MgO单晶冲击变形产生点缺陷吸收谱的实时测量

Real-Time Absorption Spectrum Measurements of Deformation-Induced Point Defects in Single Crystal MgO

为研究冲击塑性变形产生的缺陷对MgO单晶透明性的影响,采用40通道(波长)纳秒时间分辨高温计和冲击波原位光源技术,对在一维应变冲击加载下MgO单晶的透射谱进行了实验测量。冲击波加载方向垂直于样品(100)晶面,测谱范围为400~800nm,得到了2个压力点(约50GPa和约70GPa)的吸收系数随波长的变化曲线,从实测曲线发现了6个明显的特征吸收峰,其中心波长分别为410、460、490、520、580和660nm。通过对比分析,确定出410、460、490和580nm处的吸收峰为F聚心吸收,520nm处的吸收峰为V-心吸收,而660nm处的吸收峰则可能为与填隙原子相关的吸收。这是在冲击压缩条件下,首次实时观测到的MgO单晶样品冲击塑性变形产生的点缺陷色心吸收现象。

The purpose of this study is to investigate the effects of deformation-induced defects on optical transparency of MgO single crystal under shock loading.With the nanosecond-time-resolved 40-wavelength radiation pyrometer and shock-compressed in situ light source techniques,transmission spectrums of single crystal MgO shocked along〈100〉direction on two-stage gus gun were measured.Spectrums of the measurements ranged from 400 to 800nm.Curves of absorption coefficients versus wavelengths under≈50GPa and ≈70GPa were obtained.Color center absorption peaks(410,460,490,580 nm assigned to aggregate F type centers;520nm to V-center;660nm probably to absorption related with interstitial atom)indicate point defects created during shock plastic deformation process.It is for the first time that color centers of point defects were observed in real time.