Study of the Evolution of Nanoparticle Crystallization and Optical Properties in Glass Ceramics

玻璃陶瓷中纳米颗粒结晶和光学性能的演变研究

• 批准号: 1001381
• 负责人: Jacqueline Johnson
• 金额: $ 28.91万
• 依托单位: University of Tennessee Space Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1001381&HistoricalAwards=false
• 关键词: Study; Evolution; Nanoparticle; Crystallization; Optical

The goal of this project is to determine the microstructural and chemical origins of the optical properties of Europium-doped fluorozirconate glasses, additionally doped with chlorine nanocomposite materials. The glass ceramics have potential applications as an x-ray imaging plate, for example in a digital mammography system. A further goal of the research is to provide insights into ways in which the material could be optimized for this application. Europium-doped fluorozirconate glasses, additionally doped with chlorine, can be heat-treated in such a way that it forms a novel nanocomposite material containing barium chloride nanocrystals, with the ability to convert ionizing radiation (usually x-rays) into stable electronhole pairs. These can be read out afterwards with a scanning laser beam in a so-called "photostimulated luminescence" (PSL) process. Optical studies have shown that the nanocomposite glasses gives out five times more light than the equivalent volume of the single crystal. The reason for this increased light output is not understood but the answer lies in the interface between the nanoparticles and its host glass matrix, as a result of the formation of the barium chloride nanoparticles. The ideal technique to analyze the structure and composition across nanoscale interfaces is by transmission electron microscopy (TEM). Ex situ TEM analysis has previously been carried out on samples that were annealed at various temperatures but this only provides a snapshot of the available science. The planned TEM studies include high resolution imaging of the atomic-scale structure of the nanocrystals and their interfaces with the glass matrix, in conjunction with energy-filtered TEM (EFTEM) composition mapping of the chemical distribution in and around the nanocrystals. Further, samples, which have previously been heat-treated in a furnace or irradiated by a laser with different energies and pulse length, in order to induce nanocrystal nucleation, will be examined and the three nucleation techniques, ex situ thermal, laser, and in situ thermal will be compared.The University of Tennessee Space Institute regularly runs summer science camps for K-12 and employs summer interns. The entire UTSI staff participates in the outreach efforts. Dr. Johnson has developed a detailed seven week summer research experience program for a combination of high-school and undergraduate students. The students receive a glass-ceramic sample and go through a program of characterization, oral presentation, report preparation, career day and mock grant writing workshop. The program culminates in the preparation of a journal article. The PI regularly acts as a mentor for the Introduce a Girl to Engineering day, which is a program at Argonne for Middle School female students.

该项目的目的是确定Eurozirozirconate玻璃的光学特性的微观结构和化学起源，并还用氯纳米复合材料掺杂。玻璃陶瓷具有潜在的应用作为X射线成像板，例如在数字乳房摄影系统中。 该研究的另一个目标是提供有关该应用程序对材料进行优化的方式的见解。 掺杂的氟二氯二甲酸玻璃杯还可以用氯掺杂，以这种方式进行热处理，以使其形成含有含氯化钡纳米晶体的新型纳米复合材料，并能够将电离辐射（通常是X射线）转换为稳定的电子霍尔。这些可以在所谓的“光刺激发光”（PSL）过程中使用扫描激光束后读出这些。光学研究表明，纳米复合玻璃给单晶体的同等体积的光赋予了五倍。尚不清楚这种增加的光输出的原因，但答案在于纳米颗粒与其宿主玻璃基质之间的界面，这是由于氯化钡纳米颗粒的形成而导致的。分析纳米级界面的结构和组成的理想技术是通过透射电子显微镜（TEM）。以前对在各种温度下退火的样品进行了现场分析，但这仅提供可用科学的快照。计划的TEM研究包括纳米晶体的原子尺度结构的高分辨率成像及其与玻璃基质的界面，以及纳米晶体内和周围化学分布的能量过滤TEM（EFTEM）组成映射。此外，将检查以前已经在炉子中对炉子进行热处理或由具有不同能量和脉搏长度的激光器进行热处理的样品，以诱导纳米晶体成核，并将进行三种成核技术，即现场热，激光和原位热线训练赛跑步。整个UTSI工作人员都参加了外展工作。约翰逊博士已经开发了一项详细的七周夏季研究经验计划，以组合高中生和本科生。学生会收到玻璃陶瓷样本，并通过表征，口头介绍，报告准备，职业日和模拟赠款写作讲习班的计划。该计划最终以期刊文章的准备。 PI定期担任介绍一个女孩到工程日的导师，这是Argonne的中学女学生的计划。