The Series MgCr2O4-MgFe2O4 |
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| Authors: | WALTER C ALLEN |
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| Affiliation: | School of Ceramics, Rutgers, The State University, New Brunswick, New Jersey 08903 |
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| Abstract: | The characteristics of spinels in the series MgCr2O4-MgFe2O4 were determined. The plot of cell size vs. molar composition is unusual in series showing complete solid solution because an unusually large deviation from Vegard's law was observed. This deviation is caused by changes in spinel structure with composition and temperature, and an equation was derived which applies a correction in terms of the degree of inversion. The effects of temperature on compositions high in MgFe2O4 include changes in density and refractive index. Solid solution of forsterite in MgCr2O4 decreases the cell size to 8.329 A but apparently is less than 1%. Changes in composition caused by vapor loss or by dissociation are small enough that this series is essentially binary below 1400° C. |
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