Explaining stability of transition metal carbides –and why TcC does not exist
Explaining stability of transition metal carbides –and why TcC does not exist
复制标题
解释过渡金属碳化物的稳定性以及为什么 TcC 不存在
DOI：
10.1039/c5ra24656c
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发表时间：
2016
期刊：
影响因子：
3.9
通讯作者：
V. Yu. Murzin
中科院分区：
文献类型：
--
作者：
Qinggao Wang;Konstantin E. German;Artem R. Oganov;Huafeng Dong;Oleg D. Feya;Ya. V. Zubavichus;V. Yu. Murzin
我们分析了过渡金属（TM）碳化物的形成，由TM-TM和TM-C键的强度，以及由C材料引起的晶格畸变决定。随着TM的d带的填充增加，TM-C键从周期表的左边到右边变得越来越弱，越来越少的C原子进入TM晶格。事实证明，锝（Tc）是碳化物形成的关键点，指导我们解决长期存在的争议。预测的Tc碳化物与X射线吸收光谱的测量结果一致，在2000 K以上分解为立方Tc和石墨。因此，我们表明，被称为TcC（岩盐结构）实际上是一个高温立方相元素锝。
We analyze the formation of transition metal (TM) carbides, as determined by the strength of TM–TM and TM–C bonds, as well as lattice distortions induced by C interstitials. With increasing filling of the d-band of TMs, TM–C bonds become increasingly weak from the left of the periodic table to the right, with fewer and fewer C atoms entering the TMs lattice. Technetium (Tc) turns out to be a critical point for the formation of carbides, guiding us to resolve a long-standing dispute. The predicted Tc carbides, agreeing with measured X-ray absorption spectra, should decompose to cubic Tc and graphite above 2000 K. Consequently, we show that what has been claimed as TcC (with rocksalt structure) is actually a high-temperature cubic phase of elemental technetium.