Modeling of the Surface Impedance of Conductive Ferromagnetic Films on Different Substrates

Nurgaliev, T.

doi:10.12693/aphyspola.113.187

Cited by 1 publication

(2 citation statements)

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“…In a strict sense this frequency must be the same than the microwaves that are being employed for heating. However, Joule Effect for these materials is somehow controversial 6), 7) and without leaving out that impedance is highly sensitive to frequency, there are reports 8) showing strong increments of both, resistance and reactance, at 1 MHz in La0.7Sr0.3MnO3. It was considered in this work that using DC resistance approach gives a conservative figure for considering in the model.…”

Section: Experimental Arrangementmentioning

confidence: 99%

“…It was observed during the analysis of the permittivity that as this value was increased, the electric field and the power absorption were decreasing, and consequently, the temperatures calculated by the model were lower than the experimental ones (Eqs. [7][8][9]. This difference can be compensated in the model with higher dielectric losses, which means that values of electric permittivity obtained with the supposition of purely resistive heating, corresponds to the minimal values of permittivity of the manganite.…”

Section: Jcs-japanmentioning

confidence: 99%

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Estimating resistive and dielectric effects during microwave heating of Fe0.22Ni0.67Mn2.11O4

Aguilar-Garib

García

Valdez

2009

J. Ceram. Soc. Japan

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Dielectric approaches for estimating microwave heating of ceramics and polymers assuming that resistive effects are small enough to be neglected have been applied quite often. However, these approaches are not valid for semiconductors. Permittivity and resistivity are very sensitive to chemical composition; therefore it is difficult to extrapolate properties from similar materials as can be done with thermal properties. The objective of this work is to estimate the dielectric and resistive contributions during microwave heating, solving the electromagnetic and heat transfer equations by means of Finite Element Method (FEM) using the software ANSYS TM . The experiments were performed over a parallelepiped made of compacted and sintered powders of the manganite, which is a negative thermal coefficient thermistor, placed inside a waveguide and exposed to 2.45 GHz microwaves at different powers. Temperature was taken with sheathed thermocouples that also served as electrodes for monitoring electric resistance. Matching experimental data and simulation results provided values for the properties within acceptable range. An operative model for simulating heating of a sample placed in a waveguide was built, considering either resistive or dielectric effects, which in turn helps to estimate these properties applying it jointly with the experimental technique shown.

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Section: Experimental Arrangementmentioning

confidence: 99%

Section: Jcs-japanmentioning

confidence: 99%