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Metal – Ceramic Core-Shell Nanostructures Shashank Priya, Virginia Polytechnic Institute and State University, DMR 0757502. - PowerPoint PPT Presentation

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Metal Ceramic Core-Shell Nanostructures

Shashank Priya, Virginia Polytechnic Institute and State University, DMR 0757502We have developed solid state reaction process for large-scale synthesis of single grain, two-phase BaTiO3-(Mn0.5Zn0.5)Fe2O4 nanomaterials. The grains of BTO-rich samples were found to exhibit a rod-like morphology with a high aspect ratio and diameter of 200 nm, whereas the grains of the MZF-rich samples had a tetrahedral/octahedral cross-section with a span of 200nm. Such a synthesis of two-phase perovskite/spinel single crystal grains with controlled grain geometries offers the potential to engineer new types of multi-ferroic materials.

Next, we have developed the process for coating nickel-metal on the ceramic particles in order to realize the electro-magnetostrictive effect. We utilized ionic interaction as the driving force for coating nickel onto ferrite particles by developing electro-less method. Ni coating onto ferrite was found to occur in the range of pH 10~12. We have been able to spread the monolayer of these composite particles onto glass substrates and characterize their magnetic response using MFM.

1Y. Yang, S. Priya, Y. U. Wang, J.-F. Li and D. Viehland, Solid-state synthesis of perovskite-spinel nanocomposites, J. Mater. Chem.19, 4998 5002 (2009).Y. Yang, S. Priya, J. F. Li, and D. Viehland, Two phase coexistence in single crystal Mn0.5Zn0.5Fe2O4 BaTiO3 Nanomaterials via solid-state reaction, J. Amer. Ceram. Soc. 92 [7], 1552-1555 (2009).S. Yang, C. Ahn, C. S. Park, Y. Yang, D. Viehland, and S. Priya, Synthesis and Characterization of Electromagnetostrictive Core-shell Particles for Magnetoelectric Devices, J. Amer. Ceram. Soc., (to be submitted). The abstract for the manuscript is given below. Please note that this manuscript is under preparation so the abstract is just for guidance and is not the final version.

We report the synthesis and characterization of electromagnetostrictive (EMS) core/shell particles which offer inherent advantage for magnetoelectric composites by eliminating the need for magnetic DC bias. The EMS particles consisted of ceramic-metal core-shell composite structure. Manganese ferrite (MnFe2O4) core-particles were synthesized with average particle size in the range of 200 nm and nickel (Ni) shell with uniform thickness of 1 nm was coated onto the core-particles. The working principle of EMS composite particle is as follows. When an electric field is applied to the conducting metal shell, it induces current through the material resulting in a closed magnetic flux. The flux then results in the deformation of manganese ferrite due to magnetostricion. MnFe2O4/Ni composite particles embedded in epoxy matrix were found to possess the EMS coefficient of at 7.8 Hz by applying the AC electric field of 11 V/mm with DC bias.

High School and Undergraduate Research, Summer 2009 Shashank Priya, Virginia Polytechnic Institute and State University, DMR 0757502

Jaclyn Brennan, Summer Undergraduate Researcher: Initial experiments were conducted using copper wire around the PLA core instead of platinum as a novel fabrication method. Despite various attempts to produce uniform and consistent deposition through electro-polishing methods and solution modifications, synthesis resulted in minimal adherence of pyrole and inconsistent results. Platinum remains the metal of choice for these linear actuators. Next, we will experiment with nickel metal. Alex Thayer, High school student: This summer I have learned a great deal about engineering and smart materials but there is always more to learn. I have learned all about CAD software and about different types of tools and devices used to make these creations possible. In future I plan to CAD a planetary gear system to allow three degrees of freedom in a wrist. After that I will try to optimize the dynamic finger motion to be as similar to a humans as possible. I also plan to make a cavity in the skull to put servo motors.

Michael Ko, Summer Undergraduate Researcher: My goal was to design and model a functional artificial hand and arm with the ability to type on a computer keyboard using servo motors and piezoelectric sensors. I started with last years model to encompass more efficiency and better human-like functionality. In the process, I have learned computer-aided designing and mechanisms and kinematics of robotic hand as compared with human hand. I have also gained knowledge on smart materials.

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