Gong Jianxiao, Jain Prashant K
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Nat Commun. 2019 Jul 23;10(1):3285. doi: 10.1038/s41467-019-11229-2.
The engineering of nanoscale features enables the properties of solid-state materials to be tuned. Here, we show the tunable preparation of cuprous sulfide nanocrystals ranging in internal structures from single-domain to multi-domain. The synthetic method utilizes in-situ oxidation to grow nanocrystals with a controlled degree of copper deficiency. Copper-deficient nanocrystals spontaneously undergo twinning to a multi-domain structure. Nanocrystals with twinned domains exhibit markedly altered crystallographic phase and phase transition characteristics as compared to single-domain nanocrystals. In the presence of twin boundaries, the temperature for transition from the ordered phase to the high-copper-mobility superionic phase is depressed. Whereas the superionic phase is stable in the bulk only above ca. 100 °C, cuprous sulfide nanocrystals of ca. 7 nm diameter and a twinned structure are stable in the superionic phase well below ambient temperature. These findings demonstrate twinning to be a structural handle for nanoscale materials design and enable applications for an earth-abundant mineral in solid electrolytes for Li-S batteries.
纳米尺度特征的工程化使得固态材料的性能得以调控。在此，我们展示了可控制备内部结构从单畴到多畴的硫化亚铜纳米晶体。该合成方法利用原位氧化来生长具有可控铜缺陷程度的纳米晶体。缺铜纳米晶体会自发孪生成多畴结构。与单畴纳米晶体相比，具有孪晶畴的纳米晶体表现出明显改变的晶体相和相变特性。在存在孪晶界的情况下，从有序相转变为高铜迁移率超离子相的温度会降低。虽然超离子相在体相中仅在约100℃以上稳定，但直径约7nm且具有孪晶结构的硫化亚铜纳米晶体在远低于环境温度的情况下在超离子相中却是稳定的。这些发现表明孪晶是纳米尺度材料设计的一种结构手段，并使得一种储量丰富的矿物在锂硫电池的固体电解质中得到应用成为可能。
