title: LiCa₃As₂H and Ca₁₄As₆X₇ (X = C, H, N): two new arsenide hydride phases grown from Ca/Li metal flux.
abstract: The reaction of arsenic with sources of light elements in a Ca/Li melt leads to the formation of two new arsenide hydride phases. The predominant phase Ca14As6X7 (X = C(4-), N(3-), H(-)) exhibits a new tetragonal structure type in the space group P4/mbm (a = 15.749(1) Å, c = 9.1062(9) Å, Z = 4, R1 = 0.0150). The minor phase LiCa3As2H also has a new structure type in the orthorhombic space group Pnma (a = 11.4064(7) Å, b = 4.2702(3) Å, c = 11.8762(8)Å, Z = 4, R1 = 0.0135). Both phases feature hydride and arsenide anions separated by calcium cations. The red color of these compounds indicates they should be charge-balanced. DOS calculations on LiCa3As2H confirm a band gap of 1.4 eV; UV-vis spectroscopy on Ca14As6X7 shows a band gap of 1.6 eV. Single-crystal neutron diffraction studies were necessary to determine the mixed occupancy of carbon, nitrogen, and hydrogen anions on the six light-element sites in Ca14As6X7; these data indicated an overall stoichiometry of Ca14As6C(0.445)N(1.135)H(4.915).
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.
authors.forename: Trevor V
authors.initials: TV
authors.lastname: Blankenship
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang
authors.forename: Christina
authors.initials: C
authors.lastname: Hoffmann
authors.forename: Susan E
authors.initials: SE
authors.lastname: Latturner