Broadband dielectric spectroscopy of conducting polyaniline

Dielectric and magnetic properties of new rare-earth substituted Ba-hexaferrites in the 2–18GHz frequency range

“…The obvious absence of ferromagneticresonance in this particular frequency range was anticipated due to high coercivity and anisotropy of Dy-and Gd-substituted hexaferrite; indeed in these or similar samples H c ranges from $400 to 450 kA/m[15,16]. The relatively small ripple in our data is not related to any material's properties, but it is attributed to the small volume fraction of ferrite fillers, as the oscillation of the e r (f) and m r (f) values, measured with the transmission-line technique, is typical in low-loss composites[22][23][24][25]. The trend lines, added…”

“…Complex relative permittivity (e* r ¼ e 0 r Àje 00 r ) and permeability (m* r ¼ m 0 r Àjm 00 r ) of the composites were extracted from the S-parameters by using a specially written Matlab routine, implementing the Nicholson-Ross-Weir method [20,21], including airgap and sample position corrections [22].…”

Dielectric relaxation in metal-coated particles: the dramatic role of nano-scale coatings

“…The former is appropriate for isolated particle microstructures and is most relevant to the experimental results presented in this paper. The latter is appropriate when particles have a tendency to agglomerate, forming clusters and connected networks [3]. The effective properties of a conducting-particle-filled composite as a function of filler concentration and frequency may be obtained by solving equation (4) after substituting for the matrix and filler permittivities (which will typically be complex).…”

In-Plane Impedance Spectroscopy of Doped Polyaniline Films

“…The half oxidized PANI (emeraldine base) can be doped by protonic acids to render conductivity to the polymer. The impedance of HCl doped PANI has been measured in the form of films [3][4][5][6] and powders [5][6][7][8][9][10][11][12][13][14]. The effect of HCl dopant concentration on the impedance of PANI has been previously investigated [5,[7][8][9]11,12].…”