Hydrothermal Solutions:Solving Materials Problems with Novel Crystal Growth Ideas

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Date/Time:Thursday, 28 Apr 2011 - Saturday, 30 Apr 2011
Location:11:00 am, Room 18/19 PHYSICS
Channel:Condensed Matter Physics
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Dr. Colin McMillen Clemson University Department of Chemistry and Center for Optical Materials Science and Engineering Technology (COMSET)

The development of new device technology, particularly laser and optical technologies is quite often a materials-driven process. New materials and new configurations of well-known materials are often needed to access extreme or unusual wavelengths, improve resolution, generate higher output power, improve beam quality, and miniaturize devices. For a variety of reasons crystal growth technology, especially in the United States, does not seem to have advanced at the pace necessary to meet the needs of a rapidly growing optics community. Thus, many good ideas never see the light of day due to a lack of available crystals. This seminar will briefly overview some of our efforts to address these needs for advanced optical single crystals and crystal architectures in three general areas using hydrothermal crystal growth and epitaxy.

The first area of interest is the development of borate-based crystals as non-linear optical materials for the generation of deep-UV light. As there are no commercially available materials capable of second harmonic generation below 200 nm we have grown crystals of several noncentrosymmetric borates, including KBe2BO3F2 (KBBF) and related analogs, and have begun characterizing their properties. A second research focus is the single crystal growth of highly refractory oxides such as ThO2, Sc2O3 and Lu2O3 which are of interest as high power laser host materials because of their high thermal conductivities. We have used our hydrothermal method to grow bulk single crystals of these materials from aqueous solutions at about a quarter of their melting points, which should lead to significantly lower thermal strain and improved crystal quality. Interesting trends in thermal conductivity have been identified and will be discussed. Finally a very new area of research of ours is the hydrothermal growth of multifunctional microlaser single crystals. Garnet-based crystals such as YAG and LuAG offer a seemingly endless array of possibilities since functionality can be imparted by lanthanide and/or transition metal doping in these hosts. Layers of doped material have been grown on undoped seed crystals and on top of other doped layers to create monolithic single crystals that possess regions with unique functionality. This has opened the door for the growth of single crystals containing both lasing and passive q-switching capabilities as well as gradient doping and single crystal waveguide configurations.