Influence of dopant size and electron affinity on the electrical conductivity and thermoelectric properties of a series of conjugated polymers

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.

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Electrical conductivity studies on silica phases and the effects of phase transformation

American Mineralogist ◽

10.2138/am-2019-7120 ◽

2019 ◽

Vol 104 (12) ◽

pp. 1800-1805

Author(s):

George M. Amulele ◽

Anthony W. Lanati ◽

Simon M. Clark

Keyword(s):

Electrical Conductivity ◽

Activation Volume ◽

Activation Enthalpy ◽

Hydrogen Charge ◽

Charge Compensation ◽

Composition Analysis ◽

Conductivity Measurements ◽

Pressure System ◽

Electrical Conductivities ◽

Silica Phases

Abstract Starting with the same sample, the electrical conductivities of quartz and coesite have been measured at pressures of 1, 6, and 8.7 GPa, respectively, over a temperature range of 373–1273 K in a multi-anvil high-pressure system. Results indicate that the electrical conductivity in quartz increases with pressure as well as when the phase change from quartz to coesite occurs, while the activation enthalpy decreases with increasing pressure. Activation enthalpies of 0.89, 0.56, and 0.46 eV, were determined at 1, 6, and 8.7 GPa, respectively, giving an activation volume of –0.052 ± 0.006 cm3/mol. FTIR and composition analysis indicate that the electrical conductivities in silica polymorphs is controlled by substitution of silicon by aluminum with hydrogen charge compensation. Comparing with electrical conductivity measurements in stishovite, reported by Yoshino et al. (2014), our results fall within the aluminum and water content extremes measured in stishovite at 12 GPa. The resulting electrical conductivity model is mapped over the magnetotelluric profile obtained through the tectonically stable Northern Australian Craton. Given their relative abundances, these results imply potentially high electrical conductivities in the crust and mantle from contributions of silica polymorphs. The main results of this paper are as follows:The electrical conductivity of silica polymorphs is determined by impedance spectroscopy up to 8.7 GPa.The activation enthalpy decreases with increasing pressure indicating a negative activation volume across the silica polymorphs.The electrical conductivity results are consistent with measurements observed in stishovite at 12 GPa.

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Mechanosynthesis and Thermoelectric Properties of Fe, Zn, and Cd-Doped P-Type Tetrahedrite: Cu12-xMxSb4S13

Materials ◽

10.3390/ma14133448 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3448

Author(s):

Francisco Arturo López Cota ◽

José Alonso Díaz-Guillén ◽

Oscar Juan Dura ◽

Marco Antonio López de la Torre ◽

Joelis Rodríguez-Hernández ◽

...

Keyword(s):

Thermoelectric Properties ◽

Figure Of Merit ◽

Powder Processing ◽

High Energy ◽

Secondary Phases ◽

Ambient Conditions ◽

Cadmium Sulfate ◽

Electrical Conductivities ◽

Compositional Changes ◽

P Type

This contribution deals with the mechanochemical synthesis, characterization, and thermoelectric properties of tetrahedrite-based materials, Cu12-xMxSb4S13 (M = Fe2+, Zn2+, Cd2+; x = 0, 1.5, 2). High-energy mechanical milling allows obtaining pristine and substituted tetrahedrites, after short milling under ambient conditions, of stoichiometric mixtures of the corresponding commercially available binary sulfides, i.e., Cu2S, CuS, Sb2S3, and MS (M = Fe2+, Zn2+, Cd2+). All the target materials but those containing Cd were obtained as single-phase products; some admixture of a hydrated cadmium sulfate was also identified by XRD as a by-product when synthesizing Cu10Cd2Sb4S13. The as-obtained products were thermally stable when firing in argon up to a temperature of 350–400 °C. Overall, the substitution of Cu(II) by Fe(II), Zn(II), or Cd(II) reduces tetrahedrites’ thermal and electrical conductivities but increases the Seebeck coefficient. Unfortunately, the values of the thermoelectric figure of merit obtained in this study are in general lower than those found in the literature for similar samples obtained by other powder processing methods; slight compositional changes, undetected secondary phases, and/or deficient sintering might account for some of these discrepancies.

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Universal mobility characteristics of graphene originating from charge scattering by ionised impurities

Communications Physics ◽

10.1038/s42005-021-00518-2 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Jonathan H. Gosling ◽

Oleg Makarovsky ◽

Feiran Wang ◽

Nathan D. Cottam ◽

Mark T. Greenaway ◽

...

Keyword(s):

Electrical Conductivity ◽

Carrier Density ◽

Carrier Mobility ◽

Carrier Transport ◽

Analytical Models ◽

Pristine Graphene ◽

High Electron ◽

Boltzmann Transport ◽

Transport Parameters ◽

Wide Range

AbstractPristine graphene and graphene-based heterostructures can exhibit exceptionally high electron mobility if their surface contains few electron-scattering impurities. Mobility directly influences electrical conductivity and its dependence on the carrier density. But linking these key transport parameters remains a challenging task for both theorists and experimentalists. Here, we report numerical and analytical models of carrier transport in graphene, which reveal a universal connection between graphene’s carrier mobility and the variation of its electrical conductivity with carrier density. Our model of graphene conductivity is based on a convolution of carrier density and its uncertainty, which is verified by numerical solution of the Boltzmann transport equation including the effects of charged impurity scattering and optical phonons on the carrier mobility. This model reproduces, explains, and unifies experimental mobility and conductivity data from a wide range of samples and provides a way to predict a priori all key transport parameters of graphene devices. Our results open a route for controlling the transport properties of graphene by doping and for engineering the properties of 2D materials and heterostructures.

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