CAREER: Synthesis and Characterization of One-Dimensional Chemical Nanostructures

化学系的先进材料计划将这一职业奖项授予哈佛大学，以研究一维化学纳米结构。获得这一奖项后，朴宏坤教授将研究利用尺寸分布均匀、隔离良好的催化剂纳米颗粒，通过化学气相沉积方法合成直径和螺旋度可控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质以及全局径向变形和电子传输性质之间的耦合。由钛酸钡和相关化合物制备的单个单晶纳米线的合成以及随后通过变温扫描电子显微镜对其进行表征也将与该奖项一起进行。用来研究纳米线的铁电和压电性的扫描探针显微镜应该提供指导热力学以及相变和极化转换动力学的基础知识。静电力显微镜将通过测量纳米线上的局部极化来进行读和写。国际学生联合会将在其他教职员工的帮助下，为中学生讲授材料科学和纳米技术方面的知识，作为“大学早期意识计划”的一部分，以吸引学生从事与科学相关的研究和职业。大直径单壁碳纳米管(SWNTs)的直径和螺旋度可以通过化学气相沉积的方法得到，这些纳米管具有良好的隔离性和均匀的尺寸分布，这些纳米管可能在器件中具有潜在的机电应用。此外，还将由钛酸钡及其相关化合物制备单晶铁电纳米线，并用变温扫描探针显微镜测定其铁电和压电性能。这些实验将确定单个纳米线的相变作为温度和纳米线直径的函数。“大学早期意识计划”将让在校学生了解科学的不同方面，并将吸引他们进行科学方面的深造。

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.