Highlights

Nanoparticles in ZBLAN Glass Ceramics

Scientific Achievement

The use of the scanning electron microscope (SEM) in the electron microscopy center (EMC) enabled me to obtain images of the distribution of nanoparticles within the glass ceramics. One of the images appeared in a publication is still being used in presentations as the interest in this work has continued to grow.

We were able to determine the size and distribution of the nanoparticles without the lengthy preparation time needed for transmission electron microscopy (TEM). We learned for the first time that the particles cluster on heat treatment. As the optically active element is embedded in the nanoparticles this will have a significant effect on the light output of the materials. We were only able to image the particles above a threshold size so we are moving on to high resolution TEM at this point.

As well as using the SEM the project made extensive use of the sample preparation laboratory for cutting and polishing the samples. A polished surface and specific size is needed for X-ray diffraction, photoluminescence, X-ray luminescence, and imaging. The EMC set up a liquid N₂-cooled, ion milling apparatus specifically for this project.

Significance

The images obtained by SEM are highly significant as they showed very clearly the clustering of the particles, which is likely to have an effect on the photoluminescent properties so crucial to the practical applications of these materials. The SEM results opened our mind to the possibility of pulsed laser deposition for the synthesis of these materials in order to get control over the position of the nanoparticles within the glass matrix. This idea was described in a recently successful NIH proposal and was a contributing factor to obtaining a $1.8M grant. As I have now joined an institution that has a “Center for Laser Applications”, the synthesis of these materials by PLD is a straightforward proposition. Further, a collaboration obtained a Phase I SBIR to focus on the scale-up of the glass plate. With three groups working on this, the work is moving very quickly.

The research will be followed up with the development of the glass ceramic plate for mammography over the next four years with the above-mentioned funding. An R&D100 award recognized the work in 2007. An LDRD grant was awarded in the area of up- and down-conversion for solar applications. Beyond the already funded research the plate has the potential for homeland security applications in gamma and neutron detection and for dual energy computed tomography being pursued in collaboration with the University of Chicago.

Performers

J. A. Johnson (UTSI-MS&E; Argonne-NE)