CAREER: Manipulating Barocaloric Effects in Two-Dimensional Perovskites

职业：操纵二维钙钛矿中的气压效应

• 批准号: 2238113
• 负责人: Jarad Mason
• 金额: $ 82.3万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2028-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2238113&HistoricalAwards=false
• 关键词: CAREER; Manipulating; Barocaloric; Effects; Two

Non-technical summary:Phase transitions (i.e., going from a solid to a liquid) enable large changes in the properties of a material to be triggered by a small change in an external stimulus, and thus provide a versatile mechanism for the design of advanced, responsive materials. Despite the tremendous importance of phase transitions, creating materials that transition between two phases—each with a particular set of desired properties—is a challenge. Through this award, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, Prof. Jarad Mason aims to advance the basic science of phase transitions through a fundamental study of the structural and chemical factors that control transitions between ordered and disordered states within hybrid (i.e., organic and inorganic) materials, as well as how these transitions are affected by the application of pressure. Such phase transitions offer exciting opportunities for addressing many critical societal challenges, including how to reversibly store high densities of thermal energy and how to develop more sustainable cooling technologies that do not rely on environmentally harmful volatile refrigerants. In addition, this project aims to broaden participation in scientific research and to facilitate public engagement in basic science and technological innovations through curriculum development, mentorship of high school students, and outreach to K-12 students, high school teachers, and the general public. Technical summary:Barocaloric effects are thermal changes in a material that result from the application or removal of hydrostatic pressure. These effects, which can be used to drive solid-state cooling, heat pump, and thermal energy storage cycles, are strongest when a material experiences a large change in volume and entropy over a narrow temperature range, such as during a sharp order–disorder phase transition. Although critical to realizing the full potential of barocaloric effects, it remains difficult to predictably manipulate order-disorder phase transitions in the solid state, and much remains to be understood about the specific structural and chemical factors that contribute to barocaloric effects at a molecular level. With this CAREER project, Prof. Mason will address these challenges through a systematic investigation of barocaloric effects associated with chain-melting phase transitions in two-dimensional hybrid perovskites. Owing to their synthetic tunability, two-dimensional perovskites serve as a powerful platform to establish fundamental structure–property relationships that advance the development of barocaloric materials. Specifically, the principal hypothesis guiding this research is that the organic bilayers and inorganic sheets in two-dimensional metal–halide perovskites can be synthetically tuned to control the entropy changes, enthalpy changes, volume changes, hysteresis, and kinetics of chain-melting transitions and, consequently, their barocaloric properties. In this project, new materials synthesis and in-depth characterization by X-ray diffraction, calorimetry, neutron scattering, and infrared and solid-state NMR spectroscopies are utilized to investigate the thermodynamics, kinetics, and reversibility of order–disorder transitions in two-dimensional perovskites.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：相变（即从固体到液体）使得外部刺激的微小变化能够触发材料性质的巨大变化，从而为先进的设计提供了一种通用的机制尽管相变非常重要，但创造在两个相之间转变的材料（每个相都具有一组特定的所需性能）是一项挑战，该奖项由固态和材料化学项目资助。材料研究NSF 的 Jarad Mason 教授旨在通过对控制混合（即有机和无机）材料内有序和无序状态之间转变的结构和化学因素以及这些转变如何进行基础研究来推进相变的基础科学。这种相变为解决许多关键的社会挑战提供了令人兴奋的机会，包括如何可逆地存储高密度热能以及如何开发不依赖于对环境有害的挥发物的更可持续的冷却技术。此外，该项目旨在通过课程开发、对高中生的指导以及对 K-12 学生、高中教师和普通民众的宣传，扩大科学研究的参与范围并促进公众参与基础科学和技术创新。技术摘要：气压热效应是由于施加或去除静水压力而引起的材料的热变化，这些效应可用于驱动固态冷却、热泵和热能存储循环，当这些效应最强时。物质经历了巨大的变化尽管对于实现压热效应的全部潜力至关重要，但在狭窄的温度范围内（例如在急剧的有序-无序相变期间）仍然难以预测地操纵固态中的有序-无序相变，并且还有很多工作要做。通过这个职业项目，梅森教授将通过系统研究与链熔化相变相关的气压效应来解决这些挑战。由于其合成的可调性，二维钙钛矿可以作为建立基本结构-性能关系的强大平台，从而促进压热材料的发展。具体来说，指导这项研究的主要假设是有机双层。二维金属卤化物钙钛矿中的无机片和无机片可以通过综合调节来控制熵变、焓变、体积变化、滞后和动力学。在该项目中，利用新材料的合成和通过 X 射线衍射、量热法、中子散射以及红外和固态核磁共振光谱进行的深入表征来研究热力学，二维钙钛矿中有序-无序转变的动力学和可逆性。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。