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(Mg,Fe)SiO3钙钛矿是下地幔中最主要的候选矿物成分之一,关于其高温高压特性的研究对于深层地幔状态的理解和地震波变化规律的探索具有重要意义.应用第一性原理计算了MgSiO3和(Mg0.75,Fe0.25)SiO3在0—140GPa静水压范围内的晶体结构和弹性模量,并由Voigt-Reuss-Hill方程计算了地震波速随压力的变化,利用准简谐近似下的Debye模型模拟了高温效应,分析了Fe2+取代Mg2+后镁铁钙钛矿弹性和热学性质的变化,推断Fe2+取代行为软化了MgSiO3等含镁的地球深部矿物的地震波速.为解释地幔中某些区域的地震波速软化现象提供了一个有力的理论依据.
(Mg, Fe) SiO3 perovskite is one of the most important candidate mineral components in the lower mantle, and the study of its high temperature and high pressure properties is of great significance for the understanding of the deep mantle condition and exploration of the variation of seismic waves.Using the first principle The crystal structure and elastic modulus of MgSiO3 and (Mg0.75Fe0.25) SiO3 in the hydrostatic pressure range of 0-140GPa were calculated. The variation of seismic velocity with pressure was calculated by the Voigt-Reuss-Hill equation. The Debye model under harmonic approximation simulates the high temperature effect, and analyzes the change of elastic and thermal properties of Mg-Fe-Ca-Mg after Fe2 + replaces Mg2 +. It is deduced that the Fe2 + substitution behavior softens the seismic velocity of Mg2 + The seismic wave velocity softening in some areas of the mantle provides a strong theoretical basis.