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Anisotropic light absorption of the calcium aluminoferrite phase in portland cement clinker
The solid solution of MgO in Ca2FeAlO5 and the resulting change in anisotropic absorption have been studied. The solid solution of MgO was investigated by directly determining the chemical formulas of the solid solutions of the system CaFeAlO5-MgO by electron probe microanalysis. Mg ions replace exclusively Fe and Al ions in the octahedral sites in the structure; they neither replace Ca ions nor enter the interstitial sites. The solubility limit of MgO at 1350 degrees C was 0.75 wt-%, which was half the amount hitherto reported. Similarly, incorporation of Si ions in the tetrahedral sites has been confirmed. The optic orientation of Ca2FeAlO5 and its solid solutions is X=b, Y=c, Z=a. Absorption anisotropy is weak for Ca2FeAlO5 with Y, Z (reddish orange) >X (yellowish orange). With incorporation of MgO, absorption becomes extremely strong for light vibrating parallel to the X-axis. The strong absorption in the presence of Mg ions has been ascribed to the occurence of tetravalent iron ions under oxidizing atmospheric conditions, which compensates the deficiency of positive charge caused by the substitution of Mg for Fe and Al.
Anisotropic light absorption of the calcium aluminoferrite phase in portland cement clinker
The solid solution of MgO in Ca2FeAlO5 and the resulting change in anisotropic absorption have been studied. The solid solution of MgO was investigated by directly determining the chemical formulas of the solid solutions of the system CaFeAlO5-MgO by electron probe microanalysis. Mg ions replace exclusively Fe and Al ions in the octahedral sites in the structure; they neither replace Ca ions nor enter the interstitial sites. The solubility limit of MgO at 1350 degrees C was 0.75 wt-%, which was half the amount hitherto reported. Similarly, incorporation of Si ions in the tetrahedral sites has been confirmed. The optic orientation of Ca2FeAlO5 and its solid solutions is X=b, Y=c, Z=a. Absorption anisotropy is weak for Ca2FeAlO5 with Y, Z (reddish orange) >X (yellowish orange). With incorporation of MgO, absorption becomes extremely strong for light vibrating parallel to the X-axis. The strong absorption in the presence of Mg ions has been ascribed to the occurence of tetravalent iron ions under oxidizing atmospheric conditions, which compensates the deficiency of positive charge caused by the substitution of Mg for Fe and Al.
Anisotropic light absorption of the calcium aluminoferrite phase in portland cement clinker
Anisotrope Lichtabsorption der Calciumaluminoferritphase in Portlandzement
Maki, I. (author) / Fukuda, K. (author) / Oba, E. (author) / Yoshida, H. (author) / Mitsumatsu, M. (author) / Ito, S. (author)
Cement and Concrete Research ; 25 ; 863-869
1995
7 Seiten, 3 Bilder, 3 Tabellen, 24 Quellen
Article (Journal)
English
Fremdatomzusatz , Portlandzement , Aluminium , Ferrit (Oxidkeramik) , Magnesiumoxid , chemische Zusammensetzung , Kristallisation , Sauerstoff , Partialdruck , Kristall , Kristallographie , optische Absorption , Anisotropie , Phasenzusammensetzung , Calciumferrit , feste Lösung , Sauerstoffatmosphäre , oktaedrische Koordination , Zwischengitterlücke
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