Large variation of vacancy formation energies in the surface of crystalline ice
Large variation of vacancy formation energies in the surface of crystalline ice
复制标题
结晶冰表面空位形成能的巨大变化
DOI：
10.1038/nmat3096
复制
发表时间：
2011-10-01
期刊：
影响因子：
41.2
通讯作者：
Slater, B.
中科院分区：
文献类型：
--
作者：
Watkins, M.;Pan, D.;Slater, B.
解决云层中冰粒子表面的原子结构，在大气中遇到的温度范围内，与理解冰上的非均相催化有关，仍然是一个实验挑战。通过使用第一性原理计算，我们表明晶体冰表面在空位形成能量方面表现出显着的变化，类似于非晶态材料。我们发现空位形成能低至0.1-0.2 eV，这导致空位浓度高于预期。因为空位的反应性与其形成能量相关，所以冰粒的反应性可能比之前认为的更强。我们还发现，空位显著降低了邻近空位的形成能，从而促进了点蚀，有助于预熔和准液体层的形成。这些表面特性是由质子无序和几何约束的松弛引起的，这表明其他受挫材料可能具有不寻常的表面特性。
Resolving the atomic structure of the surface of ice particles within clouds, over the temperature range encountered in the atmosphere and relevant to understanding heterogeneous catalysis on ice, remains an experimental challenge. By using first-principles calculations, we show that the surface of crystalline ice exhibits a remarkable variance in vacancy formation energies, akin to an amorphous material. We find vacancy formation energies as low as similar to 0.1-0.2 eV, which leads to a higher than expected vacancy concentration. Because a vacancy's reactivity correlates with its formation energy, ice particles may be more reactive than previously thought. We also show that vacancies significantly reduce the formation energy of neighbouring vacancies, thus facilitating pitting and contributing to pre-melting and quasi-liquid layer formation. These surface properties arise from proton disorder and the relaxation of geometric constraints, which suggests that other frustrated materials may possess unusual surface characteristics.