The orthorhombic-to-monoclinic phase transition in NbCrP – Peierls distortion of the chromium chain

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, Pnma, a = 619.80(2), b = 353.74(4), c = 735.24(6) pm, wR = 0.0706, 288 F 2 values, 20 variables at 240 K and P121/c1, a = 630.59(3), b = 739.64(4), c = 933.09(5) pm, β = 132.491(6)°, wR = 0.0531, 1007 F 2 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 Pnma is crucial for the phase transition. The estimated charge modulation is consistent with the interpretation as Peierls transition.

Peierls Distortion, Large Seebeck Coefficient, and Dispersibility of Green Solution Phase Synthesized Tellurium Nanoparticles

Tellurium (Te) is an appealing material for thermoelectric and many other applications due to its layered structures and highly anisotropic nature. We synthesized the Te nanoparticles (NPs) using facile, efficient,...

Suppressing Ge-vacancies to Achieve High Single-Leg Efficiency in GeTe with Ultra-High Room Temperature Power Factor

GeTe is among the best medium-temperature thermoelectrics. Its high performance originates from band convergence at phase transition and low lattice thermal conductivity due to Peierls distortion. In most works, the...

Chemical understanding of resistance drift suppression in Ge–Sn–Te phase-change memory materials

The degree of Peierls distortion and the fraction of tetrahedral units in amorphous Ge–Sn–Te phase-change memory materials are gradually reduced as the Sn content gets richer.