Etude des propriétés structurales, élastiques et sismiques des composants FeO, MgO et (Fex,Mg(1-x))O en utilisant le modèle PREM

Abstract

By using the calculations either in one of our studies which tackled with the FeO or another of Karki and his colleagues about the MgO, which both determined Structural, Elastic and Seismic properties at different pressures, through which the values of the same properties of the compounds (Mg(1-x),Fex)O are determined according to the relations of Hashin & Strekman considering the melting of an x rate of Iron in MgO, especially at the pressures conformed to the PREM model representing the earth material. Comparing the in hands results concluded from these calculations brings out signification conclusion: they show the sensitivity of phase transition in the majority of the FeO properties except for the density, the bulk modulus and the bulk sound wave velocity. The most of the properties values are increasing especially in the case of MgO where it’s generally higher. Whereas, for the compounds of (Mg(1-x),Fex)O are characterized by the formation of a band to its superposition according to the x rate, and the values of each property is getting closer to its value in FeO with the increasing of this rate, so the values of these compounds for the structural properties, the bulk modulus and bulk sound wave velocity are going to be limited between both oxides values. It had also been possible to determine a lot of depths or pressures with which these properties parameters are going to conform, resulting from a change in the difference sign or setting the property values between the compared materials. The number of these depths is different from one case to another, and the greatest number which can be reached is six depths. Moreover, the total separation is not going to happen unless for the two longitudinal and transversal wave velocities in the case of FeO being compared with the compounds of (Mg(1-x),Fex)O, for the density and the shear modulus being compared with the earth material. In all wave velocities in the case of MgO being compared with the earth material, for the shear modulus in the case of the compounds of (Mg(1-x),Fex)O being compared with the earth material. The nonconformity of all the properties in the meantime with the earth material, though its little occurrence in the wave velocities in the case of (Mg(1-x),Fex)O compounds, this assures of the non-presence of any of these materials alone in the deep earth layers. By comparing the results of our study with other work and for several reasons in particular in the values of the shear modulus, except that generally the change is in accordance with either pressure or by the change of molar fraction to the content of the iron in (Mg(1-x),Fex)O components and the difference appears only in the change of the same module mentioned