1
|
Romaka VV, Rogl G, Buršíková V, Buršík J, Michor H, Grytsiv A, Bauer E, Giester G, Rogl P. Physical properties of {Ti,Zr,Hf} 2Ni 2Sn compounds. Dalton Trans 2021; 51:361-374. [PMID: 34897329 DOI: 10.1039/d1dt03198h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Physical properties, i.e. electrical resistivity (4.2-800 K), Seebeck coefficient (300-800 K), specific heat (2-110 K), Vickers hardness and elastic moduli (RT), have been defined for single-phase compounds with slightly nonstoichiometric compositions: Ti2.13Ni2Sn0.87, Zr2.025Ni2Sn0.975, and Hf2.055Ni2Sn0.945. From X-ray single crystal and TEM analyses, Ti2+xNi2Sn1-x, x ∼ 0.13(1), is isotypic with the U2Pt2Sn-type (space group P42/mnm, ternary ordered version of the Zr3Al2-type), also adopted by the homologous compounds with Zr and Hf. For all three polycrystalline compounds (relative densities >95%) the electrical resistivity of the samples is metallic-like with dominant scattering from static defects mainly conditioned by off-stoichiometry. Analyses of the specific heat curves Cpvs. T and Cp/T vs. T2 reveal Sommerfeld coefficients of γTi2Ni2Sn = 14.3(3) mJ mol-1 K-2, γZr2Ni2Sn = 10(1) mJ mol-1 K-2, γHf2Ni2Sn = 9.1(5) mJ mol-1 K-2 and low-temperature Debye-temperatures: θLTD = 373(7)K, 357(14)K and 318(10)K. Einstein temperatures were in the range of 130-155 K. Rather low Seebeck coefficients (<15 μV K-1), power factors (pf < 0.07 mW mK-2) and an estimated thermal conductivity of λ < 148 mW cm-1 K-1 yield thermoelectric figures of merit ZT < 0.007 at ∼800 K. Whereas for polycrystalline Zr2Ni2Sn elastic properties were determined by resonant ultrasound spectroscopy (RUS): E = 171 GPa, ν = 0.31, G = 65.5 GPa, and B = 147 GPa, the accelerated mechanical property mapping (XPM) mode was used to map the hardness and elastic moduli of T2Ni2Sn. Above 180 K, Zr2Ni2Sn reveals a quasi-linear expansion with CTE = 15.4 × 10-6 K-1. The calculated density of states is similar for all three compounds and confirms a metallic type of conductivity. The isosurface of elf shows a spherical shape for Ti/Zr/Hf atoms and indicates their ionic character, while the [Ni2Sn]n- sublattice reflects localizations around the Ni and Sn atoms with a large somewhat diffuse charge density between the closest Ni atoms.
Collapse
Affiliation(s)
- V V Romaka
- Institute of Materials Chemistry, Universität Wien, Währingerstr. 42, A-1090 Wien, Austria. .,Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden), Helmholtzstr. 20, D-01069 Dresden, Germany
| | - G Rogl
- Institute of Materials Chemistry, Universität Wien, Währingerstr. 42, A-1090 Wien, Austria.
| | - V Buršíková
- Institute of Physical Electronics, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic
| | - J Buršík
- Institute of Physics of Materials, Czech Academy of Sciences, Žižkova 22, 61662 Brno, Czech Republic
| | - H Michor
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstr. 8-10, A-1040 Wien, Austria
| | - A Grytsiv
- Institute of Materials Chemistry, Universität Wien, Währingerstr. 42, A-1090 Wien, Austria.
| | - E Bauer
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstr. 8-10, A-1040 Wien, Austria
| | - G Giester
- Institute of Mineralogy and Crystallography, Universität Wien, Althanstr. 14, A-1090 Wien, Austria
| | - P Rogl
- Institute of Materials Chemistry, Universität Wien, Währingerstr. 42, A-1090 Wien, Austria.
| |
Collapse
|
2
|
Tavassoli A, Grytsiv A, Rogl G, Romaka VV, Michor H, Reissner M, Bauer E, Zehetbauer M, Rogl P. The half Heusler system Ti1+xFe1.33−xSb–TiCoSb with Sb/Sn substitution: phase relations, crystal structures and thermoelectric properties. Dalton Trans 2018; 47:879-897. [DOI: 10.1039/c7dt03787b] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Phase equilibria for Heusler Phase Ti1+xFe1.33−xSb at 800 °C and calculated isosurfaces (ϒ = 0.42) of the electron localization function in TiFe1.25Sb.
Collapse
Affiliation(s)
- A. Tavassoli
- Institute of Materials Chemistry and Research
- University of Vienna
- A-1090 Wien
- Austria
- Physics of Nanostructured Materials
| | - A. Grytsiv
- Institute of Materials Chemistry and Research
- University of Vienna
- A-1090 Wien
- Austria
- Institute of Solid State Physics
| | - G. Rogl
- Institute of Materials Chemistry and Research
- University of Vienna
- A-1090 Wien
- Austria
- Institute of Solid State Physics
| | - V. V. Romaka
- Department of Materials Science and Engineering
- Lviv Polytechnic National University
- 79013 Lviv
- Ukraine
| | - H. Michor
- Institute of Solid State Physics
- TU Wien
- A-1040 Wien
- Austria
| | - M. Reissner
- Institute of Solid State Physics
- TU Wien
- A-1040 Wien
- Austria
| | - E. Bauer
- Institute of Solid State Physics
- TU Wien
- A-1040 Wien
- Austria
- Christian Doppler Laboratory for Thermoelectricity
| | - M. Zehetbauer
- Physics of Nanostructured Materials
- Faculty of Physics
- University of Vienna
- A-1090 Wien
- Austria
| | - P. Rogl
- Institute of Materials Chemistry and Research
- University of Vienna
- A-1090 Wien
- Austria
- Christian Doppler Laboratory for Thermoelectricity
| |
Collapse
|
3
|
Paschinger W, Rogl G, Grytsiv A, Michor H, Heinrich PR, Müller H, Puchegger S, Klobes B, Hermann RP, Reinecker M, Eisenmenger-Sitter C, Broz P, Bauer E, Giester G, Zehetbauer M, Rogl PF. Ba-filled Ni-Sb-Sn based skutterudites with anomalously high lattice thermal conductivity. Dalton Trans 2016; 45:11071-100. [PMID: 27328131 DOI: 10.1039/c6dt01298a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel filled skutterudites BayNi4Sb12-xSnx (ymax = 0.93) have been prepared by arc melting followed by annealing at 250, 350 and 450 °C up to 30 days in vacuum-sealed quartz vials. Extension of the homogeneity region, solidus temperatures and structural investigations were performed for the skutterudite phase in the ternary Ni-Sn-Sb and in the quaternary Ba-Ni-Sb-Sn systems. Phase equilibria in the Ni-Sn-Sb system at 450 °C were established by means of Electron Probe Microanalysis (EPMA) and X-ray Powder Diffraction (XPD). With rather small cages Ni4(Sb,Sn)12, the Ba-Ni-Sn-Sb skutterudite system is perfectly suited to study the influence of filler atoms on the phonon thermal conductivity. Single-phase samples with the composition Ni4Sb8.2Sn3.8, Ba0.42Ni4Sb8.2Sn3.8 and Ba0.92Ni4Sb6.7Sn5.3 were used to measure their physical properties, i.e. temperature dependent electrical resistivity, Seebeck coefficient and thermal conductivity. The resistivity data demonstrate a crossover from metallic to semiconducting behaviour. The corresponding gap width was extracted from the maxima in the Seebeck coefficient data as a function of temperature. Single crystal X-ray structure analyses at 100, 200 and 300 K revealed the thermal expansion coefficients as well as Einstein and Debye temperatures for Ba0.73Ni4Sb8.1Sn3.9 and Ba0.95Ni4Sb6.1Sn5.9. These data were in accordance with the Debye temperatures obtained from the specific heat (4.4 K < T < 140 K) and Mössbauer spectroscopy (10 K < T < 290 K). Rather small atom displacement parameters for the Ba filler atoms indicate a severe reduction in the "rattling behaviour" consistent with the high levels of lattice thermal conductivity. The elastic moduli, collected from Resonant Ultrasonic Spectroscopy ranged from 100 GPa for Ni4Sb8.2Sn3.8 to 116 GPa for Ba0.92Ni4Sb6.7Sn5.3. The thermal expansion coefficients were 11.8 × 10(-6) K(-1) for Ni4Sb8.2Sn3.8 and 13.8 × 10(-6) K(-1) for Ba0.92Ni4Sb6.7Sn5.3. The room temperature Vickers hardness values vary within the range from 2.6 GPa to 4.7 GPa. Severe plastic deformation via high-pressure torsion was used to introduce nanostructuring; however, the physical properties before and after HPT showed no significant effect on the materials thermoelectric behaviour.
Collapse
Affiliation(s)
- W Paschinger
- Institute of Materials Chemistry & Research, University of Vienna, Währinger Straße 42, A-1090 Vienna, Austria.
| | - G Rogl
- Institute of Materials Chemistry & Research, University of Vienna, Währinger Straße 42, A-1090 Vienna, Austria. and Christian Doppler Laboratory for Thermoelectricity, Vienna, Austria and Institute for Solid State Physics, TU-Wien, Wiedner Hauptstr. 8, A-1040 Vienna, Austria and Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - A Grytsiv
- Institute of Materials Chemistry & Research, University of Vienna, Währinger Straße 42, A-1090 Vienna, Austria. and Christian Doppler Laboratory for Thermoelectricity, Vienna, Austria and Institute for Solid State Physics, TU-Wien, Wiedner Hauptstr. 8, A-1040 Vienna, Austria
| | - H Michor
- Institute for Solid State Physics, TU-Wien, Wiedner Hauptstr. 8, A-1040 Vienna, Austria
| | - P R Heinrich
- Institute for Solid State Physics, TU-Wien, Wiedner Hauptstr. 8, A-1040 Vienna, Austria
| | - H Müller
- Institute for Solid State Physics, TU-Wien, Wiedner Hauptstr. 8, A-1040 Vienna, Austria
| | - S Puchegger
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - B Klobes
- Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI, JARA-FIT, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - R P Hermann
- Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI, JARA-FIT, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Reinecker
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Ch Eisenmenger-Sitter
- Institute for Solid State Physics, TU-Wien, Wiedner Hauptstr. 8, A-1040 Vienna, Austria
| | - P Broz
- Faculty of Science, Deparment of Chemistry, Masaryk University, Kotlářská 267/2, 611 37 Brno, Czech Republic
| | - E Bauer
- Christian Doppler Laboratory for Thermoelectricity, Vienna, Austria and Institute for Solid State Physics, TU-Wien, Wiedner Hauptstr. 8, A-1040 Vienna, Austria
| | - G Giester
- Institute of Mineralogy and Crystallography, University of Vienna, Althanstr. 14 (UZA 2), A-1090 Vienna, Austria
| | - M Zehetbauer
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - P F Rogl
- Institute of Materials Chemistry & Research, University of Vienna, Währinger Straße 42, A-1090 Vienna, Austria. and Christian Doppler Laboratory for Thermoelectricity, Vienna, Austria
| |
Collapse
|
4
|
Failamani F, Grytsiv A, Giester G, Polt G, Heinrich P, Michor H, Bauer E, Zehetbauer M, Rogl P. Ba5{V,Nb}12Sb19+x, novel variants of the Ba5Ti12Sb19+x-type: crystal structure and physical properties. Phys Chem Chem Phys 2015; 17:24248-61. [PMID: 26327293 DOI: 10.1039/c5cp04000k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The novel compounds Ba5{V,Nb}12Sb19+x, initially found in diffusion zone experiments between Ba-filled skutterudite Ba0.3Co4Sb12 and group V transition metals (V,Nb,Ta), were synthesized via solid state reaction and were characterized by means of X-ray (single crystal and powder) diffraction, electron probe microanalysis (EPMA), and physical (transport and mechanical) properties measurements. Ba5V12Sb19.41 (a = 1.21230(1) nm, space group P4[combining overline]3m; RF(2) = 0.0189) and Ba5Nb12Sb19.14 (a = 1.24979(2) nm, space group P4[combining overline]3m; RF(2) = 0.0219) are the first representatives of the Ba5Ti12Sb19+x-type, however, in contrast to the aristotype, the structure of Ba5V12Sb19.41 shows additional atom disorder. Temperature dependent ADPs and specific heat of Ba5V12Sb19.41 confirmed the rattling behaviour of Ba1,2 and Sb7 atoms within the framework built by V and Sb atoms. Electrical resistivity of both compounds show an upturn at low temperature, and a change from p- to n-type conductivity above 300 K in Ba4.9Nb12Sb19.4. As expected from the complex crystal structure and the presence of defects and disorder, the thermal conductivity is suppressed and lattice thermal conductivity of ∼0.43 W m(-1) K(-1) is near values typical for amorphous systems. Vicker's hardness of (3.8 ± 0.1) GPa (vanadium compound) and (3.5 ± 0.2) GPa (niobium compound) are comparable to Sb-based filled skutterudites. However, the Young's moduli measured by nanoindentation for these compounds EI(Ba4.9V12Sb19.0) = (85 ± 2) GPa and EI(Ba4.9Nb12Sb19.4) = (79 ± 5) GPa are significantly smaller than those of skutterudites, which range from about 130 to 145 GPa.
Collapse
Affiliation(s)
- F Failamani
- Institute of Materials Chemistry and Research, Faculty of Chemistry, University of Vienna, Währingerstraße 42, A-1090 Vienna, Austria.
| | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Gürth M, Grytsiv A, Vrestal J, Romaka VV, Giester G, Bauer E, Rogl P. On the constitution and thermodynamic modelling of the system Ti–Ni–Sn. RSC Adv 2015. [DOI: 10.1039/c5ra16074j] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Experimental and calculated phase equilibria for the system Ti–Ni–Sn.
Collapse
Affiliation(s)
- M. Gürth
- Institute of Material Chemistry and Research
- University of Vienna
- A-1090 Wien
- Austria
- Christian Doppler Laboratory for Thermoelectricity
| | - A. Grytsiv
- Institute of Material Chemistry and Research
- University of Vienna
- A-1090 Wien
- Austria
- Christian Doppler Laboratory for Thermoelectricity
| | - J. Vrestal
- Masaryk University
- CEITEC
- Brno
- Czech Republic
| | - V. V. Romaka
- Department of Materials Science and Engineering
- Lviv Polytechnic National University
- 79013 Lviv
- Ukraine
| | - G. Giester
- Institute of Mineralogy and Crystallography
- University of Vienna
- A-1090 Wien
- Austria
| | - E. Bauer
- Christian Doppler Laboratory for Thermoelectricity
- Wien
- Austria
- Institute of Solid State Physics
- TU-Wien
| | - P. Rogl
- Institute of Material Chemistry and Research
- University of Vienna
- A-1090 Wien
- Austria
- Christian Doppler Laboratory for Thermoelectricity
| |
Collapse
|
6
|
Khan AU, Rogl G, Kriegisch M, Michor H, Müller H, Bauer E, Grytsiv A, Giester G, Rogl P. Ti8(Ti(x)Mn(1-x))6Mn39 ('TiMn(~4)'): a metallic spin fluctuation system. J Phys Condens Matter 2013; 25:106002. [PMID: 23389037 DOI: 10.1088/0953-8984/25/10/106002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The crystal structure of Ti(8)(Ti(x)Mn(1-x))(6)Mn(39), x = 0.187, was obtained from x-ray single-crystal diffraction data, confirming it to have rhombohedral symmetry (space group [Formula: see text]; a(hex) = 1.100 70(2) nm, c(hex) = 1.944 11(4) nm; R(F) = 0.0293) and isotypism with the prototype Mo(0.38)Cr(0.16)Co(0.46) (the so-called R-phase). On the basis of electron probe micro-analyser results and structure determination, the homogeneity region of the phase TiMn(~4) was determined for temperatures in the range 800 °C < T < 1200 °C and is in between 16.0 at.% Ti and 20 at.% Ti. Various physical properties, determined in the temperature range from ~2 K to room temperature, characterize the compound with composition TiMn(4.26) as a metallic spin fluctuation system, evidenced from a T(3)lnT dependence of the heat capacity in combination with large values of the electronic Sommerfeld constant of the order of 140 mJ mol(-1) K(-2). The occurrence of a small anomaly in the heat capacity and magnetization data around 10 K is attributed to a scenario involving spin freezing phenomena, since a fraction of the order of 10% of all Mn-Mn distances within the unit cell are above a critical distance, where Mn atoms carry a spontaneous magnetic moment.
Collapse
Affiliation(s)
- Atta U Khan
- Institute of Physical Chemistry, University of Vienna, Währingerstrasse 42, A-1090 Wien, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
|
8
|
Falmbigl M, Kneidinger F, Chen M, Grytsiv A, Michor H, Royanian E, Bauer E, Effenberger H, Podloucky R, Rogl P. Cage-forming compounds in the Ba-Rh-Ge system: from thermoelectrics to superconductivity. Inorg Chem 2013; 52:931-43. [PMID: 23286379 PMCID: PMC3557931 DOI: 10.1021/ic302139r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phase relations and solidification behavior in the Ge-rich part of the phase diagram have been determined in two isothermal sections at 700 and 750 °C and in a liquidus projection. A reaction scheme has been derived in the form of a Schulz-Scheil diagram. Phase equilibria are characterized by three ternary compounds: τ(1)-BaRhGe(3) (BaNiSn(3)-type) and two novel phases, τ(2)-Ba(3)Rh(4)Ge(16) and τ(3)-Ba(5)Rh(15)Ge(36-x), both forming in peritectic reactions. The crystal structures of τ(2) and τ(3) have been elucidated from single-crystal X-ray intensity data and were found to crystallize in unique structure types: Ba(3)Rh(4)Ge(16) is tetragonal (I4/mmm, a = 0.65643(2) nm, c = 2.20367(8) nm, and R(F) = 0.0273), whereas atoms in Ba(5)Rh(15)Ge(36-x) (x = 0.25) arrange in a large orthorhombic unit cell (Fddd, a = 0.84570(2) nm, b = 1.4725(2) nm, c = 6.644(3) nm, and R(F) = 0.034). The body-centered-cubic superstructure of binary Ba(8)Ge(43)□(3) was observed to extend at 800 °C to Ba(8)Rh(0.6)Ge(43)□(2.4), while the clathrate type I phase, κ(I)-Ba(8)Rh(x)Ge(46-x-y)□(y), reveals a maximum solubility of x = 1.2 Rh atoms in the structure at a vacancy level of y = 2.0. The cubic lattice parameter increases with increasing Rh content. Clathrate I decomposes eutectoidally at 740 °C: κ(I) ⇔ (Ge) + κ(IX) + τ(2). A very small solubility range is observed at 750 °C for the clathrate IX, κ(IX)-Ba(6)Rh(x)Ge(25-x) (x ∼ 0.16). Density functional theory calculations have been performed to derive the enthalpies of formation and densities of states for various compositions Ba(8)Rh(x)Ge(46-x) (x = 0-6). The physical properties have been investigated for the phases κ(I), τ(1), τ(2), and τ(3), documenting a change from thermoelectric (κ(I)) to superconducting behavior (τ(2)). The electrical resistivity of κ(I)-Ba(8)Rh(1.2)Ge(42.8)□(2.0) increases almost linearly with the temperature from room temperature to 730 K, and the Seebeck coefficient is negative throughout the same temperature range. τ(1)-BaRhGe(3) has a typical metallic electrical resistivity. A superconducting transition at T(C) = 6.5 K was observed for τ(2)-Ba(3)Rh(4)Ge(16), whereas τ(3)-Ba(5)Rh(15)Ge(35.75) showed metallic-like behavior down to 4 K.
Collapse
Affiliation(s)
- M Falmbigl
- Institute of Physical Chemistry, University of Vienna, Währingerstrasse 42, A-1090 Wien, Austria
| | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Romaka V, Rogl P, Romaka L, Stadnyk Y, Melnychenko N, Grytsiv A, Falmbigl M, Skryabina N. Phase equilibria, formation, crystal and electronic structure of ternary compounds in Ti–Ni–Sn and Ti–Ni–Sb ternary systems. J SOLID STATE CHEM 2013. [DOI: 10.1016/j.jssc.2012.08.023] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
10
|
|
11
|
Khan A, Broz P, Niu H, Bursik J, Grytsiv A, Chen XQ, Giester G, Rogl P. The system Ta–V–Si: Crystal structure and phase equilibria. J SOLID STATE CHEM 2012. [DOI: 10.1016/j.jssc.2011.12.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
12
|
|
13
|
Falmbigl M, Chen MX, Grytsiv A, Rogl P, Royanian E, Michor H, Bauer E, Podloucky R, Giester G. Type-I clathrate Ba8NixSi46−x: Phase relations, crystal chemistry and thermoelectric properties. Dalton Trans 2012; 41:8839-49. [PMID: 22699461 DOI: 10.1039/c2dt30279a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- M Falmbigl
- Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Rogl G, Grytsiv A, Melnychenko-Koblyuk N, Bauer E, Laumann S, Rogl P. Compositional dependence of the thermoelectric properties of (Sr(x)Ba(x)Yb₁₋₂x)(y)Co₄Sb₁₂ skutterudites. J Phys Condens Matter 2011; 23:275601. [PMID: 21685555 DOI: 10.1088/0953-8984/23/27/275601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
High temperature thermoelectric (TE) properties for triple-filled skutterudites (Sr(x)Ba(x)Yb₁₋₂x)(y)Co₄Sb₁₂ were investigated for alloy compositions in two sections of the system: (a) for x = 0.25 with a filling fraction y ranging from 0.1 to 0.25 and (b) for 0 < x < 0.5 and y = 0.11 + 0.259x. The representation of the figure of merit, ZT, as a function of skutterudite composition, defined the compositional range (0.25 < x < 0.4; 0.18 < y < 0.24) with ZT over 1.4 at 800 K. It was shown that an enhanced TE performance for these triple-filled skutterudites is caused by low electrical resistivities and low lattice thermal conductivities, as well as by a fine tuning of the chemical composition. Low temperature measurements for the samples with the highest ZT values showed that even a small change of the filler ratios changes the contribution of scattering effects, the carrier concentration and the mobility.
Collapse
Affiliation(s)
- G Rogl
- Institute of Physical Chemistry, University of Vienna, Wien, Austria
| | | | | | | | | | | |
Collapse
|
15
|
Rogl G, Puchegger S, Zehetbauer M, Grytsiv A, Rogl P. Dependence of the Elastic Moduli of Skutterudites on Density and Temperature. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/opl.2011.845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTThe dependency of Young’s and shear modulus on relative density and temperature was determined for three series of skutterudites: p-type MmyFe3CoSb12 (y = 0.70, 0.80), p-type DDyFe3CoSb12 (y = 0.65, 0.68) and n-type Sr0.07Ba0.07Yb0.07Co4Sb12. For all three groups of materials the dependency of Young’s modulus, E, on the density and temperature is linear: E(d) = 4.1(1)×d – 268(3) GPa (d is the relative density in %), ΔE/ΔT = 0.20(1) GPa/K, thus allowing extrapolation of E as a function of temperature and towards 100% density.
Collapse
|
16
|
Khan AU, Grytsiv A, Yan X, Rogl P, Saccone A, Pomjakushin V, Giester G. Phase relations and crystal structure of τ6-Ti2(Ti(0.16)Ni(0.43)Al(0.41))3. Inorg Chem 2011; 50:4537-47. [PMID: 21491895 DOI: 10.1021/ic200245m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ti(2)(Ti(0.16)Ni(0.43)Al(0.41))(3) is a novel compound (labeled as τ(6)) in the Ti-rich region of the Ti-Ni-Al system in a limited temperature range 870 < T < 980 °C. The structure of τ(6)-Ti(2)(Ti,Ni,Al)(3) was solved from a combined analysis of X-ray single crystal and neutron powder diffracton data (space group C2/m, a = 1.85383(7) nm, b = 0.49970(2) nm, c = 0.81511(3) nm, and β = 99.597(3)°). τ(6)-Ti(2)(Ti,Ni,Al)(3) as a variant of the V(2)(Co(0.57)Si(0.43))(3)-type is a combination of slabs of the MgZn(2)-Laves type and slabs of the Zr(4)Al(3)-type forming a tetrahedrally close-packed Frank-Kasper structure with pentagon-triangle main layers. Titanium atoms occupy the vanadium sites, but Ti/Ni/Al atoms randomly share the (Co/Si) sites of V(2)(Co(0.57)Si(0.43))(3). Although τ(6) shows a random replacement on 6 of the 11 atom sites, it has no significant homogeneity range (~1 at. %). The composition of τ(6) changes slightly with temperature. DSC/DTA runs (1 K/min) were not sufficient to define proper reaction temperatures due to slow reaction kinetics. Therefore, phase equilibria related to τ(6) were derived from X-ray powder diffraction in combination with EPMA on alloys, which were annealed at carefully set temperatures and quenched. τ(6) forms from a peritectoid reaction η-(Ti,Al)(2)Ni + τ(3) + α(2) ↔ τ(6) at 980 °C and decomposes in a eutectoid reaction τ(6) ↔ η + τ(4) + α(2) at 870 °C. Both reactions involve the η-(Ti,Al)(2)Ni phase, for which the atom distribution was derived from X-ray single crystal intensity data, revealing Ti/Al randomly sharing the 48f- and 16c-positions in space group Fd3̅m (Ti(2)Ni-type, a = 1.12543(3) nm). There was no residual electron density at the octahedral centers of the crystal structure ruling out impurity stabilization. Phase equilibria involving the τ(6) phase have been established for various temperatures (T = 865, 900, 925, 950, 975 °C, and subsolidus). The reaction isotherms concerning the τ(6) phase have been established and are summarized in a Schultz-Scheil diagram.
Collapse
Affiliation(s)
- Atta U Khan
- Institute of Physical Chemistry, University of Vienna, Währingerstrasse 42, A-1090 Wien, Austria
| | | | | | | | | | | | | |
Collapse
|
17
|
Nasir N, Grytsiv A, Melnychenko-Koblyuk N, Rogl P, Bauer E, Lackner R, Royanian E, Giester G, Saccone A. Clathrates Ba(8){Zn,Cd}(x)Si(46-x), x∼7: synthesis, crystal structure and thermoelectric properties. J Phys Condens Matter 2009; 21:385404. [PMID: 21832369 DOI: 10.1088/0953-8984/21/38/385404] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Novel ternary type-I clathrate compounds Ba(8){Zn,Cd}(x)Si(46-x), x∼7 have been synthesized from the elements by melting and reacting in quartz ampoules. Structural investigations for both compounds, i.e. x-ray single-crystal data at 300, 200 and 100 K for Ba(8)Zn(7)Si(39) and Rietveld data for Ba(8)Cd(7)Si(39), confirm cubic primitive symmetry consistent with the space group type [Formula: see text] (a(Ba(8)Zn(7)Si(39)) = 1.043 72(1) nm; a(Ba(8)Cd(7)Si(39)) = 1.058 66(3) nm). Whereas for Ba(8)Zn(7)Si(39) site 16i is completely occupied by Si atoms, a random atom distribution with different Zn/Si ratio exists for the two sites, 6d (0.77Zn+0.23Si) and 24k (0.91Si+0.09Zn). No vacancies are encountered and all atom sites are fully occupied. This atom distribution is independent of temperature. Rietveld refinements for Ba(8)Cd(7)Si(39) show that the 6d site is fully occupied by Cd atoms, leaving only the 24k site for a random occupation (0.96Si+0.04Cd) consistent with the chemical formula Ba(8)Cd(7)Si(39). The temperature-dependent x-ray spectra for Ba(8)Zn(7)Si(39) define an Einstein mode, Θ(E,U33) = 80 K. Studies of transport properties show electrons as the majority charge carriers in the system. Although the Cd- and Zn-based samples are isoelectronic, a significantly different electronic transport points towards substantial differences in the electronic density of states in both cases.
Collapse
Affiliation(s)
- N Nasir
- Institute of Physical Chemistry, University of Vienna, A-1090 Wien, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Bauer E, Grytsiv A, Chen XQ, Melnychenko-Koblyuk N, Hilscher G, Kaldarar H, Michor H, Royanian E, Giester G, Rotter M, Podloucky R, Rogl P. Superconductivity in novel Ge-based skutterudites: {Sr,Ba}pt4Ge12. Phys Rev Lett 2007; 99:217001. [PMID: 18233241 DOI: 10.1103/physrevlett.99.217001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Indexed: 05/25/2023]
Abstract
Combining experiments and ab initio models we report on SrPt4Ge12 and BaPt4Ge12 as members of a novel class of superconducting skutterudites, where Sr or Ba atoms stabilize a framework entirely formed by Ge atoms. Below T(c)=5.35 and 5.10 K for BaPt4Ge12 and SrPt4Ge12, respectively, electron-phonon coupled superconductivity emerges, ascribed to intrinsic features of the Pt-Ge framework, where Ge-p states dominate the electronic structure at the Fermi energy.
Collapse
Affiliation(s)
- E Bauer
- Institute of Solid State Physics, Vienna University of Technology, A-1040 Wien, Austria
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Grytsiv A, Chen XQ, Rogl P, Podloucky R, Schmidt H, Giester G, Pomjakushin V. Crystal chemistry of the G-phases in the {Ti, Zr, Hf}–Ni–Si systems. J SOLID STATE CHEM 2007. [DOI: 10.1016/j.jssc.2006.11.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
20
|
Katrych S, Grytsiv A, Bondar A, Rogl P, Velikanova T, Bohn M. Structural materials: metal–silicon–Boron. The Nb-rich corner of the Nb–Si–B system. J SOLID STATE CHEM 2004. [DOI: 10.1016/j.jssc.2003.02.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
21
|
|
22
|
Grytsiv A, Kaczorowski D, Leithe-Jasper A, Rogl P, Godart C, Potel M, Noël H. EuZn2Si2 and EuZn2Ge2 Grown from Zn or Ga(ln)/Zn Flux. J SOLID STATE CHEM 2002. [DOI: 10.1006/jssc.2001.9350] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|