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NSF NanoSystems Engineering Research Center Translational Applications of Nanoscale Multiferroic Systems (TANMS) Fabrication and Characterization of Magneto-Refractive Glass Pranathi M Rao, A. Garcia, S. Strutner, G. Carman Department of Mechanical and Aerospace Engineering, University of California, Los Angeles University of California, Los Angeles University of California, Berkeley Cornell University California State University, Northridge Swiss Federal Institute of Technology, ETH Zurich Abstract Motivation Fabrication Process Utilization of a magneto-refractive glass in optical fibers will result in magnetic field sensors. A magneto-refractive material’s index of refraction shifts when in the presence of a magnetic field. Literature shows La 0.65 Sr 0.35 MnO 3 has magneto-refractive qualities. The fabrication of the magneto-refractive glass involved sol-gel chemistry, a process used to create a suspension of nanocomposite particles of LSMO cores and SiO 2 shells. A glass slide was dip-coated into the suspension and then baked at 500℃. These slides were used to test the material. Changes had to be made to the original sample recipe due to the lack of desired results. Improvements included O 2 plasma treatment before dip-coating and spin-coating the glass substrates. Recipes concerning the core-shell particle size were found but were not tested. Monodispersity of nanocomposite particle size would allow a more uniform distribution on the glass substrate. The uniformity in distribution will increase the accuracy of the data collected during characterization. To fabricate and characterize a magneto- refractive glass. Sol-Gel chemistry: a process resulting in nanocomposite core-shell particles. • Magneto-refractive materials see a shift in the index of refraction when in the presence of a magnetic field. • Index of refraction is the ratio between the speed of light in a vacuum and the speed of light in the a given material • The index of refraction is used to characterize the bending and reflection of light. Improvements • Ingredient Change: Cyclohexane and Igepal - Cyclohexane takes the role of the solvent and Igepal acts as the surfactant. These chemicals are used instead of Isopropanol and soap. 1 • Dip-Coating: Improved surface wetting characteristic - Putting the glass substrate in an O 2 plasma will cause the water to have a stronger attraction to the glass and thus lead to better dipcoating results. • Spin-Coating: Better distribution of particles on surface • SEM imaging: Capable of measuring size of core shell particles - If the silicon wafer was pretreated with a solution of KOH, water, and ethanol then the imaging will be of a higher quality. • Stober process: Creating Monodispersity - Creating a relationship between the concentrations of ingredients - [TEOS] = 0.22 – 1.24M ; [NH 3 ] = 0.81[TEOS]; [H 2 0] = 6.25[TEOS] 2 Characterization Setup • The characterization of the material involves a laser to shoot an incident ray at a certain angle onto the material with the unknown index of refraction and a photo diode to measure the intensity of the reflected ray. • The test is conducted with and without the presence of a magnetic field and a shift in the reflectivity would then indicate a shift in the index of refraction thus confirming the magneto-refractive properties of LSMO. Future Steps The fabrication process needs to result in relative monodispersity in the solutions. The characterization of the material will depend on the uniform distribution of LSMO particles on the glass substrate This work was supported by the National Science Foundation through the Cooperative Agreement Award EEC-1160504 for Solicitation NSF 11-537 (TANMS) managed by Dr. Deborah J. Jackson and supported by the Aero Institute. Special thanks to Laura Schellas, Wei Yang Sun, Kyle Wetzlar. Acknowledgements Objective Background Magneto-refractive glass can be used in an optical fiber as a magnetic field sensor Solvent NH 3 TEOS LSMO Surfactant H2O Goal: LSMO core/SiO 2 shell Snell’s Law Fresnel’s Equation Bending (Refracted Ray) Reflected Intensity References Dipcoat a glass substrate into solution. Bake the glass slides at 500℃ in order to dry out alcohol and water 1. Li, T.; Moon, J.; Morrone, A.A.; Mecholsky J.J.; Talham D.R.; Adair J. H. Langmuir, 15, (1999), 4328-4334. 2. 2. Wang, X.; Shen Z. ; Sang, T.; Cheng X.; Li, M.; Chen, L.; Wang Z. Journal of Colloid and Interface Science, 341, (2010), 23-29. 3. Celzard, A.; Mareche, J.F. Journal of Chemcial Education (2002) 79. 4. Yasumori, A.; Matsumoto, H.; Hayashi, S,; Okada, K. Journal of Sol-Gel Science and Technology, 18, (2000), 249-258. Fabrication Results ) , ( n R R Spin coating Original Dipcoating Methods Glass slides undergone O 2 plasma Dipcoated 3.81 cm 3.81 cm 10X 0.5mm 0.5mm 10X 0.5mm 10X 1.27 cm Optical Image Optical Image Optical Image SEM Image By Wei Yang sun and Kyle Wetzlar Fabrication Analysis • O 2 plasma treatment resulted in better distribution and adhesion of the core-shell particles onto the glass slides. • Spincoating resulted in a thicker coating but the SEM images showed an undesirable morphology of the particles. N S
