CAJ | 학술논문

采用自旋极化的密度泛函理论(DFT)对正交与六方的Fe2C晶体体相与表面性质进行了研究,计算了晶胞的聚合能、磁矩以及低指数晶面的表面能.研究结果表明,两种晶型Fe2C 的磁性质相似,但正交堆积的Fe2C比六方堆积的Fe2C更稳定.正交晶系Fe2C低指数晶面的稳定性以 (011) > (110) > (100) > (101) > (001) 顺序降低.对一系列碳化程度不同的碳化铁最稳定表面(Fe2C(011)、Fe3C(001)和Fe4C(100))表面能的比较显示,碳化铁表面的相对稳定性与碳化度非线性相关.另外,与面心立方(BCC)铁最稳定表面(110)相比,Fe2C、Fe3C及Fe4C晶体最稳定表面具有较低的表面能,表明铁表面碳化在热力学上是有利的.
채용자선겁화적밀도범함이론(DFT)대정교여륙방적Fe2C정체체상여표면성질진행료연구,계산료정포적취합능、자구이급저지수정면적표면능.연구결과표명,량충정형Fe2C 적자성질상사,단정교퇴적적Fe2C비륙방퇴적적Fe2C경은정.정교정계Fe2C저지수정면적은정성이 (011) > (110) > (100) > (101) > (001) 순서강저.대일계렬탄화정도불동적탄화철최은정표면(Fe2C(011)、Fe3C(001)화Fe4C(100))표면능적비교현시,탄화철표면적상대은정성여탄화도비선성상관.령외,여면심립방(BCC)철최은정표면(110)상비,Fe2C、Fe3C급Fe4C정체최은정표면구유교저적표면능,표명철표면탄화재열역학상시유리적.
Spin-polarized density functional theory (DFT) calculations have been performed on the structure and stability of Fe2C. It is found that orthorhombic Fe2C is more stable than hexagonal Fe2C by 0.16eV on the basis of the computed cohesive energies. The structures and stability of the orthorhombic-Fe2C low index surfaces have also been investigated at the same level and the low index surfaces have the decreased stability order of (011) > (110) > (100) > (101) > (001). Comparison of the most stable Fe3C, Fe4C and Fe2C surfaces shows that there is no linear correlation of surface energy and carbon content. And comparison of their most stable surfaces with the body-centered cubic Fe shows that these carbide surfaces have lower surface energies than the most stable (110) surface of body-centered cubic Fe, indicating that the surface thermodynamics favor carburization at Fe surfaces.