Evers Jürgen, Möckl Leonhard, Oehlinger Gilbert, Köppe Ralf, Schnöckel Hansgeorg, Barkalov Oleg, Medvedev Sergey, Naumov Pavel
Department of Chemistry, Ludwig-Maximilian University of Munich , Butenandtstraße 5-13, D-81377 Munich, Germany.
Karlsruher Institut für Technologie (KIT), Institut für Anorganische Chemie , Engesserstraße 15, Gebäude 30.45, D-76131 Karlsruhe, Germany.
Inorg Chem. 2017 Jan 3;56(1):372-377. doi: 10.1021/acs.inorgchem.6b02294. Epub 2016 Dec 21.
SiO exhibits a high-pressure-high-temperature polymorphism, leading to an increase in silicon coordination number and density. However, for the related compound SiS such pressure-induced behavior has not been observed with tetrahedral coordination yet. All four crystal structures of SiS known so far contain silicon with tetrahedral coordination. In the orthorhombic, ambient-pressure phase these tetrahedra share edges and achieve only low space filling and density. Up to 4 GPa and 1473 K, three phases can be quenched as metastable phases from high-pressure high-temperature to ambient conditions. Space occupancy and density are increased first by edge and corner sharing and then by corner sharing alone. The structural situation of SiS up to the current study resembles that of SiO in 1960: Then, in its polymorphs only Si-O tetrahedra were known. But in 1961, a polymorph with rutile structure was discovered: octahedral Si-O coordination was established. Now, 50 years later, we report here on the transition from 4-fold to 6-fold coordination in SiS, the sulfur analogue of silica.
二氧化硅呈现出高压高温多晶型现象，导致硅配位数和密度增加。然而，对于相关化合物硫化硅，尚未观察到这种由压力诱导的四面体配位行为。迄今为止已知的硫化硅的所有四种晶体结构中，硅均为四面体配位。在正交晶系的常压相中，这些四面体共用棱边，仅实现了较低的空间占有率和密度。在高达4吉帕斯卡和1473开尔文的条件下，三种相可以作为亚稳相从高压高温淬火至常压条件。空间占有率和密度首先通过共用棱边和顶点增加，然后仅通过共用顶点增加。直至当前研究，硫化硅的结构情况类似于1960年时的二氧化硅：当时，在其多晶型物中仅已知硅氧四面体。但在1961年，发现了一种具有金红石结构的多晶型物：确立了八面体硅氧配位。如今，50年后，我们在此报告二氧化硅的硫类似物硫化硅中从四重配位到六重配位的转变。
