title: New monoclinic phase at the composition Cu2SnSe3 and its thermoelectric properties.
abstract: A new monoclinic phase (m2) of ternary diamond-like compound Cu2SnSe3 was synthesized by reaction of the elements at 850 K. The crystal structure of m2-Cu2SnSe3 was determined through electron diffraction tomography and refined by full-profile techniques using synchrotron X-ray powder diffraction data (space group Cc, a = 6.9714(2) Å, b = 12.0787(5) Å, c = 13.3935(5) Å, β = 99.865(5)°, Z = 8). Thermal analysis and annealing experiments suggest that m2-Cu2SnSe3 is a low-temperature phase, while the high-temperature phase has a cubic crystal structure. According to quantum chemical calculations, m2-Cu2SnSe3 is a narrow-gap semiconductor. A study of the chemical bonding, applying the electron localizability approach, reveals covalent polar Cu-Se and Sn-Se interactions in the crystal structure. Thermoelectric properties were measured on a specimen consolidated using spark plasma sintering (SPS), confirming the semiconducting character. The thermoelectric figure of merit ZT reaches a maximum value of 0.33 at 650 K.
authors.affiliation: Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Strasse 40, 01187 Dresden, Germany.
authors.forename: Jing
authors.initials: J
authors.lastname: Fan
authors.forename: Wilder
authors.initials: W
authors.lastname: Carrillo-Cabrera
authors.forename: Lev
authors.initials: L
authors.lastname: Akselrud
authors.forename: Iryna
authors.initials: I
authors.lastname: Antonyshyn
authors.forename: Lidong
authors.initials: L
authors.lastname: Chen
authors.forename: Yuri
authors.initials: Y
authors.lastname: Grin