Synthesis, Structure, and Properties of Clathrate Si_30.3(8)P_15.7(8)Se_7.930(3)

Abstract

The new clathrate single crystal Si P Se 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 Si P Se 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.

Supramolecular Organization in Confined Nanospaces

“…While negatively charged frameworks (the most abundant ones) trap cations, the positively charged lattices of “inverse” clathrates are particularly interesting because, unlike most zeolites, they encapsulate anions – normally halides, but also tellurium or selenium . For instance, the silicon‐phosphorus framework of Figure a traps Se in a partially covalent embrace, leading to a semiconductive material of potential thermoelectric use …”