CAS: Using Narrow Bands and Competing Exchange Interactions as Design Principles for Magnetocaloric Materials

CAS：使用窄带和竞争交换相互作用作为磁热材料的设计原则

• 批准号: 2203512
• 负责人: Fazel Fallah Tafti
• 金额: $ 25.05万
• 依托单位: Boston College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2203512&HistoricalAwards=false
• 关键词: CAS; Using; Narrow; Bands; Competing

Non-technical Abstract:Magnetism is a fascinating physical phenomenon that enables modern sensing, logic, and memory devices. A less-known application for magnetism is in refrigeration technology through a mechanism called the magnetocaloric effect (MCE). A magnetic refrigerator is similar to regular refrigerators, except instead of compressing and decompressing a gas, it magnetizes and demagnetizes a solid-state material to create the low temperatures. Materials used for this application typically contain rare-earth elements, for example gadolinium and erbium. These elements are expansive and not readily available, especially not in the U.S.. With this project, supported by the Solid State and Materials Chemistry program and the Condensed Mater Physics program in the Division of Materials Research, the researchers at Boston College synthesize new materials that exhibit a giant MCE and contain only minimal amounts of rare-earth elements. In this way the project addresses critical aspects of sustainability by eliminating ozone-depleting refrigeration gases and by minimizing the rare-earth content of the magnetocaloric materials. This interdisciplinary project provides a platform for training the next generation of materials scientists with a deep understanding of quantum chemistry and the ability to implement fundamental science to solve the societal problems. Additionally, this project provides career workshops for pre-college students from underrepresented minorities in the Boston area and research opportunities for students from Jackson State University, a HBCU.Technical Abstract:Materials that exhibit a magnetocaloric effect (MCE), the reversible change of temperature as a function of magnetic field, provides a sustainable platform for refrigeration technology. Magnetic refrigerators are considerably less energy consuming than regular refrigerators and do not rely on ozone-depleting gases. The main challenge for commercializing magnetic refrigerators is the lack of materials with a large refrigeration capacity (RC) made from earth-abundant elements. Giant magnetocaloric materials are either made from toxic elements such as P and As, or have a large rare-earth content. As such, the synthesis of giant magnetocaloric materials that are non-toxic and have little to no rare-earth content is a critical aspect of sustainability. With this support researchers from Boston College synthesize such materials by following two chemical design principles, namely narrow bandwidths and competing exchange interactions. The narrow bandwidth leads to a magnetic transition near room temperature via the Stoner mechanism. The critical temperature can be adjusted by doping, which enables the design of multi-stage magnetic refrigerators. Competing exchange interactions broaden the magnetic transition and lead to entropy release over a wide temperature range, thereby enhancing RC. The investigated materials have less than ten per cent rare-earth content. The researchers elucidate novel mechanisms for achieving giant MCE in these materials with minimal rare-earth content. The educational impacts include the engagement of underrepresented students in a multidisciplinary research project between chemistry and physics as well as training students at the national high-magnetic field and synchrotron radiation facilities.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.

非技术摘要：磁性是一种引人入胜的物理现象，可实现现代感测，逻辑和记忆设备。鲜为人知的磁性应用是通过一种称为磁化效应（MCE）的机制在制冷技术中。磁性冰箱类似于常规冰箱，除非不是压缩和解压缩气体，否则它将磁化并消除固态材料以产生低温。用于此应用的材料通常包含稀土元素，例如gadolinium和erbium。这些元素是广泛的，并且不容易获得，尤其是在美国。在该项目中，在材料研究部的固态和材料化学计划和凝结的孕妇物理学计划的支持下，波士顿学院的研究人员合成了展示巨型MCE的新材料，并且仅包含最少稀有稀有读物的元素。通过这种方式，该项目通过消除消耗臭氧的冷藏气并最大程度地减少磁源材料的稀土含量来解决可持续性的关键方面。这个跨学科项目为培训下一代材料科学家提供了一个平台，对量子化学的了解以及实施基本科学解决社会问题的能力有了深刻的了解。此外，该项目为波士顿地区占人生不足的少数群体的预科学生提供了职业讲习班，并为杰克逊州立大学的学生，HBCU.Technical摘要：材料（MCE），磁性效果（MCE），可逆变化作为磁场的功能，为可持续的平台提供了可持续性的平台。磁性冰箱的消耗量要比常规冰箱要少得多，并且不依赖臭氧的气体。商业化磁性冰箱的主要挑战是缺乏由土壤丰富元素制成的较大制冷能力（RC）的材料。巨型磁电材料要么由P和AS等有毒元素制成，要么具有较大的稀土含量。因此，无毒且几乎没有稀土含量的巨型磁静电材料的合成是可持续性的关键方面。通过这项支持，来自波士顿学院的研究人员通过遵循两个化学设计原理，即带宽狭窄和竞争交流相互作用来合成此类材料。狭窄的带宽导致通过石器机构在室温附近的磁过渡。可以通过掺杂来调节临界温度，从而实现多阶段磁性冰箱的设计。竞争交换相互作用扩大了磁过渡，并导致熵释放在广泛的温度范围内，从而增强了RC。研究的材料的稀土含量少于百分之十。研究人员阐明了在这些材料中实现巨大MCE的新机制，其稀土含量最少。教育影响包括在化学和物理学之间的多学科研究项目中，人数不足的学生以及在国家高磁性领域和同步辐射设施中培训学生。该奖项反映了NSF的法定任务，并通过该基金会的知识优点和广泛的影响来评估NSF的法定任务。