B1 结构的化学计量过渡金属碳化物的普遍相转变。

Universal phase transitions of B1-structured stoichiometric transition metal carbides.

机构信息

State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.

出版信息

Inorg Chem. 2011 Oct 3;50(19):9266-72. doi: 10.1021/ic200356x. Epub 2011 Sep 9.

DOI:10.1021/ic200356x

PMID:21902281

Abstract

The high-pressure phase transitions of B1-structured stoichiometric transition metal carbides (TMCs, TM = Ti, Zr, Hf, V, Nb, and Ta) were systematically investigated using ab initio calculations. These carbides underwent universal phase transitions along two novel phase-transition routes, namely, B1 → distorted TlI (TlI') → TlI and/or B1 → distorted TiB (TiB') → TiB, when subjected to pressure. The two routes can coexist possibly because of the tiny enthalpy differences between the new phases under corresponding pressures. Four new phases result from atomic slips of the B1-structured parent phases under pressure. After completely releasing the pressure, taking TiC as representative of TMCs, only its new TlI'-type phase is mechanically and dynamically stable, and may be recovered.

摘要

使用第一性原理计算系统地研究了 B1 结构的化学计量过渡金属碳化物（TMCs，TM = Ti、Zr、Hf、V、Nb 和 Ta）的高压相转变。这些碳化物在压力下沿两种新的相转变途径经历普遍的相转变，即 B1 → 扭曲的 TlI（TlI'）→ TlI 和/或 B1 → 扭曲的 TiB（TiB'）→ TiB。这两种途径可能共存，是因为在相应压力下新相之间的焓差很小。四个新相是由 B1 结构母体相在压力下的原子滑移产生的。完全释放压力后，以 TiC 为 TMCs 的代表，只有其新的 TlI'型相在力学和动力学上是稳定的，并且可能被恢复。