J 2024

Constitution, physical properties and thermodynamic modeling of the Hf-Mn system

BROŽ, Pavel, Xinlin YAN, Vitaliy ROMAKA, Olga FABRICHNAYA, Mario J KRIEGEL et. al.

Basic information

Original name

Constitution, physical properties and thermodynamic modeling of the Hf-Mn system

Authors

BROŽ, Pavel (203 Czech Republic, guarantor, belonging to the institution), Xinlin YAN, Vitaliy ROMAKA, Olga FABRICHNAYA, Mario J KRIEGEL, Vilma BURŠÍKOVÁ (203 Czech Republic, belonging to the institution), Jiri BURSIK, Jan VŘEŠŤÁL (203 Czech Republic, belonging to the institution), Gerda ROGL, Herwig MICHOR, Ernst BAUER, Markus EIBERGER, Andriy GRYTSIV, Gerald GIESTER and Peter F ROGL

Edition

Journal of Alloys and Compounds, Lausanne, Elsevier Science, 2024, 0925-8388

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10403 Physical chemistry

Country of publisher

Switzerland

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

Impact factor

Impact factor: 6.200 in 2022

Organization unit

Faculty of Science

UT WoS

001142152500001

Keywords in English

Intermetallics; Crystal structure; Laves phase; Phase diagrams; Physical properties; DFT

Tags

Tags

International impact, Reviewed
Změněno: 22/3/2024 14:46, Mgr. Pavla Foltynová, Ph.D.

Abstract

V originále

The Hf-Mn system is of a long-time interest due to the intermetallic Laves phase HfMn2, a hydrogen storage material. Although this system has been experimentally investigated by several authors and critical reviews and thermodynamic modelling have been performed, there is still a lack of reliable information, particularly as the phase "HfMn" (sometimes labelled as "Hf3Mn2" or "Hf2Mn") is suspected to be oxygen stabilized. This work includes a thorough investigation of the Hf-Mn phase equilibria employing diffusion zones, thermal analysis, powder and single crystal X-ray analyses, analytical electron microscopy as well as physical property studies of the Laves phase (magnetic susceptibility, specific heat, electrical resistivity and mechanical properties). The phase near "HfMn" was shown (TEM, WDX electron microprobe data, X-ray single crystal analysis) to be an oxygen stabilized phase with the formula Hf3+xMn3_xO1_y (defect eta-W3Fe3C type). Properties such as magnetic susceptibility/magnetization; 2-300 K, specific heat (2-1100 K), electrical resistivity (2-300 K) classify HfMn2 as a metallic spin-fluctuation system with itinerant paramagnetism, originating from 3d states at Mn-sites and local moment paramagnetism of antisite Mn-atoms at Hf-sites. Mechanical properties (elastic moduli from density functional theory (DFT) and nanoindentation as well as hardness) group the Laves phase among rather hard and brittle intermetallics. DFT modeling revealed that Hf3+xMn3_x is thermodynamically unstable, but significant gains in enthalpy of formation arise from the inclusion of oxygen atoms, stabilizing the eta phase. All phase diagram and DFT data together with the former literature information were used for the thermodynamic CALPHAD-type modelling of the Hf-Mn system.

Links

8J21AT015, research and development project
Name: Intenzivní plastická deformace - cesta k termoelektrickým materiálům s vysokou konverzní účinností
Investor: Ministry of Education, Youth and Sports of the CR, Austria