Composition Dependence of The Electrical Conductivity of n-p Ceramic Composite

1994 ◽  
Vol 357 ◽  
Author(s):  
Seok-Taek Jun ◽  
Gyeong-Man Choi
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundaries ◽  
Ceramic Composite ◽  
Composition Dependence ◽  
Volume Fraction ◽  
Ceramic Composites ◽  
Equivalent Circuits ◽  
Total Resistance ◽  
Impedance Response

AbstractElectrical properties of ZnO-CuO ceramic composites with varying composition were investigated. The electrical conductivity increased with increasing CuO volume fraction between 1 mol% to 95 mol%. Impedance response showed three semicircles, indicating three resistive elements contributing to the total resistance of the composite. A new model based on the equivalent circuits was developed to explain the contribution of grain boundaries to the resistance of the composite. The change of electrical conductivity was explained by the probability change of two equivalent circuits.

Modelling of Electrical Conductivity of n-p Ceramic Composite Using Equivalent Circuits

1995 ◽  
Vol 411 ◽  
Author(s):  
Gyeong Man Choi ◽  
Seok Taek Jun
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Ceramic Composite ◽  
Composition Dependence ◽  
Equivalent Circuits ◽  
Total Conductivity ◽  
Fractional Change ◽  
Total Electrical Conductivity ◽  
Type Semiconductor ◽  
P Type

ABSTRACTComposition dependence of electrical conductivity of ceramic composite was analyzed using a ZnO(n-type semiconductor)-CuO(p-type semiconductor) composite as a model. The contributions from grain and grain boundaries to the total conductivity of the composite were determined. New equivalent circuits were proposed which represented the distribution and connection of n and p grains and the total electrical conductivity was analyzed using the proposed circuits. Dominant equivalent circuit changed with composition and the total conductivity was determined by the exponential fractional change of two equivalent circuits. Effect of grain size on the grain boundary and total conductivity were also examined.

Composition-Dependent Electrical Conductivity of Ionic-Electronic Composite

1997 ◽  
Vol 500 ◽  
Author(s):  
M. Park ◽  
G. M. Choi
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Electromotive Force ◽  
Composition Dependence ◽  
Force Measurement ◽  
Ionic Transport ◽  
Charge Carriers ◽  
Stabilized Zirconia ◽  
Ionic Charge ◽  
Polarization Technique

ABSTRACTComposition. dependence of electrical conductivity of ionic-electronic composite was camined using yttria(8mol%) stabilized zirconia-NiO composites. The contributions of ectronic and ionic charge carriers to the electrical conductivity were determined by Hebb-Vagner polarization technique and electromotive force measurement of galvanic cell. Up to 6 sol% NiO addition, the conductivity decreased since the electronic NiO acted as an insulator in onic matrix. However the ionic transport was dominant until NiO content reaches 26 vol%. Mixed conduction was observed between 26 and 68 vol% of NiO. The effects of composition on he electrical properties were explained by the microstructure and thus by the distribution of two hases.

Ceramic composite membranes based on Bi3Ru3O11 – Bi1,6Er0,4O3 for obtaining of oxygen

2021 ◽  
Vol 6 ◽  
pp. 22-28
Author(s):  
P. E. Dergacheva ◽  
◽  
I. V. Kulbakin ◽  
S. V. Fedorov ◽  
A. S. Lysenkov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Ceramic Composite ◽  
Oxygen Permeability ◽  
Total Porosity ◽  
Composite Membranes ◽  
Ceramic Composites ◽  
Argon Atmosphere ◽  
Pure Oxygen ◽  
Total Conductivity ◽  
Temperature Dependence Of Conductivity

Using hot uniaxial pressing in an argon atmosphere with a stress of 35 MPa and with a holding at 800 °C for 1 hour, ceramic composites of Bi3Ru3O11 – 50, 65 wt % Bi1,6Er0,4O3 were obtained. It was found that phase composition of the composites does not change during gas chromatographic testing at 800 °C and well corresponds to the specified one. Microstructure of the obtained composites was tested and the formation of dense composites with a total porosity of less than 1% and with a uniform distribution of the Bi3Ru3O11 and Bi1,6Er0,4O3 components in bulk of material was demonstrated. Transport properties (total conductivity, oxygen fluxes and selectivity of separating oxygen over nitrogen) of the obtained composites at 600 – 800 °C had been investigated. Thus, at 800 °C the electrical conductivity of Bi3Ru3O11 – 50, 65 wt % Bi1,6Er0,4O3 was about 200 and 50 Ohm–1∙cm–1, respectively, while the metallic nature of their temperature dependence of conductivity is correlated to that for the Bi3Ru3O11. The value of oxygen permeability for the obtained ceramic composites of about 7∙10–9 mol·cm–1·s–1 at 800 °C, which is compared to other membrane materials based on bismuth oxide, demonstrated the potential of their further use in the tasks for obtaining of pure oxygen from air.

scholarly journals Microstructure Characteristics of Ce-ZTA Ceramic Composites Obtained by Liquid Phase Sintering

2006 ◽  
Vol 530-531 ◽  
pp. 421-424
Author(s):  
Haine Beck ◽  
Maria do Carmo de Andrade Nono ◽  
Francisco Piorino Neto
Keyword(s):  
Ceramic Composite ◽  
Glassy Phase ◽  
Volume Fraction ◽  
Tetragonal Zirconia ◽  
Ceramic Composites ◽  
Liquid Phase Sintering ◽  
Scanning Electronic Microscopy ◽  
Powder Samples ◽  
Zirconia Toughened Alumina ◽  
Crystalline Matrix

Zirconia-toughened alumina (ZTA) ceramics with Ce-TZP (tetragonal zirconia polycrystalline doped with ceria) volume fraction on 33% were prepared with the addition.. The influence of glass infiltrated method was investigated. Coprecipitated Zr and Ce hydroxide mixture was obtained from ZrOCl2.8H2O and CeCl3. 7H2O aqueous solution. CeO2-ZrO2 calcinated powder was compacted and the compacted samples were sintered at 1180°C. Powder samples were characterized by scanning electronic microscopy (SEM), The volume fraction of each phase, the grains size and shapes, and the porosity were investigated with SEM. The relative density and shrinkage was investigate too. The results showed that the crystalline matrix was composed by SiO2 -B2O3-La2O3-Al2O3-Ce-TZP and revealed the important role played the glassy phase in the densification of this ceramic composite.

scholarly journals Impedance Analyses of Alumina-Molybdenum (Al2O3-Mo) Composites

2012 ◽  
Vol 60 (2) ◽  
pp. 277-281
Author(s):  
S. Hussain ◽  
O. Sbaizero
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Grain Boundary ◽  
Composition Dependence ◽  
Ceramic Composites ◽  
The Other ◽  
Alumina Matrix ◽  
Low Frequencies ◽  
Internal Surfaces ◽  
The One

The microstructure and electrical properties of Al2O3-Mo composites were investigated. Different amounts of molybdenum (5, 10, 20, 25 vol%) were added to alumina matrix and the resulting mixture was hot pressed to produce dense metal toughened-ceramic composites. The electrical properties of the composites were examined using impedance spectroscopy in the temperature range 250° C - 1000° C at 50° C temperature intervals. From the analysis, two readily resolvable arcs were found to be present: the one at higher frequencies is the intragranular (grain) response of the bulk; the other is the intergranular (grain boundary) response caused in the internal surfaces of polycrystalline specimens at low frequencies. The effects of grains and grain boundaries on the electrical properties of the composites vary with the composition and temperature. The temperature and composition dependence of grain and grain boundary conductivities are explained by the microstructure.DOI: http://dx.doi.org/10.3329/dujs.v60i2.11533 Dhaka Univ. J. Sci. 60(2): 277-281, 2012 (July)

scholarly journals Effect of reduced graphene oxide (rGO) compaction degree and concentration on rGO-polymer composites printability and cell interactions

2021 ◽  
Author(s):  
Maria Camara Torres ◽  
Ravi Sinha ◽  
Siamak Eqtesadi ◽  
Rune Wendelbo ◽  
Marco Scatto ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Electrical Properties ◽  
Bulk Density ◽  
Polymer Composites ◽  
Reduced Graphene Oxide ◽  
Volume Fraction ◽  
Scale Production ◽  
Melt Compounding ◽  
Reduced Graphene

Graphene derivatives combined with polymers have attracted enormous attention for bone tissue engineering applications. Among others, reduced graphene oxide (rGO) is one of the preferred graphene-based fillers for the preparation of composites via melt compounding, and their further processing into 3D scaffolds, due to its established large-scale production method, thermal stability, and electrical conductivity. In this study, rGO (low bulk density 10g/L) was compacted by densification using a solvent (either acetone or water) prior to melt compounding, to simplify its handling and dosing into a twin-screw extrusion system. The effects of rGO bulk density (medium and high), densification solvent, and rGO concentration (3, 10 and 15% in weight) on rGO dispersion within the composite, electrical conductivity, printability and cell-material interactions were studied. High bulk density rGO (90 g/L) occupied a low volume fraction within polymer composites, offering poor electrical properties but a reproducible printability up to 15 wt% rGO. On the other hand, the volume fraction within the composites of medium bulk density rGO (50 g/L) was higher for a given concentration, enhancing rGO particle interactions and leading to enhanced electrical conductivity, but compromising the printability window. For a given bulk density (50 g/L), rGO densified in water was more compacted and offered poorer dispersability within the polymer than rGO densified in acetone, and resulted in scaffolds with poor layer bonding or even lack of printability at high rGO percentages. A balance in printability and electrical properties was obtained for composites with medium bulk density rGO densified in acetone. Here, increasing rGO concentration led to more hydrophilic composites with a noticeable increase in protein adsorption. Moreover, scaffolds prepared with such composites presented antimicrobial properties even at low rGO contents (3 wt%). In addition, the viability and proliferation of human mesenchymal stromal cells (hMSCs) was maintained on scaffolds with up to 15% rGO and with enhanced osteogenic differentiation on 3% rGO scaffolds.

scholarly journals Optical and Electrical Properties of Graphite Thin Films Prepared by Different Methods

2020 ◽  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Electron Beam ◽  
Electrical Properties ◽  
Grain Boundaries ◽  
Barrier Height ◽  
Electron Beam Evaporation ◽  
Specific Electrical Conductivity ◽  
Simultaneous Increase ◽  
Optical And Electrical Properties

The paper reports on the structural, optical and electrical properties of graphite thin films prepared by two methods: the vacuum-free method "Pencil-on-semiconductor" and via the electron beam evaporation. Graphite thin films prepared by the non-vacuum method has annealed at a temperature of 920K.The transmission spectra of the investigated graphite films and the electrical properties of these thin films were measured at T = 300 K. The value of the height of barriers Eb at the grain boundaries and the temperature dependence of the electrical conductivity in the range ln(σ·T1/2) = f(103/T) were determined, It is established that the height of the barrier at the grain boundaries for the drawn graphite films is Eb = 0.03 eV, for annealed Eb = 0.01 eV and for the graphite films deposited by the electron beam evaporation Eb = 0.04 eV, ie for annealed film the barrier height is the smallest. It is shown that graphite films deposited by the electron beam evaporation reveals the highest transmittance (T550 ≈ 60%), and the transmission of drawn films is the lowest, annealing leads to its increase. The minimum values ​​of transmission at a wavelength λ = 250nm are due to the scattering of light at the defects that are formed at the grain boundaries. Annealed graphite films have been found to possess the best structural perfection because they have the lowest resistivity compared to non-annealed films and electron-beam films and have the lowest barrier height. Simultaneous increase of transmission in the whole spectral range, increase of specific electrical conductivity and decrease of potential barrier at grain boundaries of the annealed drawn graphite film clearly indicate ordering of drawn graphite flakes transferred onto anew substrate, which led to the reduction of light scattering and the improvement of charge transport due to the larger area of ​​overlap between graphite flakes.

Reversible Force-Resistivity Behavior of Thin Films of the TTF-Tcnq Family

1996 ◽  
Vol 436 ◽  
Author(s):  
W. Vollmann ◽  
H.-U. Sonntag
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Potential Barrier ◽  
Film Plane ◽  
Barrier Width ◽  
Dependent Potential ◽  
Sample Resistance

AbstractThe electrical properties of vacuum sublimed thin films of TTF-TCNQ and its derivatives mainly are determined by electron barriers at grain boundaries. The electrical conductivity is thermal activated and exhibits a significant dependence on a force acting perpenticularly to the film plane. The sample resistance R decreases continiously with increasing force F. TCNQ thin films on steel show a similar R-F relation. The effect has been observed already at forces of 1 N, but also up to about 60 kN. An explanation of these phenomena is given by a grain boundary limited hopping mechanism with pressure dependent potential barrier width and height. Morphology investigations by SEM support the model.

scholarly journals Preparation of Electrical Conducting Polymer CompositesFrom Polyvinylchloride (PVC) Resin and StudyingSome its Electrical Properties

2009 ◽  
Vol 6 (4) ◽  
pp. 775-783
Author(s):  
Baghdad Science Journal
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Lithium Fluoride ◽  
Volume Fraction ◽  
Petri Dish ◽  
Light Weight ◽  
Rate Process ◽  
Electrolyte System ◽  
Electrical Conducting

The D.C electrical and thermoelectrically properties of randomly mixed isolator – electrolyte system as (Al/ PVC – LiF/Al) junction consisting of polyvinyl chloride (PVC)resin reinforced with Lithium Fluoride (LiF) powder were studied. A comparison is made the properties of (PVC) material with varying percentage of (LiF) powder (0%, 30%, 50%, 80%)to find out the effect of reinforcement of isolator material. The composites dissolving in 10ml form tettraHaedroflourn (THF) and Solution were the castled in Petri dish and Laved it dry in the air, The out coming Sample were disc - Like shape of a diameter of about 3cm and thickness reneged between (0.01- 0.018) cm . The composites dissolving in 10ml form tettraHaedroflourn (THF) and Solution were the castled in Petri dish and Laved it dry in the air, The out coming Sample were disc - Like shape of a diameter of about 3cm and thickness reneged between (0.01- 0.018) cm . The experimental results show that current and the conductivity of (PVC - LiF) composites increase by three orders of magnitude when the volume fraction (LiF Vol.%) increase and so dose with temperature. The activation energy of the thermal rate - process of the electrical conductivity is determined and found to decrease with increasing the LiF vol. % content. We find that this composite has good conductivity, light weight and easily manufactured. These very good ideal characteristics can make the composite very suitable to be used commercially

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