Synthesis And Physical Properties Of Layered Compounds TXTe₃

Layered compounds have unique compositions and crystal structures,in which there is a strong spin-orbit coupling interaction,so they have many novel physical properties.Cr Si Te3 is a ferromagnetic semiconductor with an indirect band gap.Our previous theoretical results show that the Al XTe3?X=Si,Ge?are direct semiconductors.They showed a large Seebeck coefficient?about 500?V/K?in the temperature range of 300-600 K.In this paper,we mainly studied the preparation and structure,performance characterization of TXTe3?T=Cr,Al;X=Si,Ge?.The main results are as follows:?1?As target products,four kinds of samples of Cr Si Te3,Cr Ge Te3,AlSiTe₃,and AlGeTe₃ were synthesized by solid phase reaction methods with Si,Ge and Te elements as the raw materials.The crystal structure and magnetic properties were studied by means of XRD diffraction analysis,EDS energy spectrum analysis and scanning electron microscopy.The materials of Cr Si Te3 and Cr Ge Te3 were obtained as main phase.However,layered compounds AlSiTe₃ and AlGeTe₃ are very difficult to obtain single phase materials by solid-state reaction.?2?In the process of preparing AlSiTe₃,the binary layered compound Si₂Te₃ material was found as main phase.Considering the spin-orbit coupling effect of Bi2Te3 and its layered structure characteristics of the typical thermoelectric materials,we studied the physical characteristics of Si₂Te₃ in depth.The binary compound Si₂Te₃ showed typical electrical transport properties of semiconductor materials.At the same time,it has a very low thermal conductivity at room temperature,which is only 0.33 m-1K-1 W.Low thermal conductivity is one of the most significant characteristics for exploring new type of high performance thermoelectric materials.?3?Monolayer of Si₂Te₃ crystal was successfully prepared by micro mechanical stripping method for the further study of the photoelectric properties and thermoelectric properties.