Spahr Dominik, Stękiel Michał, Zimmer Dominik, Bayarjargal Lkhamsuren, Bunk Katja, Morgenroth Wolfgang, Milman Victor, Refson Keith, Jochym Dominik, Byrne Peter J P, Winkler Björn
Goethe University, Institute of Geosciences, Crystallography, Frankfurt, Germany.
Dassault Systèmes BIOVIA, Cambridge, United Kingdom.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2020 Dec 1;76(Pt 6):979-991. doi: 10.1107/S205252062001238X. Epub 2020 Nov 3.
High-pressure single-crystal to 20 GPa and powder diffraction measurements to 50 GPa, show that the structure of PbSnO strongly distorts on compression with an elongation of one axis. A structural phase transition occurs between 10 GPa and 12 GPa, with a change of space group from Pbam to Pnam. The resistivity decreases by more than six orders of magnitude when pressure is increased from ambient conditions to 50 GPa. This insulator-to-semiconductor transition is accompanied by a reversible appearance change from transparent to opaque. Density functional theory-based calculations show that at ambient conditions the channels in the structure host the stereochemically-active Pb 6s lone electron pairs. On compression the lone electron pairs form bonds between Pb ions. Also provided is an assignment of irreducible representations to the experimentally observed Raman bands.
高压下单晶可达20吉帕，粉末衍射测量可达50吉帕，结果表明，PbSnO的结构在压缩时会强烈畸变，其中一个轴会伸长。在10吉帕至12吉帕之间发生结构相变，空间群从Pbam变为Pnam。当压力从环境条件增加到50吉帕时，电阻率降低超过六个数量级。这种绝缘体到半导体的转变伴随着从透明到不透明的可逆外观变化。基于密度泛函理论的计算表明，在环境条件下，结构中的通道容纳立体化学活性的Pb 6s孤电子对。在压缩时，孤电子对在Pb离子之间形成键。还给出了对实验观察到的拉曼带的不可约表示的归属。
