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

该项目的目标是确定掺铕氟锆酸盐玻璃的光学性质的微观结构和化学起源，另外掺杂氯纳米复合材料。玻璃陶瓷具有作为X射线成像板的潜在应用，例如在数字乳房X射线照相系统中。 该研究的另一个目标是深入了解材料可以针对该应用进行优化的方式。 掺铕的氟锆酸盐玻璃，另外掺杂有氯，可以热处理的方式，它形成一种新的纳米复合材料含有氯化钡纳米晶体，具有转换电离辐射（通常是X射线）成稳定的电子空穴对的能力。这些可以随后在所谓的“光激发光”（PSL）过程中用扫描激光束读出。光学研究表明，纳米复合玻璃发出的光是同等体积的单晶的五倍。这种增加的光输出的原因尚不清楚，但答案在于纳米颗粒与其主体玻璃基质之间的界面，这是氯化钡纳米颗粒形成的结果。分析纳米级界面结构和组成的理想技术是透射电子显微镜（TEM）。非原位TEM分析以前已经在不同温度下退火的样品上进行过，但这只提供了可用科学的快照。计划中的TEM研究包括纳米晶体的原子级结构及其与玻璃基质的界面的高分辨率成像，以及纳米晶体内部和周围化学分布的能量过滤TEM（EFTEM）成分映射。此外，样品，这是以前已经在炉中热处理或激光照射不同的能量和脉冲长度，以诱导纳米成核，将被检查和三个成核技术，非原位热，激光，和原位热将进行比较。田纳西州空间研究所大学定期举办暑期科学夏令营的K-12和雇用暑期实习生。UTSI的全体工作人员都参与了外联工作。约翰逊博士为高中生和本科生制定了一个详细的为期七周的暑期研究经验计划。学生们收到一个玻璃陶瓷样品，并通过一个程序的表征，口头陈述，报告准备，职业日和模拟赠款写作研讨会。该计划的高潮是一篇期刊文章的准备。 PI定期担任导师介绍一个女孩到工程日，这是一个方案，在阿贡为中学生。

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.