Graphene Platelets-Based Magnetoactive Materials with Tunable Magnetoelectric and Magnetodielectric Properties

• Main Authors: Ioan Bica, Eugen Mircea Anitas
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Nanomaterials
• Subjects: magnetoactive materials; magnetoelectric effects; magnetodielectric effects; graphene; cotton fabric; silicone oil
• Online Access: https://www.mdpi.com/2079-4991/10/9/1783

We fabricate hybrid magnetoactive materials (hMAMs) based on cotton fibers, silicone oil, carbonyl iron and graphene nanoplatelets (nGr) at various mass concentrations <inline-formula><math display="inline"><semantics><msub><mi mathvariant="sans-serif">Φ</mi><mi>nGr</mi></msub></semantics></math></inline-formula>. The obtained materials are used as dielectric materials for manufacturing plane electrical capacitors. The equivalent electrical capacitance <inline-formula><math display="inline"><semantics><msub><mi>C</mi><mi>p</mi></msub></semantics></math></inline-formula> and resistance <inline-formula><math display="inline"><semantics><msub><mi>R</mi><mi>p</mi></msub></semantics></math></inline-formula> are measured in an electric field of medium frequency <i>f</i>, without and respectively with a magnetic field of magnetic flux density <i>B</i> in the range from 0.1 T up to 0.5 T. The results are used to extract the components <inline-formula><math display="inline"><semantics><msubsup><mi>ϵ</mi><mrow><mi>r</mi></mrow><mo>′</mo></msubsup></semantics></math></inline-formula> and <inline-formula><math display="inline"><semantics><msubsup><mi>ϵ</mi><mrow><mi>r</mi></mrow><mo>″</mo></msubsup></semantics></math></inline-formula> of the complex relative permittivity <inline-formula><math display="inline"><semantics><msubsup><mi>ϵ</mi><mrow><mi>r</mi></mrow><mo>*</mo></msubsup></semantics></math></inline-formula>, and to reveal the magnitude of the induced magnetoelectric couplings <inline-formula><math display="inline"><semantics><msub><mi>k</mi><mi>x</mi></msub></semantics></math></inline-formula> and magnetodielectric effects <inline-formula><math display="inline"><semantics><mrow><mi>M</mi><mi>D</mi><mi>E</mi></mrow></semantics></math></inline-formula>. It is shown that <inline-formula><math display="inline"><semantics><msubsup><mi>ϵ</mi><mrow><mi>r</mi></mrow><mo>′</mo></msubsup></semantics></math></inline-formula>, <inline-formula><math display="inline"><semantics><msubsup><mi>ϵ</mi><mrow><mi>r</mi></mrow><mo>″</mo></msubsup></semantics></math></inline-formula>, <inline-formula><math display="inline"><semantics><msub><mi>k</mi><mi>x</mi></msub></semantics></math></inline-formula> and MDE are significantly influenced by <inline-formula><math display="inline"><semantics><mrow><mi>f</mi><mo>,</mo><mi>B</mi></mrow></semantics></math></inline-formula> and <inline-formula><math display="inline"><semantics><msub><mi mathvariant="sans-serif">Φ</mi><mi>nGr</mi></msub></semantics></math></inline-formula>. We describe the underlying physical mechanisms in the framework of dipolar approximation and using elements of dielectric theory. The tunable magnetoelectric and magnetodielectric properties of hMAMs are useful for manufacturing electrical devices for electromagnetic shielding of living organisms.