Letter: A method for controlling alkali-metal oxide activities in one-atmosphere experiments and its application to measuring the relative activity coeficients of NaO0.5 in silicate melts
Letter: A method for controlling alkali-metal oxide activities in one-atmosphere experiments and its application to measuring the relative activity coeficients of NaO0.5 in silicate melts
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信件：一种在单气氛实验中控制碱金属氧化物活度的方法及其在测量硅酸盐熔体中NaO0.5相对活度系数中的应用
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发表时间：
2005
期刊：
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通讯作者：
H. O’Neill
中科院分区：
文献类型：
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作者：
H. O’Neill
摘要：在高温下的一气氛钢丝环实验中，通过将含有碱金属熔体的坩埚悬浮在样品下方，可以控制碱金属氧化物的活性。利用NaO0.5- sio2熔体储层，应用该方法测定了CMAS-NaO0.5熔体中NaO0.5相对于钙长石-透辉石共晶组成中NaO0.5的活度系数。结果表明，相对活度系数随SiO2的增加而显著降低，随CaO和MgO的增加而增加，但对AlO0.5不敏感，后者的行为与假设Na-Al组分的熔体热力学“准晶”模型不一致。
Abstract The activity of alkali metal oxides can be controlled in one-atmosphere wire-loop experiments at high temperature by suspending a crucible containing alkali silicate melt beneath the samples. The method has been applied to measuring the activity coefficient of NaO0.5 in a series of CMAS-NaO0.5 melts relative to that in the anorthite-diopside eutectic composition at 1400 °C, using a reservoir of NaO0.5-SiO2 melt. The results show that this relative activity coeficient decreases strongly with SiO2, increases with CaO and MgO, but is insensitive to AlO0.5 This latter behavior is inconsistent with “quasi-crystalline” models of melt thermodynamics that hypothesize Na-Al species.