Content Of Ag2O Research Articles

A comprehensive examination of zinc-boro-vanadate glass reinforced with Ag2O in physical, optical, mechanical, and radiation shielding aspects

This study explored the zinc-boro-vanadate (ZBV) glass reinforced with Ag2O to show radiation shielding competencies. A glass system with composition 20ZnO-55B2O3-(25-x)V2O5-xAg2O, where x ranges from 0 to 10 with the steps of 2.5 mol%, was designed. Some physical and optical calculations were employed to figure out glass density (ρglass), molar volume (Vm), oxygen molar volume (OMV), oxygen packing density (OPD), refractive index (n), dielectric constant (ϵ), and metalization criterion (M) for the glass system of ZBV0 to ZBV10. According to the findings, one can specify that the increasing content of Ag2O enhanced both the physical and optical features of the ZBV series. The glass density was increased from 3.3150 to 3.6930 g/cm3, while the refractive index was raised from 3.0693 to 3.1216 with the insertion ratio of Ag2O from 0 to 10 mol%. The ZBV10 sample having the maximum Ag2O of 10 mol% ensured to improve physical and optical properties. The shielding properties of the examined glass samples were investigated to evaluate their ability for radiation protection purposes. The Monte Carlo N-Particle Transport Code 5 (MCNP-5) was utilized to assess the projected gamma photons' average track length on the investigated glass samples. Then, the linear attenuation coefficient (LAC), half-value layer (HVL), transmission factor (TF), and radiation protection efficiency (RPE) were calculated based on the simulated gamma photons' average track length. The obtained results showed that the highest LAC values increased from 71.999 to 91.979 cm−1. Moreover, the thicker HVL decreased from 9.869 to 9.332 cm−1, increasing the Ag2O insertion ratio between 0 and 10 mol%, respectively. The mentioned data confirmed that substitution of the V2O5 by the Ag2O enhance the gamma-ray shielding capacity of the explored series of glass.

Effects of Ag2O doping on dielectric properties of (Pb0.96La0.04)(Zr0.9Ti0.1)0.99O3 antiferroelectric ceramics

Antiferroelectric ceramics are superior energy storage materials with high energy storage densities, small size, low price, etc. In this paper, with (Pb0.96La0.04)(Zr0.9Ti0.1)0.99O3 (PLZT4/90/10) as a representative, the effect of silver oxide doping on the dielectric properties of ceramics was investigated. PLZT4/90/10 ceramics prepared by the solid phase method was doped with 0 wt%, 0.1 wt%, 0.5 wt%, 1.0 wt% and 1.5 wt% of Ag2O, and the effect of the addition of Ag2O was analyzed on dielectric, energy storage and conductive properties. Ag+ replaces the A-position of Pb2+ in the lattice, which leads to generate more oxygen vacancy in the lattice. Incorporation of silver oxide improves the releasable energy storage density (Wre) and the energy release efficiency (η). When the content of Ag2O is 1.0%, the releasable energy density reaches the maximum value of 2.22 J/cm3 and the energy release efficiency is raised to 78.69%. The releasable energy density and the energy release efficiency are listed at different temperatures for different doping amounts. It can be seen that Ag2O doping can also promote the temperature stability of the energy storage density. In addition, the doping of Ag2O has a good effect on smoothing the temperature dependence curves of dielectric constant and improving the resistivity of ceramics of PLZT4/90/10 ceramics. As the dielectric constant, energy storage density and other aspects are concerned, Ag2O doping has a beneficial effect on the performance of capacitor applications for PLZT4/90/10 ceramics.

Influence of silver ion concentration on dielectric characteristics of Li2O-Nb2O5-P2O5 glasses

In this work we have studied the dielectric properties of Li2O-Nb2O5-P2O5: Ag2O glasses as a function of Ag2O concentration. Auxiliary studies viz., optical absorption, photoluminescence (PL), XPS and IR spectra have also been performed on these glasses. IR spectral studies have indicated that the host glass network doped with 1.0 mol% of Ag2O is highly polymerized. Optical absorption and PL studies have clearly exhibited absorption and emission bands due to surface plasmon resonance (SPR). From these studies, the presence of Ag0 -Ag+ clusters is established in the glass network and the concentration of such clusters is found to be the highest in the glass doped with 1.0 mol% of Ag2O. Finally, we have performed extensive studies on dielectric properties viz., dielectric constant, loss, electric moduli, impedance spectra and a.c. conductivity over broad ranges of frequency (0.01 Hz–1 MHz) and temperature (303–513 K). The glasses doped with higher content of Ag2O exhibited higher values of dielectric constant especially at lower frequencies and higher temperatures. The larger contribution from space charge polarization is predicted to be responsible for such higher values. In the glasses doped with low contents of Ag2O (<1.0 mol%) the polaron conductivity (due to the polaronic transfer between Ag0 and Ag+ ions) seemed to be dominant, whereas in the glasses containing more than 1.0 mol% of Ag2O, the ionic conduction (due to the diffusion of Ag+ and Li+ ions) appear to prevail. The impedance diagrams drawn between Z′ and Z″ have further supported the above-mentioned conclusions. From the overall analysis of the results of dielectric properties (including a.c. conductivity) with the aid of experimental results on spectroscopic studies, it is concluded that the glass containing more than 1.0 mol% of Ag2O exhibited predominantly ionic conductivity and hence such glasses may be useful as electrolytes for ionic conducting batteries.

Eco-friendly and effective strategy to synthesize ZnO/Ag2O heterostructures and its excellent photocatalytic property under visible light

ZnO/Ag2O photocatalysts with heterostructure were synthesized by a green and effective mechanochemical method. The preparation process was taken in solid state at room temperature with a short grinding time. The as-made products showed a high degree of crystallinity without post-calcination treatment. Such synthetic method does not involve any organic solvents and the reaction matrix can be recycled. The as-prepared ZnO/Ag2O samples show excellent photocatalytic activity and photostability for degradation of different organic dyes under visible light. The content of Ag2O plays an important role in the photocatalytic activity, which can be tuned by the precursor AgNO3. The photodegradation rate constant (k) of the optimal ZnO/Ag2O sample under visible light is nearly 0.1004 min−1 for methylene blue (MB), 0.063 min−1 for rhodamine B (RHB) and 0.07 min−1 for methyl orange (MO), which are much better than the pure ZnO (0.0075 min−1). The enhancement of the visible light photocatalytic activity could be attributed to the heterojunction interfaces induced by the match of crystal lattice and energy band between the Ag2O and ZnO. The Ag2O generates the excited-state electrons under visible light irradiation. The excited electrons on Ag2O could directly transfer to the conduction band (CB) of ZnO, making ZnO/Ag2O present remarkable visible light photocatalytic activity.

Dielectric features, relaxation dynamics and a.c. conductivity studies on Ag+ mixed lead arsenate glass ceramics

The objective of this study is to investigate the influence of silver ions on a.c. conductivity and dielectric properties of lead arsenate glass ceramics. PbO–As2O3 glasses mixed with different concentrations of Ag2O were prepared by conventional melt quenching technique and later were ceramicized by heat treatment at crystallization temperature for about 72 h. The prepared samples were characterized by XRD, SEM and DSC techniques. The SEM studies have indicated the samples are embedded with different crystal phases of varying sizes from 0.2 to 1.0 µm and the fraction of crystal phases as well as the size of the crystallites increased with increase of Ag2O concentration. The X–ray diffraction studies have revealed that the samples composed of different crystal phases viz., Ag3AsO4, AgPb4(AsO4)3, Pb2As2O5 and PbAs2O4 entrenched in the residual amorphous phase. The spectroscopic studies viz., optical absorption and IR spectroscopic studies have revealed a gradual increase in the degree of depolymerization of the glass network with increase in the concentration of Ag2O. Photoluminescence studies have indicated that the investigated glass ceramics contain silver ion clusters; the concentration of such clusters is predicted to be higher in the samples containing higher content of Ag2O. Finally, we have carried out extensive studies on dielectric properties viz., dielectric constant, loss, electric moduli, impedance spectra and a.c. conductivity over broad ranges of continuous frequencies (3–100 kHz) and temperatures (298–600 K). The obtained results were quantitatively analyzed in terms of different polarization mechanisms. The relaxation effects exhibited by the electric moduli were analyzed in a detailed way by different methods. Spreading of relaxation times for dipoles was established and the possible dipoles responsible for such relaxation effects were suggested. The observed increase of a.c. conductivity with the concentration of Ag2O is attributed to the contribution of both polaronic and ionic transport. Finally, it is concluded that the samples crystallized with higher content of Ag2O exhibit predominantly ionic conductivity and hence such glass ceramics may be useful as solid electrolytes for solid state batteries.

Recyclable CoFe2O4–Ag2O magnetic photocatalyst and its visible light-driven photocatalytic performance

A magnetically separable photocatalyst, the composite compound CoFe2O4–Ag2O, was fabricated successfully by a simple precipitation method and used for photodegradation of organic pollutants under visible light (>420 nm) irradiation. Its magnetic separation performance was evaluated. Results showed that the CoFe2O4–Ag2O with 60-wt% content of Ag2O had the best photocatalytic performance, stability, and magnetic separation performance. Methyl orange, methylene blue, rhodamine B, and phenol can be completely photodegraded by the CoFe2O4–Ag2O photocatalyst in a short period. After five cycles, CoFe2O4–Ag2O kept its performance stability. As prepared, CoFe2O4–Ag2O (60%) has a coercivity of 2500 Oe and a saturation magnetization of 22.45 emu g−1; it can be completely separated magnetically in 20 s with magnetic recovery mass rate of 85% under an external magnetic field. This superb photocatalytic performance and separation recovery confirms that the CoFe2O4–Ag2O photocatalyst is a promising candidate for future use in photo-oxidative degradation of organic contaminants.

Electrical and physicochemical properties of some Ag2O-containing lithia iron silica phosphate glasses

The present paper reports the influence of Ag2O addition at the expense of Li2O on the local structure of xAg2O·(30 − x)Li2O·10Fe2O3·10SiO2·50P2O5 glass matrix (with x = 0, 0.5, 1, 1.5 and 2 mol %). The phosphate structural units of the network former are assessed from Fourier transform infrared (FT-IR) spectroscopy. The addition of Ag2O to the glass network matrix ≤1 mol % leads to the occurrence of a depolymerization process of the phosphate structure and consequently, to the appearance of a distortion of the PO4 tetrahedra. When the content of Ag2O is increased from 1.5 up to 2 mol %, a remarkable polymerization process has been observed. The density, molar volume, microhardness and chemical durability have been investigated in order to study the effect of Ag2O/Li2O replacements on the physicochemical properties the studied glasses. The AC electrical properties are affected to a great extent with composition. These results are related to the internal structure of the glass samples. The conductivity, dielectric constant and dielectric loss of the studied glasses were studied using the frequency response in the interval 100 Hz–100 kHz and the effect of compositional changes on the measured properties was investigated. Measurements showed that the electrical responses of glass samples were different and complex for interpretation. The increase of Ag2O addition at the expense of Li2O contents (from 0 to 1 mol %) led to increase the conductivity, dielectric constant and dielectric losses of samples. The addition of more Ag2O at the expense of Li2O (from 1.5 to 2 mol %), resulting into decreasing the conductivity, the dielectric constant and dielectric losses of the studied glasses. The experimental data of the glass samples were argued to the internal structure of the glasses and the nature and role-played by weakening or increasing the rigidity of the structure of the sample. It could be concluded, therefore, that the AC electrical properties of the samples were influenced by the distribution of its constituents, connectivity, and number of free charges.

Experimental investigation on hydrogen adsorption performance of composite adsorbent in the tank with high vacuum multilayer insulation

Hydrogen is one of the main residual gases in the high vacuum multilayer insulated tank. H 2 adsorption performance of the composite adsorbent was investigated by using a test bench, an X-ray diffraction and a scanning electron microscopy. The composite adsorbent is composed of molecular sieve 5A and getter that includes the different proportion of PdO and Ag 2O. The getter shall is laid as flat as possible when fed into the tank. Leakage and outgassing rate can be decreased by 64% after placing getter. The crystal phase structure of PdO and Ag 2O in getter is unchanged by adsorption performance. Experimental results showed that the H 2 adsorption rate is high at the initial stage, and then it starts to become slow during a relatively long period. The type IV isotherms were obtained with these samples, and the H 2 adsorption principle is also discussed. The optimum percentage content of Ag 2O in the getter is 22%. Under the allowed highest pressure, the composite adsorbent that includes 15% Ag 2O, 85% PdO and molecular sieve 5A is preferentially used in the tank interlayer. The experimental results and performance analyses can be used in the design of the high vacuum multilayer insulated tank.

Composite cathode Bi1.14Sr0.43O2.14-Ag for intermediate-temperature solid oxide fuel cells

Composites consisting of strontium stabilized bismuth oxide (Bi1.14Sr0.43O2.14, SSB) and silver were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria electrolyte. There were no chemical reactions between the two components. The microstructure of the interfaces between composite cathodes and Ce0.8Sm0.2O1.9 (SDC) electrolytes was examined by scanning electron microscopy (SEM). Impedance spectroscopy measurements show that the performance of cathode fired at 700 °C is the best. When the content of Ag2O is 70 wt%, polarization resistance values for the SSB-Ag cathodes are as low as 0.2 Ωcm2 at 700 °C and 0.29 Ωcm2 at 650 °C. These results are much smaller than some of other reported composite cathodes on doped ceria electrolyte and indicate that SSB-Ag composite is a potential cathode material for intermediate temperature SOFCs.

Phase diagram of V2O5-MoO3-Ag2O system

The results concerning the synthesis, structure and thermal properties of V2O5-MoO3-Ag2O samples in the vanadium rich region of ternary system are presented in the form of quasi-binary phase diagrams in which at constant V2O5/MoO3 molar ratios, equal 9:1, 7:3 and 1:1, the content of Ag2O was variable. A new ternary phase isostructural with NaVMoO6 has been detected in the investigated system.

Electrical impedance spectroscopy and aging behavior of glasses containing silver oxide and metallic silver nanoparticles

In this study we present the data on the observed electrical behavior of glasses in the xAg2O(1−x)PbO3B2O3 [0⩽x⩽1] system with the underlying aim of analyzing the contribution of silver nanoparticles in these glasses. We measured the dielectric response in the frequency region 10Hz–30MHz at room temperature and at 1kHz in the temperature region of 10–300K; dc conductivity was measured in the region of 80–300K. Analysis of the data shows that the parameters that describe the properties do not vary linearly with the content of Ag2O (parameter x) and the relative contribution of crystalline precipitates of Ag2O and that of Ag nanoparticles must be taken into consideration. Therefore, we interpret the electrical data in conjunction with the structural information obtained by X-ray diffraction, scanning electron microscopy (SEM) and photoluminescence (presented elsewhere) and show how the electrical properties reveal the presence of silver nanoparticles. Our data show that there is a clear break in the trend at x=0.5; at this composition SEM micrographs show a large amount of silver nanoparticles dispersed in the body of the glass. We also describe changes in the glasses that we observe when they are exposed to air for a long period.

Concentration-dependent acoustic and electrical properties of highly conducting Bi3.5Pb0.5Sr3Ca3Cu4Oz + xAg2O-type glassy precursors for high-T c superconductors

Abstract We report the concentration-dependent electrical conductivity and acoustic parameters of the (Bi-Pb)4Sr3Ca3Cu4Oz + xAg2O (x = 0-10 wt%)-type glassy precursors for high T c superconductors. Unlike (Bi, Pb)4Sr3Ca3Cu4OZ, or many other transition-metal oxide glasses, these Ag-containing glasses are highly conducting. Unlike many other transition-metal oxide glasses, the small-polaron hopping mechanism of conduction is found not to be applicable for these glasses, which might be due to a partial contribution of the Ag ions to the conductivity. The velocities of sound, elastic constants, microhardness, acoustic impedance and Debye temperatures are found to decrease monotonically, as does the density, with increasing Ag concentration. On the other hand, the thermal expansion coefficient, internal friction and Poisson's ratio increase with increasing content of Ag2O. The concentration-dependent acoustic parameters and the corresponding derived quantities indicate a softening of the glass structure with a...

Ag2O-B2O3glassy systems: network coherence behaviour as seen from molecular dynamics calculations

A study of molecular dynamics in ionic glasses Ag2O-B2O3 is presented. The analysis of the random structures obtained indicates that they are built up from triangular and tetrahedral distorted units BO3 and BO4. These units are connected by bridging oxygen atoms. The coordination change of the boron from three (typical of the pure boron oxide) to four is due to the addition of the metallic oxide, which acts as a network modifier. The formation rate of the tetrahedral BO4 groups follows the x/(1-x) law, x being the molar fraction of Ag2O, up to approximately 0.25 molar fraction, giving rise to a corresponding increase of the network coherence degree that defines the network connectivity. For a higher content of Ag2O an additional mechanism of non-bridging oxygen formation starts. These two mechanisms work in opposition to each other, decreasing the network coherence. The silver ions seem to be almost homogeneously distributed throughout the network to ensure charge neutrality.