摘要
采用三层夹心靶结构,利用铜箔与抛光蓝宝石之间良好的接触条件,使用辐射式高温计观测到c取向蓝宝石在130～172 GPa冲击高压下的红外辐射。实验信号显示,位于近红外波段的蓝宝石冲击辐射随着压力的增加而变强;强度对比显示,蓝宝石的近红外发射强于界面发射。基于冲击作用下滑移带的温度高于冲击平衡温度的概念,将蓝宝石体内滑移带温度作为蓝宝石发射温度代入线性吸收公式,从而将蓝宝石发光强度的增加和界面冷却引起的发光强度下降相结合;将得到的界面一蓝宝石发射强度数值模拟结果与实验结果相比较,发现二者能够重合。由实验信号的上升趋势得到三个压力下0.85μm近红外波长处蓝宝石的冲击吸收系数数值。
Alumina is very important ceramic material; it has a unique combination of mechanical and optical properties. Alumina single crystal （sapphire） is commonly used as transparency window in shock wave measurements. When doped with Cr^3＋ , alumina is used as a pressure calibant in static high pressure experiments. In addition it is believed to be one of the major constituent of the Earth＇s mantle. Understanding of its optical property under high pressure is very important for the use of it in high pressure experiments and other material regions. However, sapphire or other transparent windows are indispensable in shock temperature measurements of opaque material. Recently, a few of sapphire＇s emission at lower than 50 GPa pressure range had been reported; whether this phenomenon detected at higher pressures is yet an open question. In this paper, infrared radiation of shock loaded sapphire has been observed to 172 GPa, using 1 ns time-resolved photomultiplier. As an un-polished 20-micro-thickness copper foil being sandwiched by two sapphires for a shock target, the intensity received by photomuhiplier demonstrates a durative increase characteristic. It is the fact that thermal diffusion occurred at contact interface can＇t cause this intensity-amplified current, the observed radiance continuously increases with time must origin from sapphire window. Under 130 - 172 GPa, the near infrared radiance of sapphire increases with shock stress. The fitting curve shows the absorptive parameter varies from 0.8 to 2.1 cm^- 1 at 850 nm in the experimental calculation about the color temperature of shocked pressure range. Up to now, there is no quantitative sapphire for explaining this emission. In the previous works, inhomogeneous hot spots distributed in shocked sapphire are regarded as the radiance source of sapphire, these hot spots, named ＂adiabatic shear band＂, are yielded by high speed local deformation. To our interpretation, adiabatic shear band usually exists in high-speed shock compressed material; its su
出处
《发光学报》
EI
CAS
CSCD
北大核心
2007年第5期741-747,共7页
Chinese Journal of Luminescence
基金
中国工程物理研究院预研基金(51478030404QT2201)
关键词
冲击高压
蓝宝石
红外辐射
Shock-induced
sapphire
infrared
radiation
