Simultaneous Measurements Of Electrical Conductivity Research Articles

Electrical Conductivity and In Situ SAXS Probing of Block Copolymer Nanocomposites Under Mechanical Stretching.

Elastomers based on block copolymers can self-organize into ordered nanoscale structures, making them attractive for use as flexible conductive nanocomposites. Understanding how ordered structures impact electrical properties is essential for practical applications. This study investigated the morphological evolution of flexible conductive elastomers based on polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers with aligned single- or multi-wall carbon nanotubes (SWCNTs or MWCNTs) and their electrical conductivity under large deformations. Oriented nanocomposites were obtained through injection molding and characterized using two different setups: tensile testing monitored by in situ small-angle X-ray scattering (SAXS) and tensile testing with simultaneous electrical conductivity measurements. Our findings demonstrate that structural orientation significantly influences electrical conductivity, with higher conductivity in the longitudinal direction due to the preferred orientation of carbon nanotubes. Tensile testing demonstrated that carbon nanotubes accelerate the process of realignment of the ordered structure. As a consequence, higher deformations reduced the conductivity of samples with longitudinal alignment due to the disruption of percolation contacts between nanotubes, while in samples with a transverse alignment the process promoted the formation of a new conductive network, increasing electrical conductivity.

Simultaneous electrical impedance and optical absorption spectroscopy for rapid characterization of oxygen vacancies and small polarons in doped ceria.

Mixed ionic-electronic conductors (MIECs) play a central role in emerging energy conversion and energy efficient computational technologies. However, it is both challenging and resource demanding to characterize MIECs over the broad range of experimental conditions of interest, thereby significantly limiting their study and applications. Here, a novel method of a simultaneous measurement of electrical conductivity and optical absorption of thin films in out-of-equilibrium state, i.e. during a reduction process, is employed for a comprehensive study of a MIEC oxide, PrxCe1-xO2-δ (PCO). It enables, orders of magnitude faster than by established techniques, characterization of the oxygen vacancy and small polaron formation and transport as a function of temperature (demonstrated here down to 200 °C), in a wide range of deviation from stoichiometry, δ. For instance, at 600 °C the PCO properties were obtained during a ten minute reduction process, in the pO2 range from 1 to 10-13 bar. The experimental results show that the oxygen vacancy mobility is constant while the small polaron mobility is linear in δ, in the whole pO2 range, which yields the total conductivity quadratic in δ. Furthermore, the method was applied to study the modification of PCO's transport properties with composition change. It was shown that increasing x from 0.1 to 0.2 suppresses the ionic mobility and, at the same time, enhances the small polaron mobility. Finally, the optically determined δ was used to define an instantaneous oxygen activity in PCO that can be accessed in the out-of-equilibrium experiments. This work opens up new possibilities to study the effects of microstructure, strain and other applied external stimuli on the transport and thermodynamic properties of PCO and similar types of MIEC materials.

Electroacoustic Quantification of Surface Bound Ligands in Functionalized Silica and Iron Oxide Nanoparticles

AbstractThe electrokinetic sonic amplitude (ESA) is one of the most versatile techniques for deriving the zeta potential of nanoparticles before, during and after surface functionalization with different ligands, thus overcoming current limitations of well‐established electrophoretic measurement principles. We present a novel method for direct quantification of accessible hydroxide groups available on the surface of silica nanoparticles by the ESA effect, supported by simultaneous electrical conductivity measurements. Moreover, the in‐operando determination of varying zeta potential during addition of carboxylic acids demonstrate a profound way to quantify surface‐bound ligands, which still poses a challenge in following the surface modification of nanoparticles. In this study, phase pure cuboidal hematite particles were chosen as a model system with an initial zeta potential between +50 and +55 mV in ethanol. Using both citric acid and 10‐undecynoic acid as surface‐modifiers, the correlation between the degree of surface functionalization and zeta potential was investigated. The decrease of zeta potential of hematite particles during the titration of 10‐undecynoic acid or citric acid could be directly correlated to a successful surface functionalization in contrast to a surface protonation, which would be expected in case of both carboxylic acids. Furthermore, the addition of 10‐undecynoic acid led to a stabilization effect on the zeta potential of cuboidal hematite particles. These results highlight the hitherto unexplored potential of ESA techniques as a quantification method in nanoparticle surface modification.

Simultaneous measurements of electrical conductivity and seismic wave velocity of partially molten geological materials: effect of evolving melt texture

Comparison between geophysical observations and laboratory measurements yields contradicting estimations of the melt fraction for the partially molten regions of the Earth, highlighting potential disagreements between laboratory-based electrical conductivity and seismic wave velocity measurement techniques. In this study, we performed simultaneous acoustic wave velocity and electrical conductivity measurements on a simplified partial melt analogue (olivine + mid oceanic ridge basalt, MORB) at 2.5 GPa and up to 1650 K. We aim to investigate the effect of ongoing textural modification of partially molten peridotite analog on both electrical conductivity and sound wave velocity. Acoustic wave velocity (Vp and Vs) and EC are measured on an identical sample presenting the same melt texture, temperature gradient, stress field and chemical impurities. We observe a sharp decrease of acoustic wave velocities and increase of electrical conductivity in response to melting of MORB component. At constant temperature of 1650 K, electrical conductivity gradually increases, whereas acoustic velocities remain relatively constant. While the total MORB components melt instantaneously above the melting temperature, the melt interconnectivity and the melt distribution should evolve with time, affecting the electrical conduction. Consequently, our experimental observations suggest that acoustic velocities respond spontaneously to the melt volume fraction for melt with high wetting properties, whereas electrical conduction is significantly affected by subsequent melt texture modifications. We find that acoustic velocity measurements are thus better suited to the determination of the melt fraction of a partially molten sample at the laboratory time scale (~ h). Based on our estimations, the reduced Vs velocity in the major part of the low velocity zone away from spreading ridges can be explained by 0.3–0.8 vol% volatile-bearing melt and the high Vp/Vs ratio obtained for these melt fractions (1.82–1.87) are compatible with geophysical observations.

Leaching characteristics of nitrate nitrogen in an apple orchard andosol under significant snow accumulation

The purpose of this study was to clarify nitrogen (N) leaching behavior as affected by snowmelt percolation in an Andosol soil planted with an established apple orchard, with the aim of supporting fertilization management that preserves the soil environment while maximizing apple production. Simultaneous measurements of electrical conductivity (EC), pH, NO3-N, and NH4-N (inorganic-N concentration) of the apple orchard soil pore water were taken. The adsorption nature of NO3-N and NH4-N were also monitored using Langmuir type and Logistic type adsorption isotherms. Numerical analysis relevant to the spatiotemporal dynamics of inorganic-N in soil pore water was also conducted during the growing and non-growing period for apples. The level of soil pore water EC resulting from fertilizer application was characteristically altered by downward leaching over time. Regarding the NO3-N concentration of soil pore water in the investigated area with heavy snow accumulation, the bulk of the fertilizer applied from January to July 2016 was leached down to z=100cm within 5 to 6months. In the apple orchard during and after snowfall, the numerical results revealed that when NO3-N<100mgL−1, NO3-N was leached without being adsorbed by the soil. In addition, since the NO3-N concentration in soil water after the disappearance of snow was very low, it is necessary to apply N fertilizer in early April (initial growth stage of current shoots and anthogenesis) in order to maximize apple tree growth. Extreme N-leaching due to percolated snowmelt in early spring (a 35-cm movement within 0.5months) was observed in the apple orchard planted on Andosol soil. Therefore, it was inferred that concentrations of inorganic-N in the soil during April were reset to zero, and that N supplementation in the apple orchard is necessary for maximizing apple production.

EVALUATION OF GLACIER MELT CONTRIBUTION TO RUNOFF IN THE NORTH CAUCASUS ALPINE CATCHMENTS USING ISOTOPIC METHODS AND ENERGY BALANCE MODELING

Frequency and intensity of river floods rise observed in the North Caucasus during last decades is considered to be driven by recent climate change. In order to predict possible future trends in extreme hydrological events in the context of climate change, it is essential to estimate the contribution of different feed sources in complicated flow-forming processes in the alpine part of the North Caucasus. A study was carried out for the Djankuat River basin, the representative for the North Caucasus system. Simultaneous measurements of electrical conductivity, isotopic and ion balance equations, and energy balance modeling of ice and snow melt were used to evaluate the contribution of different sources and processes in the Djankuat River runoff regime formation. A forecast of possible future changes in the Djankuat glacier melting regime according to the predicted climate changes was done.

An apparatus for simultaneous measurement of electrical conductivity and thermopower of thin films in the temperature range of 300–750 K

An automated apparatus capable of measuring the electrical conductivity and thermopower of thin films over a temperature range of 300-750 K is reported. A standard dc resistance measurement in van der Pauw geometry was used to evaluate the electrical conductivity, and the thermopower was measured using the differential method. The design of the instrument, the methods used for calibration, and the measurement procedure are described in detail. Given the lack of a standard National Institute of Standards and Technology (Gaithersburg, Md.) sample for high temperature thermopower calibration, the disclosed calibration procedure shall be useful for calibration of new instruments.

A Real-Time Monitoring System Using a Multimodal Sensor with an Electrical Conductivity Sensor and a Temperature Sensor for Cow Health Control

A multimodal sensor composed of an electrical conductivity (EC) sensor and a temperature sensor on the same Si chip was successfully fabricated using compatible complementary metal oxide semiconductor (CMOS) technology. The EC sensor measured the electrical conductivity between Pt electrodes, and the temperature sensor measured the forward voltage of a p–n junction diode. We confirmed the output signal in a wide dynamic range of ECs. For real-time measurement in the rumen of cows, a wireless system was fabricated. The system included a sensor, a battery, an antenna, an analog signal-processing circuit board, an AC-to-DC converter board, and a receiver–transmitter board. We adjusted the wireless system design with focus on the measurement range to adapt the system to the rumen. Real-time and simultaneous measurements of EC and temperature in the rumen using the multimodal sensor unit were performed. The wireless system successfully received signals continuously, and enabled the measurement of the rumen conditions in real time.

Blue-shift in photoluminescence of ion-milled HgCdTe films and relaxation of defects induced by the milling

Simultaneous measurements of electrical conductivity, the Hall coefficient, and photoluminescence (PL) spectra of ion-milled Hg 1 − x Cd x Te films ( x ∼ 0.30 and 0.38) were performed during post-milling ageing of the films at 293 K. In the course of the PL study, a ‘relaxation’ of the blue-shift of the PL band of ion-milled Hg 0.70Cd 0.30Te was observed. The relaxation was caused by the decrease of the electron concentration due to gradual disintegration of defects induced by the milling. It is shown that while ion milling substantially changes the electrical properties of Hg 1 - x Cd x Te, its PL spectrum in the long-term is affected insignificantly.

Characterization of New Materials in A Four-Sample Thermoelectric Measurement System

ABSTRACTSeveral new materials in the CsBi4Te6, A2Bi8Se13, (A = K, Rb, Cs), HoNiSb, Ba/Ge/B (B = In, Sn), and AgPbBiQ3 (Q = S, Se, Te) systems have shown promising characteristics for thermoelectric applications. New synthesis techniques are able to produce samples at much higher rates than previously possible. This has led to a persistent challenge in thermoelectric materials research of rapid and comprehensive characterization of samples. This paper presents a description of a new 4-sample transport measurement system and the related measurement techniques. Special features of the system include fully computer-controlled operation (implemented in LabView™) for simultaneous measurement of electrical conductivity, thermo-electric power, and thermal conductivity. This system has been successfully used to characterize several new thermoelectric materials (including some of the above-mentioned compounds) and reference materials exhibiting a wide range of thermal conductivities.

Electrical transport properties of calcium zirconate at high temperature

Simultaneous measurements of electrical conductivity and thermoelectric power of 1 mol% InO 1.5 doped CaZrO 3 were made at 1523, 1473, 1373 and 1273 K under oxygen partial pressure, P O 2 , between 10 −14 and 1 atm using dried O 2+Ar and CO+CO 2 gas mixtures. InO 1.5 doped CaZrO 3 was found to be the hole–oxide ion mixed conductor under a dry atmosphere. The partial conductivity of holes was predominant in the high P O 2 region and was proportional to P 1/4 O 2 . The partial conductivity of oxide ions without p O 2 dependency was predominant in the low p O 2 region. Partial thermoelectric powers of holes and oxide ions were theoretically evaluated from the total thermoelectric power measurements, and the electrical transport properties of holes, i.e. the mobility of holes was estimated using so-called Jonker's analysis. The present results suggest the comparable concentration of holes with calcia stabilized zirconia and the higher mobility of holes in CaZr 0.99In 0.01O 2.995.

Description of the universal vitreous behaviour of solids with low-energy excitations and its application to the processes in polymer materials irradiated with heavy ions

Due to the fact, that anomalous behaviour of most different physical characteristics in vitreous solids compared with crystalline solids can be described by the action of a system of additional low-energy excitations, the application of this model to processes in polymer films irradiated with heavy ions, was studied. The irradiated polymer films were etched with simultaneous electrical conductivity measurements. It was shown, that the dependence of the radial etching rate on the distance from the trajectory of the heavy ion up to a determined radius can be described by the response function developed from the model of low-energy excitations.

Connections of the model of low-energy excitations with characteristics of the polymer material and irradiation and etching conditions

Abstract Polyethylene terephthalate films irradiated with 129 Xe and 35 Cl ions were etched under various conditions. The pore growth was controlled by simultaneous electrical conductivity measurements. From these etching curves the dependence of the radial pore etch rate on the distance from the trajectory of the heavy ion was calculated. It is shown, that in a determined range at the initial stage of pore formation it is proportional to the response function of the model of low-energy excitations. The influence of the etchant concentration and the sensitization on the radial pore etch rate was studied.

A versatile high-temperature sample holder for simultaneous measurement of electrical conductivity of four pellet samples

A new sample holder is described for simultaneous measurement of the electrical conductivity of four pellet samples at different temperatures up to about 700 degrees C. The rigid construction of the device also permits easy loading and unloading of samples into and out of a tube furnace.

Simultaneous Measurement of Electrical Conductivity and the Amount of Adsorbed Oxygen in Porous ZnO

Abstract Changes in electrical conductivity and the amount of adsorbed oxygen in porous ZnO were measured simultaneously in the temperature range of 200–600 °C. The saturated amount of adsorbed oxygen increased initially, went through a maximum at 500 °C, and then decreased with increasing temperature. The conductivity decreased exponentially with increase in the amount of adsorbed oxygen, which indicates that the energy barrier formed due to the chemisorbed oxygen controls the total conductivity. In a high temperature region, not only the chemisorbed oxygen, but also the oxygen diffused into the grain boundaries played important roles in changing the electrical conductivity. The diffused oxygen was examined by means of a depth profile of tracer 18O measured by SIMS. The formation of the energy barrier at the grain boundary was confirmed by current-voltage characteristic measurements.

Thermodynamic and conductivity studies of nonstoichiometric cerium dioxide by coulometric titration: A simultaneous measurement

Simultaneous measurements of thermodynamic properties (Δ H̄ o2 and Δ S̄ o2) and electrical conductivity (σ) for constant compositions in nonstoichiometric cerium dioxide (CeO 2− x ) were carried out by coulometric titration in the temperature range 800–945°C and oxygen-partial-pressure range 10 −10 to 10 −21 atm. The thermodynamic quantities, Δ H̄ o2 and Δ S̄ o2 were calculated in the regime 1.86 × 10 −3 ⩽ x ⩽ 3.16 × 10 −2. In previous studies of metal oxides (e.g., CeO 2− x ), the electron mobility (μ) has been determined by combining separate experimental measurement of x and σ. In this study, the electrochemical, constant-composition technique is used as a fast and direct method for obtaining thermodynamic data and simultaneous measurements of the electrical conductivity.

Defect Structure and Electrical Properties of Single‐Crystal Ba0.03Sr0.97TiO3

The electrical conductivity and thermoelectric power of single‐crystalline Ba0.03Sr0.97TiO3 were measured over a wide temperature (800° to 1100°C) and oxygen partial pressure (105 to 10‐15 Pa) range. Our experimental data, like those of previous workers on nominally undoped BaTiO3 or SrTiO3, support a defect model based on doubly ionized oxygen vacancies, electrons, holes, and accidental acceptor impurities. The simultaneous measurement of electrical conductivity and thermoelectric power, together with precise experimental data obtained with an advanced thermoectric power measurement technique, enabled us to determine for the first time reliable values for the preexponential factors and the activation energies which characterize the defect equilibrium constants. These calculated values, together with the defect model, were found to give an excellent fit to the experimental data, and were used to generate the boundaries, in Po2‐1/T space, of the various defect regimes.

Electronic-transport behavior in single-crystalline Ba0.03Sr0.97TiO3.

Simultaneous measurements of electrical conductivity \ensuremath{\sigma} and thermoelectric power Q were performed on a single crystal of ${\mathrm{Ba}}_{0.03}$${\mathrm{Sr}}_{0.97}$${\mathrm{TiO}}_{3}$ over an extensive range of temperature (500--1100?deC) and oxygen partial pressure (${10}^{\mathrm{\ensuremath{-}}18}$--1 atm) under thermal-equilibrium conditions. Analysis of the atmosphere dependence of \ensuremath{\sigma} and Q were found to be consistent with a defect model based on the generation and annihilation of shallow-donor-like oxygen vacancies and compensating background acceptor impurities. Following a theoretical approach proposed by Becker and Frederikse and by Jonker, analysis of the combined \ensuremath{\sigma} and Q data allowed, for the first time, determination of both electron [${\ensuremath{\mu}}_{e}$(950 ?(deC)=0.23 ${\mathrm{cm}}^{2}$/V?c] and hole [${\ensuremath{\mu}}_{e}$(950 ?(deC)=0.10 cm/V?c] mobilities at elevated temperatures. Further, large derived values for the electronic scattering factors (${A}_{e}$,${A}_{h}$=3.0) and temperature-independent Q-versus-${\mathrm{log}}_{10}$\ensuremath{\sigma} slopes strongly support a nonactivated large-polaron mobility mechanism for both electrons and holes.

A comparison of laboratory measured electrical conductivity in rocks with theoretical conductivity based on derived pore aspect ratio spectra

Compressional and shear wave velocities and electrical conductivity have been measured simultaneously on three saturated samples of granite up to 0.4 GPa effective pressure and one of chalk up to 0.04 GPa effective pressure. The velocity–pressure data have been inverted using the non-interactive theory of Kuster & Toksöz to produce pore aspect ratio spectra. Archie's Law, and a model devised by Hoening have been used to calculate a theoretical electrical conductivity from the derived pore spectra. In general there is good agreement between the observed conductivity and the conductivity calculated using Hoening's equation applied to ‘cigar-shaped’ cracks. Predicted conductivities obtained via Archie's Law are in approximate agreement using a power of two and are much less than the observed values using a power of one. The results suggest that simultaneous electrical conductivity measurements might provide an important constraint in interpreting velocity—pressure data in terms of pore spectra.

Influence of dislocations on electrical conductivity of CdTe

Simultaneous measurements of electrical conductivity and flow stress have been made on p- and n-type CdTe single crystals deformed in compression at room temperature. Observed changes in conductivity always correspond to a shift of the Fermi energy towards the conduction band and are consistent with the creation of an excess of dislocation donors. An energy-band diagram for the native point-defect states and dislocation states in CdTe is formulated based upon observed electrical, optical, and mechanical behavior.