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

摘要金刚石纳米晶体被广泛应用于光学生物成像、量子信息处理、光催化、电场和磁场的光学检测、空间定位磁共振成像以及金刚石薄膜的播种生长等领域。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，金刚石纳米晶体通过高炸药（即TNT）的爆炸，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中直接生长，直接在实验室中合成。尺寸是金刚石纳米晶体的一个关键参数，因为它会影响这些材料通过肾脏过滤从体内清除的速度。此外，组成对金刚石纳米晶体至关重要，因为它决定了其光学和电子特性。目前还没有能够同时控制金刚石纳米晶体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产生有价值的基础知识。此外，目前在金刚石材料中还没有已知的浅n型供体。这项研究还将继续在金刚石纳米晶体中进行n型电导率的实验演示，这将对整个社会有价值，通过实现有益的高频，高功率光电器件，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通过开发与华盛顿大学现有工程课程相结合的数值计算模块，为高年级本科生建立一条学习途径，以发展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，或者为继续他们的研究生教育做好准备。向阿拉斯加土著小学生、阿拉斯加大学阿拉斯加土著科学与工程项目的本科生以及华盛顿大学土著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：目前科学文献中还没有合理合成具有精确尺寸和成分的纳米金刚石的方法。该提案的智力价值在于为如何使用高压/高温扩散掺杂在纳米金刚石中产生精确尺寸和光电点缺陷提供了新的知识。在固态和材料化学项目的支持下，将在5年内实现四个主要的研究里程碑：1)测试假设，即减小非晶碳纳米颗粒的晶粒尺寸将减少通过高压/高温技术生产纳米级金刚石晶粒所需的热力学条件。非晶碳表面碳原子的化学势与尺寸有关（源于吉布斯-汤姆逊效应），这可能降低非晶碳/金刚石相变的最低温度和压力。2)基于球坐标下能量偏微分方程的解析特征函数展开解，建立了高吸收非晶碳材料在激光加热金刚石砧槽中光热加热的预测数值模型。3)分子掺杂策略将用于控制模型点缺陷的浓度，在金刚石晶格中使用硅或镍杂原子。4)先前从非晶碳中合成掺杂金刚石纳米晶体的结果将为观察理论上提出的金刚石多原子n型缺陷中心提供高风险/高回报的实验工作。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纳米金刚石性质的综合理解

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