Mesoza Cordova Dmitri Leo, Kam Taryn Mieko, Gannon Renae N, Lu Ping, Johnson David C
Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, Oregon 97403, United States.
Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
J Am Chem Soc. 2020 Jul 29;142(30):13145-13154. doi: 10.1021/jacs.0c05505. Epub 2020 Jul 14.
In solid-state chemistry, the direct reaction of elements at low temperatures is limited by low solid-state interdiffusion rates. This and the limited number of processing parameters often prevent the synthesis of metastable compounds. Precisely controlling the number of atoms and nanoarchitecture of layered elemental precursors enabled the selective synthesis of two closely related metastable tin vanadium selenides via near-diffusionless reactions at low temperatures. Although the nanoarchitectures of the precursors required to form (SnSe) and (SnSe) are very similar, controlling the local composition of the Sn|Se layers in the precursors enables the selective synthesis of either compound. The metastable alloy SnVSe was preferentially formed over (SnSe), which has the identical composition, by modifying the nanoarchitecture of the precursor. Ex situ in-plane X-ray diffraction and X-ray reflectivity collected as a function of annealing temperature provided information on lateral and perpendicular growth of (SnSe). The presence of Laue oscillations throughout the self-assembly provided atomic-scale information on the thickness of the (SnSe) domains, giving insights into the self-assembly process. A reaction mechanism is proposed and used to rationalize how composition and nanoarchitecture control the reaction pathway through the free energy landscape.
在固态化学中，元素在低温下的直接反应受到低固态互扩散速率的限制。这一点以及有限的加工参数常常阻碍亚稳化合物的合成。精确控制层状元素前驱体的原子数量和纳米结构，使得通过低温下的近无扩散反应选择性合成两种密切相关的亚稳锡钒硒化物成为可能。尽管形成(SnSe)和(SnSe)所需的前驱体纳米结构非常相似，但控制前驱体中Sn|Se层的局部组成能够选择性合成任意一种化合物。通过改变前驱体的纳米结构，相较于具有相同组成的(SnSe)，优先形成了亚稳合金SnVSe。作为退火温度函数收集的非原位面内X射线衍射和X射线反射率提供了有关(SnSe)横向和垂直生长的信息。在整个自组装过程中劳厄振荡的存在提供了关于(SnSe)畴厚度的原子尺度信息，有助于深入了解自组装过程。提出了一种反应机制，并用于解释组成和纳米结构如何通过自由能态势控制反应途径。
