2019/08/01 by R. L. Moore, Moore, Rick L.
Engineering · Materials Science · #Characterization and Applications of Magnetic Nanoparticles #Electromagnetic wave absorption materials #Magnetic Properties and Synthesis of Ferrites
paper · pdf · doi:10.48550/arxiv.1908.00603
Maxwell-Garnett Theory (MGT), Bruggeman Effective Medium Theory (BEMT),\nCoherent Model Approximation (CMA), Scaled Effective Medium Theory (ScEMT) and\nmodels of Schlomann (E. Schlomann, Phys. Rev. B, 182, 7, 632 (10 June 1969) and\nE. Schlomann, Conf. on Mag. and Mag. Materials, AIEE Spec. Publ. T-91, 600\n(1956)) are applied to predict magnetic susceptibility, resonant and relaxation\nfrequency in polymer-magnetic particle composites. Particulates had aspect\nratios near unity; bulk low frequency susceptibilities ranging from\napproximately 5 to 4000 and particle volume fractions between 1 and 100%.\nPrevious publications demonstrated that ScEMT improved the prediction of DC\nsusceptibility as compared to classical models. This paper first modifies BEMT\nand ScEMT for volume fractions below about 10%. A ScEMT based model of\ncomposite resonant frequency is presented and compared to MGT, CMA models and\nmeasurement. Model and measurement comparisons of resonant frequency are\nfollowed by model-measurement comparisons of relaxation frequency. CMA, MGT,\nmodels of Schlomann, and volumetric scaled modifications of Schlomann are\ntested in the relaxation frequency study. The paper emphasizes the broad\napplication of the models and therefore composite data for a wide range of\nparticulate chemistries are presented ScEMT predictions of susceptibility and\nresonant frequency continue to show reasonable agreement with measurement and\nrepresent improvement over the CMA and MGT models. ScEMT modifications to\nSchlomann show overall best agreement with relaxation frequency measurement.\nCMA and MGT are most accurate for modest susceptibility (~ < 100) while ScEMT\nmodified Schlomann models are most accurate for large susceptibility.\n