Density, Structure and Chemistry of Iron in Silicate Melts

该提案的主要目标是：1）解决含铁硅酸盐熔体中体积混合特性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、温度和体积组成变化的能力。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组成的密度。预期的结果将使改进的预测偏摩尔体积的硅酸盐熔体中的亚铁和三价铁，在硅酸盐熔体中的所有铁形态的组成依赖性，和含铁系统中的矿物熔体反应的压力依赖性。 以前获得的穆斯堡尔和拉曼光谱数据，结合本研究和文献的组成数据，将导致更好的细化硅酸盐熔体中存在的含铁分子的结构，并导致改善氧化还原模型，这样的熔体。 更准确地预测天然硅酸盐熔体中铁的氧化还原状态随压力、温度和体相组成的变化。 这些目标的实现将导致更现实的了解火成系统的行为及其在行星演化中的作用。更广泛的影响拟议的实验室实验将提供一个理想的机会，让优秀的本科研究人员参与科学过程，并积极参与前沿科学。在本实验室工作过的大部分本科生都参加过至少一次全国性的重大科学会议。这笔赠款还将为博士学位提供资金。研究人员这项工作本身有许多超出直接目标的应用（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).