Single Crystal Growth And Characterization Of Transition Metal Chalcogenides And Transition Metal Carbides

Many transition metal chalcogenides and transition metal carbides have special band structure,which could lead to many interesting physic properties,including charge density wave phase transition,superconducting phase transition,large magnetoresistance,quantum oscillation,etc.And these physical phenomena are very sensitive to the structure of samples.So single crystal growth is the first step of the experiment in condensed matter physics.Technology of single crystal growth is not only of great significance in crystallography and material science,but also worthy of study in condensed matter physics.As a research hotspot in physics,single crystal of transition metal carbides is not easy to grow with their high melting point.Although transition metal chalcogenides can be synthesized by a traditional process,their quality and size cannot meet the requirements of condensed matter experiment.In this article,three different mater:ials are studied,and their structure and electrical transport properties are completely characterized.The main contents of the paper can be divided into the following aspect:(1)Hexagonal Mo2C single crystal is synthesized by La-C flux method for the first time.Its structure is characterized by transmission electron microscope(TEM)and X-ray diffractometer(XRD).And it is found that the bulk of hexagonal Mo2C single crystal is a superconductor with T,=2.9K by electrical and magnetic properties measurements.Its Hc2-T curve is fitted by the WHH model,and its superconductin g parameters are estimated at the temperature of 2K.(2)Large hexagonal PtSe2 single crystal is synthesized by Cu-Se flux method for the first time.The purity of sample is proved by the measurement of composition and structure.Electrical transport properties are characterized and it was found that PtSe2 is not a simple metal with a large magnetoresistance.(3)High quality TiTe2 single crystal is grown by three different routes.The samples grown by different ways are compared by XRD,EDS,electrical transport measurement and Raman spectra.And many physics properties of these samples are characterized.It is prove that these is no Charge Density Wave(CDW)transition in bulk TiTe2 single crystal by electrical transport properties.