title: Synthesis, structure, and properties of two Zintl phases around the composition SrLiAs.
abstract: Two atomic arrangements were found near the equiatomic composition in the strontium-lithium-arsenic system. Orthorhombic o-SrLiAs was synthesized by reaction of elemental components at 950 °C, followed by annealing at 800 °C and subsequent quenching in water. The hexagonal modification h-SrLi(1-x)As was obtained from annealing of o-SrLiAs at 550 °C in dynamic vacuum. The structures of both phases were determined by single-crystal X-ray diffraction: o-SrLiAs, structure type TiNiSi, space group Pnma, Pearson symbol oP12, a = 7.6458(2) Å, b = 4.5158(1) Å, c = 8.0403(3) Å, V = 277.61(2) Å(3), R(F) = 0.028 for 558 reflections; h-SrLi(1-x)As, structure type ZrBeSi, space group P6(3)/mmc, Pearson symbol hP6, a = 4.49277(9) Å, c = 8.0970(3) Å, V = 141.54(1) Å(3), RF = 0.026 for 113 reflections. The analysis of the electron density within the framework of the quantum theory of atoms in molecules revealed a charge transfer according to the Sr(1.3+)Li(0.8+)As(2.1-), in agreement with the electronegativities of the individual elements. The electron localizability indicator distribution indicated the formation of a 3D anionic framework [LiAs] in o-SrLiAs and a rather 2D anionic framework [LiAs] in h-SrLi(1-x)As. Magnetic susceptibility measurements point to a diamagnetic character of both phases, which verifies the calculated electronic density of states.
authors.affiliation: Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 200050, China.
authors.forename: Xian-Juan
authors.initials: XJ
authors.lastname: Feng
authors.forename: Yurii
authors.initials: Y
authors.lastname: Prots
authors.forename: Marcus Peter
authors.initials: MP
authors.lastname: Schmidt
authors.forename: Stefan
authors.initials: S
authors.lastname: Hoffmann
authors.forename: Igor
authors.initials: I
authors.lastname: Veremchuk
authors.forename: Walter
authors.initials: W
authors.lastname: Schnelle
authors.forename: Ulrich
authors.initials: U
authors.lastname: Burkhardt
authors.forename: Jing-Tai
authors.initials: JT
authors.lastname: Zhao
authors.forename: Yuri
authors.initials: Y
authors.lastname: Grin