Study On The Growth And Physical Properties Of Single Crystal CrSbSe₃

With the rapid expansion of semiconductor market,the research and application of semiconductor materials have attracted more and more attention.The magnetic semiconductor materials,with both the logic property of semiconductor materials and the storage property of magnetic materials,have been widely concerned.However,after more than ten years of development,the magnetic semiconductors still face difficulties in preparing magnetic semiconductors that can work at room temperature.Therefore,it is of great significance for the development and application of magnetic semiconductor materials to study the controllable preparation technology of room-temperature magnetic semiconductor materials,explore the effective measures to improve its Curie temperature to make it work at room temperature,and conduct a comprehensive physical property test of its electrical,magnetic,thermal and optical properties.In this paper,the quasi-one-dimensional CrSbSe3 single crystals were grown by using self-fluxing method.The impact of the composition,temperature and growth time on the size of the products were studied.The Raman vibration properties,optical band gap and the Pb-doping effect on the electrical and magnetic properties were also analyzed.The detailed conclusions are listed as following:(1)The self-fluxing method was used to grow CrSbSe₃.The product was orthorhombic phase,the space group was Pnma,the cell parameters were a=91.475(6)nm,b=37.872(3)nm,c=134.264(11)nm,and the theoretical density was 5.864 g/cm³.The crystal size is about10 mm,and the flux remains little after annealing.(2)The angle resolved polarized Raman of materials were analyzed.According to the experimental data and the corresponding Raman intensity formula,the Raman vibration mode is determined.It is found that the vibration modes in the vertical configuration are A_g¹,A_g²,A_g⁴,B¹_1g and B²_1g,and in the parallel configuration are A_g¹,A_g²,A_g³,B¹_1g and B²_1g.The results show that in both vertical and parallel configurations,the pulldown modes are symmetric about 60°angle.At the same time,the temperature dependent Raman of the crystal surface(00l)is analyzed.The results show that the first-order temperature coefficients of vibration modes A_g¹,A_g²,A_g³,B¹_1g and B²_1g are-0.0032,-0.0007,-0.0021,-0.0074 and-0.0075 cm^-1K^-1,respectively.According to the experimental data fitting,the first-order temperature coefficient can be obtained under different vibration modes,and the size of the first-order temperature coefficient is compared with the common two-dimensional materials.It is found that the absolute value of the first-order temperature coefficient is related to the magnitude of intermolecular force.(3)The electrical properties of single crystal CrSbSe₃ and Pb doped samples are analyzed.According to the comparison of electrical properties data,it can be found that there are four orders of magnitude changes in the temperature range of 100-300 K for Pb doped samples,from near insulator to semiconductor;the resistivity of the parent sample changes little,and remains unchanged at the order of 10⁴?·cm.According to the calculation of impurity activation energy,the impurity activation energy of Pb doped samples is less than the energy required by the parent intrinsic excitation,so that the temperature change can cause large resistivity change,so Pb doping can effectively improve the electrical properties of CrSbSe₃.(4)The magnetic properties of single crystal CrSbSe₃ and Pb doped samples are analyzed.According to the comparison of magnetic data,it can be found that Pb doping not only reduces Curie temperature,but also reduces the molar susceptibility.The Curie temperature of the sample decreases to 65 K after Pb doping from 71 K of the parent Curie temperature,but the magnetic susceptibility is isotropic.It can be concluded from the hysteresis loop that for the saturation magnetization and the saturation magnetic moment,both the parallel b direction and the vertical b direction of the magnetic field of the Pb doped sample are larger than that of the parent sample,and the two directions show the anisotropy of the saturation magnetization.(5)The optical band gap of single crystal CrSbSe₃ is measured.The result shows that the band gap is 0.7 e V,which is same to the result of 0.7 e V derived from conductivity in literature.It shows that CrSbSe₃ is a narrow band gap semiconductor.