• Kuwata, Yoshiki
• Kotegawa, Hisashi
• Kösters, Jutta
• Seidel, Stefan
• Pöttgen, Rainer
• Paulsen, Christian Jens Gert
• Harima, Hisatomo
• Tou, Hideki
• Sugawara, Hitoshi

Abstract

<jats:title>Abstract</jats:title><jats:p>The equiatomic metal-rich phosphide NbCrP shows a structural phase transition around 125 K. The structures of the high- and low-temperature modifications were refined from single crystal X-ray diffractometer data of an un-twinned crystal: TiNiSi type, <jats:italic>Pnma</jats:italic>, <jats:italic>a</jats:italic> = 619.80(2), <jats:italic>b</jats:italic> = 353.74(4), <jats:italic>c</jats:italic> = 735.24(6) pm, <jats:italic>wR</jats:italic> = 0.0706, 288 <jats:italic>F</jats:italic><jats:sup>2</jats:sup> values, 20 variables at 240 K and <jats:italic>P</jats:italic>12<jats:sub>1</jats:sub>/<jats:italic>c</jats:italic>1, <jats:italic>a</jats:italic> = 630.59(3), <jats:italic>b</jats:italic> = 739.64(4), <jats:italic>c</jats:italic> = 933.09(5) pm, <jats:italic>β</jats:italic> = 132.491(6)°, <jats:italic>wR</jats:italic> = 0.0531, 1007 <jats:italic>F</jats:italic><jats:sup>2</jats:sup> values, 57 variables at 90 K. The structural phase transition is of a classical Peierls type. The equidistant chromium chain in HT-NbCrP (353.7 pm Cr–Cr) splits pairwise into shorter (315.2 pm) and longer (373.2 pm) Cr–Cr distances. This goes along with a strengthening of Cr–P bonding. The superstructure formation is discussed on the basis of a group–subgroup scheme. Electronic structure calculations show a lifting of band degeneracy. Protection of the non-symmorphic symmetry of space group <jats:italic>Pnma</jats:italic> is crucial for the phase transition. The estimated charge modulation is consistent with the interpretation as Peierls transition.</jats:p>

Topics

• impedance spectroscopy
• single crystal
• chromium
• phase
• phase transition
• space group
• twinned