Constitution of the systems {V,Nb,Ta}-Sb and physical properties of di-antimonides {V,Nb,Ta}Sb-2

Author(s)
Fainan Failamani, Pavel Broz, Daniele Maccio, Stephan Puchegger, Helmut Müller, Leonid P. Salamakha, Herwig Michor, Andrij Grytsiv, Adriana Saccone, Ernst Bauer, Gerald Giester, Peter Franz Rogl
Abstract

The binary phase diagrams {V,Nb,Ta}-Sb below 1450 °C were studied by means of XRPD, EPMA, and DTA measurements. In the V-Sb system, five stable binary phases were observed in this investigation: V

3+xSb

1-x, →T-V

3Sb

2, hT-V

2-xSb, V

7.46Sb

9, V

1-xSb

2. The V-Sb phase diagram is characterized by two degenerate eutectic reactions: L→V

3+xSb

1-x+(V) (T > 1450 °C at 18.1 at.% Sb) and LV

1-xSb

2+(Sb) (T=(621 ± 5)°C at ∼99 at.% Sb), three peritectic reactions: L + V

3+xSb

1-x+hT-V

2-xSb (T=(1230 ± 10)°C at ∼42 at.% Sb), L + hT-V

2-xSb+V

7.46Sb

9 (T=(920 ± 10)°C at ∼87 at.% Sb), and L + V

7.46Sb

9+V

1-xSb

2 (T=(869 ± 5)°C at ∼88 at.% Sb), a peritectoid reaction: V

3+xSb

1-x + hT-V

2-xSb→T-V

3Sb

2 at (875 ± 25)°C, a eutectoid reaction: hT-V

2-xSb →T-V

3Sb

2+V

7.46Sb

9 at (815 ± 15)°C and congruent melting of V

3+xSb

1-x (T > 1450 °C). An X-ray single crystal study of V

5Sb

4C

1-x proved the existence of interstitial elements in the octahedral voids of a partially filled Ti

5Te

4-type structure (x∼0.5; R

F2 = 0.0101), therefore this phase (earlier labeled "V

5Sb

4") was excluded from the binary equilibrium phase diagram. V

5Sb

4C

1-x is the first representative of a filled Ti

5Te

4-type structure. A re-investigation of the Nb-Sb system removed the contradiction between the hitherto reported phase diagrams and confirmed the version derived by Melnyk et al. (see ref. [1]). Three binary phases exist in the Ta-Sb system: Ta

3+xSb

1-x, Ta

5Sb

4, TaSb

2. Due to instrumental limits (<1450 °C), only the peritectic reaction of TaSb L + Tab+ TaSb ((1080 ± 10)°C at ∼92 at.% Sb) and a degenerate Sb-rich eutectic reaction (L+TaSb (622 ± 5)° ∼99 at.% Sb) have been determined. Physical properties (mechanical and transport properties) of binary di-antimonides were investigated with respect to a potential use of these metals either as diffusion barriers or electrodes for thermoelectric devices based on skutterudites. All group-V metal di-antimonides have low metallic-type resistivity and relatively high thermal conductivity. Magnetic field has little influence on the resistivity of V at low temperature, while on {Nb,Ta}Sb it increases the resistivity, especially on NbSb The coefficient of thermal expansion (CTE) decreases from V to TaSb, particularly the CTE value of NbSb is in the range of average n-type filled skutterudites. In contrast to the CTE value, elastic moduli increase from V to TaSb. The value for V is in the range of Sb-based skutterudites, whereas the values for {Nb,Ta}Sb are significantly higher.

Organisation(s)
Department of Physical Chemistry, Faculty Center for Nano Structure Research, Department of Mineralogy and Crystallography, Department of Materials Chemistry
External organisation(s)
Christian Doppler Research Association, Masaryk University, Università degli Studi di Genova, Technische Universität Wien
Journal
Intermetallics
Volume
65
Pages
94-110
No. of pages
17
ISSN
0966-9795
DOI
https://doi.org/10.1016/j.intermet.2015.05.006
Publication date
10-2015
Peer reviewed
Yes
Austrian Fields of Science 2012
104003 Inorganic chemistry, 104017 Physical chemistry, 104011 Materials chemistry, 105113 Crystallography
Keywords
ASJC Scopus subject areas
Mechanics of Materials, Mechanical Engineering, Metals and Alloys, Materials Chemistry, Chemistry(all)
Portal url
https://ucrisportal.univie.ac.at/en/publications/constitution-of-the-systems-vnbtasb-and-physical-properties-of-diantimonides-vnbtasb2(5a989f8b-7d8d-436a-b142-4e9cb235686e).html