纳米α-Fe_2O_3的制备及其正电子湮没谱学研究

The Preparation and Positron Annihilation Spectroscopy Study of Nanometerα-Fe_2O_3

对氧化铁颗粒进行了X射线衍射谱(XRD)测量和正电子湮没寿命谱(PALS)测量,分别运用Jade和Lifetime软件拟合数据,研究了纳米氧化铁颗粒的结构、缺陷以及自由电子密度.XRD测量结果表明了氧化铁是简单六方晶系,空间群是R-3c(167),其相应的点阵常数分别是三个基矢的长度a=b=0.530 42 nm,c=1.374 60 nm.PALS测量结果表明了正电子在氧化铁材料中的寿命成分有三种,值分别约是τ_1=150.7 ps,τ_2=333.0 ps,τ_3=725.0 ps,主要寿命成分是短寿命τ_1和中等寿命τ_2两种,分别对应的缺陷种类是近似单空位大小的自由体积缺陷和微孔洞缺陷,且其对应的强度比I_1/I_2值为1.52,表明实验试样的界面缺陷以单空位为主,验证了正电子的寿命越短,湮没率越大,则自由电子密度越大.

In this paper, the X-ray diffraction （XRD） and positron annihilation lifetime spectroscopy （PALS） measurements of iron oxide particles are performed, the structure, defects and free electron density of nanometer iron oxide particles were studied by using Jade and Lifetime software to fit the date respeetively.XRD measurement results show that the iron oxide is Primitive Hexagonal, the space group is R-3c （167） , and the correspond- ing lattice constants are the length of three basis vectors： a = b = 0. 530 42 nm, c = 1.374 60 nm.The results of PALS measurement showed that the lifetime of the positron in the iron oxide material has three kinds,which are about 150.7 ps（τ1 ）,333.0 ps（ τ2 ） ,and 725.0 ps（ τ3 ）.The main life components are two kinds of short lifeτ1and medium lifeτ2 ,respectively, corresponding to the defect types are the free volume defects of the single va- cancy size and micro cavity defects, and the corresponding intensity ratio is 1.52,which in- dicates that the interface defects of the experimental samples are dominated by single va- cancies.The PALS experiment proved that the shorter the lifetime of the positron, the greater the annihilation rate, the greater the free electron density.