Extended Defects in Olivine and their Impact on Diffusive Reaction Kinetics

橄榄石的扩展缺陷及其对扩散反应动力学的影响

• 批准号: 1144668
• 负责人: Reid Cooper
• 金额: $ 32.07万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-15 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1144668&HistoricalAwards=false
• 关键词: Extended; Defects; Olivine; their; Impact

This project comprises an experimental study examining (a) the effects of thermodynamic potentials?temperature, pressure and, particularly, chemical potentials of oxygen, oxides and halides?on the formation and persistence of extended defects in olivine and (b) the effect of such extended defects on transport coefficients of rare earth cations and halide anions. The analytical techniques to be employed for characterization of the defects emphasize high-resolution, energy-filtered transmission electron microscopy (TEM; HRTEM) and (local-electrode) atom-probe tomography (APT; LEAPTM). The proposed APT work is developmental: we are among the earliest investigators in the petrology community attempting to apply this promising technique?in which one can characterize the location within a crystal of specific atoms (and potentially isotopes)?to the characterization of minerals (which are, to first order, electronic insulators) and of mineral reactions.The capability of the Earth and planetary sciences community to understand the thermomechanical and thermochemical evolution of the terrestrial planets requires a deep and supple understanding of ionic diffusive dynamics in silicate and oxide mineral and their melts. Because of the number of chemical components in geological systems, there are a variety of kinetic paths available for diffusion-effected reactions, particularly under conditions of a high driving potential, i.e., where phases out of equilibrium with one another are suddenly placed in contact. This situation happens frequently in nature; it happens almost always in experiments used to understand mineral dynamics. For example, this research addresses directly a current controversy in petrology where the transport coefficient for rare-earth cations in ferromagnesian olivine has been measured in different experiments?both considered authoritative and ?good??and yet indicate a kinetics difference of almost 104! Metastable (and perhaps transient) defect structures in olivine in the faster case are anticipated; we will characterize these structures, their thermochemical persistence and their impact on dynamics. This project will (a) educate a graduate student in these particular aspects of petrology, mineral physics and ionic materials science and (b) discern the possibilities and develop the approaches of APT/LEAPTM for application to minerals and synthetic, multicomponent oxides. The research has application, also, to the design and characterization of new materials for use as oxide electrodes in batteries and fuel cells. Our work will emphasize petrology; we are, however, aware of the potential of the research for societal needs with regards to energy technology.

该项目包括一项实验研究，研究（a）热力学潜力？温度，压力，尤其是氧，氧化物和卤化物的化学潜力对橄榄石中扩展缺陷的形成和持久性以及（b）（b）这种扩展缺陷对稀土阳离子和卤化物繁殖的运输系数的影响。 用于表征缺陷的分析技术强调高分辨率，能量过滤的透射电子显微镜（TEM； HRTEM）和（本地 - 电极）原子 - 探针断层扫描（APT； Leaptm）。 提出的合适工作是发展的：我们是岩石学社区中试图运用这种有前途的技术的最早的研究者之一？在哪个可以表征特定原子（以及潜在的同位素）晶体内的位置，以表征矿物质的特征？陆地行星需要对硅酸盐和氧化物矿物质及其熔体中离子扩散动力学的深入了解。 由于地质系统中的化学成分数量，有多种动力学路径可用于扩散有效的反应，尤其是在高驱动势的条件下，即突然将相互平衡的相位置于接触中。 这种情况在自然界经常发生。它几乎总是在用于了解矿物动力学的实验中发生。 例如，这项研究直接解决了岩石学当前的争议，在这种争议中，在不同的实验中已经测量了富特罗曼尼亚橄榄石中稀土阳离子的运输系数？既被视为权威，又表示？ 预计在更快的情况下，橄榄石中的可稳态（也许是瞬时）缺陷结构。我们将表征这些结构，它们的热化学持久性及其对动态的影响。该项目将（a）教育研究生在岩石学，矿物质物理学和离子材料科学的这些特定方面，以及（b）辨别可能性，并开发出适用于矿物质和合成的多组分氧化物的APT/LEAPTM的方法。 这项研究还针对新材料的设计和表征，以用作电池和燃料电池中的氧化物电极。 我们的工作将强调岩石学；但是，我们意识到研究对能源技术的社会需求的潜力。