title: Metastable Ni7B3: A New Paramagnetic Boride from Solution Chemistry, Its Crystal Structure and Magnetic Properties.
abstract: We trapped an unknown metastable boride by applying low-temperature solution synthesis. Single-phase nickel boride, Ni7B3, was obtained as bulk samples of microcrystalline powders when annealing the amorphous, nanoscale precipitate that is formed in aqueous solution of nickel chloride upon reaction with sodium tetrahydridoborate. Its crystal structure was solved based on a disordered Th7Fe3-type model (hexagonal crystal system, space group P63mc, no. 186, a = 696.836(4) pm, c = 439.402(4) pm), using synchrotron X-ray powder data. Magnetic measurements reveal paramagnetism, which is in accordance with quantum chemical calculations. According to high-temperature X-ray diffraction and differential scanning calorimetry this nickel boride phase has a narrow stability window between 300 and 424 °C. It crystallizes at ca. 350 °C, then starts decomposing to form Ni3B and Ni2B above 375 °C, and shows an exothermic effect at 424 °C.
authors.affiliation: Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt , Alarich-Weiss-Str. 12, 64287 Darmstadt, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hofmann
authors.affiliation: Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt , Alarich-Weiss-Str. 12, 64287 Darmstadt, Germany.
authors.forename: Nalan
authors.initials: N
authors.lastname: Kalyon
authors.affiliation: Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt , Alarich-Weiss-Str. 12, 64287 Darmstadt, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Kapfenberger
authors.affiliation: Materials Department and Materials Research Laboratory, University of California Santa Barbara , Santa Barbara California 93106, United States.
authors.forename: Leo
authors.initials: L
authors.lastname: Lamontagne
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg , Hans-Meerwein-Str. 4, 35032 Marburg, Germany.
authors.forename: Salman
authors.initials: S
authors.lastname: Zarrini
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg , Hans-Meerwein-Str. 4, 35032 Marburg, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Berger
authors.affiliation: Materials Department and Materials Research Laboratory, University of California Santa Barbara , Santa Barbara California 93106, United States.
authors.forename: Ram
authors.initials: R
authors.lastname: Seshadri
authors.affiliation: Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt , Alarich-Weiss-Str. 12, 64287 Darmstadt, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Albert