The oxidation state of europium in silicate melts as a function of oxygen fugacity, composition and temperature
The oxidation state of europium in silicate melts as a function of oxygen fugacity, composition and temperature
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DOI：
10.1016/j.chemgeo.2015.07.002
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发表时间：
2015-09-14
期刊：
影响因子：
3.9
通讯作者：
Mosselmans, J. F. W.
中科院分区：
文献类型：
--
作者：
Burnham, A. D.;Berry, A. J.;Mosselmans, J. F. W.
铕L-III边X射线吸收近边结构（XANES）光谱记录了一系列合成玻璃和熔体的氧逸度（fO（2）s，从-14到+6对数单位相对于石英-铁橄榄石-磁铁矿，QFM，缓冲）和温度（1250-1500摄氏度）范围内的平衡。Eu 3 +/Sigma Eu（其中Sigma Eu = Eu 2 + + Eu 3+）值由光谱确定，精确度为+/-0.015。Eu 3 +/Sigma Eu在研究范围内随fO（2）从0到1系统地变化，随着熔融聚合和温度的降低而增加，并且可以通过经验方程描述：Eu 3 + / Sigma Eu = 1/1+10（2）（-0.25 log fO）（-6410/T-14.2 Lambda+10.1），其中Lambda是熔体的光学碱度，T是以K为单位的温度。Eu 3 +/Sigma Eu在玻璃和熔体平衡在相同的条件下是在良好的协议，无铁系统。对于含铁的组合物的反应Eu 2 + + Fe 3 + = Eu 3 + + Fe 2+发生在淬火过程中的玻璃和高的温度值的Eu 3 +/Sigma Eu是不保存在冷却，在现场测量是必不可少的确定Eu 3 +/Sigma Eu在自然熔体。(C)2015 Elsevier B. V.版权所有。
Europium L-III-edge X-ray absorption near edge structure (XANES) spectra were recorded for a series of synthetic glasses and melts equilibrated over a range of oxygen fugacities (fO(2)s, from - 14 to + 6 logarithmic units relative to the quartz-fayalite-magnetite, QFM, buffer) and temperatures (1250-1500 degrees C). Eu3+/Sigma Eu (where Sigma Eu = Eu2+ + Eu3+) values were determined from the spectra with a precision of +/- 0.015. Eu3+/Sigma Eu varies systematically with fO(2) from 0 to 1 over the range studied, increases with decreasing melt polymerisation and temperature, and can be described by the empirical equation: Eu3+ / Sigma Eu = 1/1+10(2)(-0.25 log fO)(-6410/T-14.2 Lambda+10.1), where Lambda is the optical basicity of the melt and T is the temperature in K. Eu3+/Sigma Eu in glasses and melts equilibrated at the same conditions are in excellent agreement for Fe-free systems. For Fe-bearing compositions the reaction Eu2+ + Fe3+ = Eu3+ + Fe2+ occurs during quenching to a glass and the high temperature value of Eu3+/Sigma Eu is not preserved on cooling; in situ measurements are essential for determining Eu3+/Sigma Eu in natural melts. (C) 2015 Elsevier B.V. All rights reserved.