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

非技术描述：在电子工业中，对存储器装置的小型化的推动已经驱动了对纳米颗粒和膜的尺寸依赖性性质的极大兴趣，所述纳米颗粒和膜为这些装置提供所需的性能。实现这些设备的一个关键特性是铁电性，其中材料在暴露于电场时存储能量，这可用于保存电子信息。然而，这种铁电行为往往会随着材料和器件的缩小而消失。在最小的纳米粒子中寻找铁电性已经跨越了几十年，但成功有限。相反，对于传统材料中的小颗粒/晶粒尺寸，已经观察到铁电行为的损失。然而，有一些有前途的新材料，包括那些含有元素铪的材料，最近在非常小的尺寸下显示出铁电行为。这个项目旨在阐明这种铁电行为的出现，在铌基纳米粒子的尺寸减小。这项研究是通过促进合作和多样性与研究生和教师跨越材料科学和化学工程团队完成的。此外，这项工作涉及高中生和大学生，旨在通过纳入代表性不足的群体来扩大参与。一系列促进和强调多样性的研讨会正在进行中，以帮助提高代表性不足的群体的保留率。该项目的首要目标是利用新的合成方法来合成纳米材料和基于纳米材料的纳米颗粒。最近的计算工作已经预测，铁电正交相将是稳定的，由于表面能量的颗粒之间的3至5 nm或8至16 nm的氧化物和氧化物锆，分别。本研究旨在通过实验验证这些（和其他）假设，并证明铁电性质的独立和巩固的纳米粒子的氧化铝为基础的系统。除了新颖的合成，先进的表征将被用来确认晶体结构和电子性能在本地和散装长度scales.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.