Density, Structure and Chemistry of Iron in Silicate Melts

智力价值这项建议的主要目标是1)解决还原含铁硅酸盐熔体中体积混合性质的相对较差的约束方面，2)解决此类熔体中铁形态反应的压力和温度依赖性，以及3)使用光谱证据来研究硅酸盐熔体中铁物种的结构。这项工作将提高我们预测硅酸盐熔体中铁氧化还原状态随压力、温度和主体成分变化的能力。该团队将首次测量与天然岩浆相关的以亚铁为主的硅酸盐熔体成分的密度。预期的结果将使对硅酸盐熔体中亚铁和三氧化二铁的偏摩尔体积、硅酸盐熔体中所有铁形态的组成依赖关系以及含铁体系中矿物熔体反应的压力依赖关系的预测得到改进。以前获得的穆斯堡尔和拉曼光谱数据，结合本研究和文献中的组成数据，将有助于更好地改进硅酸盐熔体中存在的含铁分子结构，并改进此类熔体的氧化还原模型。为了更准确地预测天然硅酸盐熔体中铁氧化还原状态随压力、温度和体积组成的变化。这些目标的实现将导致对火成岩系统的行为及其在行星进化中的作用的更现实的理解。广泛的影响拟议的实验室实验将提供一个理想的机会，让优秀的本科生研究人员参与科学进程，并积极参与尖端科学。大多数曾在该实验室工作的本科生至少参加过一次国家重大科学会议。这笔赠款还将为博士研究人员提供资金这项工作本身有许多超出眼前目标的应用(例如，在宇宙化学、行星学和材料科学领域)。

Intellectual MeritThe primary goals of this proposal are to 1) resolve relatively poorly constrained aspects of volume mixing properties in reduced iron-bearing silicate melts, 2) resolve pressure and temperature dependence of iron speciation reactions in such melts, and 3) use spectroscopic evidence to investigate the structure of iron species in silicate melts. This work will improve our ability to predict iron redox state in silicate melts as a function of pressure, temperature and bulk composition.This team will perform the first measurements of the density of ferrous iron-dominated silicate melt compositions that are relevant to natural magmas. The expected results will enable improved predictions of partial molar volumes of ferrous and ferric iron in silicate melts, the compositional dependence of all iron speciation in silicate melts, and the pressure dependence of mineral-melt reactions in iron-bearing systems. Previously obtained Mossbauer and Raman spectroscopic data, combined with compositional data from this study and the literature will lead to better refinement of the structure of iron-bearing molecules present in silicate melts and lead to improvement of redox models for such melts. To more accurately predict iron redox state in natural silicate melts as a function of pressure, temperature and bulk composition. Achievement of these goals will lead to more realistic understanding of the behavior of igneous systems and their role in planetary evolution.Broader ImpactsThe proposed laboratory experiments will provide an ideal opportunity for involving good undergraduate researchers in the scientic process and their active participation in cutting edge science. Most undergraduates who have worked in this laboratory have participated in at least one major national scientific meeting. This grant also will provide funding for a Ph.D. researcherThe work itself has many applications beyond the immediate goals (e.g., in the fields of cosmochemistry, planetology, and material science).