CAREER: Pressure-Induced Amorphization and Materials Synthesis Under High Pressure Techniques

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9733956 Kruger This is a CAREER Award project involving high pressure techniques in two separate areas of research. An objective of the work is to synthesize and study, novel and potentially technologically relevant materials. The research employs pressure-induced amorphization, the pressure-induced destruction of long range crystalline order to produce an amorphous materials. X-ray diffraction study of pressure-amorphized samples will yield the pair correlation function, G(r). The pressure variation of this function will be correlate structures of the pressure-amorphized glasses with the starting crystals, as well as with conventionally synthesized, melt quenched glasses. Raman scattering will be used to study the boson peak of these glasses which will result in a deeper understanding of the glasses as well as the boson peak itself. Numerous theoretical studies have predicted the stability of various phases of carbon nitride, some theoretical studies indicating that certain phases should have bulk moduli rivaling that of diamond. There is significant interest, both theoretical, and practical, in realizing such materials. The PI will apply high pressures and high temperatures to carbon-nitrogen mixtures in order to synthesize some of the theoretically predicted superhard phases of carbon nitride. Study of the equation of state of the materials will help determine which phases are most likely to be superhard, and hence should be made in larger quantities for more detailed study. The education component of this project involves extensive undergraduate research activity, lectures at local high-schools, and mentoring activity associated with the local student Chapter of the American Physical Society. %%% This is a CAREER Award project involves high pressure (up to 100 million atmospheres) techniques to synthesize and study, novel and potentially technologically relevant materials. One relatively recently observed technique employs compression alone to turn a cry stal into a glass. In this way a variety of glasses will be prepared. X-ray and optical scattering techniques will be used to characterize the structural transition from the crystalline to the glassy state. Relationships are sought between the new glasses, the starting crystals, and traditional model glasses. A second project involves the use of high pressures to try to synthesis new, superhard materials. By analogy with the graphite to diamond conversion, high pressures and temperatures will be applied to graphite-nitrogen mixtures in an attempt to synthesize some of the theoretically predicted superhard phases of carbon nitride. The education component of this project involves extensive undergraduate research activity, lectures at local high-schools, and mentoring activity associated with the local student Chapter of the American Physical Society. ***