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Processing of bulk nanocrystalline oxide materials for optical and magnetic applications

Javier E. GarayDepartment of Mechanical EngineeringMaterials Science and Engineering ProgramUniversity of California, RiversideNanocrystalline materials display significantly different properties and behaviors than their microcrystalline counterparts, yet their direct application in products has been hindered by the difficulty in producing them reliably and efficiently. One reason is that consolidation of nanocrystalline powders usually results in large grain size increase and therefore loss of enhanced nanocrystalline properties. Recently, the versatile material processing technique of spark plasma sintering (SPS) has proven effective in overcoming the grain growth challenge—it is now possible to efficiently produce viable nanocrystalline parts. The method draws its effectiveness from large electric current densities that serve to heat the materials and also alter the processing kinetics. After an overview of our processing techniques, I will present results on large-sized, fully dense oxides with grain sizes much less that 100 nm. The materials have very different properties than traditional materials. Properties presented include improved visible light transmittance, enhanced toughness, and ferri-antiferromagnetic coupling leading to exchange bias. The results will be discussed in terms of crystal length scale effects and proximity of nanoscale phases.

Location: Seaver Science Library, Rm 150

Audiences: Everyone Is Invited

Contact: April Mundy