The evolution of iron local vibrational mode (Fe LVM) and phase transitions in n-type iron-doped indium phosphide (InP:Fe) were investigated at ambient temperature. In-situ angle-dispersive X-ray diffraction measurements revealed that InP:Fe starts to transform from zinc-blende (ZB) to rock-salt (RS) structure around 8.2(2) GPa and completes around 16.0(2) GPa. The Raman shift of both transverse and longitudinal optical modes increases monotonically with increasing pressure, while their intensities become indiscernible at 11.6(2) GPa, suggesting that the pressure-induced phase transition is accompanied by significant metallization. In contrast, originally absent at ambient pressure, the Raman shift of Fe LVM appears at ∼420 cm−1 near 1.2 GPa and exhibits a dome shape behavior with increasing pressure, reaching a maximum value of ∼440 cm−1 around 5 GPa, with an apparent kink occurring around the ZB-RS transition pressure of ∼8.5(2) GPa. The Fe K-edge X-ray absorption near edge structure (XANES) confirmed the tetrahedral site occupation of Fe3+ with a crystal field splitting parameter Δt = 38 kJ·mole−1. Our calculations indicate that the energy parameters governing the phase transition are Δt = 0.49 and Δo = 1.10 kJ·mole−1, respectively, both are much smaller than Δt = 38 kJ·mole−1 at ambient.
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机译:在环境温度下研究了n型掺杂铁的磷化铟(InP:Fe)中铁局部振动模式(Fe LVM)的演化和相变。原位角分散X射线衍射测量表明,InP:Fe在8.2(2)GPa附近开始从闪锌矿(ZB)转变为岩盐(RS)结构,并在16.0(2)GPa附近完成。横向和纵向光学模式的拉曼位移随压力的增加而单调增加,而其强度在11.6(2)GPa时变得不清楚,这表明压力引起的相变伴随着明显的金属化。相反,原本在环境压力下不存在的Fe LVM的拉曼位移出现在1.2 GPa附近的420 cm -1 sup>处,并且随着压力的增加呈现出圆顶形状,达到最大值440 cm -1 sup>约为5 GPa,ZB-RS转变压力约为8.5(2)GPa时出现明显的扭结。 Fe K边缘X射线近边缘结构(XANES)吸收证实了Fe 3 + sup>的四面体位点占据,其晶体场分裂参数为Δt= 38 kJ·mole -1 sup>。我们的计算表明,控制相变的能量参数分别为Δt= 0.49和Δo= 1.10 kJ·mole -1 sup>,均远小于Δt= 38 kJ·mole -1 sup>。
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