CAREER: Synthesis and Characterization of One-Dimensional Chemical Nanostructures

化学系的先进材料计划将这项职业奖授予哈佛大学，以研究一维化学纳米结构。 凭借该奖项，Hongkun Park教授将研究通过化学气相沉积法使用具有均匀尺寸分布的隔离良好的催化剂纳米颗粒合成具有可控直径和螺旋度的大直径单壁碳纳米管（SWNTs）。 扫描探针显微镜（SPM）将被用来确定这些单壁碳纳米管的机电性能和全局径向变形和电子输运性能之间的耦合。 由钛酸钡和相关化合物制备的单个单晶纳米线的合成及其随后的变温SPM表征也将与该奖项一起进行。 SPM研究纳米线的铁电和压电性能，应该提供基础知识，支配的热力学以及动力学的相变和极化开关。 静电力显微镜将被用来通过测量纳米线上的局部电极化来“读”和“写”。 PI在其他教职员工的帮助下，将为中学生举办材料科学和纳米技术讲座，作为“早期大学意识计划”的一部分，以吸引学生从事与科学相关的学习和职业。采用化学气相沉积法，利用粒径分布均匀的催化剂纳米颗粒，可以合成出直径和螺旋度可控的大直径单壁碳纳米管（SWNTs），这些碳纳米管在电子机械领域具有潜在的应用前景。 此外，单晶铁电纳米线将由钛酸钡和相关化合物制备，并通过变温扫描探针显微镜确定其铁电和压电性能。 这些实验将确定作为温度和纳米线直径的函数的各个纳米线的相变。“早期大学意识方案”将使学生接触科学的不同方面，并吸引他们继续深造科学。

The Advanced Materials Program in the Division of Chemistry makes this Career award to Harvard University to study one-dimensional chemical nanostructures. With this award, Professor Hongkun Park will study the synthesis of large-diameter Single Walled carbon Nanotubes (SWNTs) with controlled diameter and helicity by chemical vapor deposition using well-isolated catalyst nanoparticles with uniform size distributions. Scanned-probe microscopy (SPM) will be used to determine electromechanical properties and the coupling between global radial deformation and electron transport properties of these SWNTs. Synthesis of individual single-crystalline nanowires prepared from barium titanate and related compounds and their subsequent characterization by variable-temperature SPM will also be carried out with this award. The SPM to study ferroelectric and piezoelectric properties of nanowires should provide fundamental knowledge that governs the thermodynamics as well as the kinetics of phase transition and polarization switching. Electrostatic force microscopy will be used to 'read' and 'write' by measuring the local electric polarization on the nanowires. The PI, with the help of other faculty members, will give lectures in materials science and nanotechnology to middle school students as part of the "Early College Awareness Program" to attract students to science related studies and careers. Large-diameter Single Walled carbon Nanotubes (SWNTs) with controlled diameter and helicity will be synthesized by chemical vapor deposition using well-isolated catalyst nanoparticles with uniform size distributions, and these nanotubes may have potential electromechanical applications in devices. In addition, single-crystalline ferroelectric nanowires will be prepared from barium titanate and related compounds and their ferroelectric and piezoelectric properties determined by variable-temperature scanned-probe microscopy. These experiments will determine phase transitions of individual nanowires as a function of temperature and nanowire diameter. "Early College Awareness Program" will expose school students in different aspects of science, and will attract them for advanced studies in science.