Isothermal section at 600 °C of the Yb−Pd−Sn system (Pd ≤ 75 at.%)

Accepted Manuscript Isothermal section at 600 °C of the Yb−Pd−Sn system (Pd ≤ 75 at%) F. Gastaldo, M. Giovannini, A.M. Strydom, R.F. Djoumessi, I. Čurlík, M. Reiffers, P. Solokha, A. Saccone PII:

S0925-8388(16)33052-3

DOI:

10.1016/j.jallcom.2016.09.289

Reference:

JALCOM 39123

To appear in:

Journal of Alloys and Compounds

Received Date: 6 May 2016 Revised Date:

2 September 2016

Accepted Date: 27 September 2016

Please cite this article as: F. Gastaldo, M. Giovannini, A.M. Strydom, R.F. Djoumessi, I. Čurlík, M. Reiffers, P. Solokha, A. Saccone, Isothermal section at 600 °C of the Yb−Pd−Sn system (Pd ≤ 75 at%), Journal of Alloys and Compounds (2016), doi: 10.1016/j.jallcom.2016.09.289. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Isothermal section at 600 °C of the Yb− −Pd− −Sn system (Pd ≤ 75 at%) F. Gastaldo1, M. Giovannini*,1,2, A.M. Strydom3, R. F. Djoumessi3, I. Čurlík4, M. Reiffers4,5, P. Solokha1, A. Saccone1 1

Department of Chemistry, University of Genova, Via Dodecaneso 31, I-16146 Genova, Italy CNR-SPIN, Corso Ferdinando Maria Perrone 24, I-16152, Genova, Italy 3 Highly Correlated Matter Research Group, Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa 4 Faculty of Humanities and Natural Sciences, University of Prešov, ul. 17. novembra 1, SK 080 78 Prešov, Slovakia 5 Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, SK 043 53 Košice, Slovakia

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Keywords: Phase Diagrams, Intermetallics, Rare Earth Alloys and Compounds

ABSTRACT

Phase equilibria in the Yb−Pd−Sn ternary system at 600 °C were established in the Pd ≤ 75 at.% concentration range employing X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe micro-analysis (EPMA). Besides the known intermetallic compounds, three new

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ternary intermetallics were revealed in the system, together with homogeneity ranges into the ternary field for some binary phases. Magnetic properties for the new compounds were investigated revealing stable Yb states Yb3+ for Yb3Pd4Sn13 and Yb2+ for Yb5Pd39Sn56, whereas for Yb13Pd40Sn31

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1. Introduction

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an unstable valency of Yb is suggested.

The ternary intermetallics RxTyXz (R = Ce and Yb, T = transition metals and X = p-block elements) are potentially good candidates to exhibit or combine unusual electronic and magnetic effects, such as superconductivity, intermediate valence, heavy fermion (HF) behavior, Kondo interactions and quantum phase transitions. These interesting phenomena can be found especially in Yb- and Ce-based intermetallics due to hybridization of f-electrons and conduction electrons [1-3]. Furthermore, the systematic search for new Yb-compounds is motivated from the fact that, in *

Contact person: Tel: +39 010 3536648 Fax: +39 010 3536163 E-mail: [email protected]

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ACCEPTED MANUSCRIPT comparison to the intensively studied Ce-based compounds, much less studies were devoted to Yb compounds likely due to preparation difficulties associated with its high vapor pressure. Recently we studied the phase relationships at 600 °C of the Yb–Pd–Sn system from 25 to 100 at. % Yb, motivated by the intriguing physical properties of some of the ternary compounds in the system [4] such as Yb2Pd2Sn [5], YbPd2Sn [6] and Yb3Pd2Sn2 [7].

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The present study is devoted to extend the isothermal section into the whole range of compositions with the aim of a systematical search for new intermetallic compounds of potential interest in the Yb−Pd−Sn system.

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2. Literature data

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2.1 Binary boundary systems

Information about Yb−Sn and Yb−Pd binary systems are already reported in our previous publication on the Yb−Pd−Sn system [4].

The Pd-Sn phase diagram has been assessed by Massalski et al. [8] on the basis of the results below 1000 °C obtained in the range 36-43 at.% Sn [9,10]. The Pd−Sn system is rather complex due to the presence of several intermediate phases, order-disorder transitions, and the formation of

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long-period superstructures [11]. In particular, there are several phases with structures related to NiAs [12]. This is the case for instance of Pd2Sn (Co2Si-type), γ-Pd2Sn (Ni2In-type) and PdSn (MnP-type). Moreover, according to an experimental investigation of the solid-state phase equilibria from 38 to 42 at.%. Sn of the Pd-Sn system, four phases have been differentiated, namely

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Pd20Sn13, α-Pd3Sn2, β-Pd3Sn2 and δ-Pd3Sn2 [10]. Although these phases have complex structures, all of them are defined to be superstructures based on the parent NiAs-type. However, the crystal

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structure details related to these phases are still unknown, except for the structure of Pd20Sn13 which is reported in a recent paper by Klein et al. and described as a trigonal defect variant of the AlB2 structure type, where 1/8 of the boron atoms are missing [13]. In addition to the compounds reported in the assessment of Massalski, one more monoclinic phase was reported in a recent investigation, namely Pd5Sn7 [14], which forms peritectically at ∼ 617°C. The Pd−Sn phase diagram modified by adding Pd5Sn7 is reported by Okamoto [15]. In the study of the isothermal section at 600°C Pd5Sn7 was not found, and for this reason it is not reported. Moreover, PdSn4 and PdSn3 are not relevant for this experimental investigation, because they form respectively at 295 and 345 °C and, therefore, we did not find them at 600°C. On the other hand,

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ACCEPTED MANUSCRIPT PdSn2 arises from a peritectic formation at 600 °C, and it was found in several samples annealed at this temperature.

2.2. Yb–Pd–Sn ternary system The partial isothermal section at 600 °C of the Yb–Pd–Sn system from 25 to 100 at.% Yb

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has been recently studied [4]. The isothermal section is characterized by the existence of eight ternary compounds which are briefly described below.

The ternary phase YbPdSn (τ1) forms in low- and high-temperature modifications: YbPdSn (LT) of hexagonal ZrNiAl-type structure, and YbPdSn (HT) of orthorhombic TiNiSi-type structure

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[4]. The first one exists for temperatures around 600 °C, whereas the second one, forming at around 1000 °C, is usually found in as-cast samples. Specific heat and magnetization measurements performed on YbPdSn (LT) revealed an antiferromagnetic order at TN = 0.2 K [16].

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The τ2 phase Yb2Pd2Sn (Mo2FeB2-type structure), which exhibits some solubility range, shows an intriguing behavior due to the presence of two pressure driven quantum critical-transitions as evidenced by measurements of electrical resistivity and µSR under pressure [5]. The Heuslertype compound YbPd2Sn (τ3), which crystallizes with cubic Cu2MnAl-type structure, displays a coexistence of superconductivity (Tc = 2.3 K) and antiferromagnetism (TN = 0.22 K) [6]. Moreover,

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τ3 exhibits a range of Pd/Sn solid solubility starting from the stoichiometric composition and extending up to 3-4 % of Sn atoms substituted by Pd atoms [4]. YbPdSn2 (τ4) crystallizes in the orthorhombic MgCuAl2-type structure, a ternary ordered variant of Re3B [17].

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Yb2Pd3Sn5 (τ5), crystallizing in the orthorhombic Yb2Pt3Sn5-type, contains two Yb independent crystallographic sites where both Yb atoms are in divalent states [18].

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The crystal structure of the orthorhombic Yb3Pd2Sn2 (τ6), of the same Yb3Pd2Sn2 structure type, has been determined ab initio from powder XRD data [7]. Also in this case a close to divalent Yb behavior emerges from magnetic susceptibility, and

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Yb Mössbauer spectroscopic

measurements [7].

Finally the two compounds τ7 and τ8, quite close in compositions, were found in the region between 32–36 at.% Yb and 41–46 at.% Sn. All attempts of obtaining single phases failed for both compounds due to the peritectic formation and closeness of compositions. While for τ7 a AlB2 structure type was suggested, the crystal structure of τ8 is still unknown.

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3. Experimental details The metals used as starting materials were palladium (foil, 99.95 mass% purity, Chimet,

(pieces, 99.9 mass% purity, MaTecK, Julich, Germany).

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Arezzo, Italy), tin (bar, 99.999 mass% purity, NewMet Koch, Waltham Abbey, UK) and ytterbium

The samples, each with a total weight of 0.8 – 1.0 g, were prepared by induction melting in sealed tantalum crucibles under a stream of pure argon. In order to obtain a proper homogeneity

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during the melting, the crucibles were subjected to continuous shaking. Samples in the Pd-rich corner have been synthesized by arc melting in order to avoid the reaction between metals and

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tantalum crucibles. After the melting, all the alloys were annealed in a resistance furnace at 600 °C for two weeks and finally water quenched. Moreover, the samples corresponding to the composition of τ9 (the samples N.8 and N. 24 in Table 1) were synthesized using an alternative synthetic route in order to improve the amount of the phase. A tantalum sealed crucible containing the stoichiometric amount of the starting elements was closed in evacuated quartz vial and placed in a resistance furnace equipped with a thermal cycle controller and a mechanical stirring system. A continuous

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rotation, at a speed of 100 rpm, was applied to the vial during the following thermal cycle: heating from room temperature to a final temperature of 600 °C with a rate of 10 °C/min followed by a slow cooling (0.1 °C/min) to 350 °C. The furnace was then switched off and the alloys were left to cool till room temperature.

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The microstructure of the samples was investigated by optical and scanning electron microscopy and by quantitative electron probe microanalysis (EPMA). X-Ray diffraction (XRD)

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was performed on powder samples using the vertical diffractometer X’Pert MPD (Philips, Almelo, The Netherlands) with Cu Kα radiation. The XRD patterns from the samples were processed using the PowderCell [19] program. The indexing of the reflections was generally performed overlying the experimental spectrum of a sample with the theoretical one. The lattice parameters were calculated by CellRef [20] program. Magnetic measurements were done using a SQUID (superconducting quantum interference device) type magnetometer (MPMS) from Quantum Design (San Diego, USA). Single crystal of τ10 was extracted from the mechanically fragmented alloy of Yb5Pd39Sn56 nominal composition, selected with the aid of a light optical microscope (Leica DM4000 M, Leica Microsystems Wetzlar GmbH, Welzlar, Germany) operated in the dark field mode and mounted on glass fibers using quick-drying glue. Intensity data were collected at ambient conditions (295 K)

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ACCEPTED MANUSCRIPT using a four-circle Bruker Kappa APEXII CCD area-detector diffractometer equipped by the graphite monochromatized Mo Kα radiation (λ=0.71073 Å). The instrument was operated in the ω scan mode. Intensity data were collected over the reciprocal space up to ∼30° in θ with exposures of 20 s per frame. Crystal-to-detector distance was fixed to 5 cm. The acquired scans (exposure for 20 s per frame) were integrated using SAINT-Plus [21] and the

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highly redundant final dataset was corrected for Lorentz and polarization effects. Semiempirical absorption corrections (SADABS) [21] were applied to all data. Details on the structure refinement can be found in the Supporting Information in the form of CIF file. The CIF has also been deposited with Fachinformationszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany: depository

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numbers CSD-430680). Some details of the data collection and refinement for the studied crystals are summarized in Table 3. The crystal structure solution, requiring a detailed description, is

4. Results and discussion

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4.1 Phase equilibria and phase formation

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discussed in paragraph 4.2.

More than thirty samples in the Yb−Pd−Sn ternary system were prepared and characterized. The experimental results obtained from selected samples by using EPMA and XRD analysis are

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listed in Table 1. The partial isothermal section of the Yb−Pd−Sn ternary system at 600 °C obtained from our present work is reported in Fig. 1, where current data are plotted in conjunction with the

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literature data [4] forming the isothermal section of the Yb−Pd−Sn system (Pd ≤ 75 at%). The crystal data concerning the ternary phases are listed in Table 2, whereas photomicrographs of selected samples are depicted in Figs. 2-4. At the temperature of 600 °C the Sn-rich region of the diagram shows the presence of the liquid phase. The dashed line drawn in this area indicate the fields in which the liquid phase coexists with two solid phases. Regarding the binary boundary Pd−Sn system, the existence of the compounds at 600 °C reported in the literature was confirmed, with the exception of Pd5Sn7 [14] which was not found in any of the samples prepared in this work. For this reason, it was not included in the isothermal section. Some binary phases (Pd2Sn, Pd3Sn and YbPd3) were found to extend into the ternary system. In particular, the determination of phase equilibria in the Pd-rich region was hampered by the existence of solid solutions (Pd-based, YbPd3- and Pd3Sn-based) with

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ACCEPTED MANUSCRIPT similar crystal structures and very close compositions. For this reason, the phase equilibria in the range Pd > 75 at% have not been established. For the same reason, the precise limits of YbPd3 solid solution was not determined and are depicted by dashed lines. Concerning τ8, we made some efforts in order to solve its structure preparing samples on its composition. Unfortunately we did not succeeded either to find a single crystal or to index its to the incongruent formation of τ8 and the closeness with τ7.

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powder XRD pattern. In fact, we always obtained the phase τ8 together with τ7 and other phases due

The new ternary compounds reported in the present work are briefly described in the following.

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4 .2 Crystal structure of τ10

Analysis of systematic absences for this data set clearly indicates a base centered monoclinic

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unit cell and three plausible space groups: C2 (no. 5), Cm (no. 8), and C2/m (no. 12). A chemically reasonable structural model (in C2/m space group) was found by charge-flipping algorithm implemented in Jana2006 [22].

This structural model contains 3 Pd and 3 Sn independent sites (in the final model – completely occupied sites) with two more additional prominent peak maxima along the (010) direction at 0, y, 0

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with y = 0, and 0.32. A relief-mode representation of the difference Fourier map from 0.3 ≤ x ≤ 0.7, 1.0 ≤ y ≤ -1.0 and z = 0 is shown in Fig. 5a. Recently, Romaka et al. [14] published on crystal structure of the binary Pd5Sn7 compound. For the latter, a similar difference Fourier peaks presence were interpreted as being originated from single partially occupied Sn site. This fact prompted us to

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check on the existence of binary Pd5Sn7 phase, but no evidence of its presence were revealed in samples № 4, 12 and 13 under conditions applied in current investigations. Taking into account the

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presence of a small amount of Yb (ca. 5 at% from EPMA data) in the title compound, the improved structural model was obtained simulating Yb/Sn distributions in the additional peaks positions using the SHELXL programs [23] within the Windows version of WinGx [24] (a possible Yb/Pd mixing scenario was discarded because of a strong disagreement with a phase composition and worse residuals).

Because of the chemically unreasonable short distances between these peaks and the already defined atomic positions the occupancy was allowed to refine freely in further cycles for these sites (the highest peak at 0, 0, 0 was assigned to be Yb, the other peak – Sn atom). After that, the residuals dropped drastically, the sum of the mentioned partially occupied Yb and Sn sites gave 0.99 and the composition of this model perfectly matches the measured one (Yb5Pd39Sn56). Further, the sum of the occupation factors for them was fixed to be unity. As a check for the correct

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ACCEPTED MANUSCRIPT composition, the site occupancy factors (SOF) were varied in a separate series of least-squares cycles along with the displacement parameters. The only Pd3 site manifest some deficiency, giving SOF value of 0.94(1). At the end, all the atoms were refined anisotropically (for Yb/Sn pair of atoms the ISOR restraint was applied assuming that they play the same role in crystal structure being situated inside octagonal channels formed within Sn–Pd network). The assumed model

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converged at R1 = 2.06 %, wR2 = 3.99 % and GOF = 1.06 (see Table 3). No missed higher crystallographic symmetry in the final models was found by PLATON [25]. Refined positional parameters have been standardized by STRUCTURE TIDY program [26] and are listed in Table 4. When analyzing the interatomic distances in the final structural model, the strong interaction

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between Pd and Sn atoms became evident: corresponding interatomic distances are remarkably shorter than the sum of atomic radii [27] oscillating from 2.72 Å to 2.87 Å. On the other hand, similar interactions between Pd and Sn were revealed in a numerous series of polar intermetallic

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compounds containing rare earth elements. Examples of analogous interactions are found in Yb3Pd2Sn2 [7], Yb2Pd3Sn5 [18], YbPdSn2 [17] and among the series RPdSn (with R =La, Pr, Nd) [28] and R3Pd4Sn6 (with R = La, Pr) [29]. In Fig. 5b, a perspective view of the crystal space of the title compound is shown highlighting a complex three dimensional network of Pd–Sn heterocontacts. Within this network, a set of voluminous octahedral channels form, the spaces of

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which are filled by a mixture of Yb and Sn species (see text above). To simplify a bit a description of this disordering one can imagine the statistical altering of Yb atoms and Sn–Sn dumbbells (distanced at 2.77 Å) along this channels. A similar disordering behavior are characteristic for a few

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structure types, see for instance La2-xMg17+x [30].

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4.3 Crystal structures of τ9 and τ11

A ternary phase τ9 with an approximate composition Yb16Pd20Sn64 was found in samples № 1, 8, 20, 22, 24 (see micrograph in Fig. 2). Attempts to obtain a single phase for this compound failed. In fact, due to the incongruent formation of the phase, some secondary phases were present in traceable amount. Nevertheless, the XRD pattern of the phase τ9 was successfully indexed on the basis of cubic Yb3Rh4Sn13 structure type [31]. The ternary phase τ11 with the composition 15 at. % Yb, 48 at. % Pd 36 at. % Sn has been found in several samples № 6, 7, 10, 11, 14, 17. However, all attempts to synthesize single phase lead to the formation of τ11 with the presence of secondary phases (see e.g. Fig. 4). The XRD pattern of the phase τ11 was successfully indexed by analogy with the hexagonal phase Y13Pd40Sn31 [32]. Therefore, τ11 can be assumed to be isostructural with the hexagonal hP168-Y13Pd40Sn31. The XRD

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ACCEPTED MANUSCRIPT indexed patterns of τ9 in sample N.8 of Table 1 and τ11 in sample N. 17 of Table 1 are reported in the supported information. 4.4 Magnetic properties

The magnetic susceptibility χ(T) of τ10 is shown in Fig. 6. The susceptibility values obtained

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are very small, and proceed in a monotonous and only very weakly temperature dependent fashion. There is no unambiguous paramagnetism that can be associated with the Yb ions in this compound. The compound τ11, Yb13Pd40Sn31 on the other hand presents sizeable and paramagnetic values of magnetic susceptibility and a strong temperature dependence, -see Fig. 7. We conclude

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from this that Yb is in the magnetic trivalent state. However, the temperature progression upon cooling does not present a stable-moment Curie-Weiss behavior. Instead, a loss of susceptibility is evident in the middle range of temperature before χ(T) again increases towards low temperature.

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Here, as shown in the inset of Fig. 7 the magnetization becomes field- and temperature dependent. We note that this compound also presents only very weak magnetization values. This observation, together with the loss of susceptibility over a broad temperature range suggest an unstable valence and the probability of strong hybridization of Yb3+ with the conduction electrons. In the compound τ9, Yb3Pd4Sn13 , a stable moment behavior of the magnetic susceptibility is found, see Fig 8, and we model this according to the Curie-Weiss law for a single paramagnetic

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(

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species, namely the Yb3+ ions; χ (T ) = C / ((T − θ P ) , with C = µB2 / 3kB Ng2 J( J + 1) . Here θ P is the Weiss temperature, µB is the Bohr magneton, k B is Boltzmann’s constant, N is the number of magnetic atoms and J is the total angular momentum quantum number associated with the magnetic atom.

the

Yb3+

ions.

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The fit in Fig. 8 yields θ P = −30 K which indicates a dominant antiferromagnetic interaction among Furthermore

we

find

for

the

effective

magnetic

moment

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µeff = g2 J( J + 1)µB2 = 1.84 µB / Yb . The theoretical full free-ion Yb3+ moment amounts to 4.54 µB .

Since the crystal structure of this compound presents only a single site for the Yb atoms, we conclude that Yb is in a homogenously distributed strongly hybridized state which produces a much reduced magnetic moment.

5. Summary The isothermal section of the ternary Yb−Pd−Sn system at 600°C has been experimentally investigated up to Pd ≤ 75 at.% using XRD and SEM/EPMA. The binary phases do not extend into the ternary field with the exception of Pd3Sn, Pd2Sn and YbPd3. Eleven ternary compounds are

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ACCEPTED MANUSCRIPT three of them were found during the present study, namely τ9

present in this system, and

(Yb3Pd4Sn13) , τ10 (Yb5Pd39Sn56) and τ11 (Yb13Pd40Sn31). The crystal structures of the novel compounds were determined. Investigation of magnetic properties revealed stable Yb states Yb3+

ACKNOWLEDGMENT

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for τ9 and Yb2+ for τ10, whereas for τ11 an unstable valency of Yb is suggested.

The authors thank D.M. Proserpio (Università degli Studi di Milano, Italy) for providing access to single crystal diffractometer. AMS thanks the SA NRF (93549) and the FRC and URC of UJ. RFD

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thanks UJ for a GES Scholarship to pursue MSc degree studies.

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References M. Giovannini, I. Čurlík, F. Gastaldo, M. Reiffers, J.G. Sereni, J. Alloys Comp. 627 (2015) 20.

[2]

P. Carretta, M. Giovannini, M. Horvatic, N. Papinutto, A. Rigamonti, Phys. Rev. B 68 (2003) 2204041.

[3]

I. Čurlík, M. Giovannini, J. G. Sereni, M. Zapotoková, S. Gabáni, and M. Reiffers Phys. Rev. B 90 (2014) 224409.

[4]

M. Giovannini, R. Pasero, A. Saccone, Intermetallics 18 (2010) 429.

[5]

T. Muramatsu, T. Kanemasa, T. Kagayama, K. Shimizu, Y. Aoki, H. Sato, M. Giovannini, P. Bonville, V. Zlatic, I. Aviani, R. Khasanov, C. Rusu, A. Amato, K. Mydeen, M. Nicklas, H. Michor, E. Bauer, Phys. Rev. B 83 (2011) 180404.

[6]

H. A. Kierstead, B. D. Dunlap, S. K. Malik, A. M. Umarji, G. K. Shenoy, Phys. Rev. B 32 (1985) 135.

[7]

P. Solokha, I. Čurlík, M. Giovannini, N.R. Lee-Hone, M. Reiffers, D.H. Ryan, A. Saccone, J. Solid State Chem. 184 (2011) 2498.

[8]

T.B. Massalski, J.L. Murray, L.H. Bennet, H. Baker, editors. Binary alloy phase diagrams. Material Park, OH: ASM; 1990.

[9]

K. Schubert, H.L. Lukas, H.G. Meissner, S. Bhan, Z. Metallkd. 50 (1959) 534.

[10]

N. Sarah, K. Arasafi and K. Schubert, Z. Metallkd. 72 (1981) 517.

[11]

G. Ghosh, Metall. Mater. Trans. A 30A (1999) 5.

[13]

SC

M AN U

TE D

EP

AC C

[12]

RI PT

[1]

M.A. Kareva, E.G. Kabanova, G.P. Zhmurko, V. N. Kuznetsov, A. V. Yatsenko, Russ. J. Inorg. Chem. 57 (2012) 502.

W. Klein, H. Jin, V. Hlukhyy, T.F. Fässler, Acta Crystallogr. E Crystallogr. Commun 71 (2015) 807.

[14]

V.V. Romaka, A. Tkachuk and V.A. Romaka, J. Alloys Compd. 496 (2010) L7.

[15]

H. Okamoto, J. Ph. Eq. and Diff. 33 (2010) 253.

[16]

T. Görlach, S. Putselyk, A. Hamann, T. Tomanić, M. Uhlarz, F.M. Schappacher, R. Pöttgen, H.v. Löhneysen Phys. Rev. B 76, (2007) 205112.

[17]

D. Kußmann and R. Pöttgen, Z. Naturforsch B 56 (2001) 446.

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ACCEPTED MANUSCRIPT Y. Muro, K. Yamane, M.-S. Kim, T. Takabatake, C. Godart, P. Rogl, J. Phys. Soc. Jpn. 72 (2003) 1745.

[19]

W. Kraus, G. Nolze, J. Appl. Cryst. 29 (1996) 301.

[20]

D. Altermatt and I.D. Brown, Acta Crystallogr. Sect. A 34 (1987) 125.

[21]

Bruker (2014). APEX2, SAINT-Plus, XPREP, SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.

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[18]

V. Petříček, M. Dušek, L. Palatinus, Z. Kristallogr. 229 (2014) 345.

[23]

G.M. Sheldrick, Acta Cryst. A 64 (2008) 112.

[24]

L.J. Farrugia, J. Appl. Cryst. 45 (2012) 849-854.

[25]

A.L. Spek PLATON, a multipurpose crystallographic tool. Utrecht University, The Netherlands, 2002.

[26]

L. Gelato, E. Parthé, J. Appl. Crystallogr. 20 (1987) 139.

[27]

J. Emsley, The Elements, Oxford University Press, Oxford, 1999.

[28]

J.F. Riecken, G. Heymann, W. Hermes, U. Ch. Rodewald, R.D. Hoffmann, Hubert Huppertz, and R. Pöttgen, Z. Naturforsch 63b (2008) 695.

[29]

D. Niepman, R. Pöttgen, B. Kunnen, G. Kotzyba, B.D. Mosel, Chem. Mater. 12 (2000) 533.

[30]

G. Capurso, M. Naik, S. Lo Russo, A. Maddalena, A. Saccone, F. Gastaldo, S. De Negri, J. Alloys Compd. 580 (2013) S159.

[31]

P. Villars, K. Cenzual, Pearson’s crystal data, Release. Ohio, USA: ASM Int., 2016.

M AN U

TE D

EP

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[32]

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[22]

J.L. Hodeau, M. Marezio, J.P. Remeika, Acta Crystallogr. Sect. B 40 (1984) 26.

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ACCEPTED MANUSCRIPT Captions

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Fig. 1. Isothermal section at 600 °C of the Yb−Pd−Sn (Pd ≤ 75 at%).

Fig. 2 SEM images (BSE mode) of sample № 8. The bright grey phase is τ9, whereas the dark grey phase is PdSn2.

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Fig. 3 SEM images (BSE mode) of sample № 13, grey matrix: τ10, white crystals: τ5.

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Fig. 4 SEM images (BSE mode) of samples N. 17. Grey matrix: τ11, black phase: PdSn Fig. 5. a) Relief mode of the difference Fourier map of “Pd5Sn6” (preliminary model of Pd5-xSn6(YbySn2(1-y)), x=0.06(1), y=0.57(1)) in the region 0 ≤ x ≤ 1, 0 ≤ y ≤ 0.5 and z = 0; b) Perspective view of the τ10 crystal structure: a complex three dimensional Pd–Sn bonding network is evidenced by black sticks hosting a Yb/Sn disordered position inside voluminous

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octagonal channels. The red frame indicates the structural unit cell.

Fig. 6. Molar magnetic susceptibility of τ10 in a constant applied field of 0.1 T.

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Fig. 7. (main panel) Magnetic susceptibility per mole Yb of τ11 in a constant applied field of 0.01T. (inset) Magnetization extracted per Yb is linear in field at 20 K, but strong curvature develops at

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1.75 K.

Fig. 8. Inverse magnetic susceptibility per mole Yb of τ9 in a constant applied field of 0.1 T. The solid line is a fit of the Curie-Weiss expression as discussed in the text.

Table 1 – Crystallographic and EPMA data of selected Yb-Pd-Sn ternary alloys alloys annealed at 600°C.

Code №

Alloy Nominal Comp. (at.%)

Phasesa

EPMA at.%

Crystal Structure

Lattice parameters (nm)

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ACCEPTED MANUSCRIPT Yb;Pd;Snb

a

b

c

0.4458(2) 0.3885(1)

2.6351(5) 0.6322(2)

1

Yb14.3Pd14.3Sn71.4

τ9 YbSn3

15.9;20.0,64.1 27.1; 0.0;73.9

cP40−Yb3Rh4Sn13 cP4AuCu3

0.9743(5) 0.4671(6)

2

Yb10Pd40Sn50

τ5 PdSn

19.9;30.5;49.6 0.0;50.8;49.2

oP40−Yb2Pd3Sn5 oP8−FeAs

0.7310(5) 0.6113(1)

3

Yb10Pd60Sn30

τ3 γ-Pd2Sn

24.3;51.0;24.7 0.0;65.4;34.6

cF16−Cu2MnAl hP6−Ni2In

0.6644(1) 0.4409(4)

4

Yb37Pd19Sn44

τ10 τ5 PdSn2

4.9;39.8;55.3 19.6;30.2;50.2 0.0;33.7;66.3

mS26–Pd5Sn7 oP40−Yb2Pd3Sn5 oS24–PdSn2

1.2930(9) 0.7310(5)

0.4319(5) 0.4435(7)

0.9544(1) 2.6456(7)

5

Yb18Pd25Sn57

τ5 PdSn2

21.3;30.3;49.4 0.0;33.6;66.4

oP40−Yb2Pd3Sn5 oS24–PdSn2

0.7324(2) 0.6490(6)

0.4445(4) 0.6480(9)

2.6413(9) 1.2170(1)

6

Yb17Pd43Sn40

τ11 τ5 PdSn

15.4;48.4;36.2 20.9;30.5;48.6 0.0;50.7;49.3

hP168−Y13Pd40Sn31 oP40−Yb2Pd3Sn5 oP8−FeAs

1.9824(1) 0.7314(3)

0.4441(2)

0.9224(1) 2.6414(7)

7

Yb10Pd54Sn36

Pd20Sn13 τ11 τ3

0.0;60.1;39.9 15.4;48.2;36.4 23.6;51.0;25.4

hP66−Pd20Sn13 hP168−Y13Pd40Sn31 cF16−Cu2MnAl

8c

Yb16Pd20Sn64

τ9 PdSn2

15.4;19.8;64.8 0.0;33.8;66.2

cP40−Yb3Rh4Sn13 oS24–PdSn2

β (°)

0.5634(8)

RI PT

111.40

0.8794(8) 1.9769(3) 0.6630(8)

SC

0.9756(3) 0.6467(2)

1.6881(5) 0.9238(9)

0.6494(6)

1.2179(3)

Yb6Pd60Sn34

Pd20Sn13 τ3

0.0;62.5;37.5 25.2;48.6;26.2

hP66− Pd20Sn13 cF16−Cu2MnAl

0.8787(8) 0.6637(5)

10

Yb21Pd43Sn36

τ5 τ3 τ11

21.4;28.7;49.9 26.4;48.9;24.7 15.8;47.4;36.8

oP40−Yb2Pd3Sn5 cF16−Cu2MnAl hP168−Y13Pd40Sn31

0.7308(7) 0.6648(1) 1.9824(2)

11

Yb4Pd23Sn42

τ11 Pd20Sn13 PdSn

15.7;48.0;36.3 0.0;59.5;40.5 0.0;50.8;49.2

hP168−Y13Pd40Sn31 hP66− Pd20Sn13 oP8−FeAs

1.9817(6) 0.8784(3) 0.6136(6)

0.3878(8)

0.9230(9) 1.6913(5) 0.6327(6)

mS26−Pd5Sn7 oP8−FeAs oS24−PdSn2

1.3156(9) 0.6069(9) 0.6472(8)

0.4348(3) 0.3963(2) 0.6484(4)

0.9481(5) 0.6417(5) 1.2149(7)

111.49

0.4339(8)

0.9490(9)

111.58

M AN U

9

0.4441(5)

2.6471(9) 0.9224(1)

Yb1Pd40Sn59

τ10 PdSn PdSn2

13

Yb5Pd39Sn56

τ10 τ5

5.4;39.1;55.5 19.4;29.3;51.3

mS26–Pd5Sn7 oP40−Yb2Pd3Sn5

1.3045(4)

14

Yb15.4Pd48.2Sn36.4

τ11 τ3 Pd20Sn13

15.4;48.6;36.0 25.0;50.3;24.7 0.0;59.6;40.4

hP168−Y13Pd40Sn31 cF16−Cu2MnAl hP66− Pd20Sn13

1.9817(2) 0.6634(7) 0.8800(1)

YbPd3 Pd2 Sn(Yb) τ3

23.9;73.3; 2.8 0.0;67.7;32.3 24.4;51.0;24.6

cP4−Cu3Au oP12−Co2Si cF16−Cu2MnAl

0.0.403(9) 0.5635(8) 0.6649(1)

Pd3Sn(Yb) Pd2Sn

4.9;75.3;19.8 1.3;67.9;30.8

cP4−Cu3Au oP12−Co2Si

τ11 Pd20Sn13 YbPd2Sn(*) Yb2Pd3Sn5(*)

13.4;50.6;36.0 0.0;60.8;39.2

hP168−Y13Pd40Sn31 hP66− Pd20Sn13 cF16−Cu2MnAl oP40−Yb2Pd3Sn5

1.9824(5) 0.8781(7)

0.9222(7) 1.6908(5)

0.0;69.2;40.8

hP6−Ni2In

0.4396(5)

0.5642(6)

PdSn2 PdSn

0.0;38;62 0.0;50.0;49.0

oS24−PdSn2 oP8−FeAs

τ9 PdSn2 Sn(liq)

16.9;28.9;54.2 0.0;30.2;69.8 3.1; 3.8;93.1

cP40−Yb3Rh4Sn13 oS24−PdSn2

Pd3Sn(Yb) Pd2 Sn(Yb)

10;75;15 5;68;27

cP4−Cu3Au oP12−Co2Si

τ5 τ9 PdSn2

18.8;30.4;50.9 13.9;22.9;63.2 0.0;31.8;63.2

oP40−Yb2Pd3Sn5 cP40−Yb3Rh4Sn13 oS24−PdSn2

Yb4Pd74Sn22

17d

Yb15.4Pd48.2Sn36.4

18

Pd63.5Sn36.5

19

Pd43Sn57

20

Yb10Pd15Sn75

21

Yb12Pd71Sn17

22

Yb14Pd23Sn67

γ-Pd2Sn

AC C

16

EP

Yb15Pd67Sn18

TE D

12

15

4.1;39.6;56.3 0.0;50.7;49.3 0.0;34.4;65.6

1.6942(3)

23

Yb15Pd73Sn12

Yb(Sn)Pd3 Pd3 Sn(Yb) Pd2Sn(Yb)

19.4;75.0;5.6 11.8;75.2;12.9 4.4;67.1;28.5

cP4−Cu3Au cP4−Cu3Au oP12−Co2Si

24c

Yb16Pd20Sn64

τ9 PdSn2 YbSn3

15.2;20.4;64.4 0.0;33.5;66.5 27.6;0.0;72.4

cP40−Yb3Rh4Sn13 oS24−PdSn2 cP4−AuCu3

a

Reported in order to their amount. All compositions are reported as atomic percent with accuracy ± 0.5 at.%. c Alloys synthesized by thermal treatment. b

0.9743(2) 0.6480(8)

0.7318(4) 0.9743(1) 0.6468(9)

0.9749(1) 0.6466(3) 0.4678(3)

0.9241(5) 1.6905(2) 0.4309(1)

0.8120(5)

0.6473(9)

1.2135(1)

0.4443(1)

2.6441(1)

0.6485(6)

1.2167(4)

0.6484(2)

1.2159(7)

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ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

d Sample annealed at 730 °C/1 week. (*) Phase detected only by XRD

- 14 -

ACCEPTED MANUSCRIPT Tab. 2–Crystallographic data of ternary compounds found at 600 °C in the Yb-Pd-Sn system. Phase / maximum homogeneity range

Crystal system Pearson symbol-prototype

Lattice parameters (nm)

τ1 YbPdSn (LT)

Hexagonal hP9–ZrNiAl

0.7587(2)

0.3762(1)

[4]

τ2 Yb2Pd2Sn

Tetragonal tP10−Mo2FeB2

0.7577(2) 0.7560(2)

0.3637(1) 0.3636(1)

[4]

τ3 YbPd2Sn

Cubic cF16–Cu2MnAl

τ4 YbPdSn2

Orthorhombic oS16–MgCuAl2

0.4422(2)

1.110(5)

0.7383(2)

[4]

τ5 Yb2Pd3Sn5

Orthorhombic oP40–Yb2Pd3Sn5

0.732(2)

0.447(1)

2.645(6)

[4]

τ6 Yb3Pd2Sn2

Orthorhombic oP56-Yb3Pd2Sn2

0.5826(2)

1.6839(3)

τ7 YbPd0.7Sn1.3

Hexagonal hP3–AlB2

0.468

τ8 Yb35Pd20Sn45

Unknown

-

τ9 Yb3Pd4Sn13

Cubic cP40−Yb3Rh4Sn13

0.9743(5)

τ10 Yb5Pd39Sn56

Monoclinic mS28-3.26−Own

1.2943(3)

τ11 Yb13Pd40Sn31

Hexagonal hP168–Y13Pd40Sn31

1.9824(5)

b

0.4370(1)

Ref.

[4]

1.3873(5)

[7]

0.367

[4]

-

[4]

M AN U

TE D EP AC C

SC

0.6654(2) 0.6641(2)

-

β(°)

c

RI PT

a

0.9623(2) 0.9222(7)

[This work] 111.660(3)

[This work] [This work]

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ACCEPTED MANUSCRIPT

Table 3. Crystallographic data for τ10 single crystals together with some experimental details of the structure determination. Empirical formula

Pd5-xSn6(YbySn2(1-y));

Yb5Pd39Sn56

Structure type

Own

Crystal system

Monoclinic

Space group

C2/m (12)

Mw, [g/mol]

1437.87

Pearson symbol–Wyck. sequence, Z

mS28-3.26–i5gda, 2

Unit cell dimensions: а [nm]

1.2943(3) 0.4370(1) 0.9623(2)

β [°]

111.660(3)

M AN U

b [nm] c [nm]

3

V [nm ]

0.5058(2) 3

Calculated density [g/cm ]

9.440

Extinction coefficient

0.00162(6)

−1

30.28

Unique reflections

958 (Rint = 0.0398)

Reflections I > 2σ(I)

836 (Rsigma = 0.0255)

Data/parameters

958/48

GOF on F (S) final R indices [I > 2σ(I)] R indices (all data)

1.06

R1 = 0.0206; wR2 = 0.0380 R1 = 0.0275;wR2 = 0.0399

3.82/-3.17

AC C

EP

∆ρfin (max/min), [e/Å3]

TE D

abs coeff (µ), mm

2

SC

Phase composition (EDXS data, at%)

RI PT

x=0.06(1), y=0.57(1)

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ACCEPTED MANUSCRIPT

Table 4. Atomic coordinates, equivalent isotropic displacement parameters for the τ10 single crystal.

Pd1

Wyck. site 4i

Site

x/a

y/b

z/c

m

0.38590(4)

0

0.17782(6)

Pd2

4i

m

0.62861(4)

0

0.30092(6)

Pd3

2d

2/m

0

½

1/2

Sn1

4i

m

0.27151(4)

0

0.38204(5)

4i

m

0.00849(4)

0

0.33619(5)

4i

m

0.74927(4)

0

0.12097(5)

Yb

2a

2/m

0

0

0

Sn4

4g

2

0

0.3169(3)

0

0.0108(1)

M AN U TE D EP AC C

Ueq, Å2 0.0107(1)

0.94(1)

0.0087(2)

0.0095(1)

0.0095(1)

0.0098(1)

0.57(1)

0.0594(5)

0.42(1)

0.0153(3)

SC

Sn2 Sn3

SOF≠ ≠1

RI PT

Atom

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT

EP

TE D

M AN U

SC

RI PT

New phase equilibria in the isothermal section at 600°C of the Yb-Pd-Sn system Three new ternary compounds were found Single crystal study of one of the new ternary compounds revealed a new structure type Studies of magnetic properties revealed an unstable valency for one of the new compounds

AC C

• • • •