Guarneri Ludovica, Jakobs Stefan, von Hoegen Alexander, Maier Stefan, Xu Ming, Zhu Min, Wahl Sophia, Teichrib Christian, Zhou Yiming, Cojocaru-Mirédin Oana, Raghuwanshi Mohit, Schön Carl-Friedrich, Drögeler Marc, Stampfer Christoph, Lobo Ricardo P S M, Piarristeguy Andrea, Pradel Annie, Raty Jean-Yves, Wuttig Matthias
I. Physikalisches Institut (IA), RWTH Aachen University, 52056, Aachen, Germany.
II. Physikalisches Institut (IIA), RWTH Aachen University, 52056s, Aachen, Germany.
Adv Mater. 2021 Oct;33(39):e2102356. doi: 10.1002/adma.202102356. Epub 2021 Aug 6.
The chemical bond is one of the most powerful, yet much debated concepts in chemistry, explaining property trends in solids. Recently, a novel type of chemical bonding was identified in several higher chalcogenides, characterized by a unique property portfolio, unconventional bond breaking, and sharing of about one electron between adjacent atoms. This metavalent bond is a fundamental type of bonding in solids, besides covalent, ionic, and metallic bonding, raising the pertinent question as to whether there is a well-defined transition between metavalent and covalent bonds. Here, three different pseudo-binary lines, namely, GeTe Se , Sb Te Se , and Bi Sb Se , are studied, and a sudden change in several properties, including optical absorption ε (ω), optical dielectric constant ε , Born effective charge Z*, electrical conductivity, as well as bond breaking behavior for a critical Se or Sb concentration, is evidenced. These findings provide a blueprint to experimentally explore the influence of metavalent bonding on attractive properties of phase-change materials and thermoelectrics. Particularly important is its impact on optical properties, which can be tailored by the amount of electrons shared between adjacent atoms. This correlation can be used to design optoelectronic materials and to explore systematic changes in chemical bonding with stoichiometry and atomic arrangement.
化学键是化学中最强大但也备受争议的概念之一，用于解释固体中的性质趋势。最近，在几种高级硫族化物中发现了一种新型化学键，其特点是具有独特的性质组合、非常规的键断裂以及相邻原子之间约一个电子的共享。这种准价键是固体中除共价键、离子键和金属键之外的一种基本键型，引发了关于准价键和共价键之间是否存在明确转变的相关问题。在此，研究了三条不同的伪二元线，即GeTe - Se、SbTe - Se和Bi - Sb - Se，并证明了包括光吸收ε(ω)、光学介电常数ε、玻恩有效电荷Z*、电导率以及临界Se或Sb浓度下的键断裂行为等几种性质的突然变化。这些发现为实验探索准价键对相变材料和热电材料诱人性质的影响提供了蓝图。特别重要的是其对光学性质的影响，这可以通过相邻原子之间共享的电子数量来调整。这种相关性可用于设计光电子材料，并探索化学键与化学计量和原子排列的系统变化。
