A Systematic Dopant-selection Strategy for Advanced Manufacturing of High Strength Transparent Magnesium Aluminate Spinel

高强度透明镁铝尖晶石先进制造的系统掺杂剂选择策略

• 批准号: 2016279
• 负责人: Masashi Watanabe
• 金额: $ 49.94万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2016279&HistoricalAwards=false
• 关键词: Systematic; Dopant; selection; Strategy; Advanced

Optically transparent magnesium aluminate spinel (MgAl2O4, MAS) is one of the candidates to use in extreme environments such as spacecraft and military vehicle windows, in which conventional silicate glasses or polymers are not suitable. Currently, the processing of MAS materials with high strength and high transparency requires high costs, which is one of the major limiting factors to prevent the MAS materials from the applications. A promising path for achieving high density without loss of strength and transparency is via modification of grain boundary (GB) structures and chemistry with the addition of ppm-level impurities. These impurities at the GBs can alter the motion of boundaries leading to improved materials strength. The work will develop a system for identifying appropriate dopants to modify GB atomic arrangements for improved mechanical strength and transparency. MAS materials with enhanced strength and sufficient transparency can be produced by chemical additives identified through this work. the results. This approach will provide a new route for manufacturing transparent polycrystalline MAS, applicable for the large-scale manufacturing of polycrystalline MAS and potentially other ceramics needed to maintain the nation’s global competitiveness and enhance national defense. The information and approaches will be disseminated through an annual microscopy school.Four different types of earth-abundant elements will be doped into polycrystalline and controlled bi-crystal MAS materials, instead of rare-earths to alter the GB strength and hence mechanical performance. The dopant selection is based on the following criteria: (A) dopants must be larger cations than the native cations Mg2+ and Al3+ for effective GB segregation, (B) dopants ideally take 3+ state rather than 2+ to occupy both cation sites, and (C) dopants should have higher stability in their oxide forms (i.e. stronger bonding with oxygen anions) than either Al or Mg. If these criteria are proven experimentally, this approach would provide a new strategy for designing GB configuration and chemistry, and hence controlling the GB strength by selecting dopants. The GB structures and chemistry will be quantitatively characterized by advanced electron microscopy together with sophisticated micro-mechanical testing to measure the GB fracture toughness. Based on experimental results, we will establish a concept for identifying appropriate dopants to modify atomic arrangements for improved mechanical strength and transparency. The concept established in this project should be relevant to other ternary or more component ionic compounds such as the perovskites SiTiO3 and LaMnO3 and be applicable to other binary ceramics materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

光学透明的镁铝尖晶石（MgAl2O4，MAS）是用于极端环境如航天器和军用车辆窗户的候选材料之一，其中常规的硅酸盐玻璃或聚合物是不合适的。目前，高强度高透明MAS材料的加工成本高，是阻碍MAS材料应用的主要因素之一。在不损失强度和透明度的情况下实现高密度的有希望的途径是通过添加ppm级杂质来修改晶界（GB）结构和化学。GB中的这些杂质可以改变边界的运动，从而提高材料强度。这项工作将开发一个系统，用于识别适当的掺杂剂，以修改GB原子排列，提高机械强度和透明度。通过本工作确定的化学添加剂可以生产具有增强的强度和足够的透明度的MAS材料。结果。这种方法将为制造透明多晶MAS提供新的途径，适用于大规模制造多晶MAS和保持国家全球竞争力和增强国防所需的其他陶瓷。这些信息和方法将通过每年的显微镜学校传播。四种不同类型的地球丰富的元素将被掺杂到多晶和受控双晶MAS材料中，而不是稀土，以改变GB强度，从而改变机械性能。掺杂剂的选择基于以下标准：（A）为了有效的GB分离，掺杂剂必须是比天然阳离子Mg 2+和Al 3+更大的阳离子，（B）掺杂剂理想地采取3+态而不是2+态以占据两个阳离子位点，以及（C）掺杂剂在其氧化物形式下应具有比Al或Mg更高的稳定性（即与氧阴离子更强的键合）。如果这些标准得到实验证明，这种方法将提供一种新的策略，用于设计GB配置和化学，从而通过选择掺杂剂来控制GB强度。GB的结构和化学性质将通过先进的电子显微镜和精密的微观力学测试进行定量表征，以测量GB的断裂韧性。根据实验结果，我们将建立一个概念，确定适当的掺杂剂，以修改原子排列，提高机械强度和透明度。该项目中建立的概念应该与其他三元或更多组分的离子化合物相关，如钙钛矿SiTiO 3和LaMnO 3，并适用于其他二元陶瓷材料。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Spatial resolution in transmission electron microscopy

• DOI: 10.1016/j.micron.2022.103304
• 发表时间: 2022-06-12
• 期刊: MICRON
• 影响因子: 2.4
• 作者: Egerton, R. F.;Watanabe, M.
• 通讯作者: Watanabe, M.

Evolution in X-ray analysis from micro to atomic scales in aberration-corrected scanning transmission electron microscopes

• DOI: 10.1093/jmicro/dfab026
• 发表时间: 2021-07-15
• 期刊: MICROSCOPY
• 影响因子: 1.8
• 作者: Watanabe, M.;Egerton, R. F.
• 通讯作者: Egerton, R. F.

EELS Spectrum Imaging of Ca Segregation at Grain Boundaries in Magnesium Aluminate Spinel

镁铝尖晶石晶界处 Ca 偏析的 EELS 光谱成像

• DOI: 10.1093/micmic/ozad067.191
• 发表时间: 2023
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: Campos-Quiros, Alexander;Kundu, Animesh;Watanabe, Masashi
• 通讯作者: Watanabe, Masashi

Effect of Ca Doping on the Microstructure and Mechanical Properties of Magnesium Aluminate Spinel

Ca掺杂对镁铝尖晶石微观结构和力学性能的影响

• DOI: 10.1017/s1431927622009886
• 发表时间: 2022
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: Campos-Quiros, Alexander;Kundu, Animesh;Watanabe, Masashi
• 通讯作者: Watanabe, Masashi