新能源材料与器件专业“锂离子电池课程设计”的改革与探索

“锂离子电池课程设计”是新能源材料与器件专业的一门重要实践课程，是为配合《锂电池原理与结构》而开设。基于“锂离子电池课程设计”的课程培养目标，对课程设计的现状进行分析，随后有针对性地提出了分阶段培养体系构建方案，将课程设计分为课前预习、课堂学习与实践及成果展示3个阶段，全方位的提升学生学习的积极性、创新能力、理论应用于实践能力及团队合作能力，最后，通过评价体系改革和课后反馈巩固和进一步提升教学改革效果，最终为工科实践类课程提供借鉴。     

Phase Transition Behavior of LiCr 0.35 Mn0.65O2 under High Pressure by Electrical Conductivity Measurement

The electrical conductivity of powdered LiCr 0.35 Mn0.65O2 is measured under high pressure up to 26.22 GPa in the temperature range 300-413 K by using a diamond anvil cell. It is found that both conductivity and activation enthalpy change discontinuously at 5.36 GPa and 21.66 GPa. In the pressure range 1.10-5.36 GPa, pressure increases the activation enthalpy and reduces the carrier scattering, which finally leads to the conductivity increase. In the pressure ranges 6.32-21.66 GPa and 22.60-26.22 GPa, the activation enthalpy decreases with pressure increasing, which has a positive contribution to electrical conductivity increase. Two pressure-induced structural phase transitions are found by in-situ x-ray diffraction under high pressure, which results in the discontinuous changes of conductivity and activation enthalpy.     

DAC垫片孔侧壁绝缘程度对电导率测量结果的影响

通过有限元方法,计算了DAC内垫片孔侧壁与样品发生不同程度短路的情况下,范德堡法测量样品电阻率的相对误差. 发现垫片孔侧壁与样品短路面积小于20％时,相对误差可以控制在10％以内. 而当短路面积超过25％时,相对误差迅速增大. 研究中还发现,电极越靠近样品边缘,相对误差越小.     

Pressure- and temperature-dependent luminescence from Tm3+ ions doped in GdYTaO4

Luminescent properties of Tm³⁺-doped GdYTaO₄ are studied for exploring their potential applications in temperature and pressure sensing.Two main emission peaks from ³H₄→³H₆ transition of Tm³⁺are investigated.Intensity ratio between the two peaks evolves exponentially with temperature and has a highest sensitivity of 0.014 K^?1 at 32 K.The energy difference between the two peaks increases linearly with pressure increasing at a rate of 0.38 meV/GPa.Intensity ratio between the two peaks and their emission lifetimes are also analyzed for discussing the pressure-induced variation of the sample structure.Moreover,Raman spectra recorded under high pressures indicate an isostructural phase transition of GdYTaO₄ occurring at 4.46 GPa.     

PbMoO4原位高压拉曼光谱和电导率的研究

 钼酸铅（PbMoO₄）具有高的声光品质因数、低的声损耗、良好的声阻抗匹配等性质，被广泛应用于声光偏转器、调制器、可调滤光器、声表面波器件等各类声光器件，其优异的低温闪烁性能亦引起人们的注意，具有在核设备方面的应用潜力。为探讨其晶体结构和物理性质，在金刚石对顶砧上原位测量了PbMoO₄的拉曼光谱，并测量了其在几个不同压力点下电导率随温度的变化。实验发现，压力在12.5 GPa时，拉曼峰完全消失，说明压力在10.8～12.5 GPa之间PbMoO₄样品出现了非晶态转变。当从26.5 GPa卸压到9.4 GPa时，PbMoO₄的拉曼谱在低波数出现无序化，而在2.4 GPa压力下858 cm^-1峰又重新出现，说明样品结构由无序向晶化回复。压力在10.8 GPa以上时，电导率随着温度的增加而显著增加，且随着压力的增加也明显增加。     

利用金属垫片做为电极在金刚石对顶砧上精确测量样品电导率的研究

利用传统的四电极方法在金刚石对顶砧（DAC）上进行原位的样品电导率测量时,如果金属垫片样品孔内壁不能完全绝缘,测量结果将会存在很大的误差.为避免该实验误差的产生,作者提出了用双电极模型进行电导率测量的方法,即在DAC砧面上制备一个圆形测量电极的同时,将金属垫片样品孔的内壁做为第二个测量电极,并利用有限差分方法对电导率进行计算.通过这种方式,由金属垫片不绝缘而产生很大测量误差的问题得以解决.实验结果表明测量相对误差被控制在7％以下.