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Synthesis, Structure, and Properties of Clathrate Si30.3(8) P15.7(8) Se7.930(3)
Hui Zhang1,2, Wei Peng1,2, Gang Mu1,2
1Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, P.R. China.
Abstract:
The new clathrate single crystal Si30.3(8) P15.7(8) Se7.930(3) was synthesized through a solid-state reaction, and it was characterized to have a unit cell parameter a=19.7614(1) Å and belong to space group Fm3‾ . In this clathrate structure, a Se1-Si3 bond forms in place of the tetrakaidecahedron structure, and pental dodecahedral cages composed of Si and P atoms encapsulate Se2, Se3, and Se4 guest atoms. Similar structures are observed in partial Te- and Ge-substituted compounds. Theoretical calculations based on an ordered formula Si32 P14 Se7 showed a semiconducting electronic structure with a band gap of 0.711 eV. A photoelectric response was observed in this compound at room temperature. Across the whole temperature range, this material exhibited a weak temperature-dependent diamagnetic signal, and no phase transition or thermal anomaly was observed in heat capacity measurements.