Polarization Caloritronics: a pathway to electrically-controlled heat switches

偏振热电学：电控热开关的途径

• 批准号: 2133718
• 负责人: Joseph Heremans
• 金额: $ 38.08万
• 依托单位: Ohio State University
• 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: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2133718&HistoricalAwards=false
• 关键词: Polarization; Caloritronics; pathway; electrically; controlled

Most human energy consumption goes to create heat, for example, to generate electricity in power plants or to power of cars and planes with fuel combustion. Heat switches are important devices that control electricity flow based on temperature. They enable important applications such as magnetic and electric greenhouse-gas-free cooling technologies, solar-thermal power generators, and automotive exhaust waste heat recovery systems. Most heat switches are either mechanical switches that wear out and cannot support millions of cycles, or they are based on phase transitions, which work only at one fixed temperature. Ferroelectric materials have potential to overcome these limitations. This project will develop the fundamental knowledge needed to design heat switches from bulk ferroelectric materials.Heat is carried by vibrations of the atoms, called “phonons” in electrically insulating solid. Magnets, such as iron, are solids in which each atom carries its own little magnet, called a “magnetic moment”, and when all the atomic magnetic moments align, the solid gains a net magnetization. In ferroelectric solids, atoms have local atomic dipole moments where one side of the atom is more positively charged and the opposite side is more negative. These atomic dipole moments align in ferroelectric materials just like the atomic magnetic moments align in magnets, giving a net polarization. In magnets, heat can be carried by thermal fluctuations (somewhat like Brownian motion) of the atomic magnetic moments, called “magnons”. The proposal investigates the nature of the thermal fluctuations of the dipole moments in ferroelectrics, the analogs of magnons. These are tentatively labeled “ferrons” and have not been studied explicitly before. Preliminary results suggest that ferrons are phonons that involve the vibrations of the atoms that carry dipole moments and, like most phonons, they carry heat. Theoretically, an applied voltage should influence their heat-carrying capability; preliminary experiments confirm this. The detailed theory of the influence of an external electric field on the thermal conductivity of ferrons will be developed and tested experimentally in this project. The goal is to provide design rules to develop new materials from the ground up in which the thermal conductivity is affected greatly by applied voltage, making them suitable for heat switches.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.

人类的大部分能源消耗用于产生热量，例如，在发电厂发电，或通过燃料燃烧为汽车和飞机提供动力。热开关是根据温度控制电流的重要装置。它们能够实现重要的应用，如磁力和电动无温室气体冷却技术、太阳能-热能发电机和汽车废热回收系统。大多数热开关要么是磨损的机械开关，无法支持数百万次循环，要么是基于相变，只能在一个固定的温度下工作。铁电材料有可能克服这些限制。这个项目将发展从大块铁电材料设计热开关所需的基本知识。热是通过原子的振动来传递的，这种原子在电绝缘固体中被称为“声子”。像铁这样的磁体是固体，其中每个原子都携带着自己的小磁铁，称为“磁矩”，当所有原子的磁矩对齐时，固体获得净磁化。在铁电固体中，原子有局部原子偶极矩，原子的一侧带正电荷，另一侧带负电荷。这些原子偶极矩在铁电材料中排列，就像原子磁矩在磁体中排列一样，产生净极化。在磁体中，热可以通过原子磁矩的热涨落(有点像布朗运动)来携带，这种磁矩被称为“磁子”。该提议研究了铁电体中偶极矩的热涨落的本质，铁电体是磁子的类似物。它们暂时被贴上了“费龙”的标签，以前还没有被明确研究过。初步结果表明，费龙是一种声子，它涉及携带偶极矩的原子的振动，并且像大多数声子一样，它们携带热量。从理论上讲，外加电压应该影响它们的载热能力；初步实验证实了这一点。在这个项目中，我们将建立外加电场对费朗热导率影响的详细理论，并进行实验验证。其目标是提供设计规则，从头开始开发热导率受外加电压影响很大的新材料，使其适用于热开关。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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

Polarization transport in ferroelectrics

• DOI: 10.1103/physrevapplied.20.050501
• 发表时间: 2023-11
• 期刊: Physical Review Applied
• 影响因子: 4.6
• 作者: G. Bauer;P. Tang;R. Iguchi;J. Xiao;K. Shen;Z. Zhong;T. Yu;S. M. Rezende;J. Heremans;K. Uchida