CAREER: Synthesis, Phase Transitions, and Device Integration of Nanoscale Vanadium Oxides: A Research and Education Program

职业：纳米级氧化钒的合成、相变和设备集成：研究和教育项目

• 批准号: 0847169
• 负责人: Sarbajit Banerjee
• 金额: $ 60万
• 依托单位: SUNY at Buffalo
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0847169&HistoricalAwards=false
• 关键词: CAREER; Synthesis; Phase; Transitions; Device

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Technical SummaryVanadium oxides have a rich and complex phase diagram originating from the facile accessibility of different vanadium oxidation states and the various structural distortions adopted to accommodate non-stoichiometry and point defects. The proposed research project focuses on understanding the influence of finite size on the properties of two intriguing vanadium oxides, VO2 and V2O5. Bulk VO2 shows a dramatic insulator?metal phase transition at ~67°C and represents a textbook problem in solid-state chemistry and physics. The proposed work is inspired by our preliminary results showing a strong size dependence of the phase-transition temperature and hysteresis for VO2 nanostructures prepared by hydrothermal methods. Chemical vapor deposition and hydrothermal approaches for the fabrication of VO2 nanostructures with controlled shape, size, and growth direction will be explored. A systematic investigation of the crystal growth mechanism will be performed to obtain rational and predictive control over the nanostructure dimensions. A combination of ensemble X-ray absorption spectroscopy, Raman spectroscopy, and X-ray diffraction measurements will be used in conjunction with single-nanowire electrical transport and Raman spectroscopy measurements to understand the influence of finite size on the insulator?metal phase transition in these nanostructures. Another aspect of the proposed CAREER proposal will involve the fabrication of V2O5 nanowires and their dielectrophoretic integration within device structures. Simultaneous electrical conductivity and Raman spectroscopy measurements of single nanowires will be performed within device geometries to understand the influence of finite size in modifying the electrical transport and surface conductance of these nanowires in the presence of alcohol vapors. The synthesis and device integration of anisotropic VO2 and V2O5 nanostructures will pave the way for their implementation in optical switching devices, thermochromic coatings, Mott field-effect transistors, alcohol sensors, and waveguides.Non-Technical SummaryNanoscale materials often show properties that are not exhibited by their bulk counterparts. The proposed research effort is focused on understanding how such properties can be harnessed for practical applications such as making faster electronic circuits for use in the next generation of computers, ?smart? window materials that change color with temperature, and accurate sensors for detecting low concentrations of vapors. Vanadium dioxide, one of the materials that will be explored in this project, is a transparent insulator at room temperature but upon heating to 67°C becomes an excellent conductor that is almost completely opaque. The proposed research will focus on shifting this transition closer to room temperature wherein this dramatic effect can be used to construct ultrafast nanoelectronic circuits and temperature-sensitive coatings. An integrated outreach and education program is also proposed emphasizing teacher professional development, classroom engagement, and curricular reform at the middle-school level at a local urban high-needs school. These activities will serve to build sustained mentoring relationships between faculty, graduate students, undergraduate students, and middle-school teachers and students. This effort will seek to actively engage Buffalo Public School middle-school students from economically disadvantaged backgrounds in appreciating science and technology at a critical and formative time period. The collaborative development of attractive curricular material and challenging laboratory experiments along with sustained classroom visitation and after-school science activities will form the cornerstone of this program. A freshman seminar course will be developed to discuss the broader societal implications of nanotechnology.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。技术摘要钒氧化物具有丰富而复杂的相图，源于不同钒氧化态的容易获得性以及为适应非化学计量和点缺陷而采用的各种结构扭曲。拟议的研究项目侧重于了解有限尺寸对两种有趣的钒氧化物VO 2和V2 O 5性质的影响。大量的VO 2显示出一个戏剧性的绝缘体？在~67°C下的金属相变，代表了固态化学和物理学中的教科书问题。我们的初步研究结果表明，通过水热方法制备的VO 2纳米结构的相变温度和滞后具有很强的尺寸依赖性。我们将探索化学气相沉积和水热方法来制造具有可控形状、尺寸和生长方向的二氧化钒纳米结构。将进行晶体生长机制的系统研究，以获得合理的和预测性的控制纳米结构的尺寸。一个组合的合奏X射线吸收光谱，拉曼光谱，和X射线衍射测量将被用于与单纳米线的电传输和拉曼光谱测量，以了解有限的大小对绝缘体的影响？这些纳米结构中的金属相变。所提出的CAREER提案的另一个方面将涉及V2 O 5纳米线的制造及其在器件结构内的介电泳集成。同时电导率和拉曼光谱测量的单纳米线将在设备的几何形状内进行，以了解有限的尺寸在修改这些纳米线的电传输和表面电导的影响，在酒精蒸汽的存在下。各向异性VO 2和V2 O 5纳米结构的合成和器件集成将为它们在光开关器件、热致变色涂层、莫特场效应晶体管、酒精传感器和waveguide.Non-Technical SummaryNanoscale材料中的应用铺平道路。拟议的研究工作的重点是了解如何利用这些属性的实际应用，如使更快的电子电路用于下一代计算机，？聪明吗随温度改变颜色的窗户材料，以及用于检测低浓度蒸汽的精确传感器。二氧化钒是本项目将探索的材料之一，在室温下是透明的绝缘体，但在加热到67°C时成为几乎完全不透明的优良导体。拟议的研究将集中在将这种转变更接近室温，其中这种戏剧性的效果可用于构建超快纳米电子电路和温度敏感涂层。一个综合的推广和教育计划，也提出了强调教师专业发展，课堂参与，并在中学一级的课程改革在当地城市高需求的学校。这些活动将有助于在教师、研究生、本科生和中学教师与学生之间建立持续的指导关系。这项努力将寻求积极参与布法罗公立学校中学生从经济上处于不利地位的背景在欣赏科学和技术在一个关键和形成的时间段。合作开发有吸引力的课程材料和具有挑战性的实验室实验，沿着持续的课堂访问和课后科学活动将构成该计划的基石。一个新生研讨会课程将开发讨论纳米技术的更广泛的社会影响。