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

非技术摘要金刚石纳米晶正被考虑用于一系列应用，包括光学生物成像、量子信息处理、光催化、电场和磁场的光学检测、空间局域磁共振成像，以及用于金刚石薄膜生长的种子。在自然界中，钻石纳米晶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撞击。最近，通过烈性炸药(即TNT)的引爆、碳纳米颗粒的脉冲激光照射或在非平衡大气压等离子体反应堆中直接生长，在实验室内直接合成了金刚石纳米晶。大小是钻石纳米晶体的一个关键参数，因为它影响这些物质通过肾脏过滤从体内清除的速度。此外，组成对金刚石纳米晶至关重要，因为它决定了金刚石的光学和电学性质。目前还没有能够同时控制钻石纳米晶体的尺寸和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，目前在钻石材料中还没有已知的浅n型施主。这项研究还将通过使有益的高频、高功率光电设备用于信息处理、紫外线净水和极端环境涂层，来进行钻石纳米晶体内n型导电性的实验演示，这将对整个社会具有价值。这里提出的教育推广努力将为高年级本科生建立一条学习途径，通过开发整合在华盛顿大学现有工程课程中的数值计算模块，发展具有先进数值方法的技能。这些技能将为学生在光电材料行业的职业生涯做好准备，或继续他们在研究生院的教育。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与工程专业的本科生以及威斯康星大学原住民联盟的推广工作将有助于激励和留住下一代未被充分代表的材料科学家。技术摘要目前，科学文献中没有合理合成具有精确尺寸和成分的纳米钻石的选择。这一提议的智力价值在于产生了新的知识，即如何使用高压/高温扩散掺杂来产生精确的纳米钻石尺寸和光电子点缺陷。在固态和材料化学计划的支持下，将在5年内实现四个主要研究里程碑：1)测试减小非晶碳纳米颗粒的颗粒尺寸将降低通过高压/高温技术生产纳米级钻石颗粒所需的热力学条件的假设。非晶态碳表面碳原子的化学势与尺寸有关(源于Gibbs-Thomson效应)，这可能降低非晶态碳/金刚石相变的最低温度和压力。2)基于能量偏微分方程球坐标下的解析本征函数展开解，建立了高吸收非晶碳材料在激光加热金刚石砧腔中的光热预测模型。3)分子掺杂策略将被用来控制在金刚石晶格中使用硅或镍杂原子的模型点缺陷的浓度。4)从非晶碳合成掺杂金刚石纳米晶的先前结果将为高风险/高回报的实验工作提供参考，以观察到理论上提出的钻石中的多原子n型缺陷中心。实验和理论方法将提供对非晶碳颗粒的大小和组成如何决定最终的纳米金刚石性能的综合理解。

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