Syntheses, Structures and Band Gaps of KLnSiS4 (Ln = Sm, Yb)

摘要

Two new quaternary sulfides, KSmSiS4 (1) and KYbSiS4 (2), have been synthesized by high-temperature solid-state reaction. Single-crystal X-ray diffraction analyses indicate that both compounds crystallize in the space group P21/m, and the crystal data are as follows: a = 6.426(11), b = 6.582(11), c = 8.602(15) (A), ( = 107.90(13)°, Z = 2, V = 346.2(10)(A)3, Dc = 3.317 g/cm3, F(000) = 318,μ(MoKα)= 10.334 mm-1, the final R = 0.0559 and wR = 0.1370 for 1; and a = 6.3244(10), b = 6.5552(10), c = 8.5701(15)(A), β= 108.001(13)°, Z = 2, V = 337.91(9)(A)3, Dc = 3.621 g/cm3, F(000) = 334, μ(MoKα)= 15.737 mm-1, the final R = 0.0422 and wR = 0.0960 for 2∞ 2.The KLnSiS4 (Ln = Sm, Yb) structure consists of corrugated 2∞[LnSiS4]-layers which are formed by edge-sharing LnS8 bicapped trigonal prisms and SiS4 tetrahedra. The K+ cations are located in the cavities defined by S2- anions between the2∞[LnSiS4]-layers. Band-gap analyses show that compounds 1 and 2 are semiconductors with optical band-gaps of 2.40 and 2.34 eV, respectively.