• Molak, Andrzej
• Koperski, Janusz
• Szeremeta, Anna Z.
• Pawlus, Sebastian
• Leonarska, Agnieszka

Abstract

<jats:p> Electrical properties of composite consisted of epoxy-glue and powdered bismuth manganite Bi<jats:sub>12</jats:sub>MnO<jats:sub>20</jats:sub>–BiMn<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub> ceramics were studied. Samples contained 66 wt% of bismuth manganite. Secondary electron images and backscattered electron images were collected for the epoxy-glue and the epoxy-glue/bismuth manganite samples. Microanalysis shown that majority of bismuth manganite powder was homogenously distributed in epoxy-glue matrix. Lack of changes in crystallographic structure, in 300–450 K range, was deduced from the X-ray diffraction patterns. The electric impedance was measured at radio-frequencies. It was analysed using electric permittivity ɛ*( T, f ) and modulus M″(T, f ) representation. Epoxy-glue/bismuth manganite composite exhibited, at room temperature, conductivity, σ( f ) = 10<jats:sup>−5</jats:sup> to 10<jats:sup>−7</jats:sup> S m<jats:sup>−1</jats:sup>, permittivity, ɛ′≈10, losses, tan  δ = 0.2–0.8 and dispersion markedly lower than bismuth manganite ceramics. Electric relaxation was induced in epoxy-glue/bismuth manganite composite samples. The Vogel–Fulcher–Tammann equation was fitted to relaxation times temperature dependence, obtained from M″(T, f ). The estimated values of Vogel–Fulcher equation parameters were frequency f<jats:sub>0</jats:sub> = 2.2 × 10<jats:sup>8 </jats:sup>Hz, energy U<jats:sub>T</jats:sub> = 1050 K and glass transition temperature T<jats:sub>g</jats:sub> = 282 K. The relaxation times were attributed to strains, which would occur at interfacial layers between the bismuth manganite grain and the polymer matrix. </jats:p>

Topics

• dispersion
• polymer
• grain
• x-ray diffraction
• glass
• glass
• composite
• glass transition temperature
• ceramic
• interfacial
• Bismuth