Nanocrystal superlattices that exhibit improved order on heating: an example of inverse melting?
Nanocrystal superlattices that exhibit improved order on heating: an example of inverse melting?
复制标题
纳米晶超晶格在加热时表现出改善的有序性：逆熔化的一个例子？
作者：
Yixuan Yu;Avni Jain;Adrien Guillaussier;V. R. Voggu;Thomas M Truskett;Detlef;B. Korgel
掠入射小角X射线散射（GISAXS）测量显示，当加热到中等温度（50 - 60 ° C）时，直径为1.7 nm的超晶格、用十八烷基硫醇覆盖的金（Au）纳米晶体变得明显更有序。这种有序性的增强是可逆的，当冷却回室温时，超晶格返回到其最初的无序结构。无序-有序转变温度估计从GISAXS数据使用Hansen-Verlet准则。差示扫描量热法（DSC）测量的超晶格表现出的相变温度附近的吸热（与无序在冷却过程中）和吸热（与有序在加热过程中）。超晶格转变温度也大致对应于十八烷基硫醇的熔点和凝固点。因此，它似乎是一个变化，在封端的配位体包装时发生的配位体熔化的基础上的超晶格的结构转变。我们把超晶格的热诱导有序化比作逆熔化转变。
Grazing incidence small angle X-ray scattering (GISAXS) measurements reveal that superlattices of 1.7 nm diameter, gold (Au) nanocrystals capped with octadecanethiol become significantly more ordered when heated to moderate temperatures (50-60 °C). This enhancement in order is reversible and the superlattice returns to its initially disordered structure when cooled back to room temperature. Disorder-order transition temperatures were estimated from the GISAXS data using the Hansen-Verlet criterion. Differential scanning calorimetry (DSC) measurements of the superlattices exhibited exotherms (associated with disordering during cooling) and endotherms (associated with ordering during heating) near the transition temperatures. The superlattice transition temperatures also correspond approximately to the melting and solidification points of octadecanethiol. Therefore, it appears that a change in capping ligand packing that occurs upon ligand melting underlies the structural transition of the superlattices. We liken the heat-induced ordering of the superlattices to an inverse melting transition.
影响因子：
10.8
作者：
Rasch, Michael R.;Rossinyol, Emma;Korgel, Brian A.
通讯作者：
Korgel, Brian A.