Krzystyniak Maciej, Drużbicki Kacper, Romanelli Giovanni, Gutmann Matthias J, Rudić Svemir, Imberti Silvia, Fernandez-Alonso Felix
ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK.
Faculty of Physics, Adam Mickiewicz University, Umultowska St. 85, 61-614 Poznan, Poland.
Phys Chem Chem Phys. 2017 Mar 29;19(13):9064-9074. doi: 10.1039/c7cp00997f.
We apply a unique sequence of structural and dynamical neutron-scattering techniques, augmented with density-functional electronic-structure calculations, to establish the degree of polymorphism in an archetypal hydrogen-bonded system - crystalline formic acid. Using this combination of experimental and theoretical techniques, the hypothesis by Zelsmann on the coexistence of the β and β phases above 220 K is tested. Contrary to the postulated scenario of proton-transfer-driven phase coexistence, the emerging picture is one of a quantitatively different structural change over this temperature range, whereby the loosening of crystal packing promotes temperature-induced shearing of the hydrogen-bonded chains. The presented work, therefore, solves a fifty-year-old puzzle and provides a suitable framework for the use neutron-Compton-scattering techniques in the exploration of phase polymorphism in condensed matter.
我们应用一系列独特的结构和动态中子散射技术，并辅以密度泛函电子结构计算，以确定一种典型的氢键体系——结晶甲酸中的多晶型程度。利用这种实验和理论技术的结合，对泽尔斯曼提出的关于β相和β相在220 K以上共存的假设进行了检验。与质子转移驱动的相共存的假设情况相反，新出现的情况是在这个温度范围内结构变化在数量上有所不同，即晶体堆积的松弛促进了氢键链的温度诱导剪切。因此，本研究解决了一个长达50年的谜题，并为使用中子康普顿散射技术探索凝聚态物质中的相多晶型提供了一个合适的框架。
