Kurban Mustafa, Kürkçü Cihan, Yamçıçıer Çağatay, Göktaş Fahrettin
Department of Electronics and Automation, Ahi Evran University, 40100 Kırşehir, Turkey.
J Phys Condens Matter. 2019 Jul 31;31(30):305401. doi: 10.1088/1361-648X/ab1c9e. Epub 2019 Apr 25.
In this study, the structural phase transition and optoelectronic properties of perovskite-hydride MgFeH under high pressure have been performed by ab initio calculations based on GGA-PBE functional. The phase transitions were observed from the cubic structure ([Formula: see text]) to the orthorhombic [Formula: see text] and [Formula: see text] structure. During the phase transition, the [Formula: see text] and [Formula: see text] intermediate phases were predicted. The energy-volume (E-V) relationships show that the most stable phase is [Formula: see text]. The lattice parameters and volume increased as based on the phase transforms. From the electronic band analysis, the MgFeH shows a metallic character from the cubic to orthorhombic structure. The MgFeH indicates the peaks at 2.67 eV (464 nm) for [Formula: see text] phase, 5.21 eV (238 nm) for [Formula: see text] phase and 2.63 eV (471 nm) for [Formula: see text] phase. [Formula: see text] and [Formula: see text] phases correspond to the visible region. The absorption peaks are getting wider and have higher magnitude from [Formula: see text] to [Formula: see text] phase. The optical conductivity for the cubic structure with [Formula: see text] phase was found to be higher than orthorhombic structures with [Formula: see text], and [Formula: see text] phases. The reflectivity maxima decrease from [Formula: see text] to [Formula: see text].
在本研究中，基于广义梯度近似（GGA）-佩德韦-伯克-恩泽霍夫（PBE）泛函的第一性原理计算，对高压下钙钛矿型氢化物MgFeH的结构相变和光电性质进行了研究。观察到从立方结构（[化学式：见正文]）到正交晶系[化学式：见正文]和[化学式：见正文]结构的相变。在相变过程中，预测了[化学式：见正文]和[化学式：见正文]中间相。能量-体积（E-V）关系表明最稳定的相是[化学式：见正文]。晶格参数和体积随相变而增加。从电子能带分析来看，MgFeH从立方结构到正交晶系结构都表现出金属特性。MgFeH在[化学式：见正文]相时，在2.67 eV（464 nm）处有峰值；在[化学式：见正文]相时，在5.21 eV（238 nm）处有峰值；在[化学式：见正文]相时，在2.63 eV（471 nm）处有峰值。[化学式：见正文]和[化学式：见正文]相对应于可见光区域。从[化学式：见正文]相到[化学式：见正文]相，吸收峰变宽且幅度增大。发现具有[化学式：见正文]相的立方结构的光导率高于具有[化学式：见正文]、[化学式：见正文]相的正交晶系结构。反射率最大值从[化学式：见正文]到[化学式：见正文]降低。
