POH -
H. Drulis, M. Drub
2.2 Alloys between rare earth elements
2.2.2 Alloys between light rare earth elements
2.2.2.1 General remarks
The light rare earth elements crystallize in an fee, dhcp, Sm-type or bee structure, so that their alloys exhibit similar crystal structures in accordance with constituent concentration (see Figs. 1 and 2). Magnetic properties of binary alloys between light rare earth elements are represented. Survey 1 gives the subsection in which a particular alloy system is predominantly dealt with, while survey 2 provides the complete list of figures and tables containing data on the properties specified for the alloys under discussion.
Survey 1. Subsections de- voted to alloys between light rare earth elements are represented.
Subsection Ce-La 2.2.2.2 Nd-La 2.2.2.3 Pr-Nd 2.2.2.4
Survey 2. For each of the alloy systems between light rare earth elements the figures and tables are listed in which data on the properties specified is provided. Numbers in roman and italic refer to figures and tables, respectively.
Metallurg.
phase relation
Magnetic phase diagram
Modula- tion wave vector
Magneti- zation, moment
Para- magnetic properties
Supercond.
properties
Ce-La Nd-La Sm-La Eu-La Pr-Nd Pr-Sm Nd-Sm
TN, T,
4, 1 8
10, 2 58 58
Q Q3 lx,
Xg, 0, Peff T,5, 6, 1 64
64 64 64
11, 2 12, 2
Land&-Biimstein
New Series III/19dl
Kawano, Achiwa
Ref. p. 2771 2.2.2 Alloys between light rare earth elements 191 Magnetic properties of rare earth metals and alloys are mainly governed by an RKKY exchange interaction between 4f localized spins through conduction electrons. The RKKY interaction is long ranged and oscillatory so that basically spins order helically or sinusoidally. Actually crystalline field effects and magnetoelastic effects exist in addition to the RKKY interaction and modulate helical or sinusoidal structures. Magnetic structural properties such as magnetic ordering temperatures and modulation wavevectors are usually arranged as a function of the average de Gennes factor, G= C c,(g, - l)‘.Ii(Ji + l), where ci, gi, and Ji are the concentration, the LandC factor and the total angular momentum of magnetic rare earth elements, respectively.
The arrangement of the magnetic data of alloys is basically in the order of increasing atomic numbers of their constituent elements. We have roughly classified materials in three sections of light-light rare earth alloys, heavy- light rare earth alloys and heavy-heavy rare earth alloys. Since each section consists of several subsections, each one devoted to one particular alloy system, information on a particular alloy is provided by general remarks preceding these subsections. In these general remarks all figures and tables are listed for each alloy system as well as some specified properties for convenience of retrieval. For each alloy system a chronological listing of relevant references precedes the representation of the data. The complete list of references is provided in subsection 2.2.5.
2.2.2 Alloys between light rare earth elements
2.2.2.1 General remarks
The light rare earth elements crystallize in an fee, dhcp, Sm-type or bee structure, so that their alloys exhibit similar crystal structures in accordance with constituent concentration (see Figs. 1 and 2). Magnetic properties of binary alloys between light rare earth elements are represented. Survey 1 gives the subsection in which a particular alloy system is predominantly dealt with, while survey 2 provides the complete list of figures and tables containing data on the properties specified for the alloys under discussion.
Survey 1. Subsections de- voted to alloys between light rare earth elements are represented.
Subsection Ce-La 2.2.2.2 Nd-La 2.2.2.3 Pr-Nd 2.2.2.4
Survey 2. For each of the alloy systems between light rare earth elements the figures and tables are listed in which data on the properties specified is provided. Numbers in roman and italic refer to figures and tables, respectively.
Metallurg.
phase relation
Magnetic phase diagram
Modula- tion wave vector
Magneti- zation, moment
Para- magnetic properties
Supercond.
properties
Ce-La Nd-La Sm-La Eu-La Pr-Nd Pr-Sm Nd-Sm
TN, T,
4, 1 8
10, 2 58 58
Q Q3 lx,
Xg, 0, Peff T,5, 6, 1 64
64 64 64
11, 2 12, 2
Land&-Biimstein
New Series III/19dl
Kawano, Achiwa
192 2.2.2
Ce-La [Ref. p.277
2.2.2.2 Q-La
References: 73S1, 76B1, 77L1, 78P1, 85G1, 86Gl
La Ce - Cl?
17.5 K 15.0
12.5 10.0
2.5
I
Ce- to
LO 60 80 at% 100
La - Lo
Fig. 3. Metallurgical phase diagram of the Ce-La system [85Gl,86G 1-J.
Fig. 4. Magnetic ordering temperatures of Ce-La alloys [78P 1-J. The upper curve (fee) is due to the presence offcc y-Ce in the sample. The lower curves (dhcp) are due to dhcp p-Ce phase present in the sample.
9.L X-5
,) F
I 8.6
s 8.2
7.8 7.4 a
8 10 12 1L 16 K 18
T-
8.4 .10-s 1. cm3 s
x 8.0
7.8
10 11 12 13 14 15 K 16
b l-
Fig. 5. (a) Temperature dependence of magnetic mass susceptibility xB for Ce,,,,La,,,, [78P I]. (b) shows the anomaly at 14 K enlarged.
Kawano, Achiwa
Land&-BBmsteinNew Series IIIil9dl
Ref.
p.2771 2.2.2 Ce-La, Nd-La
50 K 60 Fig. 6. Temperature dependence of inverse magnetic mass susceptibility xi’ for Ce-La alloys [77L 11. P-Ce:
[76 B I].
Table 1. Magnetic properties for Ce-La alloys [73 S 1, 77 L I].
TN 0 Peff Ref.
K K kdat
p-Ce 12.7 - 38 2.60 77Ll
Ce0.9sLao.os 12.1 - 40 2.55 77Ll
Ce0.9La0., 11.2 - 45 2.50 77Ll
Ce o.ssLao.ls 10.8 - 56 2.46 77Ll
Ceo.sLao.2 10.2 - 58 2.34 77Ll
La
-216 0.58 73Sl2.2.2.3 Nd-La
References: 64M 1, 78 P 1, 86 G 1
800 I 600 k
-0 20 40 60 80 at % 100
La Nd- Nd
Fig. 7. Metallurgical phase diagram of the Nd-La system [86 G I].
--
166
K P *\ /hexagonal sites I12 I
\ \
6. A.
/’ ‘\,
\ 01
‘1.
cubic sites \
I 1.
0 \ \
0 20 40 60 80 at% ’ 3
Nd La - Lo
Fig. 8. Magnetic ordering temperatures of dhcp Nd-La alloys [78 P 11. Solid circles: [64 M 11.
Landolt-Biirnstein
New Series 111/19dl
Kawano, Achiwa
Ref.
p.2771 2.2.2 Ce-La, Nd-La
50 K 60 Fig. 6. Temperature dependence of inverse magnetic mass susceptibility xi’ for Ce-La alloys [77L 11. P-Ce:
[76 B I].
Table 1. Magnetic properties for Ce-La alloys [73 S 1, 77 L I].
TN 0 Peff Ref.
K K kdat
p-Ce 12.7 - 38 2.60 77Ll
Ce0.9sLao.os 12.1 - 40 2.55 77Ll
Ce0.9La0., 11.2 - 45 2.50 77Ll
Ce o.ssLao.ls 10.8 - 56 2.46 77Ll
Ceo.sLao.2 10.2 - 58 2.34 77Ll
La
-216 0.58 73Sl2.2.2.3 Nd-La
References: 64M 1, 78 P 1, 86 G 1
800 I 600 k
-0 20 40 60 80 at % 100
La Nd- Nd
Fig. 7. Metallurgical phase diagram of the Nd-La system [86 G I].
--
166
K P *\ /hexagonal sites I12 I
\ \
6. A.
/’ ‘\,
\ 01
‘1.
cubic sites \
I 1.
0 \ \
0 20 40 60 80 at% ’ 3
Nd La - Lo
Fig. 8. Magnetic ordering temperatures of dhcp Nd-La alloys [78 P 11. Solid circles: [64 M 11.
Landolt-Biirnstein
New Series 111/19dl
Kawano, Achiwa
194 2.2.2 Pr-Nd [Ref. p 277
2.2.2.4 Pr-Nd
References: 75 L 1, 86 G 1
01
01
0
0 20 20 40 40 60 60 80 at% 100 80 at% 100Pr Nd- Nd
Fig 9. Metallurgical phase diagram of the Pr-Nd system [86G 11.
0.28
I 0.26 c1
0 4 8 12 16 K 20 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 1 4.0
0,
0 20 40 6G 80 at% 1
Pr Nd - Nd
Fig. 10. Composition dependence of the Neel temperature TN for Pr-Nd alloys [75 L 11. The titted curve is based on a simple model.
IlB 1.25
0 Pr . Pr-5.5ot%Nd . Pr-26.3ot%Nd- o Nd
Fig. 11. Temperature dependence of the modulation Fig. 12. Magnetic moment per atom, pa,, of Pr-Nd alloys wavevector Q which describes the order on the hexagonal at 4.2 K for the magnetic field applied along [lzlO]
sites [75 L 11. [75 L I-J.
Kawano, Achiwa
Landolt-B6mrteinNew Series IIIi19dl
Ref. p. 2771 2.2.3 Alloys between heavy and light rare earth elements 195
Table 2. Comparison between the modulated moment pat determined by neutrondiffraction and the total moment on the hexagonal sites calculated from the complete crystal-field theory at T =0.4 TN for Pr-Nd alloys [75 L I]. Also shown are TN and the calculated saturation moment p,, assuming that the cubic sites remain disordered.
Nd
at% p,,(T= 0.4
TN) CPSI TN CKI
exp. theor. exp. theor.
P, CM4
theor.
100 (Nd) 2.67(2) 2.67 19.5(l) 19.6 2.98
26.3 1.30(2) 1.82 11.4(l) 11.3 1.93
5.5 0.85(3) 0.94 6.5(l) 6.5 1.02
3.0 0.66(3) 0.60 6.3”.’ 0.1 4.8 0.73
0 Pr) < 0.4 0