MAGNETORESISTANCE OF FeS1.14 SINGLE CRYSTALS FOR B // c

Measurements of the transverse magnetoresistance on natural single crystals of pyrrhotite FeS1.14 revealed a phenomenon of the order 10-3. The shape of the curves Δρ/ρ(0) vs. B for different temperatures is explained and the magnitude of the magnetoresistance can be adequately forseen by the s-d model

Interfacial and space charge dielectric effects in Polypyrrole/ZnO composites

Polypyrrole/zinc oxide composites were studied by Broadband Dielectric Spectroscopy in the frequency range 10 mHz–1 MHz for temperatures ranging from 15 K to room temperature. Lowering temperature, the dc conductivity was suppressed revealing underlying dielectric relaxation mechanisms. For 20, 30 and 40 wt.% ZnO composites, a relaxation was detected in the vicinity of range 104–10­5 Hz. Its typical mean relaxation time and its concentration dependence are compatible with Sillar's model for interfacial polarization in heterogeneous matter. At high ZnO concentrtion, a low-frequency relaxation also appeared around 0.01–10 Hz, stemming from space charge polarization. The shift of the relaxation upon temperature provides an insight to the dynamics of relaxing charge entities. Composites consisting of 10 wt.% ZnO are most suitable optoelectronic material, as they combine good electrical conduction, low capacitance effects and ohmic sample-electrode contacts. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Interfacial and space charge dielectric effects in Polypyrrole/Zinc Oxide composites

Polypyrrole/zinc oxide composites were studied by broadband dielectric spectroscopy in the frequency range 10 mHz to 1 MHz for temperature ranging from 15 K to room temperature. Lowering temperature, the dc conductivity was suppressed, revealing underlying dielectric relaxation mechanisms. For pristine polypyrrole and 10 wt% ZnO composites, no dielectric relaxation is detectable. For 20, 30 and 40 wt% ZnO composites, a relaxation was detected in the vicinity of range 104–105 Hz. Its typical mean relaxation time and its concentration dependence are compatible with Sillar's model for interfacial polarization in heterogeneous matter consisting of inclusions dispersed within a dielectric matrix. At high ZnO concentration, a low-frequency relaxation also appeared around 0.01–10 Hz, stemming from space charge polarization. The shift of the relaxation upon temperature provides an insight to the dynamics of relaxing charge entities. © 201

Metal to insulator transition in conducting polyaniline/graphene oxide composites

Broadband dielectric spectroscopy measurements of polyaniline/graphene oxide composites were conducted for an as-prepared and a thermally annealed specimen, respectively, from 15 K to room temperature. The electrical conductivity values of the annealed composite display a very modest rise denoting the important contributions of the graphene oxide component to achieving electrical stability of the polymer. Patterns of the dc conductivity as a function of temperature also reveal a metal to insulator transition at around 75 K. The transition is dominated by two key factors: temperature and annealing process. Metal-like and insulating features are subsequently detected, as well, and accordingly described to provide a qualitative inspection of the charge transfer mechanisms involved. © 2019 Author(s)

Exploring electrical conductivity within mesoscopic phases of semiconducting poly(3,4-ethylenedioxythiophene):poly(4-styrene-sulfonate) films by broadband dielectric spectroscopy

Poly(3,4-ethylenedioxythiophene): poly(4-styrene sulfonate) (PEDOT:PSS), an optically transparent organic semi-conductor, constitutes a suspension of conducting PEDOT:PSS grains, shelled by an insulating layer of PSS. While a percolation network enhances dc conductivity, structural and electrical inhomogeneity hinters electric charge flow giving rise to capacitance effects. In the present work, two distinct relaxation mechanisms are detected by Broadband Dielectric Spectroscopy. Double polarization mechanisms are predicted by bi-phase suspension dielectric theory. Within the frame of interfacial polarization, we propose a methodology to have an insight into the local conductivity of the interior of mesoscopic conducting phase. © 2013 AIP Publishing LLC

Broadband Dielectric Spectroscopy investigation of the electrical and structural heterogeneity of optically transparent organic semiconductor films

Despite the high electrical conductivity of optically transparent organic semiconductor films, their structural and electrical heterogeneity induces capacitance effects. Broadband Dielectric Spectroscopy (BDS) is employed in order to investigate two distinct relaxation mechanisms of poly(3,4-ethylenedioxythiophene) with polyelectrolyte (PEDOT:PSS) films which constitutes of a suspension of conducting PEDOT: PSS grains, shelled by an insulating layer of PSS. In this paper a general methodology is proposed in order to get an insight into the local conductivity of mesoscopic conducting phase and to calculate the activation energies of the relaxation mechanisms. (C) 2015 Published by Elsevier Ltd