Empa Swiss Federal Laboratories for Materials Science and Technology, Hydrogen & Energy, Dübendorf, Switzerland.
J Phys Chem A. 2010 Sep 23;114(37):10117-21. doi: 10.1021/jp105585h.
The hydrogen dynamics in solid and in liquid LiBH4 was studied by means of incoherent quasielastic neutron scattering. Rotational jump diffusion of the BH4- subunits on the picosecond scale was observed in solid LiBH4. The characteristic time constant is significantly shortened when the system transforms from the low-temperature phase to the high-temperature phase at 383 K. In the molten phase of LiBH4 above 553 K, translational diffusion of the BH4- units is found. The measured diffusion coefficients are in the 10(-5)cm2/s range at temperatures around 700 K, which is in the same order of magnitude as the self-diffusion of liquid lithium or the diffusion of ions in molten alkali halides. The temperature dependence of the diffusion coefficient shows an Arrhenius behavior, with an activation energy of Ea = 88 meV and a prefactor of D0 = 3.1 × 10(-4)cm2/s.
通过非相干准弹性中子散射研究了固态和液态 LiBH4 中的氢动力学。在固态 LiBH4 中观察到 BH4-亚基在皮秒尺度上的旋转跃迁扩散。当系统在 383 K 从低温相转变为高温相时，特征时间常数显著缩短。在高于 553 K 的 LiBH4 熔融相中，发现 BH4-单元的平移扩散。在大约 700 K 的温度下，测量的扩散系数在 10(-5)cm2/s 的范围内，与液态锂的自扩散或熔融碱卤化物中离子的扩散处于同一数量级。扩散系数的温度依赖性表现出 Arrhenius 行为，具有 88 meV 的激活能 Ea 和 3.1×10(-4)cm2/s 的prefactor D0。
