Preparation And High Pressure Physical Properties Of ?-? Compounds GeS,GeSe By DC Arc Method

?–?compoundsarelayeredsemiconductormaterialthat show broad application prospects in the field of photovoltaic,thermoelectric and photocatalytic materials due to their excellent optical,electrical,and thermal properties.Meanwhile,the appropriate energy gap has excellent response characteristics to visible light,and thus some of them have been widely used in electronic devices.The multi-morphological nanoscale semiconductor materials have become the frontier and hot issues of industry research by the reason of the influence on performance of components by size effect and surface effect.?-?semiconductor compounds,which is represented by GeS and GeSe,exist in dispute concerning the influence of microstructure change on their properties and which have hindered the development of photoelectric.This thesis obtained different nano-morphological GeS and GeSe materials by the plasma-assisted direct current arc discharge method,then the influence of experiment parameter(electricit,gas and air pressure)on the morphology of sample are explored.The corresponding growth mechanism and the influence of microstructure on the properties are discussed.We have also obtained the crystal structural parameters of GeSe and GeS under high pressure via in-situ high pressure study which provided the experimental basis on the application on the field of photoelectric.1)Sublime sulphur powder and germanium powder were thoroughly mixed and tableting,voltage inflated argon gas pressure was set as 14 V,40 k Pa,respectively.We collected spinous GeS sample on the top surface of carbon crucible,and hammer ship on the condensing wall and discussed the growth mechanism of those two special morphologies of GeS sample.When current voltage,nitrogen air pressure is 100 A,14 V,and 20 k Pa,we have collected spherical shaped GeS sample on the inside of roof,the result of photoluminescence spectrum,absorption spectrum and fluorescence lifetime of spherical GeS sample show that its band gap and the fluorescence lifetime is 3.35 e V,6.19 ns,respectively,and is of strong high light absorption ability This thesis obtained multi-morphological GeS nano sample which will provid the experimental basis on the application of GeS on the field of photoelectric.2)We have obtained nano-ribbonlike,enokitake-like and spherical shape GeSe sample.We discussed growth mechanism of nano-ribbonlike,enokitake-like sample of GeSe.By changing the experimental parameter(electricity,voltage and air pressure),we found that the grain size of spherical shaped GeSe was significantly influenced by the pressure of nitrogen air.The characterization of optical properties on the spherical shaped GeSe sample have shown that its band gap and the fluorescence lifetime is 3.35 e V,6.13 ns,respectively,and is of strong high light absorption ability.3)We have studied the crystal structure of GeS and GeSe under high pressure via in-situ high pressure Raman and high pressure X-ray diffraction.The results of high pressure Raman examination of GeS indicated that its crystal structure is stable up to the highest pressure 14.9 GPa.No phase transition was observed under high pressure up to 25.5 GPa by the in-situ high pressure X-ray diffraction study of GeSe.Its bulk modulus,B0,is 50.7(4)GPa by fitting B-M equation.The in-situ high pressure Raman characterization has been carried out to further explore the crystal structure of GeSe.The results indicate that the red shift of Ag(1)vibration mode and discontinuity of bond lengths and angles at 5.2 GPa originates from the lattice derformation.