CAREER: Complex Lead Oxides as Corrosion Films and Extended Inorganic Hybrids

技术概述：铅及其合金的羧酸腐蚀是历史文物（如风琴管）退化的主要原因。复合氧化铅羧酸盐作为腐蚀过程的产物，构成了一个结构丰富但尚未充分研究的化合物家族。本项目由固态与材料化学项目支持，对氧化铅羧酸盐腐蚀产物及其相关合成相的腐蚀膜的生长和组成进行了高级结构表征。实验室暴露研究将确定铅锡合金对羧酸侵蚀的敏感性如何取决于合金成分和湿度。氧化物腐蚀膜中的相识别、元素映射和高分辨率氧化态识别将深入了解每种金属在腐蚀过程中的作用。该项目旨在将对铅锡合金羧酸侵蚀的理解从现象学转移到机理上。模型研究将通过分析真实的风琴管样本和使用来自器官案例的环境数据与人工制品的退化联系起来。将采用水热法合成一系列氧化铅羧酸盐，并以观察到的腐蚀产物为基础。这些杂化材料包含基于边共享pb40o四面体的无限组分。部分电荷模型将提供对不同的0、1和2-D基于pb40的体系结构形成的解决方案影响的见解。207Pb核磁共振将补充x射线衍射表征Pb2+孤对立体活性。该项目主要在本科院校进行，并以本科生研究人员的参与为中心。该研究在艺术保护领域的应用将被用作非科学专业本科教育和跨学科K-12推广的综合计划的基础。非技术概述：铅及其合金的腐蚀导致各种物体的性能丧失，如铅酸电池和历史悠久的风琴管。特别是考虑到铅的毒性，充分了解铅与环境的相互作用及其腐蚀产物的化学性质至关重要。本项目由固态与材料化学项目支持，将利用实验室暴露实验，以及真实样品的表征，阐明铅锡合金管材腐蚀的原因和机制。作为腐蚀产物形成的化合物，以及相关的合成相，将受到详细的结构分析。研究结果将应用于保护具有重要文化意义的管风琴，这些管风琴在音乐会和录音中被欣赏，被音乐学家珍视，因为它们与著名作曲家有联系，并被视为工业化前手工和技术的实物文件。该项目将在Oberlin学院进行，这是一所主要的本科院校，具有为学生准备研究生学习和科学职业的强大传统。本科生将是项目研究所有阶段的主要参与者。他们将接受材料表征技术方面的培训，这在正规化学课程中并不总是遇到。PI将把项目研究和艺术保护之间的联系作为起点，为非理科生开设艺术材料化学的本科课程。通过与奥伯林的合作？在美国国家认可的艾伦纪念艺术博物馆（AMAM）中，学生在课程中将制作书面，音频和动手工具来创建博物馆的材料之旅。这些媒体会在AMAM中实施吗？美国建立了K-12外展计划。

TECHNICAL SUMMARY:Carboxylic acid corrosion of lead and its alloys is a major cause of degradation of historic cultural objects such as organ pipes. Complex lead oxide carboxylates form as products of this corrosion process and constitute a structurally rich yet understudied family of compounds. This project, supported by the Solid State and Materials Chemistry program, pairs analysis of the growth and composition of corrosion films with advanced structural characterization of lead oxide carboxylate corrosion products and their related synthesized phases. Laboratory exposure studies will establish how susceptibility of lead-tin alloys to carboxylic acid attack depends on alloy composition and humidity. Phase identification, elemental mapping, and high-resolution oxidation state identification in oxide corrosion films will provide insight into the role of each metal in the corrosion process. The project aims to move understanding of carboxylic acid attack of lead-tin alloys from the phenomenological to the mechanistic. Model studies will be linked to artifact deterioration through analysis of authentic organ pipe samples and use of environmental data from organ cases. Hydrothermal methods will be employed to synthesize a family of lead oxide carboxylates, for which observed corrosion products form the basis. These hybrid materials contain infinite components based on edge-sharing Pb4O tetrahedra. The partial charge model will provide insight into the solution influences governing formation of diverse 0-, 1-, and 2-D Pb4O-based architectures. 207Pb NMR will complement X-ray diffraction in characterization of Pb2+ lone pair stereoactivity. This project takes place at a primarily undergraduate institution and is centered on the participation of undergraduate researchers. Applications of the research to the field of art conservation will be used as the basis for an integrated program of education of undergraduate non-science majors and interdisciplinary K-12 outreach. NON-TECHNICAL SUMMARY:Corrosion of lead and its alloys leads to loss of performance in objects as varied as lead acid batteries and historic organ pipes. Particularly in light of its toxicity, full understanding of the interactions of lead with its environment and the chemistry of its corrosion products is critical. This project, supported by the Solid State and Materials Chemistry program, will use laboratory exposure experiments, as well as characterization of authentic samples, to elucidate the causes and mechanisms of corrosion of lead-tin alloy organ pipes. Compounds that form as corrosion products, as well as related synthesized phases, will be subjected to detailed structural analysis. Outcomes will have applications to the conservation of culturally important organs that are enjoyed in concerts and recordings, treasured by musicologists for their ties to notable composers, and valued as physical documents of pre-industrial handcraft and technology. This project will take place at Oberlin College, a primarily undergraduate institution with a strong tradition of preparing students for graduate study and careers in science. Undergraduate students will be the primary participants in all phases of the project research. They will receive training in techniques of materials characterization that are not always encountered in the canonical chemistry curriculum. The PI will use the link between the project research and art conservation as the starting point for an undergraduate course for non-science majors on the chemistry of art materials. Through partnership with Oberlin?s nationally recognized Allen Memorial Art Museum (AMAM), students in the course will produce written, audio, and hands-on tools to create a materials tour of the museum. These media will be implemented in the AMAM?s established K-12 outreach program.