A. K. Sahu; Priyambada Mallick; S. K. Satpathy; Banarji Behera
Abstract
Synthesis of polycrystalline samples of Bi1-xNdxFeO3 [x = 0.5, 0.6, 0.7 and 0.8] were demonstrated following solid-state reaction method at high temperature. The structural properties of the sample were confirmed through the X-ray diffraction technique. The dielectric study of the compounds was performed ...
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Synthesis of polycrystalline samples of Bi1-xNdxFeO3 [x = 0.5, 0.6, 0.7 and 0.8] were demonstrated following solid-state reaction method at high temperature. The structural properties of the sample were confirmed through the X-ray diffraction technique. The dielectric study of the compounds was performed at different frequencies in the range of 100 Hz – 10 6 Hz for various temperatures. The non-Debye type of relaxation process confirmed from impedance analysis. The materials showed a negative temperature coefficient of resistance (NTCR) behavior at various temperatures and frequencies. AC conductivity of the materials with frequency at different temperatures satisfied the universal power law of Johnscher. Thermistor constant (β), sensitivity factor (α), and stability factor for all the samples were calculated and confirmed the characteristics of NTC thermistor.
Richard D. Sudduth
Abstract
Two full concentration range percolation threshold models were evaluated for three different carbon fillers in both Nylon 6,6 and Lexan. A new Modified Landauer Model was introduced in this study and compared with a Percolation Threshold Model recently published by this author. These models were ...
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Two full concentration range percolation threshold models were evaluated for three different carbon fillers in both Nylon 6,6 and Lexan. A new Modified Landauer Model was introduced in this study and compared with a Percolation Threshold Model recently published by this author. These models were then utilized to address how to best characterize the interfacial surface energy, gpf, for composite electrical conduction measurements using Clingerman’s data. Three different models used for calculating the interfacial surface energies, gpf, were evaluated in this study. It was found that solid measurements used in calculating the Fowkes equation for the interfacial surface energy gave the most consistent correlations. A linear correlation was found between the Fowkes Interfacial surface energy and the b constant designated as the insulation surface interaction magnitude from the new Percolation Threshold Model. In addition, three concurrent mathematical conditions were found to occur at the same concentration for both the new percolation threshold models yielding S-shaped curves in this study. These conditions include the concentration at the Inflection Point, the concentration at the maximum slope and the maximum extrapolated percolation threshold concentration calculated at the same concentration.
Liping Peng
Abstract
We calculated the effective masses and electronic properties of Bi-doped CH3NH3PbI3 perovskites as a thermoelectric material using the VASP functional. The Bismuth doping concentration of 11.1%, 20%, 33.3% corresponding band gaps are 1.46. 0.75, 0.56 eV, respectively. The effective masses of carriers ...
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We calculated the effective masses and electronic properties of Bi-doped CH3NH3PbI3 perovskites as a thermoelectric material using the VASP functional. The Bismuth doping concentration of 11.1%, 20%, 33.3% corresponding band gaps are 1.46. 0.75, 0.56 eV, respectively. The effective masses of carriers and the band gaps decrease with the doping concentration addition. We found that the structure of Bi as an interstitial atom doped MAPbI3 were much more stable than undoped one by the crystal systemic energy, and the Bi doping made the Fermi Level shift close to the bottom of conduction band, leading to charge carrier close to the Fermi level, resulted in the higher electrical conductivity. Moreover, Bi doping produced a smaller electron effective mass with doping concentration addition, increasing the MAPbI3’s mobility. As a result, the Bi-doped MAPbI3 could simultaneously enhance the electrical conductivity and Seebeck coefficient. Our results showed that Bi doped MAPbI3 is a promising approach to develop thermoelectric and photovoltaic properties in organic-inorganic hybrid perovskite materials.
Larissa S. Montagna; Thaís L. do A. Montanheiro; Maurício R. Baldan; Ana Paula S. Oliveira; Marcelo A. de Farias; Marcele A. Hocevar; Luiza C. Folgueras; Fábio R. Passador; Ana Paula Lemes; Mirabel C. Rezende
Abstract
Bionanocomposites with properties similar to those of conventional polymers derived from petroleum have shown scientific and industrial interest. The current research discuss the effect of graphite nanosheets (GNS) addition on electrical, electromagnetic, and mechanical properties and also on morphological ...
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Bionanocomposites with properties similar to those of conventional polymers derived from petroleum have shown scientific and industrial interest. The current research discuss the effect of graphite nanosheets (GNS) addition on electrical, electromagnetic, and mechanical properties and also on morphological aspects of the natural polymer poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/GNS nanocomposites and neat PHBV prepared by casting method. Nanocomposite of PHBV/1.00 wt% GNS showed good electrical conductivity values, extending the scope of application of these materials, such as in reflectors. One of the objectives of this study was to investigate the effect of different contents of GNS in neat PHBV using dynamic mechanical analysis (DMA), which showed that the addition of GNS in PHBV matrix improved the DMA properties. Transmission electron microscopy (TEM) shows good dispersion of GNS in the PHBV matrix with stacked and intercalated graphite layers and XPS confirmed the presence of carbon and oxygen in the graphite nanosheets surface.
Carmen G. Renda; Jeferson A. Dias; Roberto Bertholdo; Alessandra A. Lucas
Abstract
The phenolic resin (PR) is widely studied as matrix for composites due to its promising mechanical properties and chemical stability. However, which regard to electrical conduction, PR is a typical insulator (electrical conductivity around 10 -12 S.cm -1 ), limiting its utilization for electric ...
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The phenolic resin (PR) is widely studied as matrix for composites due to its promising mechanical properties and chemical stability. However, which regard to electrical conduction, PR is a typical insulator (electrical conductivity around 10 -12 S.cm -1 ), limiting its utilization for electric conduction’ applications. Expanded graphite (EG) and conductive carbon black (CB) are fillers that have been utilized to increase the electrical conductivity of several polymers, but they have not yet been enough studied to composites materials with PR. Thus, this study aims at asses to produce composites of PR and EG or CB (2% w / w) and verify the influence these fillers on the composites’ electrical properties. The composites were analyzed by FT-IR (Fourier Transform-Infrared Spectroscopy), Impedance Spectroscopy (IS) and Scanning Electron Microscopy (SEM). It was verified that the electric conductivity of the PRs increased due to fillers. The composite PR/CB showed electric conductivity about five orders of magnitude higher than the PR. On the other hand, the composite PR/EG showed greatest electrical conductivity, about seven orders of magnitude higher than the PR (1.1x10 -5 S.cm -1 ). These results have shown the efficacy of those fillers in the increase of the electrical conduction in PR-based composites. Therefore, these composites materials have potential to be used as Electromagnetic Interference (EMI) shielding and electrostatic discharge (ESD).
Alpana Thakur; Sunil Kumar; Manjula Sharma; V. S. Rangra
Abstract
Graphite oxide (GO) and reduced graphene oxide (RGO) have been synthesized using chemical methods. Prepared graphite oxide and reduced graphene oxide were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. ...
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Graphite oxide (GO) and reduced graphene oxide (RGO) have been synthesized using chemical methods. Prepared graphite oxide and reduced graphene oxide were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. XRD patterns, Raman spectra and FTIR spectroscopy confirms significant structural changes while reducing GO to RGO. The obtained products were further analyzed for their optical and electrical properties using UV-Vis spectroscopy, photoluminescence spectroscopy and four-point probe. RGO has shown excellent electrical conductivity of 1.363×10 4 S/m. The bactericidal action of prepared GO and RGO was also studied against Escherichia coli and Staphylococcus aureus bacteria.
K.C. Anjaneya; J. Manjanna; V.M. Ashwin Kumar; H.S. Jayanna; C.S. Naveen
Abstract
We report the nature of rare earth ion doped ceria (REC), Ce0.8Ln0.2O2−δ, (Ln = Y 3+ , Gd 3+ , Sm 3+ , Nd 3+ and La 3+ ) as oxide ion conductors for their plausible application as electrolytes in intermediate temperature solid oxide fuel cell (SOFC). The samples were prepared by citrate-complexation ...
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We report the nature of rare earth ion doped ceria (REC), Ce0.8Ln0.2O2−δ, (Ln = Y 3+ , Gd 3+ , Sm 3+ , Nd 3+ and La 3+ ) as oxide ion conductors for their plausible application as electrolytes in intermediate temperature solid oxide fuel cell (SOFC). The samples were prepared by citrate-complexation method and characterized by XRD, SEM/ EDX and UV-Visible spectra. The cubic fluorite-type crystal structure is confirmed from XRD patterns, and the observed lattice parameters are in agreement with calculated values. The UV-Vis spectra of the particles dispersed in aqueous medium showed absorption in the UV region which is ascribed to charge-transfer transition. The dc conductivities at 673 K are in the order of Ce0.8Sm0.2O2−δ > Ce0.8Gd0.2O2−δ > Ce0.8Y0.2O2−δ > Ce0.8Nd0.2O2−δ > Ce0.8La0.2O2−δ and their corresponding activation energies are 0.85, 0.87, 0.87, 0.88 and 0.95 eV. Based on ionic and electronic transference numbers, electrical conductivity obtained here is purely ionic, i.e., oxide ion conductors.
A. N. Upadhyay; R. S.Tiwari; Kedar Singh
Abstract
The electrical and dielectric properties of 3 and 5 wt. % of multi-walled carbon nanotube (MWCNT) containing Se85Te10Ag5 glassy composites have been investigated in the frequency range 20 Hz to 2 MHz from room temperature to 387 K. It has been found that the electrical conductivity is enhanced by 6 to ...
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The electrical and dielectric properties of 3 and 5 wt. % of multi-walled carbon nanotube (MWCNT) containing Se85Te10Ag5 glassy composites have been investigated in the frequency range 20 Hz to 2 MHz from room temperature to 387 K. It has been found that the electrical conductivity is enhanced by 6 to 9 orders of magnitude up to 5 wt. % of MWCNT content resulting in transition for insulating to conducting behaviour. The activation energies for all samples have also been evaluated from the Arrhenius plot of the DC conductivity which shows a decreasing trend up to 5 wt. % MWCNT content. The largest dielectric constant of 142 (almost 10 times greater than pristine Se85Te10Ag5 glassy alloy) has been observed for 5 wt. % of MWCNT content at room temperature in low frequency range. Therefore it can be inferred that the electrical and dielectric properties of the chalcogenide glasses can be altered by the admixing or doping of carbon nanotubes (CNTs). The enhanced dielectric constant and electrical conductivity can be attributed to interface effect between MWCNT and the glassy matrix.
S. Amudha; S. Austin Suthanthiraraj
Abstract
The matrix embracing a combination of polyethylene oxide [PEO] as the host polymer component and silver trifluoromethane sulfonate [AgCF3SO3] (also known as silver triflate) as the dopant salt yielding a composite polymer electrolyte [CPE] with varying compositions based on rich contents of Oxygen/Metal ...
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The matrix embracing a combination of polyethylene oxide [PEO] as the host polymer component and silver trifluoromethane sulfonate [AgCF3SO3] (also known as silver triflate) as the dopant salt yielding a composite polymer electrolyte [CPE] with varying compositions based on rich contents of Oxygen/Metal [O/M] ratio has been prepared in the form of thin film specimens using solution casting technique and examined for its application in a solid state battery configuration as a test cell. Such composite polymeric films optimized using electrical conductivity studies have provided realization of a maximum electrical conductivity value of 2.9 ×10 -5 Scm -1 at room temperature (298 K) whereas their temperature-dependent electrical conductivity is found to obey the Arrhenius behavior. Silver ionic transference number (tAg + ) data for these polymeric composites were indomitable using ac/dc polarization technique whereas the occurrence of a transition of phase in accordance with structural and thermal parameters could be investigated by means of X-ray diffraction (XRD) and differential scanning calorimetric (DSC) analyses. The morphological and compositional analyses were carried out by employing scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX) as analytical tools. Electrochemical cells have been fabricated with the common cell configuration Ag|CPE|(I2+G+CPE) and relevant cell parameters evaluated in terms of their discharge characteristics under a constant load of 1 M at room temperature.
Prasanta Dhak; A. Kundu; K. Pramanik; P. Pramanik; D. Dhak
Abstract
Small amounts of Cu and Al-K substitution on the A and B site of BaTiO3, respectively resulting a solid solution of the type Ba1-xCuxTi1-x(AlK)xO3 (BCTAK) [x = 0.05, 0.10, 0.15, 0.20] have been investigated. The compositions have been prepared in the nanocrystalline range by chemical route. X-ray diffraction ...
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Small amounts of Cu and Al-K substitution on the A and B site of BaTiO3, respectively resulting a solid solution of the type Ba1-xCuxTi1-x(AlK)xO3 (BCTAK) [x = 0.05, 0.10, 0.15, 0.20] have been investigated. The compositions have been prepared in the nanocrystalline range by chemical route. X-ray diffraction revealed the tetragonal (P4/mmm) phase. Average crystallite size and particle size were found to be in the range between 25 nm and 35 nm which were analyzed through X-ray diffraction and transmission electron microscopy respectively. A dielectric study of these compounds as a function of temperature suggested that with increasing substitution concentration the dielectric constant decreased and the Curie temperature shifted towards the lower temperature side. Discontinuous grain growth accompanied with excellent dielectric diffuseness was found with increasing concentration of substitution. The dielectric diffuseness γ was found to be maximum to 1.91 at the substitution of BCTAK x = 0.20. The activation energy, Ea was found to decrease along with an increase in conductivity with increasing substitution concentration in BCTAK.
Raju Kumar; Rashmi Rani; Seema Sharma
Abstract
Polycrystalline samples of 1- x(Na0.5 K0.5)(Nb0.95 Ta0.05) ) -x(Bi Fe)O3 with x=0, 0.003, 0.005, 0.007) hereby denoted as NKNT-BF were prepared by the mixed oxide method. Preliminary structural studies carried out by X-ray diffraction technique showed the formation of perovskite structure with orthorhombic ...
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Polycrystalline samples of 1- x(Na0.5 K0.5)(Nb0.95 Ta0.05) ) -x(Bi Fe)O3 with x=0, 0.003, 0.005, 0.007) hereby denoted as NKNT-BF were prepared by the mixed oxide method. Preliminary structural studies carried out by X-ray diffraction technique showed the formation of perovskite structure with orthorhombic symmetry. Addition of BF in the NKNT system lowered the sintering temperature by 500C. The nature of the frequency dependence of ac conductivity of NKNT compounds follows Jonscher power law. Complex impedance and modulus spectra confirm the significant contribution of both grain and grain boundary to the electrical response of the materials. Above the ferroelectric–paraelectric phase transition temperature, the electrical conduction is governed by the thermal excitation of charge carriers from oxygen vacancies exhibiting Negative temperature coefficient (NTCR) behaviour. Detailed study on the multiferroic properties (where magnetism and ferroelectricity are strongly coupled together) of the system is under process which is likely to form key components in the development of future technology, for example, in memories and logic devices.
Faruq Mohammad; Tanvir Arfin
Abstract
In continuation to our previous work, the superparamagnetic Fe3O4@Au core-shell type nanoparticles (NPs) were further characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), electrical conductivity, impedance and cyclic voltammetry measurements. From the analysis of ...
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In continuation to our previous work, the superparamagnetic Fe3O4@Au core-shell type nanoparticles (NPs) were further characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), electrical conductivity, impedance and cyclic voltammetry measurements. From the analysis of DSC and TGA results with our Fe3O4@Au NPs of about 6.25 ± 0.6 nm size, we observed a clear endothermic peak at 310°C due to the decomposition of the oleic acid/oleylamine surface ligands and the particles found to contain more than 80% of the metallic content from the mixed compositions of gold and iron oxide were observed. Because of the conduction through the Fe3O4@Au grain, the impedance profile of the pellet exhibited a well-resolved semi-circle and an inclined spike in a far low-frequency region. The electrical conductivity of the Fe3O4@Au material found to be increased with an increase of temperature. The standard Gibbs free energy (ΔG) of the reaction provided a criterion for spontaneous changes in the equilibrium of the material. From the analysis of the results of ΔG, it appears that at 25°C temperature, ΔS found to be negative. The calculated enthalpy, ΔH = -0.635 kJ/mol, at the corresponding entropy of ΔS = -0.132 kJ/mol. Finally, the activation energy in temperature range of 25-200°C for the Fe3O4@Au core-shell material was calculated using Line fitting and the surface characterization by using cyclic voltammetry. The electrochemical redox property of the Fe3O4@Au shows quasi-reversible wave corresponding to Au 3+ /Au 2+ .In addition, the electrochemical parameters for Fe3O4@Au NPs of E c p < /sub>, E a p < /sub>, E o 1/2 and were also obtained. Since the Fe3O4@Au material has low activation energy at low temperature range which makes it a good candidate as an ion conductor and even has the potential uses in many solid state devices and also in the future prospects of electrochemistry applications.
M. Roy; S. Sahu; S. K. Barbar; S. Jangid
Abstract
Polycrystalline ceramic samples of pure and Cu +2 doped Bi4V2-xCuxO11(x=0.0 and 0.02) have been synthesized by standard solid state reaction method using high purity oxides. The dielectric constant and dielectric loss and hence ac conductivity as a function of frequency and temperature have been measured. ...
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Polycrystalline ceramic samples of pure and Cu +2 doped Bi4V2-xCuxO11(x=0.0 and 0.02) have been synthesized by standard solid state reaction method using high purity oxides. The dielectric constant and dielectric loss and hence ac conductivity as a function of frequency and temperature have been measured. The dielectric studies indicate that the material is highly lossy and hence its ac conductivity increases with the increase of temperature. The dc conductivity of material has been measured as a function of temperature from room temperature to 653 K and its activation energy was calculated using the relation σ = σo exp (- Ea/kT). The dc conductivity increases with the substitution of Cu on the vanadium site. The Modulated Differential Scanning Calorimetry (MDSC) has been used to investigate the effect of substitution on the phase transition of the compounds. The results are discussed in detail.
Anita Mekap; Piyush R. Das; R. N. P. Choudhary
Abstract
The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was ...
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The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was recorded at room temperature using a scanning electron microscope (SEM). Detailed studies of dielectric properties (εr, tan δ) and impedance parameters of the material provide an insight into the electrical properties and understanding of types of relaxation process occurred in the material. Temperature variation of dc conductivity shows that this compound exhibits negative temperature coefficient of resistance (NTCR) and frequency dependence of ac conductivity suggests that the material obeys Jonscher’s universal power law.
U. Ahmadu; S. Tomas; S. A. Jonah; A. O. Musa; N. Rabiu
Abstract
Two RC model circuits are connected in series in order to analyze the electrical and dielectric behaviour of mixed alkali Na0.25Li0.75Zr2(PO4)3 NASICON compound. However, the data obtained could best be described by one RC circuit representing the grain boundary resistance () and capacitance () in the ...
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Two RC model circuits are connected in series in order to analyze the electrical and dielectric behaviour of mixed alkali Na0.25Li0.75Zr2(PO4)3 NASICON compound. However, the data obtained could best be described by one RC circuit representing the grain boundary resistance () and capacitance () in the temperature and frequency range 300-600 K and 300 kHz to 1GHz, respectively. The values of the grain boundary activation energy obtained by fitting to the Arrhenius equation in a plot is ~ 0.40 eV, which is close to the bulk activation energy for electrical conduction. The maximum conductivity obtained is 0.3 S/m at 590 K. A non Debye character was observed in the dielectric permitivity in its frequency dependence. However, the temperature dependence of followed a linear behaviour at low temperatures and frequencies but decreased at higher temperatures. Complex non linear least squares fitting of impedance data using a composite circuit shows good fitting results with relative standard deviation less than 0.2 for all the free parameters which is indicative of the accuracy of data obtained. Similar good fitting results, using a generic battery model, suggest the applicability of the material in rechargeable lithium ion batteries.
A. P. Mishra; A. Tiwari; Rajendra K. Jain
Abstract
The coordination complexes of Co(II), Ni(II) and Cu(II) derived from 2-thiophenecarboxylidene-3-chloro-4-fluoroaniline (TCC) and 2-thiophenecarboxylidene-4-fluoroaniline (TCF) have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, ...
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The coordination complexes of Co(II), Ni(II) and Cu(II) derived from 2-thiophenecarboxylidene-3-chloro-4-fluoroaniline (TCC) and 2-thiophenecarboxylidene-4-fluoroaniline (TCF) have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, ESR, thermal, magnetic susceptibility, electrical conductivity and XRD analysis. The complexes are coloured and stable in air. Analytical data revealed that all the complexes exhibited 1:2 (metal:ligand) ratio with the coordination 4 or 6. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behavior of metal complexes shows that the hydrated complexes loses water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. The crystal system, lattice parameter, unit cell volume and number of molecules in unit cell in the lattice of complexes have been determined by XRD analysis. XRD patterns indicate crystalline nature for the complexes. The solid state electrical conductivity of the metal complexes has also been measured. Solid state electrical conductivity studies reflect semiconducting nature of the complexes.
M. G. Kulthe;R. K. Goyal
Abstract
Polymer matrix composites filled with metals are widely studied for the applications in electrostatic dissipation (ESD) and electromagnetic interference (EMI) shielding. In view of this, the electrical conductivity and the microhardness of the polymer matrix composites based on poly(vinyl chloride) (PVC) ...
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Polymer matrix composites filled with metals are widely studied for the applications in electrostatic dissipation (ESD) and electromagnetic interference (EMI) shielding. In view of this, the electrical conductivity and the microhardness of the polymer matrix composites based on poly(vinyl chloride) (PVC) as matrix and copper (Cu) as reinforcement were determined. The composites were prepared using ball milling followed by hot pressing. Both constituents PVC and Cu were mixed together in a dry condition at room temperature for 12 h, 24 h and 36 h and then blended powder was hot pressed at 175 °C and 50 MPa. The Cu content was varied from 0 to 40 wt% (9.3 vol%) in the matrix. Optical microscope showed good dispersion of Cu particles in the matrix and the degree of Cu dispersion increased with increasing ball milling time. The electrical conductivity of the composites increased approximately six orders of magnitude for 9.3 vol% Cu composite. A percolation threshold was obtained at 3.7 vol% Cu. The microhardness increased by more than 18 % compared to the pure matrix. For a given loading of Cu, the electrical conductivity and the microhardness of the composites increased with increasing ball-milling time. This was attributed to the better and uniform dispersion of the Cu particles in the matrix at higher ball milling time.