Demmel F, Fraile A, Szubrin D, Pilgrim W-C, Morkel C
ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK.
J Phys Condens Matter. 2015 Nov 18;27(45):455102. doi: 10.1088/0953-8984/27/45/455102. Epub 2015 Oct 14.
The temperature dependence of the dynamic structure factor at next-neighbour distances has been investigated for liquid aluminium. This correlation function is a sensitive parameter for changes in the local environment and its Fourier transform was measured in a coherent inelastic neutron scattering experiment. The zero frequency amplitude decreases in a nonlinear way and indicates a change in dynamics around 1.4 ∙ Tmelting. From that amplitude a generalized viscosity can be derived which is a measure of local stress correlations on next-neighbour distances. The derived generalized longitudinal viscosity shows a changing slope at the same temperature range. At this temperature the freezing out of degrees of freedom for structural relaxation upon cooling sets in which can be understood as a precursor towards the solid state. That crossover in dynamics of liquid aluminium shows the same signatures as previously observed in liquid rubidium and lead, indicating an universal character.
已对液态铝在次近邻距离下动态结构因子的温度依赖性进行了研究。这种关联函数是局部环境变化的敏感参数，其傅里叶变换是在相干非弹性中子散射实验中测量的。零频率振幅以非线性方式减小，表明在约1.4倍熔点温度附近动力学发生了变化。从该振幅可以导出广义粘度，它是次近邻距离上局部应力关联的一种度量。导出的广义纵向粘度在相同温度范围内显示出斜率变化。在此温度下，冷却时结构弛豫的自由度开始冻结，这可以理解为向固态转变的前兆。液态铝动力学中的这种转变表现出与先前在液态铷和铅中观察到的相同特征，表明具有普遍性。
