EPR measurement of the effect of glass composition on the oxidation states of europium |
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| Authors: | RV Morris LA Haskin |
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| Institution: | 1. University of Wisconsin, Madison, Wisconsin 53706 U.S.A. |
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| Abstract: | The techniques of electron paramagnetic resonance (EPR) were used to measure the concentration ratio of Eu2+ to Eu3+ in quenched silicate liquids as a function of their compositions. The compositional end members were CaAl2Si2O8 and either MSiO3 or M2Si04, M = Mg, (Ca0.5, Mg0.5), and Ca. All of the liquids were quenched from 1650 ± 25°C, 10?6.9±0.6 atm of oxygen, and 10?6.1±0.6 atm total pressure. For a particular choice of M, the ratio of Eu2+ to Eu3+ increased as much as a factor of 24 with increasing atomic ratio (Al + Si)/(O); for a constant value of (Al + Si)/(O), the ratio of Eu2+ to Eu3+ increased in the order Mg > (Ca0.5,Mg0.5) >Ca. In order to interpret the compositional dependence of the redox equilibrium of Eu in a systematic manner, the concept of a solvent coefficient was introduced. |
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