CAREER: Integrated Research & Education on Controlling the Size and Composition of Diamond Nanocrystals via Molecular Synthesis

金刚石纳米晶体被考虑用于一系列的应用，包括光学生物成像、量子信息处理、光电子学、电场和磁场的光学检测、空间定位的磁共振成像，以及用于金刚石薄膜的播种生长。 在自然界中，金刚石纳米晶体是通过非平衡事件形成的，包括恒星超新星或流星对地球的影响。 最近，金刚石纳米晶体已经在实验室内通过高能炸药（即，TNT）、碳纳米颗粒的脉冲激光照射、或通过在非平衡大气压等离子体反应器内的直接生长。 尺寸是金刚石纳米晶体的一个关键参数，因为它影响这些材料通过肾脏过滤从体内清除的速度。 此外，组成对于金刚石纳米晶体至关重要，因为它决定了光学和电子性质。 目前还没有能够控制金刚石纳米晶体的1）尺寸和2）缺陷组成的合成方案。这项研究将为控制这两个关键参数提供有价值的基础知识。 此外，目前在金刚石材料中还没有已知的浅n型施主。 这项研究还将追求金刚石纳米晶体内的n型导电性的实验证明，这对整个社会都有价值，因为它可以实现有益的高频，高功率光电设备，用于信息处理，紫外线水净化和极端环境涂层。这里提出的教育推广工作将建立一个学习途径，高年级本科生通过开发一个数值计算模块集成在现有的工程课程在华盛顿大学的发展与先进的数值方法的技能。这些技能将为学生在光电材料行业的职业生涯做好准备，或继续在研究生院接受教育。对阿拉斯加原住民小学生、阿拉斯加大学阿拉斯加原住民科学工程项目的本科生和华盛顿大学的原住民联盟的推广工作将有助于激励保留下一代代表性不足的材料科学家。技术摘要目前，在科学文献中没有选择合理合成具有精确1）尺寸和2）成分的纳米金刚石。该建议的智力价值在于产生关于如何使用高压/高温扩散掺杂来在纳米金刚石中产生精确的1）尺寸和2）光电点缺陷的新知识。在固态和材料化学计划的支持下，将在5年内追求四个主要研究里程碑：1）测试假设，即减少无定形碳纳米颗粒的粒度将减少通过高压/高温技术生产纳米金刚石颗粒所需的热力学条件。在无定形碳表面的碳原子的化学势是尺寸依赖性的（源于吉布斯-汤姆森效应），这可以降低无定形碳/金刚石相变的最低温度和压力。2)将采用预测性数值模型，在激光加热金刚石对顶砧单元中对高吸收无定形碳材料进行光热加热，该模型基于使用球坐标的能量偏微分方程的分析本征函数展开解。3)分子掺杂策略将用于控制模型点缺陷的浓度，使用金刚石晶格内的硅或镍杂原子。4)从无定形碳合成掺杂金刚石纳米晶体的先前结果将告知高风险/高回报的实验努力，以观察理论上提出的金刚石中的多原子n型缺陷中心。实验的理论方法将提供一个完整的理解如何无定形碳颗粒的大小和组成决定最终的纳米金刚石性能

Non-Technical AbstractDiamond nanocrystals are being considered for a range of applications including optical bioimaging, quantum-information-processing, photocatalysis, the optical detection of electric and magnetic fields, spatially localized magnetic resonance imaging, and also for seeding the growth of diamond thin films. In nature diamond nanocrystals are formed through non-equilibrium events including stellar supernovae or the impact of meteors on Earth. More recently, diamond nanocrystals have been synthesized directly within laboratories through the detonation of high explosives (i.e., TNT), pulsed laser irradiation of carbon nanoparticles, or through direct growth within non-equilibrium atmospheric-pressure plasma reactors. Size is a crucial parameter for diamond nanocrystals in that it impacts how quickly these materials are cleared from the body through filtration in the kidneys. Furthermore, composition is critically important for diamond nanocrystals in that it determines the optical and electronic properties. Currently there are no synthetic protocols that enable control over both the 1) size and 2) defect composition of diamond nanocrystals. This research will generate valuable fundamental knowledge for controlling both of these crucial parameters. Additionally, there currently is no known shallow n-type donor in diamond materials. This research will also pursue the experimental demonstration of n-type conductivity within diamond nanocrystals that would be valuable to society at large by enabling beneficial high-frequency, high-power optoelectronic devices for information processing, UV water-purification, and extreme environment coatings. The educational outreach efforts proposed here will build a learning pathway for senior undergraduate students to develop skills with advanced numerical methods through the development of a numerical computing module integrated within the existing engineering curriculum at the University of Washington. These skills will prepare students for careers within the optoelectronic materials industry, or for continuing their education in graduate school. Outreach efforts to Native Alaskan elementary students, undergraduates in the Alaska Native Science & Engineering Program at the University of Alaska, and Indigenous Alliance outreach at UW will help inspire & retain the next generation of underrepresented materials scientists.Technical AbstractCurrently there are no options in the scientific literature for rationally synthesizing nanodiamonds with precise 1) sizes and 2) compositions. The intellectual merit of this proposal rests on generating new knowledge for how to use high-pressure/high-temperature diffusion-doping to generate precise 1) sizes and 2) optoelectronic point-defects in nanodiamond. With support from the Solid State and Materials Chemistry program, four primary research milestones will be pursued over 5 years: 1) Test the hypothesis that reducing the grain-size of amorphous-carbon nanoparticles will reduce the thermodynamic conditions necessary to produce nanoscale diamond grains through high-pressure/high-temperature techniques. The chemical-potential for carbon atoms at the surface of amorphous-carbon is size-dependent (stemming from the Gibbs-Thomson effect) which may lower the minimum temperature and pressure of the amorphous-carbon / diamond phase-transition. 2) A predictive numerical model will be employed for photothermal heating of highly-absorbing amorphous-carbon materials in the laser-heated diamond anvil cell based on an analytical eigenfunction expansion solution for the energy partial differential equation using spherical coordinates. 3) Molecular doping strategies will be used to control the concentration of model point-defects using either silicon- or nickel- heteroatoms within the diamond lattice. 4) Prior results for synthesizing doped diamond nanocrystals from amorphous-carbon will inform high-risk / high-reward experimental efforts to observe a theoretically-proposed, polyatomic n-type defect center in diamond. The experimental & theoretical approaches will provide an integrated understanding of how the size and composition of amorphous-carbon grains determine final nanodiamond properties