New modelling capability for nano-confined phase change materials

纳米相变材料的新建模功能

• 批准号: EP/M010643/1
• 负责人: David Quigley
• 金额: $ 51.47万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FM010643%2F1
• 关键词: New; modelling; capability; nano; confined

The global demand for smaller and more energy efficient devices has been sustained by a steady decrease in the scale on which silicon microelectronics can be manufactured, from 65nm processes in the mid 2000s to 14nm in the very latest Intel processors. To continue this trend beyond the mid 2020s devices with dimensions of just 1-2nm will be required, likely using alternatives to silicon.In this regime, the cross section of a wire might be no more than 2x2 or 3x3 atoms across, where the relevant materials physics is dominated by surface and confinement effects leading to dramatically different structural and electronic properties to the corresponding bulk material. Such wires can be formed by crystallisation of a molten salt within carbon nanotubes (CNTs) of "Buckytubes", leading to the smallest cross section nano crystals possible, sometimes referred to as Feynman crystals. Research into the fundamental materials physics of these CNT-encapsulated structures is still in its infancy, with UK experimentalists leading the way. Particularly exciting recent work by one of the applicants (Sloan) has demonstrated the possibility of these wires undergoing transitions between nano-crystalline structures with markedly different properties, in response to bending strain in the CNT. These "phase change" properties open the way for nanoscale electromechanical switches and non-volatile memory, as well as providing a playground for fundamental studies of phase changes at the smallest length scale possible in a material.Our aim with the current project, inspired by these results, is to develop a computational modelling capability to aid in interpretation of experiments, understand the origin of the phase change behaviour, and guide our experimental colleagues toward compounds with potentially advantageous properties. Counterintuitively, due to a reduction in symmetry, the computational expense of simulating nanowires can be more demanding when compared to bulk crystals. We will address the limitations of currently available modelling tools when applied to these systems. This will involve significant modifications to existing software and a rigorous study of the various approximations one might employ to increase the tractability of simulations.We will apply cutting-edge methods in structure prediction to these systems, a non-trivial exercise due to the possibility wires with non-crystalline (e.g. helical) symmetry, and connect directly to relevant experiments by computing spectra related to the encapsulated wire's electronic and vibrational properties. Finally, we will study the thermodynamics and kinetics of nano-crystalline phase change, developing an understanding of when and how rapidly structural changes are affected to assess the utility of this mechanism for device applications.

全球对更小、更节能设备的需求一直受到硅微电子制造规模稳步下降的支撑，从 2000 年代中期的 65 纳米工艺到最新英特尔处理器的 14 纳米工艺。为了在 2020 年代中期继续这一趋势，将需要尺寸仅为 1-2nm 的器件，很可能使用硅的替代品。在这种情况下，导线的横截面可能不超过 2x2 或 3x3 个原子，其中相关材料物理由表面和限制效应主导，导致与相应块体材料显着不同的结构和电子特性。这种线可以通过“巴基管”的碳纳米管（CNT）内熔盐的结晶来形成，从而产生可能的最小横截面纳米晶体，有时称为费曼晶体。对这些碳纳米管封装结构的基础材料物理的研究仍处于起步阶段，英国实验家处于领先地位。其中一位申请人（斯隆）最近的工作特别令人兴奋，它证明了这些线可以响应碳纳米管的弯曲应变，在具有明显不同特性的纳米晶体结构之间进行转变。这些“相变”特性为纳米级机电开关和非易失性存储器开辟了道路，并为材料中可能的最小长度尺度的相变基础研究提供了平台。受这些结果的启发，我们当前项目的目标是开发计算建模能力，以帮助解释实验，了解相变行为的起源，并指导我们的实验同事开发具有潜在优势的化合物。 特性。与直觉相反的是，由于对称性的降低，与块状晶体相比，模拟纳米线的计算成本可能更高。我们将解决当前可用的建模工具应用于这些系统时的局限性。这将涉及对现有软件的重大修改，以及对可能采用的各种近似方法的严格研究，以提高模拟的易处理性。我们将在这些系统的结构预测中应用尖端方法，由于可能具有非晶体（例如螺旋）对称性，因此这是一项不平凡的练习，并通过计算与封装线的电子和振动特性相关的光谱直接连接到相关实验。最后，我们将研究纳米晶体相变的热力学和动力学，了解结构变化何时以及如何快速受到影响，以评估该机制在设备应用中的效用。

项目成果

Unprecedented New Crystalline Forms of SnSe in Narrow to Medium Diameter Carbon Nanotubes.

• DOI: 10.1021/acs.nanolett.9b00133
• 发表时间: 2019-04
• 期刊: Nano letters
• 影响因子: 10.8
• 作者: Charlotte A. Slade;A. Sánchez;J. Sloan

Ultrafast, high modulation depth terahertz modulators based on carbon nanotube thin films

• DOI: 10.1016/j.carbon.2020.11.008
• 发表时间: 2021-03-01
• 期刊: CARBON
• 影响因子: 10.9
• 作者: Burdanova, Maria G.;Katyba, Gleb M.;Lloyd-Hughes, James
• 通讯作者: Lloyd-Hughes, James

Active site isolation in bismuth-poisoned Pd/SiO2 catalysts for selective hydrogenation of furfural

• DOI: 10.1016/j.apcata.2018.11.016
• 发表时间: 2019-01-25
• 期刊: APPLIED CATALYSIS A-GENERAL
• 影响因子: 5.5
• 作者: Cherkasov, Nikolay;Exposito, Antonio Jose;Rebrov, Evgeny V.
• 通讯作者: Rebrov, Evgeny V.

Vibrational dynamics of extreme 2 × 2 and 3 × 3 potassium iodide nanowires encapsulated in single-walled carbon nanotubes

单壁碳纳米管封装的极限2×2和3×3碘化钾纳米线的振动动力学

• DOI: 10.1103/physrevb.98.125429
• 发表时间: 2018
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Ivanov V

Single-Atom Scale Structural Selectivity in Te Nanowires Encapsulated inside Ultra-Narrow, Single-Walled Carbon Nanotubes

封装在超窄单壁碳纳米管内的 Te 纳米线的单原子尺度结构选择性

• DOI: 10.48550/arxiv.1701.04774
• 发表时间: 2017
• 作者: Medeiros P