TY - JOUR
T1 - Novel compounds in the Sc-rich part of the systems Sc-{Co,Pd,Pt}-Ga: Structure and bonding
AU - Romaka, V.V.
AU - Rogl, Gerda
AU - Buršík, J.
AU - Grytsiv, A.
AU - Giester, G.
AU - Rogl, P.
N1 - Funding Information:
The authors acknowledge the contributions to this research in its early stage by Bac. C. Schmidleithner. Dr. V. Romaka is thankful for the support from the Austrian Federal Ministry of Science and Research (BMWF) within the Ernst Mach fellowship program and the Deutsche Forschungsgemeinschaft (DFG) within the project project-id 463049368. The authors are also grateful to the CZ-Austrian OEAD mobility project CZ08/2023 and MEYS 8J23AT014. The authors furthermore thank U. Nitzsche for technical assistance in running DFT calculations on the ITF/IFW computer cluster.
Funding Information:
The authors acknowledge the contributions to this research in its early stage by Bac. C. Schmidleithner. Dr. V. Romaka is thankful for the support from the Austrian Federal Ministry of Science and Research (BMWF) within the Ernst Mach fellowship program and the Deutsche Forschungsgemeinschaft (DFG) within the project project-id 463049368. The authors are also grateful to the CZ-Austrian OEAD mobility project CZ08/2023 and MEYS 8J23AT014. The authors furthermore thank U. Nitzsche for technical assistance in running DFT calculations on the ITF/IFW computer cluster. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. V.V. Romaka: Writing \u2013 review & editing, Investigation, Conceptualization. G. Rogl: Writing \u2013 review & editing, Investigation, Validation. J. Bursik: Writing \u2013 original draft, Investigation. A. Grytsiv: Investigation. G. Giester: Writing \u2013 review & editing, Investigation. P. Rogl: Writing \u2013 review & editing, Supervision, Project administration, Investigation, Conceptualization.
Publisher Copyright:
© 2024 The Authors
Accession Number
WOS:001249098700001
PY - 2024/9/5
Y1 - 2024/9/5
N2 - The present paper comprises a detailed structural analysis of two novel compounds in the Sc-Co-Ga system: τ3-Sc50Co13Ga3 (space group Fm-3; ε-Mg26-xAg7+x type), and τ4-Sc6Co1.73+x+yGa1-x (space group Immm; x=0.43; y=0.14; Ho6Co2Ga derivative type). Although alloys in the isothermal section are oxygen-free, the alloy of τ3, prepared for single crystal growth via partial melting in an alumina crucible, contained a minor amount of oxygen and can be considered as oxygen-stabilized Sc50Co13Ga3O1.1 (WDX-data). A search for homologous compounds in the systems Sc-{Pd,Pt}-Ga prompted the existence of two compounds Sc54{Pd,Pt,Ga}17, which from X-ray single crystal analyses proved both to be isotypic with the Hf54Os17-type structure (space group Immm). Whereas Sc54(Pd0.652Ga0.348)17 has a very limited homogeneity region at 850°C, Sc54(Pt1-xGax)17 exhibits at 850°C a large homogeneity region (076Pt17.2Ga6.8≡Sc54(Pt0.72Ga0.28)17 to novel binary Sc54Pt17. Interestingly, against the usual trend of solution hardening, hardness, Young's modulus and fracture toughness all decrease with increasing Ga-content: this effect is less pronounced for Sc54(Pd1-xGax)17 than for Sc54(Pt1-xGax)17 and is in line with DFT calculations indicating a weakening of bonding with increasing Ga content, thereby overcompensating the solution hardening effect. DFT modeling showed a common bonding feature for all the studied compounds – a strong electron localization inside the Sc6 octahedra, stacking of which leads to the formation of Mackay icosahedra in Sc54(Pd1-xGax)17, Sc54(Pt1-xGax)17, and Sc50Co13Ga3. The band structure of Sc6Co2.25Ga0.625 and Sc50Co13Ga3 indicates their metallic behavior, while Sc54(Pd1-xGax)17 and Sc54(Pt1-xGax)17 show distinct semimetal features. All investigated compounds in this work show similar trends in Bader charge distribution with a positively charged Sc-sublattice and a negatively charged sublattice formed by transition metals (Co, Pd, Pt) and Ga.
AB - The present paper comprises a detailed structural analysis of two novel compounds in the Sc-Co-Ga system: τ3-Sc50Co13Ga3 (space group Fm-3; ε-Mg26-xAg7+x type), and τ4-Sc6Co1.73+x+yGa1-x (space group Immm; x=0.43; y=0.14; Ho6Co2Ga derivative type). Although alloys in the isothermal section are oxygen-free, the alloy of τ3, prepared for single crystal growth via partial melting in an alumina crucible, contained a minor amount of oxygen and can be considered as oxygen-stabilized Sc50Co13Ga3O1.1 (WDX-data). A search for homologous compounds in the systems Sc-{Pd,Pt}-Ga prompted the existence of two compounds Sc54{Pd,Pt,Ga}17, which from X-ray single crystal analyses proved both to be isotypic with the Hf54Os17-type structure (space group Immm). Whereas Sc54(Pd0.652Ga0.348)17 has a very limited homogeneity region at 850°C, Sc54(Pt1-xGax)17 exhibits at 850°C a large homogeneity region (076Pt17.2Ga6.8≡Sc54(Pt0.72Ga0.28)17 to novel binary Sc54Pt17. Interestingly, against the usual trend of solution hardening, hardness, Young's modulus and fracture toughness all decrease with increasing Ga-content: this effect is less pronounced for Sc54(Pd1-xGax)17 than for Sc54(Pt1-xGax)17 and is in line with DFT calculations indicating a weakening of bonding with increasing Ga content, thereby overcompensating the solution hardening effect. DFT modeling showed a common bonding feature for all the studied compounds – a strong electron localization inside the Sc6 octahedra, stacking of which leads to the formation of Mackay icosahedra in Sc54(Pd1-xGax)17, Sc54(Pt1-xGax)17, and Sc50Co13Ga3. The band structure of Sc6Co2.25Ga0.625 and Sc50Co13Ga3 indicates their metallic behavior, while Sc54(Pd1-xGax)17 and Sc54(Pt1-xGax)17 show distinct semimetal features. All investigated compounds in this work show similar trends in Bader charge distribution with a positively charged Sc-sublattice and a negatively charged sublattice formed by transition metals (Co, Pd, Pt) and Ga.
KW - Bader charge distribution
KW - Crystal structure
KW - Electronic band structure
KW - Mechanical properties
KW - Scandium-rich compounds
UR - http://www.scopus.com/inward/record.url?scp=85194503067&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2024.174864
DO - 10.1016/j.jallcom.2024.174864
M3 - Article
VL - 998
SP - 1
EP - 18
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
M1 - 174864
ER -