The Characterizations Of NbSb₂ Synthesized By High Temperature And High Pressure

Topological insulators and topological semimetals have great potential in semiconductor applications due to their exotic physical properties,unique quantum state and low energy dissipation.Exploring more high-quality topological materials has become a hot topic in condensed matter physics in recent years.In recent years,it has been found that the chemical compounds of group VA exhibit many novel physical properties.High pressure is an effective means to explore new materials.In this paper,the properties of VA group compound NbSb₂ at ambient pressure and high pressure were studied and the following results were obtained:1.Monoclinic phase of NbSb₂ was successfully synthesized by means of high temperature and high pressure?HTHP?as well as self-flux method.Two synthetic methods for NbSb₂ were analyzed by X-ray diffraction?XRD?and scanning electron microscope?SEM?.NbSb₂ obtained through self-flux method had higher purity,larger crystal size and better crystallization than that prepared by HTHP.The samples prepared by HTHP have high density,high hardness,good thermal conductivity and plasticity.The pressure had a great effect on the synthesis of NbSb₂.The samples synthesized through higher pressure have dense structure and large crystal size than those at lower pressure.High resolution transmission electron microscope?HRTEM?analysis showed that the surface of NbSb₂ had many crystal defects.2.The behavior of NbSb₂ at low temperature was studied by PPMS.NbSb₂exhibited a strong metallic property,and its resistivity decreased monotonically with the decrease of temperature.There was no sign of giant magneto-resistance as reported by other studies,which may be due to the defects from our polycrystalline samples.3.The crystal structure stability of NbSb₂ under high pressure was studied by in-situ synchrotron radiation X-ray diffraction and Raman spectroscopy.In the pressure range of 0³5 GPa,the crystal structure of NbSb₂ remained monoclinic C2/m?no.12?phase and structural phase transition had not occurred.The compressibility of NbSb₂ along a,b and c axis was different,and the degree of compression of NbSb₂ showed obvious anisotropy as the pressure increased.The evolution of high pressure Raman spectra of NbSb₂ were consistent with the X-ray diffraction results.