The Emergence of Ferroic Phenomena and Size-Effects in Fluorite-Based Nanoparticles

非技术描述：电子行业对存储设备小型化的推动推动了对为这些设备提供所需性能的纳米颗粒和薄膜的尺寸相关特性的浓厚兴趣。实现这些设备的一个关键特性是铁电性，即一种材料暴露在电场中时会储存能量，这可以用来储存电子信息。然而，随着材料和器件的缩小，这种铁电行为往往会消失。在最小的纳米颗粒中寻找铁电性已经持续了几十年，但成果有限。相反，在传统材料中，观察到了小颗粒/颗粒尺寸的铁电行为的损失。然而，有一些很有希望的新材料，包括那些含有元素Hf的材料，最近在非常小的尺寸上表现出了铁电行为。这个项目试图解释在基于Hfn的纳米粒子中，随着尺寸的减小而出现这种铁电行为的原因。这项研究是通过促进与横跨材料科学和化学工程的研究生和教员团队的合作和多样性来完成的。此外，这项工作涉及高中生和本科生，旨在通过纳入代表性不足的群体来扩大参与。正在举办一系列研讨会，促进和突出多样性，以帮助留住代表性不足的群体。技术细节：该项目的主要目标是利用新的合成方法来合成Hafnia和基于Hafnia的纳米颗粒。最近的计算工作预测，由于3~5 nm和8~16 nm之间的颗粒表面能，Hafnia和Hf-Ziro氧化物的铁电正交相将会稳定下来。这项研究试图在实验上验证这些(和其他)假设，并在基于Hafnia的系统的独立和巩固的纳米颗粒中展示铁性特性。除了新的合成，还将采用先进的表征来确认局部和整体长度尺度的晶体结构和电子性质。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。

NON-TECHNICAL DESCRIPTION: The push for miniaturization of memory devices in the electronics industry has driven significant interest in the size-dependent properties of nanoparticles and films that provide the required performance for these devices. One key property that enables these devices is ferroelectricity, where a material stores energy upon exposure to an electric field, which can be used to save electronic information. However, this ferroelectric behavior tends to disappear as materials and devices shrink. The search for ferroelectricity in the smallest of nanoparticles has spanned several decades with limited success. Instead, a loss of ferroelectric behavior has been observed for small particle/grain sizes in traditional materials. However, there are promising new materials, including those containing the element hafnium, that have recently displayed ferroelectric behavior at very small sizes. This project seeks to elucidate the emergence of this ferroelectric behavior with decreasing size in hafnium-based nanoparticles. This research is accomplished by fostering collaboration and diversity with a team of graduate students and faculty spanning materials science and chemical engineering. In addition, this work involves high school students and undergraduate students, aiming to broaden participation through the inclusion of underrepresented groups. A seminar series that promotes and highlights diversity is underway to help increase retention of underrepresented groups. TECHNICAL DETAILS:The overarching goal of this project is to utilize novel synthesis methods to synthesize hafnia and hafnia-based nanoparticles. Recent computational work has predicted that the ferroelectric orthorhombic phase will be stabilized due to surface energetics for particles between 3 to 5 nm or 8 to 16 nm for hafnia and hafnium-zirconium oxide, respectively. This research seeks to experimentally validate these (and other) hypotheses and demonstrate ferroic properties in both free-standing and consolidated nanoparticles of hafnia-based systems. In addition to novel synthesis, advanced characterization will be employed to confirm crystal structure and electronic properties at both local and bulk length scales.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.