High pressure and high temperature synthesis and in-situ characterization of new compounds with special electronic transport properties, using "lone-pair" oxides, fluorides, sulphides and selenides of elements from groups 14-16

点击翻译按钮获取中文摘要

The goal of the proposed study is to synthesize novel stable structures exhibiting interesting physical and electronic transport properties. The oxides, fluorides, sulphides and selenides of elements from groups 14¿16, which exhibit the presence of lone-electron pairs, are making the subject of the study. Such compounds offer intrinsically the opportunity to delocalize the free electron pair by simultaneous application of extreme pressures and temperatures. Furthermore, such dislocations are associated with changes in the electronic behaviour, likely to trigger modifications of the transport properties: insulator-metal, and semiconductor-metal type. In such circumstances, it is envisioned that an insulator- or semiconductor-metal-superconductor transition could be also made possible. A combination of quench-type and in-situ-type experimental high pressure and high temperature techniques employing large volume multianvil devices will be used to facilitate the uncovering of such new interesting phases, and to map their stability range in the pressure-temperature-time space. In addition, chemical doping of the compounds making the subject of the study could accelerate the delocalisation process and/ or could stabilise the structures obtained at extreme conditions and help retrieve them at ambient pressures and temperatures. The means of obtaining such new phases are provided by the use of large volume high pressure and high temperature devices, in particular multianvil presses (present both in our laboratory and at HASYLAB, DESY Hamburg). The range of attainable pressures and temperatures reaches 30 GPa and 2500 °C, respectively.