Structural Features, Anisotropic Thermal Expansion, and Thermoelectric Performance in Bulk Black Phosphorus Synthesized under High Pressure

RODRIGUES, JOÃO ELIAS F. S.; LOPEZ, CARLOS A; MARTINEZ, JOSE L.; FERNÁNDEZ-DIAZ, MARIA TERESA; GAINZA, JAVIER; DURA, OSCAR J.; HUTTEL, YVES; BI?KUP, NEVENKO; SERRANO-SÁNCHEZ, FEDERICO; NEMES, NORBERT; FAUTH, FRANCOIS; ALONSO, JOSÉ ANTONIO

INORGANIC CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2020 vol. 59 p. 14932 - 14943

0020-1669

Black phosphorus (BP) allotrope has an orthorhombic crystal structure with a narrow bandgap of 0.35 eV. This material is promising for 2D technology since it can be exfoliated down to one single layer: the well-known phosphorene. In this work, bulk BP was synthesized under high-pressure conditions at high temperatures. A detailed structural investigation using neutron and synchrotron X-ray diffraction revealed the occurrence of anisotropic strain effects on the BP lattice; the combination of both sets of diffraction data allowed visualization of the lone electron pair 3s2. Temperature-dependent neutron diffraction data collected at low temperature showed that the a axis (zigzag) exhibits a quasi-temperature-independent thermal expansion in the temperature interval from 20 up to 150 K. These results may be a key to address the anomalous behavior in electrical resistivity near 150 K. Thermoelectric properties were also provided; low thermal conductivity from 14 down to 6 Wm-1K-1 in the range 323-673 K was recorded in our polycrystalline BP, which is below the reported values for single-crystals in literature.