Structural and physical characterization of NpPt2In7

A new neptunium intermetallic compound, NpPt2In7, has been synthesized in polycrystalline form and characterized by several macroscopic techniques. A Rietveld analysis of its powder X-ray diffraction pattern shows that NpPt2In7 crystallizes in a tetragonal lattice with I4/mmm symmetry and lattice parameters a= 4.58471 (3) Å, c =21.5065 (3) Å. Magnetic susceptibility, electrical resistivity, Hall effect, and heat capacity measurements indicate a metallic character and the occurrence of antiferromagnetic order below a Néel temperature TN ¼ 23 K. The transition is exceptionally robust and TN decreases by 0.2 K under a magnetic field of 9 T. A modified Curie-Weiss fit of the high-temperature magnetic susceptibility curve X(T) gives an effective magnetic moment meff = 2.54 muB close to the value expected for trivalent Np. Low temperature heat capacity measurements give a reduced Sommerfeld linear coefficient close to 25 mJ mol1K2 and a Debye Temperature Theta= 181 K. First principles, correlated-band electronic structure calculations suggest that the neptunium magnetic moment in NpPt2In7 is localized and that a quasi-two-dimensional antiferromagnetic structure could result from the competition of very weak interlayer interactions leading to very anisotropic properties.

KLIMCZUK Tomasz;  SHICK A.B.;  KHMELEVSKYI Sergej;  KOZUB A. L.;  KOLINCIO Kamil K.;  GRIVEAU Jean-Christophe;  COLINEAU Eric;  ELOIRDI Rachel;  CACIUFFO Roberto; 

2019-01-10

ELSEVIER SCIENCE SA

JRC109117

0925-8388 (online),   

https://publications.jrc.ec.europa.eu/repository/handle/JRC109117,   

10.1016/j.jallcom.2018.07.163 (online),