【摘要】 测量了磁性纳米Fe3O4颗粒的X射线衍射谱(XRD)、正电子湮没寿命谱(PALS)和符合多普勒展宽谱(CDBS),研究了不同压力和退火温度对磁性纳米Fe3O4颗粒物相、电子结构、缺陷及电子动量分布等的影响.XRD,PALS,CDBS测量结果表明:纳米Fe3O4颗粒的缺陷浓度随压力的增加而增大,但物相和缺陷类型并未发生变化;磁性纳米Fe3O4颗粒的物相、缺陷类型及缺陷数量随着退火温度的提高发生了显著的变化;大气环境中压成的纳米Fe3O4样品,相变发生在350—500℃范围内.随着退火温度的提高,纳米Fe3O4颗粒长大导致使界面缺陷数量减少、S参数变小、商谱高动量区的升高.更多还原

【Abstract】 The positron annihilation lifetime spectroscopy(PALS),coincidence doppler broadening spectroscopy(CDBS) and x-ray diffraction(XRD) are measured in the Fe3O4.The aim is to ascertain how pressure and annealing temperature influence the properties of Fe3O4 nanoparticles,such as the change of phase,electronic structure,defect and distribution of electronic momenta.The results indicate that the defect concentration of Fe3O4 nanoparticles increases with the increase of pressure,but the phase and defect type do not change.The phase type,and the guantity and type of defect change significantly as the annealing temperature varies.The phase transition of the Fe3O4 wafer pressed in atmosphere occurs when the annealing temperature is between 350 ℃ and 500 ℃.The grain size of Fe3O4 increases with the increase of the annealing temperature,which leads to the decrease in boundary defect and parameter S but it is contrary to the ratio curve.更多还原