Analysis of the electrical transport, conductivity and dielectric relaxation behavior of La0.75 Ba0.10 Sr0.15 Fe O2.875-δ (δ = 0.375 and 0.50) brownmillerite oxides

Abstract The topotactic reduction of La0.75Ba0.10Sr0.15FeO2.875 with titanium metal leads to a new isostructural material of the composition La0.75Ba0.10Sr0.15FeO2.875−δ (δ = 0.375 and 0.50). XRD analysis of phases confirms that the obtained compound adopts a brownmillerite-type structure. A slight distorted monoclinic P2/m was found to describe the crystal structure. The transport properties have been investigated by current–voltage (I–V). The electric and dielectric measurements were carried out covering a wide range of temperature (300–600 K). Our materials display semiconducting properties as well as mixed ionic and electronic conductivity. At high temperatures, the activation energy values proved to be around 907 − 630 meV, which refers basically to oxygen vacancies conduction. The analysis of dielectric properties and dielectric losses (ε’, tanδ) of both compounds vs temperature at different frequencies demonstrates two relaxer attitudes. A low dielectric loss and low electrical conductance were displayed. Relying upon these values, these materials stand for perfect candidates for micro-electronics devices.

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Study and Assessment of Defect and Trap Effects on the Current Capabilities of a 4H-SiC-Based Power MOSFET

Electronics ◽

10.3390/electronics10060735 ◽

2021 ◽

Vol 10 (6) ◽

pp. 735

Author(s):

Fortunato Pezzimenti ◽

Hichem Bencherif ◽

Giuseppe De Martino ◽

Lakhdar Dehimi ◽

Riccardo Carotenuto ◽

...

Keyword(s):

Drain Current ◽

Oxide Semiconductor ◽

Temperature Dependent ◽

Channel Mobility ◽

Blocking Voltage ◽

Current Voltage ◽

Wide Range ◽

Temperature Ranges ◽

Joint Contribution ◽

State Resistance

A numerical simulation study accounting for trap and defect effects on the current-voltage characteristics of a 4H-SiC-based power metal-oxide-semiconductor field effect transistor (MOSFET) is performed in a wide range of temperatures and bias conditions. In particular, the most penalizing native defects in the starting substrate (i.e., EH6/7 and Z1/2) as well as the fixed oxide trap concentration and the density of states (DoS) at the 4H-SiC/SiO2 interface are carefully taken into account. The temperature-dependent physics of the interface traps are considered in detail. Scattering phenomena related to the joint contribution of defects and traps shift the MOSFET threshold voltage, reduce the channel mobility, and penalize the device current capabilities. However, while the MOSFET on-state resistance (RON) tends to increase with scattering centers, the sensitivity of the drain current to the temperature decreases especially when the device is operating at a high gate voltage (VGS). Assuming the temperature ranges from 300 K to 573 K, RON is about 2.5 MΩ·µm2 for VGS > 16 V with a percentage variation ΔRON lower than 20%. The device is rated to perform a blocking voltage of 650 V.

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"Creep currents" in single frog atrial cells may be generated by electrogenic Na/Ca exchange.

The Journal of General Physiology ◽

10.1085/jgp.87.6.857 ◽

1986 ◽

Vol 87 (6) ◽

pp. 857-884 ◽

Cited By ~ 49

Author(s):

J R Hume ◽

A Uehara

Keyword(s):

Voltage Clamp ◽

Time Course ◽

Single Cells ◽

Mechanical Activity ◽

Common Mechanism ◽

Mechanical Relaxation ◽

Equilibrium Conditions ◽

Atrial Cells ◽

Current Voltage ◽

Wide Range

The objective of these experiments was to test the hypothesis that the "creep currents" induced by Na loading of single frog atrial cells (Hume, J. R., and A. Uehara. 1986. Journal of General Physiology. 87:833) may be generated by an electrogenic Na/Ca exchanger. Creep currents induced by Na loading were examined over a wide range of membrane potentials. During depolarizing voltage-clamp pulses, outward creep currents were observed, followed by inward creep currents upon the return to the holding potential. During hyperpolarizing voltage-clamp pulses, creep currents of the opposite polarity were observed: inward creep currents were observed during the pulses, followed by outward creep currents upon the return to the holding potential. The current-voltage relations for inward and outward creep currents in response to depolarizing or hyperpolarizing voltage displacements away from the holding potential all intersect the voltage axis at a common potential, which indicates that inward and outward creep currents may have a common reversal potential under equilibrium conditions and may therefore be generated by a common mechanism. Measurements of inward creep currents confirm that voltage displacements away from the holding potential rapidly alter equilibrium conditions. Current-voltage relationships of inward creep currents after depolarizing voltage-clamp pulses are extremely labile and depend critically upon the amplitude and duration of outward creep currents elicited during preceding voltage-clamp pulses. An optical monitor of mechanical activity in single cells revealed (a) a similar voltage dependence for the outward creep currents induced by Na loading and tonic contraction, and (b) a close correlation between the time course of the decay of the inward creep current and the time course of mechanical relaxation. A mathematical model of electrogenic Na/Ca exchange (Mullins, L.J. 1979. Federation Proceedings. 35:2583; Noble, D. 1986. Cardiac Muscle. 171-200) can adequately account for many of the properties of creep currents. It is concluded that creep currents in single frog atrial cells may be attributed to the operation of an electrogenic Na/Ca exchange mechanism.

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Realizing and Adjusting the Thermoelectric Application of MoO3 Monolayer via Oxygen Vacancies

10.3762/bxiv.2019.76.v1 ◽

2019 ◽

Author(s):

Wenwen Zheng ◽

Wei Cao ◽

Ziyu Wang ◽

Huixiong Deng ◽

Jing Shi ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermoelectric Properties ◽

First Principles ◽

Oxygen Vacancies ◽

Transport Theory ◽

Electronic Conductivity ◽

Boltzmann Transport ◽

Anisotropic Behavior ◽

Boltzmann Transport Theory ◽

Thermoelectric Application

We have investigated the thermoelectric properties of MoO3 monolayer and its defective structures with oxygen vacancies by using first-principles method combined with Boltzmann transport theory. Our results show that the thermoelectric properties of MoO3 monolayer exhibit an anisotropic behavior which is caused by the similar anisotropic phenomenon of electronic conductivity and thermal conductivity. Moreover, the creation of oxygen vacancies proves to be an effective way to enhance the ZT values of MoO3 monolayer which is caused by the sharp peak near the Fermi level in density of states. The increased ZT value can reach 0.84 along x-axis at 300K.

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The Cardiac Electrophysiology Web Lab

10.7287/peerj.preprints.1338v1 ◽

2015 ◽

Cited By ~ 1

Author(s):

Jonathan Cooper ◽

Martin Scharm ◽

Gary R Mirams

Keyword(s):

Cardiac Electrophysiology ◽

Computational Modelling ◽

Cell Types ◽

Virtual Experiments ◽

Online Resource ◽

Voltage Curve ◽

Current Voltage ◽

Wide Range ◽

Current Voltage Curve ◽

The Mathematical Model

Computational modelling of cardiac cellular electrophysiology has a long history, with many models now available for different species, cell types, and experimental preparations. This success brings with it a challenge: how do we assess and compare the underlying hypotheses and emergent behaviours, in order to choose a model as a suitable basis for a new study, or characterize how a particular model behaves in different scenarios? We have created an online resource for the characterization and comparison of electrophysiological cell models under a wide range of experimental scenarios. The details of the mathematical model (quantitative assumptions and hypotheses formulated as ordinary differential equations) are separated from the experimental protocol being simulated. Each model and protocol is then encoded in computer-readable formats. A simulation tool runs virtual experiments on models, and a website – https://chaste.cs.ox.ac.uk/FunctionalCuration – provides a friendly interface, allowing users to store and compare results. The system currently contains a sample of 36 models and 23 protocols, including current-voltage curve generation, action potential properties under steady pacing at different rates, restitution properties, block of particular channels, and hypo-/hyper-kalaemia. This resource is publicly available, open source, and free; and we invite the community to use it and become involved in future developments. Those interested in comparing competing hypotheses using models can make a more informed decision; those developing new models can upload them for easy evaluation under the existing protocols, and even add their own protocols.

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Fuel Cells: The Next Evolution

MRS Bulletin ◽

10.1557/mrs2005.164 ◽

2005 ◽

Vol 30 (8) ◽

pp. 581-586 ◽

Cited By ~ 17

Author(s):

Robert W. Lashway

Keyword(s):

Fuel Cells ◽

Fuel Cell ◽

Internal Combustion Engines ◽

Materials Science ◽

Electrical Conductance ◽

Electrical Energy ◽

Pure Oxygen ◽

Combustion Engines ◽

Hydrogen Fuel ◽

Wide Range

AbstractThe articles in this issue of MRS Bulletin highlight the enormous potential of fuel cells for generating electricity using multiple fuels and crossing a wide range of applications. Fuel cells convert chemical energy directly into electrical energy, and as a powergeneration module, they can be viewed as a continuously operating battery.They take in air (or pure oxygen, for aerospace or undersea applications) and hydrocarbon or hydrogen fuel to produce direct current at various outputs. The electrical output can be converted and then connected to motors to generate much cleaner and more fuelefficient power than is possible from internal combustion engines, even when combined with electrical generators in today's hybrid engines. The commercialization of these fuel cell technologies is contingent upon additional advances in materials science that will suit the aggressive electrochemical environment of fuel cells (i.e., both reducing an oxidizing) and provide ionic and electrical conductance for thousands of hours of operation.

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Electrochemical Pulsing Deposition of CTZS (Optical and Structural properties) Solar Energy Applications

ECS Meeting Abstracts ◽

10.1149/ma2018-01/31/1927 ◽

2018 ◽

Vol MA2018-01 (31) ◽

pp. 1927-1927

Author(s):

Mahfouz Ali Saeed

Keyword(s):

Thin Film ◽

Supporting Electrolyte ◽

Rotating Disk ◽

Xrd Analysis ◽

Atomic Ratio ◽

Rotating Disk Electrode ◽

Energy Applications ◽

Behavior Study ◽

Wide Range ◽

Steady State Current

Cu2(ZnSn)(S)4 (CTZS) has number of advantages over other solar this film such as CuInGaSe2 (CIGS) due to its higher band gap. Generating such thin film layers by electrochemical methods is particularly attractive because the lower generating budget and the higher throughput. According to literature it is default with many challenges to produce CTZS from electrodeposition methods due to wide range of standard potential of each elements of CTZS 1-4. Sulfur atomic ratio is about 50% of CTZS alloy which add more complexity to electrochemical processing. We introduce in this work electropulsing techniques on order to electroplate at transient current instead of steady state current. Electrolyte composition was similar to dilute concentration from the previous work which is is considerably more dilute in comparison to conventional electrolytes used in the literature1-4. The bath composition is: 0.0042 M CuSO4, 0.0031 M ZnSO4, 0.035 M SnCl2, 0.005 M Na2S2O3, and 0.045 M Na2S2O3. PHydrion is used to buffer the electrolyte to pH=2, and supporting electrolyte is 0.6 M LiCl. Experiments was conducted at a rotating disk electrode which offers measureable characterization of the rotating flow at room temperature. Electrochemical pulsing current behavior study at different off and on time and current in Fig. 1 and 2. The effects of pulsing time and current density on the CTZS thin film adhesion and atomic composition are discussed. The annealing was carried out on tube furnace under sulfur element atmosphere with no extra material addition. The amount of sulfur on the absorber layer was optimized. The alloy composition was examined using Energy-dispersive X-ray spectroscopy technique (EDS) Fig. 2. XRD analysis method used to characterized CTZS thickness and crystallography. Figure 1

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Dielectric Properties and Raman Spectroscopy in Ca-Substituted Na0.5Bi0.5TiO3 Ferroelectric Ceramics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.324.298 ◽

2011 ◽

Vol 324 ◽

pp. 298-301 ◽

Cited By ~ 3

Author(s):

Roy Jean Roukos ◽

Olivier Bidault ◽

Julien Pansiot ◽

Ludivine Minier ◽

Lucien Saviot

Keyword(s):

Raman Spectroscopy ◽

Dielectric Properties ◽

Room Temperature ◽

Rhombohedral Phase ◽

Xrd Analysis ◽

Solid State Reaction Method ◽

Ferroelectric Ceramics ◽

Dielectric Measurements ◽

X Ray Diffraction ◽

X Ray

Lead free Na0.5Bi0.5TiO3 (NBT) and (Na0.5Bi0.5TiO3)1-x(CaTiO3)x (NBT-CT) piezoelectric ceramics with the perovskite structure were studied. The NBT and NBT-CT samples were synthesized using a solid-state reaction method and characterized with X-ray diffraction (XRD), Raman spectroscopy and dielectric measurements for several compositions (x = 0, 0.07, 0.15) at room temperature. The XRD analysis showed a stabilization of a rhombohedral phase at a low concentration of Ca (0 < x <0.15), whereas Raman spectra reveal a strong modification for the sample with x = 0.15. The dielectric properties of these ceramics were studied by measuring impedance in the 79-451K temperature range for unpoled and field cooling with an electric field (FC) conditions.

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First-Principles Modeling for Current-Voltage Characteristics of Resistive Random Access Memories

MRS Proceedings ◽

10.1557/opl.2013.763 ◽

2013 ◽

Vol 1562 ◽

Author(s):

Takehide Miyazaki ◽

Hisao Nakamura ◽

Kengo Nishio ◽

Hisashi Shima ◽

Hiroyuki Akinaga ◽

...

Keyword(s):

First Principles ◽

Oxygen Vacancies ◽

Electrode Materials ◽

Random Access ◽

Model Systems ◽

Electronic Coupling ◽

Current Ratio ◽

Current Voltage ◽

Current Voltage Characteristics ◽

Non Equilibrium Green’S Function

ABSTRACTWe present results of first-principles non-equilibrium Green’s function calculations for current-voltage (IV) characteristics of the electrode/HfO2/electrode model systems. In order to investigate the effect of the electrode materials on the IV characteristics, we considered two transition metals for electrode, Ta and W, which are both body-centered-cubic elemental metals but have different valence numbers. We simulated the ON state by placing oxygen vacancies in the HfO2 layer while the OFF state was modeled with HfO2 without oxygen vacancies. At the OFF state, no electric current flowed for -1 V up to +1 V, as expected. At the ON state, however, we found that the absolute current for the Ta electrode was twice as large as that for the W electrode. The analysis of the IV characteristics shows that the electronic coupling between Ta and HfO2 is substantially stronger than that between W and HfO2. Our study demonstrates the importance of the matching between electrode and insulator materials to achieve a high ON- to OFF-current ratio in ReRAMs at a low bias.

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THE CHEMISTRY OF ETHYLENE OXIDE: III. REACTION OF ETHYLENE OXIDE IN AMINE SOLUTION

Canadian Journal of Chemistry ◽

10.1139/v51-068 ◽

1951 ◽

Vol 29 (7) ◽

pp. 585-596 ◽

Cited By ~ 10

Author(s):

A. M. Eastham ◽

B. deB. Darwent

Keyword(s):

Ethylene Oxide ◽

Chemical Nature ◽

Low Dielectric Constant ◽

Specific Rate ◽

Low Dielectric ◽

Wide Range ◽

Specific Rate Constant ◽

Solutions Of Electrolytes ◽

Strong Acids ◽

Basic Strength

A kinetic study has been made of the reaction of ethylene oxide in pyridine solution in the presence of strong acids. The rate has been found to be dependent upon the concentration of acid and of oxide over a wide range of concentrations at 25°C. The specific rate constant, however, varies markedly with the nature of the acid anion and appears to decrease with increasing basic strength of the anion. The absence of large salt effects seems to indicate that the anion effect is of a physical rather than chemical nature and the results are therefore tentatively attributed to the nature of solutions of electrolytes in solvents of low dielectric constant.

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Modelling Properties of an Alkaline Electrolyser

Energies ◽

10.3390/en13123073 ◽

2020 ◽

Vol 13 (12) ◽

pp. 3073

Author(s):

Krzysztof Górecki ◽

Małgorzata Górecka ◽

Paweł Górecki

Keyword(s):

Potassium Hydroxide ◽

Dynamic Properties ◽

Operating Conditions ◽

High Productivity ◽

Electrolysis Process ◽

Average Value ◽

Current Voltage ◽

Wide Range ◽

Current Voltage Characteristics ◽

Parameter Values

This paper proposes a model of an electrolyser in the form of a subcircuit dedicated for SPICE. It takes into account both the electric static and dynamic properties of the considered device and is devoted to the optimisation of the parameters of the signal feeding this electrolyser, making it possible to obtain a high productivity and efficiency of the electrolysis process. Parameter values the describing current-voltage characteristics of the electrolyser take into account the influence of the concentration of the potassium hydroxide (KOH) solution. A detailed description of the structure and all the components of this model is included in the paper. The correctness of the elaborated model is verified experimentally in a wide range of changes in the value of the feeding current and concentration of the KOH solution. Some computations illustrating the influence of the amplitude, average value, duty factor, and frequency of feeding current on the productivity and efficiency of the electrolysis process are performed. On the basis of the obtained results of the investigations, some recommendations for the operating conditions of electrolysers are formulated.

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