and W. G. Witteman, Phys. Rev. 170 (1968) 455. M.Kuznietz. J. Chem. Phys.. to be published. J. Grunzweig and M. Kuznietz. J. Appl. Phys. 39 J.Grunzweig. M.Kuznietz and F.Friedman. Phys. Rev. 173 (1968) 562. K. H. Buschow, J. F. Fast, A.M. Van Diepen and H. W. De Wijn. Phvs. Stat. Sol. 24 (1967) 714. M. Kuznietz. G. H. Lander and Y. Baskin, to be published.
123