Borides Mn_3-x{Rh,Ir}₅B₂ with Ti₃Co₅B₂-type: X-ray single crystal and TEM data, physical properties

Autor(en)

Gerda Rogl, Markus Eiberger, Soner Steiner, Herwig Michor, Jiri Bursik, Gerald Giester, Andriy Grytsiv, Peter Franz Rogl

Abstrakt

A cursory investigation of the phase relations in the Mn-{Rh,Ir}-B systems prompted for each system a ternary compound, Mn_3-x{Rh,Ir}₅B₂, the crystal structure of them was determined from X-ray single crystal data to be isotypic with the Ti₃Co₅B₂-type (space group P4/mbm, No. 127). In both cases the Mn-site in 2a

at the origin of the unit cell exhibits a significant defect (or Mn/B

substitution). Transmission electron microscopy studies confirm the

absence of a superstructure related to these defects/disorder. The two

phases, Mn_3-xRh₅B₂ (x∼0.34) and Mn_3-xIr₅B₂

(x∼0.85) at 950 °C show rather limited homogeneity regions pointing

towards higher Mn-contents. Whereas temperature dependent magnetization

and specific heat measurements of Mn_2.15Ir₅B₂

do not reveal any indication for a magnetic phase transition in the

temperature range from 3 to 300 K, a broad specific heat anomaly at

around 200 K and a tilde shape of the temperature dependent

magnetization of Mn_2.66Rh₅B₂ appears

indicative of an antiferromagnetic phase transition. The latter is also

reflected by an anomaly of the electrical resistivity (ρ; 4–300 K) of Mn_2.66Rh₅B₂ which displays a non-monotonous temperature dependence, whereas ρ(T) of Mn_2.15Ir₅B₂

displays a simple metallic-like behavior dominated by scattering from

defects. Elastic moduli and Poisson's ratio were determined at room

temperature from Resonant Ultrasonic Spectroscopy (RUS) data yielding

Young's moduli of E ∼ 170 GPa for Mn_2.66Rh₅B₂ and E ∼ 210 GPa for Mn_2.15Ir₅B₂. Vickers hardness HV is lower for Mn_2.66Rh₅B₂ (HV = 590 ≅ 5.79 GPa) than for Mn_2.15Ir₅B₂ (HV = 655 ≅ 6.42 GPa). The indentation fracture toughness for Mn_2.15Ir₅B₂ was IK_C = 0.71 ± 0.5 MPa m^1/2.

Organisation(en)

Institut für Materialchemie, Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Technische Universität Wien, Czech Academy of Sciences

Journal

Solid State Sciences

Band

154

Seiten

1-7

Anzahl der Seiten

7

ISSN

1293-2558

DOI

https://doi.org/10.1016/j.solidstatesciences.2024.107583

Publikationsdatum

08-2024

Peer-reviewed

Ja

ÖFOS 2012

105116 Mineralogie, 104011 Materialchemie, 105113 Kristallographie

Schlagwörter

ASJC Scopus Sachgebiete

Condensed Matter Physics, Allgemeine Chemie, Allgemeine Materialwissenschaften

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/82be73e2-d70d-4c12-b585-46b3fdd1fd2b