NIRT: Artificially Engineered Nanoscale Ferroelectrics

NIRT：人工设计的纳米级铁电体

• 批准号: 0103354
• 负责人: Darrell Schlom
• 金额: $ 120万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-01 至 2006-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0103354&HistoricalAwards=false
• 关键词: NIRT; Artificially; Engineered; Nanoscale; Ferroelectrics

0103354SchlomThe technical objective of our NIRT is to understand the fundamental science underlying the structural, dielectric, and optical response of artificially-engineered nanoscale ferroelectrics, which can be drastically different from that of conventional homogeneous ferroelectrics. Using "first-principles effective Hamiltonian" approaches (based on lattice Wannier functions) and Landau-Ginzburg-type phenomenological methods, we will predict the effect of one-dimensional composition and strain gradients, and mechanical and electrical boundary conditions on the appearance and stability of the spontaneous polarization in these systems and on the modifications of ferroelectric domain structures. These predictions will be compared against observations on corresponding nanostructures (made by reactive MBE) of perovskite ferroelectrics in which composition and strain are varied in one direction. The resulting films will be characterized via a combination of TEM, x-ray diffraction (including synchrotron studies), Raman spectroscopy, second harmonic generation, dielectric property measurements as a function of electric field and temperature, and piezoelectric and pyroelectric techniques and compared with corresponding theoretical predictions in order to refine our understanding of nanoscale ferroelectrics. Composition and strain gradients in ferroelectric films will be investigated as a means to incorporate new functionalities: enhanced dielectric and pyroelectric responses, as well as a variety of novel optical properties.%%%For over 30 years molecular beam epitaxy (MBE) has been used to build up layered semiconductor nanostructures atom-by-atom to investigate and improve our understanding of semiconductor physics and create new devices. These devices (which include laser diodes, high-performance transistors, and magnetic field sensors) have advanced healthcare, national security, communications, entertainment, and transportation-resulting in significant improvements in the quality of life for all Americans. Recent progress in research has demonstrated that this same atom-by-atom synthesis technique can be used to build up nanostructures of oxides, including ferroelectrics, with comparable nanometer-scale layering control. Since ferroelectric materials exhibit a wide variety of electrical, optical, and electromechanical properties, they are extensively used in healthcare (e.g., medical ultrasound), national defense (e.g., night vision and sonar systems), and communications (e.g., miniature capacitors for cell phones and computers). The ability to customize the layering of ferroelectric materials at the atomic-layer level opens exciting possibilities in terms of creating new functional materials that we believe can be designed (with sufficient understanding) to have exceptional properties. The improved understanding gained via this research will be applied to the development of improved (enhanced performance and smaller size) capacitors, night vision devices, and optical components. This NIRT program will also train and educate future scientists in a highly interdisciplinary research environment in a technologically-significant area of national importance. This proposal was submitted in response to the solicitation "Nanoscale Science and Engineering" (NSF 00-119). The award is jointly supported through outside sources and the NSF Ceramics and Electronic Materials programs of the Division of Materials Research in MPS with the assistance of the initiative.

0103354 Schlom我们的NIRT的技术目标是了解人工设计的纳米级铁电体的结构，介电和光学响应的基础科学，这可能与传统的均匀铁电体截然不同。 使用“第一原理有效哈密顿”的方法（基于晶格Wannier函数）和Landau-Ginzburg型唯象方法，我们将预测一维组成和应变梯度，机械和电气边界条件的外观和稳定性的自发极化在这些系统和铁电畴结构的修改的影响。 这些预测将与相应的钙钛矿铁电体的纳米结构（由反应分子束外延）的观察结果进行比较，其中组成和应变在一个方向上变化。 将通过TEM，X射线衍射（包括同步加速器研究），拉曼光谱，二次谐波产生，介电性能的测量作为电场和温度的函数，压电和热电技术的组合，并与相应的理论预测，以完善我们的理解纳米铁电体的比较。 铁电薄膜中的成分和应变梯度将被研究作为一种手段，以纳入新的功能：增强的介电和热释电响应，以及各种新颖的光学特性。30多年来，分子束外延（MBE）已被用于逐个原子地构建分层半导体纳米结构，以研究和提高我们对半导体物理的理解并创建新器件。 这些设备（包括激光二极管、高性能晶体管和磁场传感器）具有先进的医疗保健、国家安全、通信、娱乐和运输功能，从而显著改善了所有美国人的生活质量。 最近的研究进展表明，这种相同的原子-原子合成技术可用于构建氧化物的纳米结构，包括铁电体，具有可比的纳米级分层控制。 由于铁电材料表现出各种各样的电学、光学和机电性质，因此它们广泛用于医疗保健（例如，医学超声），国防（例如，夜视和声纳系统），以及通信（例如，用于蜂窝电话和计算机的微型电容器）。 在原子层水平上定制铁电材料分层的能力为创造新的功能材料提供了令人兴奋的可能性，我们相信这些材料可以被设计（有足够的理解）以具有特殊的性能。 通过这项研究获得的更好的理解将应用于改进（增强性能和更小尺寸）电容器，夜视设备和光学元件的开发。 该NIRT计划还将在具有国家重要性的技术重要领域的高度跨学科研究环境中培训和教育未来的科学家。该提案是应“纳米科学与工程”（NSF 00-119）的要求提交的。该奖项由外部来源和MPS材料研究部门的NSF陶瓷和电子材料计划共同支持。