高年级本科生参与大学物理实验教学的实践和思考

针对一些实验教学存在的问题,阐述高年级本科学生实验助教的积极意义。针对聘用实验助教过程中存在的一些实际问题,提出将来更有效开展聘用实验助教来提高实验教学质量的有效措施。     

基于PDMS金属可调谐光栅的制备工艺研究

分别利用直接法和间接法,制备了基于PDMS(聚二甲基硅氧烷)基底的金属可调谐光栅。由于在金属举离过程中PDMS遇丙酮溶液溶胀,导致直接法在机械调谐过程中光栅严重断裂,而利用间接法可以克服此问题。利用PDMS高弹性的特点,通过控制PDMS的纵、横向拉伸程度,对光栅周期进行连续、任意调谐,可获得预定的目标周期。     

Effects of Yb-doping on flux pinning properties in YBa2Cu3O7-δ

The effects of Yb-doping on the critical current density(Jc) and the critical temperature(Tc) in YBa2Cu3O7-δ(YBCO) were investigated.Rietveld refinements of X-ray diffraction showed that Yb3+ ions had partly substituted Y sites in YBCO and the unit cell volume V decreased monotonically as x increasing.Although Tc almost had no change with increasing Yb-concentration,the increase of Jc occurred as a field was applied and displayed a maximum at x=0.08.We argued that the formation of nanometric inhomogeneity may lead to the enhancement of pinning force.     

Effect of Yb2O3 additives on structure and transport properties of YBa2Cu3O7-δ

The effects of Yb2O3 particles on the microstructure and transport properties of YBa2Cu3O7-δ(YBCO) were investigated through resistance-temperature(R-T),scanning electron microscope(SEM),X-ray diffraction(XRD) and the critical current density(Jc) versus applied magnetic field(Jc-B) measurements.YBCO powder with Yb2O3 additives was synthesized using standard solid state reaction technique.Rietveld refinements of X-ray diffraction showed that both Yb2O3 and YBCO phases coexisted in the products.The critical current density(Jc) exhibited a maximum at x=0.05 in YBCO+xYb2O3 systems.Moreover,small additions of Yb2O3 in YBCO could enhance Jc by applying the magnetic field,although the superconducting temperature(Tc) decreased monotonically with increasing additive content.The characteristic behavior of Jc might come from the counterbalance of two effects simultaneously,which was caused by the inhomogeneity of grains distribution in nano-scale and degradation on superconducting properties.