AlFe单晶薄膜微结构与热力学性质研究

采用PLD方法，在573 K条件下制备了AlFe单晶合金薄膜.X射线衍射与透射电子衍射表明，AlFe空间点群为PM-3M，晶格常数a =0.297 nm (略大于bcc-Fe的晶格常数，a =0.293 nm)，且AlFe晶体结构为bcc-Fe晶格体心Fe原子被Al取代产生的新结构.采用第一性原理与准谐德拜模型研究了AlFe合金的化学势与热力学性能，计算表明AlFe合金具有更低的化学势，导致在生长过程只出现AlFe相.与此同时，AlFe合金具有与bc 关键词： PLD AlFe单晶薄膜 第一性原理 准谐德拜模型

The study of micro-structure and the thermodynamic properties of AlFe single crystal film

AlFe alloy single crystal film was prepared at 573 K by pulsed laser deposition (PLD) in this work. X-ray diffraction (XRD) and transmission electron diffraction (TED) showed that the space group of the alloy is PM-3M, lattice parameter is a=0.297 nm (just a little greater than that of bcc-Fe, a_Fe=0.293nm). Crystal lattice of AlFe was the lattice of bcc-Fe with the center Fe atom replaced by the Al atom. First-principles and quasi-harmonic Debye model were employed to study the chemical potential and thermodynamic properties of AlFe alloy. Calculations indicated that the chemical potential (μ) of AlFe is much lower than those of fcc-Al and bcc-Fe, which indicates that AlFe is the only phase formed in the process of film growth. At the same time, AlFe greatly excels the elementary substance of Al and Fe in thermodynamic properties. In the range of 150 K to 1000 K, heat capacity at constant pressure (C_p) of AlFe is much higher than that of Al or Fe, and thermal expansion coefficient (α) of AlFe is lower and more stable.