Pressure dependence of the thermal stability in LiMn2O4

Structural stability in terms of the decomposition temperature in LiMn₂O₄ was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn₂O₄ was found to have structural stability up to 5 GPa at room temperature.Under ambient pressure,the compound decomposed at 1300℃.The decomposition temperature decreased with increasing pressure,yielding more complex decomposed products.Below the decomposition temperature,the crystal structure of LiMn₂O₄ varied with pressure.The presented results in this study offer new insights into the thermal and pressure stability of LiMn₂O₄ materials as a cathode for lithium-ion batteries that can operate under extreme conditions.Therefore,these findings may serve as a useful guide for future work for improving lithium-ion batteries.     

DSC研制及KNO_3、Sn、Bi、Zn相变温度和相变焓测定

DSC是差示扫描量热计的简称。它是60年代在国际上出现的一项量热新技术。由于其功能可以和光谱仪媲美,有时也称之为热谱仪。DSC的量热原理与传统的量热学原理迥然不同。首先阐明这一原理的是Watson等人。根据Watson原理首先研制DSC的是美国Perkin-Elmer公司。DSC在自然科学和技术科学各领域中具有广泛的应用,在形形色色的工业部门中也具有种种重要用途。DSC在化学领域中的应用,主要有三个方面:其一为物质热力学性质的     

DSC研制及KNO3、Sn、Bi、Zn相变温度和相变焓测定

According to Watson′s DSC principle, a new design of electric circuit of DSC was proposed, Referring to the instrument constraction of DSC of Perkin-Elmer corporation, a new instrument construction of DSC was designed.This new electric circuit and this new instrument construction can overcome the shortcomings in de- sign of DSC of Perkin-Elmer corporation, Figure 1 is a schematic diagram of the new electric circuit. The temperatures and enthalpies of phase transitions of stan- dard materials were measured by using the new DSC. The experimental results are shown in table 1.     

二次加压对六面顶压腔压力发生效率和 压力密封性能的影响

随着六面顶压机大腔体静高压技术的发展,复杂多变的压力加载工艺被应用于高压科学研究和材料制备,但是不同压力加载工艺对压力发生效率和压力密封性能的影响尚未被充分研究。本工作在六面顶压机高压腔体和密封边内置入电路,通过原位测量Bi、Tl、Ba和锰铜丝的电阻,标定了一次加压和二次加压两种不同压力加载工艺下外部加载与腔体压力及密封边压力的对应关系。实验分析结果表明,二次加压工艺会导致腔体和密封边的压力发生效率明显降低,同时也会降低压力密封性能最差时对应的外部加载。此研究可为高压装置和压力加载工艺的优化设计提供指导。