0.1~3 000 MPa下碳化硅顶砧拉曼光谱作为压力计的研究

 利用Mao-Bell型水热金刚石压腔，以6H型碳化硅晶体作为顶砧，在常温下对碳化硅顶砧的不同点位进行拉曼光谱的原位测量，探讨了在一定条件下利用碳化硅顶砧的969拉曼峰位移作为压力标定的可行性、所具有的优点及需要改进的方面，并且得到了室温下的压力测量公式。     

不同形貌Er,Yb共掺六方NaYF4的合成及上转换发光特性研究

利用水热法成功合成了不同形貌的稀土掺杂六方NaY0.95Yb0.03Er0.02F4,包括柱状、粒状、片状、管状等.通过XRD,SEM,TEM对合成样品的物相结构及晶粒形态进行了表征,探讨络合剂EDTA用量;表面活性剂CTAB,P123,十二烷基苯磺酸钠;热溶剂水、乙二醇、聚乙二醇对晶体生长方向的影响,并对不同形态样品进行上转换发光性能测试,分析晶粒形态对上转换发光强度与寿命的影响,结果显示晶粒越小发光强度越强,相当粒径的管状样品的发光强度比粒状的强,不同晶粒形态上转换的主要能量传递模式也不相同.研究结果可以指导我们可控合成适应实际应用需求的晶粒形态及优良上转换发光性能的材料.     

Rotating wheel filter design and optimization for a uniform depth dose distribution in heavy ion therapy

Treatment planning of heavy-ion radiotherapy involves predictive calculation of not only the physical dose but also the biological dose in a patient body. The goal in designing beam-modulating devices for heavy ion therapy is to achieve uniform biological effects across the spread-out Bragg peak (SOBP). To achieve this, a mathematical model of Bragg peak movement is presented. The parameters of this model have been resolved with Monte Carlo method. And a rotating wheel filter is designed basing on the velocity of the Bragg peak movement.     

Giant Temperature Coefficient of Resistance in ZnO/Si （111） Thin Films

Giant negative temperature coefficient of resistance （TCR） was observed in ZnO/Si （111） thin films. The films were grown using the pulsed laser deposition （PLD） technique, taking Si （111） wafer as substrates, with a substrate at the temperature below 450°C in the PLD. It is found that both TCR-temperature behavior and TCR value are strongly affected by deposition temperature. The maximal TCR value over -10.9%K-1 can be observed at the deposition temperature from 20°C to 350°C and reaches to -13%K-1 at deposition temperature 20°C where the film shows X-ray diffraction amorphous. The results suggest that the ZnO/Si films demonstrate great potentials when used in a low-cost, high-performance, non-cooling and highly sensitive bolometer.     

Raman scattering under extreme conditions

Raman scattering is a versatile and powerful technique and has been widely used in modern scientific research and vast industrial applications. It is one of the fundamental experimental techniques in condensed matter physics, since it can sensitively probe the basic elementary excitations in solids like electron, phonon, magnon, etc. The application of extreme conditions(low temperature, high magnetic field, high pressure, etc.) to Raman scattering, will push its capability up to an unprecedented level, because this enables us to look into new quantum phases driven by extreme conditions, trace the evolution of the excitations and their coupling, and hence uncover the underlying physics. This review contains two topics.In the first part, we will introduce the Raman facility under extreme conditions, belonging to the optical spectroscopy station of Synergetic Extreme Condition User Facilities(SECUF), with emphasis on the system design and the capability the facility can provide. Then in the second part we will focus on the applications of Raman scattering under extreme conditions to a variety of condensed matter systems such as superconductors, correlated electron systems, charge density waves(CDW) materials, etc. Finally, as a rapidly developing technique, time-resolved Raman scattering will be highlighted here.