Study Of Controllable Growth And Properties Of Zr-Based Group IVB-V Transition Metal Trisulfide

In-depth research on two-dimensional materials found that none of material system can fully meet all the requirements of the post-silicon era.Transition metal trisulfides(TMTCs)with wide band gap and quasi-one-dimensional structure have attracted the attention of researchers in recent years.The wide range of bandgap(0.2eV-2eV)makes it suitable for the next generation of electronics and optoelectronics,and the anisotropy of quasi-one-dimensional properties provides an additional freedom for next-generation electronics device process.Currently,the research on the synthesis of transition metal trisulfide(such as ZrTe3)is mainly carried out either by sintering method,chemical vapor transport method or both to obtain ZrTe3 single crystal.These methods suffer from high time cost,poor controllability,and cumbersome processes.Thus,searching for a feasible method with low time cost and precise regulation is of great significance for the in-depth study of ZrTe3 and its versatile practical applicationsThis thesis mainly focuses on the synthesis of high-quality,size-controllable ZrTe3 single crystal by chemical vapor deposition(CVD)with low time cost and good controllability.On the basis of traditional CVD synthesis,an innovative device was added to synthesize large-area high-quality ZrTe3 single crystal through CVD method for the first time,and the synthesis time was reduced from 2-30 days for sintering and chemical vapor phase transfer(CVT)methods down to less than 2 hours.The effects of CVD growth temperature and holding time on the size and aspect ratio of ZrTe3 single crystal were also studied.The relationship between the two growth parameters and the size of ZrTe3 single crystal was systematically investigated.It was found that the size and aspect ratio of the synthesized ZrTe3 single crystal can be effectively regulated by controlling the reaction temperature and the holding time.Furthermore,the limits of the regulation of the aspect ratio of one-dimensional ZrTe3 single crystal by CVD method are found.The electrical and magnetic properties of ZrTe3 bulk single crystals were tested.For the first time,it is found that the magnetism of ZrTe3 block single crystal is induced by the interaction between ferromagnetism and diamagnetism,which is different from other MX3(M=Ti、Zr、Hf;X=S、Se)that are all exhibit diamagnetic properties.Furthermore,the Curie temperature(Tc)of ZrTe3 is greater than 300 KOn the basis of CVD synthesis of ZrTe3 single crystal,the effect of CVD growth temperature on the composition and morphology of as-grown crystals were further systematically studied.It was found that ZrTe3 single crystal was synthesized in the range of 650℃-800℃,ZrTe2 single crystals are formed in the range of 800℃-1050℃,and ZrSiTe crystals are formed in the range of 1050℃-1100℃.In terms of crystal morphology,the transition from single crystalline quasi-one-dimensional structure of ZrTe3 to single crystalline two-dimensional structure of ZrTe2 was realized,and the mechanism of growth temperature with the composition and morphology of crystal was analyzed.For the first time,a large-area and high-quality ZrTe2 single crystal was synthesized by chemical vapor deposition.The synthesis time of ZrTe2 single crystal was reduced from 10-14 days for the sintering method and chemical vapor transmission method to less than two hours.ZrTe2 bulk single crystal was tested for electrical and magnetic properties.It was found that ZrTe2 single crystal exhibited ferromagnetism,and its Curie temperature Tc was 150 K.The reason for the ferromagnetism is analyzed,and its ferromagnetism is mainly derived from the electron spin charge of Zr atoms.