Ternary NdRuSn system

Ternary NdRuSn system

J o u r n | o! A~LOY$ .&~D COMFt3L~D~ ELSEVIER Journal of Alloys and Compounds 260 (1997) L I - L 3 Letter Ternary Nd-Ru-Sn system P. S a l a m a ...

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J o u r n | o!

A~LOY$ .&~D COMFt3L~D~ ELSEVIER

Journal of Alloys and Compounds 260 (1997) L I - L 3

Letter

Ternary Nd-Ru-Sn system P. S a l a m a k h a

a,

' , P. D e m c h e n k o

~, J. St~piefi-Damm b

~lnorganic Chemistry Department, L "viv State University, Kyryla i Mefodiya 6, 290005 L "viv, Ukrabze binstituw for Low Temperature and Structure Research, Polish Academy of Sciences, 50950 Wroclaw, P.O. Box 937, Poland

Received 7 January 1997

Abstract

Phase eqailibria have been established in the ternary Nd-Ru-Sn system within 0-33 at. % Nd for an isothermal section at 870 K. Three ternary rutheniu~l stannides of neodymium have been observed: Nd3÷~RuaSn~3_~, (structure type Yb3Rh4Snt.~), NdRu~Sn2 (structure type CeNiSi 2) and -Nd25Ru,,~Sn~.~ (unknown structure). The crystal strocture of the ~Nd2RuSn 2 compound has not been solved yet. © 1997 Elsevier Science S.A. Keywords: Neodymium; Ruthenium; Tin; Phase diagram; Crystal structure

1. Introduction This work is part of a sysiematic study of the interaction of neodymium and transition metals with elements of Group IVa. For the neodyrnium-transition metal-tin combinations the isothermal sections were constructed for the systen,~s when M is Mn (at 1070 K and 820 K [1]) and Fe (at 1070 K and 770 K [2]) of Ag (at 870 K [31). The other systems have been studied previously only with respect to the formation of ternary compounds with specific composition: NdM~Sn 2 [41, Nd3MaSnt3 [5,6], NdMSn [7-9], NdM2Sn 2 [10,11], NdbMsSn 8 [12-15], Nd3Co6Sn s [16], Nd3Ni2Sn 7 [171, NdsRh4Sni0, [181, NdRuSn3 [19]. Recently we reported on the isothermal section of the Nd-Ru-Si system [20] and Nd-Ru-Ge system [21]. in this paper we present the results of an X-ray investigation of the Nd-Ru-Sn system within 0-33 at. % Nd for an isothermal section at 870 K. The binary boundary systems Ru-Sn and Nd-Ru are described in [22]. The Nd-Sn system was reinvestigated by Weitzer et al. [23] employing X-ray powder techniques and magnetic susceptibility measurements up to 600 K and 6 T. Crystallographic data of binary compounds in the

*Corresponding author. 0925-8388197I$17.00 © 1997 Elsevier Science S.A. All _d~hts reserved PII S0925-8388(97 )00163- i

terna~ Nd-Ru-Sn system (0-33 at. % Nd) are listed in Table 1.

2. Experimental derails The ternary samples used to derive the phase relations in the ternary section at 870 K, each with a total weight 1 g, were synthesized by arc melting proper weights of the constituent elements under high purity argon on a watercooled copper hearth. The starting materials were used in the form of ingots (neodymium and tin) and powder (ruthenium) of high purity (99.9 at. %). The samples were remelted twice under low electric current. The alloys were sealed afterwards in evacuated quartz tubes and annealed for 250 h at 870 K; after heat treatment the samples were quenched by submerging the silica tubes in cold water. Due to the high instability of the alloys in a moist cn,fronment, handling of the specimens was performed in an argon filled glove box. The isothermal sec6on was consh-ucted using X-ray powder film data obtained by the Debye-Scherrer technique with non-filtered CrK radiation (RKD-57.3 cameras). Lattice constants were determined from flae powder patterns (DRON-2 diffractometer, FeKet radiation). A pre-

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P. Salamakha et al. / Journal of Alloys and Compounds 260 (1997) L I - L 3

Table I Crystallographic data of the elements and binary boundary phases in Nd-Ru-Sn system Phase

Pearson symbol

Space group

Prototype

a 13Nd aNd Ru I~Sn t~Sn NdRu, NdSn., Nd3Sn7 Nd,Sn~ NdSn3 Ru,Sn~ RuSn: Ru,Sn7

ci2 hP4

hP2 t14 cF8 cF24 oC 12 oC20 oC28 cP4 tP20 tl ! 2 c140

Im3m P63/mmc P6,/mmc 14,/amd Fd3m Fd3m Cmmm Cmmm Cmmm Pm3m P4c2 I4/mcm Im3m

W a-La Mg Sn,~h,o Cd,.... d MgCu: ZrGa., Ce3Sn7 Ce2Sn ~ AuCu 3 Ru,Sn 3 CuAI_, lr3Ge 7

iiminary single crystal investigation was performed using Laue, rotation and Weissenberg film data.

References

Lattice parameters, nm b

0.413 0.36582 0.2704 0.58318 0.64892 0.7614 0.44404 0.44990 0.45688 0.47061 0.6172 0.6389 0.9351

22 22 22 22 22 22 23 23 23 23 22 22 22

I.I7966 0.4282 0.31818

i.59193 2.57881 3.51188

0.45628 0.45846 0.46139 0.9915 0.5693

3. Results

variation of the lattice parameters and volume within the Nd(Ru, Sn) 2 homogeneity range implies a rather simple substitutional model (Rs,=O.162 nm>Rs,=O.134 rim). Solubility of the third component in other binary phases was found to be negligible.

3.1. Equilibrium phase diagram of the Nd-Ru-Sn system

3.2. Solid phases

Fig. 1 shows the partial isothermal section of the Nd-Ru-Sn system at 870 K as derived from X-ray phase analysis. The phase field distribution is characterized by the existence of three ternary compounds and the formation of an rather extended solid solution range of the NdRu, compound (MgCu 2 structure type); the maximum concentration of tin in the Nd(Ru, Sn), solution is 15 at. %. The unit cell dimensions plotted as a function of the tin content are shown in Fig. 2. The rather linear increasing

Three ternary neodymium ruthenium stannides have been observed within the investigated concentration region. Nonstoichiometry and a small homogeneity range have been confiimed for NdRu~Sn 2 (0.15
870K V, n m 3 0.48 Ru~Sn,/~

dSn~ dzSns

~ i ~...,,.-~dd~Sn,

0.47

jo--------o

0.46 0.45 0.44 (

a,

nm

0.78

0.770.76~ . / . . - - C : 9 " " ' - " ' " O ' I " " " ~ Ru

NdRu2

Nd

Fig. I. Isothermal section of the Nd-Ru-Sn system (0-33 at. % Nd) at 870 K.

"' |

;

....i0

t5

0-" .-¢.---1,

20

at.%Sn

Fig. 2. Lattice parameters and volume of Nd(Ru, Sn), alloys versus concentration of tin.

P. Salamakha et al. i Journal of Alloys and Compound's 260 (1997) L I - L 3

found to adopt the cubic YbsRh4Sn~s-type of structure, Pm3n space group with a=0.9707 nm. Independently, Eisenmann and Sch~ifer (1986) [19] presented the results of an X-ray single crystal investigation of their NdRuSn 3sample with a cubic LaRuSns-type of structure (space group Pm3n, a=0.9687 nm). We have observed the formation of a homogeneity field for the Nd 3+ xRu4S.rt13- x (x= 1) compound which includes the two above mentioned compositions. The crystal structure of the --.Nd2sRu4oSn35 compound has not been evaluated yet. One more ternm,y compound has been observed in the investigated concentration region of the Nd-Ru-Sn system. A single crystal suitable for X-ray investigation was extracted from a sample with Nd4oRu2oSn4o composition. A preliminary investigation was performed using the Laue, rotation and Weissenberg methods. Analyses of the photographs data have shown cubic symmetry and the lattice parameter as a=3.075 rim. A further crystal structure determination of this compound is in progress and will be reported soon. 3.3. Remarks

When comparing the alloying behaviour of the components in the Nd-Ru-X systems for X=Si, Ge, Sn, the following similarities have been observed: i) An extended solid solution range of the NdRu 2 compound is formed for X=Si and Sn. ii) The Nd3Ru4X~3 and NdRu~X 2 compounds exist in the systems with X=Ge and Sn.

~,cknowledgments The research described in this publication was made possible in part by Grant N 7TO8A01211 from the Polish Academy of Science.

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