title: Planar symmetry incompatibility in Ru-Sn-Zn pseudo-decagonal approximants composed of novel pentagonal antiprisms.
abstract: Two new ternary compounds in the Ru-Sn-Zn system were synthesized by conventional high-temperature reactions, and their crystal structures were analyzed by means of the single crystal X-ray diffraction: Ru(2)Sn(2)Zn(3) (orthorhombic, Pnma, Pearson symbol oP28, a = 8.2219(16), b = 4.1925(8), c = 13.625(3) Å, V = 469.66(16) Å(3), Z = 4) and Ru(4.15)Sn(4.96)Zn(5.85) (orthorhombic, Pnma, Pearson symbol oP60-δ, a = 8.3394(17), b = 4.2914(9), c = 28.864(6) Å, V = 1032.98(40) Å(3), Z = 4). With the increase in the Sn content, the half-decagon structure unit with a triangle center in Ru(2)Sn(2)Zn(3) grows up to a symmetry incompatible decagonal unit with a central triangle in the common plane in Ru(4.15)Sn(4.96)Zn(5.85). Both structures can be described by hexagonal arrays of Sn-centered novel pentagonal antiprisms. In light of their pseudodecagonal diffraction in the h0l section and point group mmm, both phases are considered as new quasicrystal approximants in the Ru-Zn-Sn ternary system. The temperature dependences of the electrical resistivity for both compounds exhibit metallic behavior, but their Seebeck coefficients are of opposite sign.
authors.affiliation: Department of Chemistry, Philipps University Marburg, Marburg, Germany. xiong.dingbang@ky8.ecs.kyoto-u.ac.jp
authors.forename: Ding-Bang
authors.initials: DB
authors.lastname: Xiong
authors.forename: Norihiko L
authors.initials: NL
authors.lastname: Okamoto
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Inui