Ag Phase Research Articles

Experimental investigation on the phase equilibria of the Mg-Sn-Ag system in the Mg-rich corner

Abstract Phase equilibria of the Mg-Sn-Ag system in Mg-rich corner at 320 and 400 °C were experimentally investigated with nine ternary alloys subjected to electron probe microanalysis and X-ray diffraction techniques. No ternary compounds were observed at both isothermal sections. Two three-phase triangles, i.e. hcp (Mg) + Mg 2 Sn + Mg 3 Ag and Mg 2 Sn + Mg 3 Ag + MgAg (bcc_B2), were both observed at 320 and 400 °C. A new three-phase region of Ag 3 Sn + Mg 2 Sn + MgAg (bcc_B2) was additionally observed at 320 °C, which implied that the binary phase Ag 3 Sn has a considerable solubility of Mg in the ternary system at the temperature. And the maximal solubility of Mg in Ag 3 Sn was measured to be 27.2 at.%. This result is not consistent with the thermodynamic calculated isothermal section at 350 °C from Wang et al. [11] and put forward a new requirement or refinement for the optimization of the Mg-Sn-Ag ternary system. At 400 °C, the maximal solubility of Sn in the Mg 3 Ag phase was determined to be about 3.0 at.% Sn, and the solubility of Ag in Mg 2 Sn was negligible. The temperature of ternary eutectic reaction at Mg-rich corner (L↔hcp (Mg) + Mg 54 Ag 17 + Mg 2 Sn) was measured by differential scanning calorimetry. The partial isothermal sections in Mg-rich corner of the ternary system at 320 and 400 °C were then constructed based on the above experimental data.

Effect of nano/micro-Ag compound particles on the bio-corrosion, antibacterial properties and cell biocompatibility of Ti-Ag alloys

In this research, Ti-Ag alloys were prepared by powder metallurgy, casting and heat treatment method in order to investigate the effect of Ag compound particles on the bio-corrosion, the antibacterial property and the cell biocompatibility. Ti-Ag alloys with different sizes of Ag or Ag-compounds particles were successfully prepared: small amount of submicro-scale (100nm) Ti2Ag precipitates with solid solution state of Ag, large amount of nano-scale (20–30nm) Ti2Ag precipitates with small amount of solid solution state of Ag and micro-scale lamellar Ti2Ag phases, and complete solid solution state of Ag. The mechanical tests indicated that both nano/micro-scale Ti2Ag phases had a strong dispersion strengthening ability and Ag had a high solid solution strengthening ability. Electrochemical results shown the Ag content and the size of Ag particles had a limited influence on the bio-corrosion resistance although nano-scale Ti2Ag precipitates slightly improved corrosion resistance. It was demonstrated that the nano Ag compounds precipitates have a significant influence on the antibacterial properties of Ti-Ag alloys but no effect on the cell biocompatibility. It was thought that both Ag ions release and Ti2Ag precipitates contributed to the antibacterial ability, in which nano-scale and homogeneously distributed Ti2Ag phases would play a key role in antibacterial process.

Effects of reducing agents on the synthesis of Ag/rGO nanocomposites

A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles (AgNPs) and the reduction of graphene oxide (GO) simultaneously with five different reducing agents, sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium citrate, urea and ascorbic acid. The experimental results show that the structural properties and phase of Ag/reduced graphene oxide (Ag/rGO) nanocomposites are connected with reducing agent. AgNPs can be uniformly and compactly anchored on reduced GO (rGO) surface in the microwave field for 2 min by the assist of NaOH or KOH as reducing agent. The OH− can not only accelerate the ionization of acidic functional groups but also act as the nucleophile for Ag+. By addition of sodium citrate and urea, the GO sample remains its original structure, and Ag+ tends to form Ag2CO3, which then decomposes into Ag2O. While in the urea solution, Ag2O turns into [Ag(NH3)2]+ ions with abundant urea, then [Ag(NH3)2]+ ions are reduced to Ag0 by electrons, which leads to both Ag and Ag2O phase coexisting in the urea treated samples. In addition, it can be found that NaOH shows the best results in terms of the crystallinity and purity of Ag grains anchored on rGO surface.

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Cu electrolysis was performed using low-grade copper anode with purity 78.7 mass% at a anode current density of 200 A・m-2 in an unagitated sulfate solution containing 0.596 mol・dm-3 of Ni2+ ions as impurity at 60 ℃, and the structure of anode slime before and after passivation was analyzed. The highly-concentrated Sb, Pb and Ag were dispersed in copper anode before electrolysis. The passivation occurred at short time of 17.7 hours in the case of low-grade copper anode, and it occurred at shorter time of 11.4 hours in the solution containing Ni2+ ions as impurity. At normal dissolution of copper anode, copper parent phase dissolved in the form of dendrite and the framework of anode slime was composed of remained Cu-Ni-Sb-Sn-As compound. Cu2S and single phase of Ag and Pb were observed around this framework. At passivation, Cu, Ni and Sn dissolved from the slime framework composed of Cu-Ni-Sb-Sn-As compound, resulting in formation of Sb condensed phase. These Cu-Ni-Sb-Sn-As compound, Sb condensed phase, Cu2S compound around the slime framework, Ag and needle-shaped PbO dotted in the whole slime suppressed the diffusion of Cu2+ ions, as a result, CuSO4 was formed at interface between the slime and copper substrate. The passivation occurred at slime thickness of approximately 500μm in Ni2+-free solution, while it occurred at slime thickness of approximately 300μm in solution containing Ni2+ ions. This indicates that the passivation do not depend on only the thickness of slime. The thickness of CuSO4 formed at passivation in Ni2+-free solution was almost identical with that from the solution containing Ni2+ ions. In solution containing Ni2+ ions, the passivation occurred at less thickness of slime, showing that CuSO4 is easy to be formed in the vicinity of copper substrate due to decrease in solubility of CuSO4 and diffusion coefficient of Cu2+ ions.

Study and Calculation Electrical Properties of Silver Thin Layers by Four- Point Probe Method

In this research Ag thin layers on silicon p-type substrate with crystal orientation (100) and 300, 360 and 400 nm thicknesses by thermal evaporation was deposited. Four-point probe and XRD analysis of surface layers consequently for study electrical properties included of sheet resistance, conductivity, resistivity and investigation of Ag phase formed, was done. As result XRD was shown that at 400 nm the best state of silver face-central cubic (FCC) structure with crystal orientation (200) was formed and by Deby-Scherrer formula distance between successive plates was calculated 8.94 nm. Four-point illustrated that sheet resistance and electrical resistivity with increase thickness, decreases while conductance increases. At 400 nm thickness Ag layer has the most conductivity and the lowest resistance.

An analysis of the efficiency and sustainability of the thiosulfate-copper-ammonia-monoethanolamine system for the recovery of silver as an alternative to cyanidation

In this research, silver leaching experiments from pure phases of Ag and Ag2S were done using the S2O32−-Cu2+-MEA-NH4 alternative system and varying the S2O32− and MEA concentrations. The results revealed that MEA can stabilize the cupric ions forming several Cu-MEA complexes. It was also found that MEA can form Ag-MEA complexes, and thus it can work as a co-leaching agent for silver, mainly when metallic silver is used.Furthermore the leaching experiments with metallic silver showed a continuous oscillation process (silver dissolution-precipitation phenomenon), which was related to the formation of the redox couples Ag-MEA/Ag and Cu-NH3/Cu-MEA, as well as with the oxidative decomposition of thiosulfate which could lead to the formation of copper sulfide species. The leaching experiments with silver sulfide revealed that the presence of MEA in the leaching system is advantageous in two ways: a) it decreases the precipitation of copper oxides and b) it assists the stabilization of silver in solution avoiding its precipitation.Furthermore, the pregnant leaching solutions were treated by cementation using a metallic copper wire and the chemical and microstructural characterizations revealed that silver was deposited on the copper wire surface. When the leaching solution is re-utilized after the cementation step in a second leaching with Ag2S, it is possible to dissolve 85% of silver. This paper presents an alternative-sustainable thiosulfate leaching system which permits the recovery of silver from metallic silver or silver sulfide at short processing times.

Regioselective Atomic Rearrangement of Ag-Pt Octahedral Catalysts by Chemical Vapor-Assisted Treatment.

Thermal annealing is a common, and often much-needed, process to optimize the surface structure and composition of bimetallic nanoparticles for high catalytic performance. Such thermal treatment is often carried out either in air or under an inert atmosphere by a trial-and-error approach. Herewith, we present a new chemical vapor-assisted treatment, which can preserve the octahedral morphology of Ag-Pt nanoparticles while modifying the surface into preferred composition arrangements with site-selectivity for high catalytic activity. In situ environmental transmission electron microscope (ETEM) study reveals a relatively homogeneous distribution of Ag and Pt is generated on the surface of Ag-Pt nanoparticles upon exposure to carbon monoxide (CO), whereas Pt atoms preferably segregate to the edge regions when the gas atmosphere is switched to argon. Density functional theory (DFT) calculations suggest stabilization of Pt atoms is energetically favored in the form of mixed surface alloys when CO vapor is present. Without CO, Ag and Pt phase separate under the similar mild treatment condition. There exists a close correlation between the tunable surface structures and the catalytic activities of Ag-Pt octahedral nanoparticles.

Size-induced crossover from itinerant to localized magnetism observed for isolated Fe impurities embedded in different structural polymorphs of silver

Measurements of the local susceptibility and spin relaxation rate for isolated Fe atoms implanted in the nanocrystalline hexagonal phase of Ag (4H-Ag) show a large orbital moment, in stark contrast with the spin-dominated itinerant magnetism in conventional face centered cubic Ag. The orbital moment observed for Fe in hexagonal Ag $(\ensuremath{\approx}1\phantom{\rule{4pt}{0ex}}{\ensuremath{\mu}}_{B})$ is the largest among $d$-block hosts, and resembles $f$-electron magnetism, suggesting Hund's rule type local moment with strong spin-orbit coupling. Calculations based on density functional theory suggest that the crossover from itinerant to local moment behavior results from localization of Fe-$3d$ states due to size-induced changes in unit cell volume and symmetry.

Current perpendicular-to-plane giant magnetoresistance devices using half-metallic Co2Fe0.4Mn0.6Si electrodes and a Ag–Mg spacer

Current perpendicular-to-plane (CPP) giant magnetoresistance (GMR) effects in devices including Co2Fe0.4Mn0.6Si (CFMS)/Ag100−xMgx/CFMS structures were investigated theoretically and experimentally.First-principles transport calculation revealed that the Fermi surface matching between CFMS and L12 Ag3Mg is better than that between CFMS and fcc-Ag. In the experiments the Mg composition, x was changed from 0 to 26 at.%, in which both face centered cubic phase and L12 phase of Ag–Mg alloys are included depending on the Mg composition. It was confirmed by a cross-sectional high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image that the Ag–Mg spacer layer with L12 ordered phase was successfully fabricated for x = 22 at.%. The maximum CPP–GMR ratio and the change of the areal resistance () were 56% and 20 mm2, respectively, for x = 22 at.% at room temperature, which is much higher than that of the conventionally used pure Ag spacer devices. It was suggested from the HAADF-STEM images and the results of the temperature dependence of CPP–GMR effects that the diffusion of Mn atoms occurred less at the CFMS/Ag–Mg interfaces for the L12 ordered Ag–Mg spacer devices than the Ag spacer devices, which might be a key factor for the enhancement of the value. The newly developed L12 Ag–Mg spacer is a promising material for realizing large of the CPP–GMR devices.

Tailoring the structural and optical properties of TiN thin films by Ag ion implantation

Titanium nitride (TiN) thin films thickness of ∼260nm prepared by dc reactive sputtering were irradiated with 200keV silver (Ag) ions to the fluences ranging from 5×1015ions/cm2 to 20×1015ions/cm2. After implantation TiN layers were annealed 2h at 700°C in a vacuum. Ion irradiation-induced microstructural changes were examined by using Rutherford backscattering spectrometry, X-ray diffraction and transmission electron microscopy, while the surface topography was observed using atomic force microscopy. Spectroscopic ellipsometry was employed to get insights on the optical and electronic properties of TiN films with respect to their microstructure. The results showed that the irradiations lead to deformation of the lattice, increasing disorder and formation of new Ag phase. The optical results demonstrate the contribution of surface plasmon resonace (SPR) of Ag particles. SPR position shifted in the range of 354.3–476.9nm when Ag ion fluence varied from 5×1015ions/cm2 to 20×1015ions/cm2. Shift in peak wavelength shows dependence on Ag particles concentration, suggesting that interaction between Ag particles dominate the surface plasmon resonance effect. Presence of Ag as second metal in the layer leads to overall decrease of optical resistivity of TiN.

Green synthesis of silver nanoparticles in aloe vera plant extract prepared by a hydrothermal method and their synergistic antibacterial activity

BackgroundThere is worldwide interest in silver nanoparticles (AgNPs) synthesized by various chemical reactions for use in applications exploiting their antibacterial activity, even though these processes exhibit a broad range of toxicity in vertebrates and invertebrates alike. To avoid the chemical toxicity, biosynthesis (green synthesis) of metal nanoparticles is proposed as a cost-effective and environmental friendly alternative. Aloe vera leaf extract is a medicinal agent with multiple properties including an antibacterial effect. Moreover the constituents of aloe vera leaves include lignin, hemicellulose, and pectins which can be used in the reduction of silver ions to produce as AgNPs@aloe vera (AgNPs@AV) with antibacterial activity.MethodsAgNPs were prepared by an eco-friendly hydrothermal method using an aloe vera plant extract solution as both a reducing and stabilizing agent. AgNPs@AV were characterized using XRD and SEM. Additionally, an agar well diffusion method was used to screen for antimicrobial activity. MIC and MBC were used to correlate the concentration of AgNPs@AV its bactericidal effect. SEM was used to investigate bacterial inactivation. Then the toxicity with human cells was investigated using an MTT assay.ResultsThe synthesized AgNPs were crystalline with sizes of 70.70 ± 22-192.02 ± 53 nm as revealed using XRD and SEM. The sizes of AgNPs can be varied through alteration of times and temperatures used in their synthesis. These AgNPs were investigated for potential use as an antibacterial agent to inhibit pathogenic bacteria. Their antibacterial activity was tested on S. epidermidis and P. aeruginosa. The results showed that AgNPs had a high antibacterial which depended on their synthesis conditions, particularly when processed at 100 oC for 6 h and 200 oC for 12 h. The cytotoxicity of AgNPs was determined using human PBMCs revealing no obvious cytotoxicity. These results indicated that AgNPs@AV can be effectively utilized in pharmaceutical, biotechnological and biomedical applications.DiscussionAloe vera extract was processed using a green and facile method. This was a hydrothermal method to reduce silver nitrate to AgNPs@AV. Varying the hydrothermal temperature provided the fine spherical shaped nanoparticles. The size of the nanomaterial was affected by its thermal preparation. The particle size of AgNPs could be tuned by varying both time and temperature. A process using a pure AG phase could go to completion in 6 h at 200 oC, whereas reactions at lower temperatures required longer times. Moreover, the antibacterial effect of this hybrid nanomaterial was sufficient that it could be used to inhibit pathogenic bacteria since silver release was dependent upon its particle size. The high activity of the largest AgNPs might have resulted from a high concentration of aloe vera compounds incorporated into the AgNPs during hydrothermal synthesis.

Electrochemical deposition of Ag2Se nanostructures

AgSe based nanostructures (nanowires or nanotubes) were obtained by electrodeposition. A systematic investigation was carried out, varying concentration of the precursors, pH of the electrolytic solution, ligands, and deposition mode, to study the effect of all these parameters on the growth of nanostructures. Nanostructure morphology depends also on the type of metal that was used as support, due to the secondary reaction of hydrogen evolution. On Ni support, the H2 evolution reaction led to formation of only nanotubes, while on copper substrate also nanowires were obtained. Composition of nanostructures depends strongly on solution pH. X-ray diffraction and Raman spectroscopy showed that in thiocyanate-free bath nanostructures consist in orthorhombic Ag2Se and metallic Ag. At higher pH values, the metallic Ag phase increased and the co-deposition of Se also occurred. We also found that the use of a thiocyanate bath with a specific composition permits to obtain nanostructures of pure orthorhombic Ag2Se.

The effects of deposition time on surface morphology, structural, electrical and optical properties of sputtered Ag-Cu thin films

The preparation of designed nanostructured thin films combining nano grains of different compositions and physical properties represents a promising avenue for the exploration of novel collective behaviors with technological potentials. Herein, nanostructured Ag-Cu thin films with different surface morphology properties were grown by magnetron sputtering varying the deposition time (4-24 min) and fixing the other deposition conditions. X-ray diffraction studies corroborated that Cu and Ag tend to appear as separated phases with nanometric sizes due to the fact that these elements are rather immiscible. The deposited Cu tended to be partially oxidized with crystal sizes of several tens of nm, whereas the deposited Ag phase displayed a poor crystallinity with an average crystal size of around 3nm. However, at deposition time of few minutes, the formation of Ag-Cu crystals with a preferable crystallization orientation along the [111] direction was detected. The surface morphology of the obtained thin films was studied by atomic force microscopy determining the surface roughness and average particle sizes of the samples. These parameters were correlated with the plasmon resonance extinction bands of the different Ag-Cu films and their electrical properties, providing a reproducible route to obtain thin films with tuned electrical resistances and optical properties.

Power factor improvement of delafossite CuAlO2 by liquid-phase sintering with Ag2O addition

Thermoelectric delafossite (CuAlO2)1−x(Ag2O)x with 0<x<0.06 is prepared at three different sintering temperatures, 1323K, 1373K, and 1473K. The samples are obtained from a mixture of CuO, Al2O3, and additive Ag2O powders. The mixture is ground and then pressed with uniaxial pressure into pellets. Differential scanning calorimetry and X-ray diffraction spectroscopy show that the sintering temperature to synthesize delafossite CuAlO2 with Ag2O addition is below 1473K. X-ray diffraction patterns show the major phase of delafossite 3R-CuAlO2 along with a trace amount of 2H-CuAlO2. A small amount of the Ag phase is present in the samples depending on the amount of Ag2O addition and sintering temperature. Energy dispersive spectroscopy and backscattered electron image analyses show that the Ag phase is segregated around the grain boundary. Liquid-phase sintering is used to explain the growth mechanism. The CuAlO2 samples with Ag2O addition obviously exhibit enhanced bulk density, grain size, and electrical conductivity. The highest power factor (PF), obtained by CuAlO2 with 2at% of Ag2O sintered at 1373K, is 8.23×10−5W/(m K2) at 873K. Hence, our findings show an improvement for delafossite CuAlO2 by Ag2O addition.

Structure and properties of silver-doped calcium phosphate nanopowders

Stable and antimicrobial silver-doped calcium phosphate nanopowders were synthesized using sol–gel route by setting the atomic ratio of Ag/(Ag+Ca) at 3% and (Ca+ Ag)/P at 1.67. Prior to synthesis of nanopowders, influence of time of hydrolyzation on pH and density of precursors were comprehensively studied. Hydrolyzation time was found to have profound influence on pH of constituent precursors. Sufficient hydrolysis resulted in early maturation of sol. Scanning electron microscopy (SEM) showed the heterogeneous and agglomerated state of particles with average size of 3.9± 1.9 μm. Energy dispersive X-ray spectroscopy (EDX) presented uniform distribution of O, Ag, Ca and P elements in nanopowder. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of apatitic structure, whereas X-ray diffraction (XRD) revealed the multiphase constitution of nanopowders primarily composed of β-TCP, Ag and other hybrid phases. Crystallite size and lattice parameters of β-TCP and Ag phases were increased with the rise in calcination temperature. Thermogravimetric analysis (TGA) showed three regions of weight change and indicated the high thermal stability of nanopowders. Disk diffusion method was used to test the antimicrobial resistance of nanopowders against Escherichia coli and Staphylococcus aureus bacterial strains. All nanopowders exhibited antimicrobial resistance against both E. coli and S. aureus bacteria.

Effect of growth condition on structure and optical properties of hybrid Ag-CuO nanomaterials

This study aimed to use hydrothermal-microwave process to synthesize hybrid Ag-CuO nanomaterials. The effects of different irradiation time ranging 5–20min, and reaction temperatures ranging 120–180°C on the structure and optical properties of the samples were studied. The X-ray diffraction assessments indicated that the synthesized nanomaterials had Ag and CuO phases. The elemental analyses confirmed the presence of Ag, Cu, and O in the samples. Transmission electron microscopy images revealed non-regular and impacted shapes of Ag and CuO. Increasing the reaction temperature and irradiation time increased the absorption intensity of the samples. Furthermore, increasing the irradiation time induced a shift in the absorption edge towards larger wavelengths (red shift), while increasing the reaction temperature shifted it towards smaller wavelengths (blue shift).

Harsh service environment effects on the microstructure and mechanical properties of Sn–Ag–Cu-1 wt% nano-Al solder alloy

This paper investigates the electrical and mechanical performances of eutectic Sn-3Ag-0.5Cu (wt%) solder with the addition of Al nanoparticles. The study revealed that the elastic moduli, electrical resistivity and damping properties of such solder alloy were improved. Further, interfacial reaction phenomena on Au/Ni-plated Cu pad ball grid array substrate during isothermal aging and thermal cycle was evaluated in terms of the formation and growth kinetics of intermetallic compound (IMC) layer. A structural analysis confirmed that at their interfaces a ternary (Cu, Ni)-Sn IMC layer was adhered at the substrate surface. The thickness of this IMC layer was increased with increasing the duration of the isothermal aging and thermal cycle without any defects. In addition, the formation of Ag3Sn, Cu6Sn5, Sn–Al–Ag and AuSn4 IMC phases were evenly distributed in the solder matrix which acts as the second phase reinforcement. The measured shear strength and microhardness indicated that the exposure of the solder joints to the thermal cycles make the joints degraded faster than the situation in isothermal aging.

Synthesis of silver nanoparticles using aqueous extracts of Heterotheca inuloides as reducing agent and natural fibers as templates: Agave lechuguilla and silk

Silver nanoparticles (Ag NPs) were synthesized using a one-pot green methodology with aqueous extract of Heterotheca inuloides as a reducing agent, and the support of natural fibers: Agave lechuguilla and silk. UV–Vis spectroscopy, X-Ray photoelectron spectroscopy XPS and transmission electron microscopy TEM were used to characterize the resulting bionanocomposite fibers. The average size of the Ag NPs was 16nm and they exhibited low polydispersity. XPS studies revealed the presence of only metallic Ag in the nanoparticles embedded in Agave. lechuguilla fibers. Significant antibacterial activities against gram-negative Escherichia coli and gram-positive Staphylococcus aureus were determined. AgO as well as metallic Ag phases were detected when silk threads were used as a substrates hinting at the active role of substrate during the nucleation and growth of Ag NPs. These bionanocomposites have excellent mechanical properties in tension which in addition to the antibacterial properties indicate the potential use of these modified natural fibers in surgical and biomedical applications.

Ni/Te and Ni/Ag2Te interfacial reactions

Ag2Te is a promising thermoelectric compound, and Ni is commonly used as a barrier layer. The interfacial reactions in the Ni/Te and Ni/Ag2Te couples are examined at 200 °C and 250 °C. To illustrate the reaction paths in the Ni/Ag2Te couples, the AgNiTe isothermal sections at 200 °C and 250 °C are determined based on experimental results of this study and related phase equilibria information. There is no ternary compound phase found and the phase relationships are same at 200 °C and 250 °C. The reaction paths of the two reaction couples are identical at these two temperatures. Three intermediate phases, Ni3Te2, NiTe0.775 and NiTe2, are formed in the Ni/Te couples. The reaction rate increases significantly at 250 °C, and is about six times higher than that at 200 °C. Only the Ni3Te2 and Ag phases are observed in the Ni/Ag2Te couples. The reaction path is Ag2Te/Ni3Te2/Ag/Ni in the Ni/Ag2Te couples at both 200 °C and 250 °C.

STRUCTURAL, OPTICAL AND ELECTRICALCHARACTERIZATION OF POLYANILINE/ SILVER NANOCOMPOSITES

Nanocomposites of conducting polyaniline with Silver (PAni/Ag) have been synthesized by in-situ polymerization of aniline monomer using ammonium persulphate as an oxidizing agent. The weight percentage of silver varied from 3% to 25%. The formation of PAni/Ag composites was assessed by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and UV-Vis spectroscopy. The broadening of sharp peaks in the XRD pattern indicates the presence of nano phase of Ag. The crystallite size of PAni/Ag nanocomposite from XRD is found to be ~17.5nm. The FESEM image shows a nanoparticular structure of silver and it is also seen that the Ag nanoparticles are well dispersed in the polyaniline matrix. UV-Vis spectrogram of composites shows three peaks at ~240nm, 450 nm and 700 nm respectively in addition to ~198 and ~324 nm peak of Pure PAni. The peak around 450 nm confirms the presence of radical cation or polaron transition. The peak around 700 nm is the characteristic peak of PAni Emeraldine base. The peak around ~240 nm could be assigned to the characteristic absorption of small metallic Ag cluster. The graph of hνVs (αhν)2 was also plotted. The PL spectrum of PAni/Ag was excited with an excitation wavelength of 320 nm. Two peaks are observed at a wavelength of ~370nm and 600 nm. The DC conductivity of Pure PAni and its composites have been measured in the temperature range from 25°C to 150 °C. The DC electrical study of PAni/Ag nanocomposite clearly indicates that the Ag nanoparticles increase the electrical conductivity of polyaniline nanocomposites as compared to polyaniline.