Addition Of AgI Research Articles

Novel acousto-optic material based on Ge-Te-AgI chalcohalide glasses

A series of (GeTe4.3)100−x(AgI)x (x = 5, 10, 15, 20, 25, 30 mol%) chalcohalide glasses was prepared to investigate their potential in acousto-optic (AO) materials. Detailed thermal and optical properties of these glasses have been analyzed by DSC, XRD and FTIR. Meanwhile, refractive index, density, elastic modulus, acoustic velocity and attenuation, and the AO figure of merit (M2) were also reported. The results indicated that all these glasses presented a single glass transition temperature (Tg) and a single crystallization peak (Tx), and Tg decreases while Tx increases with the addition of AgI. X-ray power diffraction investigation showed the amorphous state of these synthesized glasses. They all have a wide transparent window from 2 to 20 μm, and acoustic attenuation was observed almost linearly proportional to the frequency at room temperature. Furthermore, refractive index and density increase, while acoustic velocity and elastic modulus decreases monotonously upon introducing AgI to GeTe4.3. The maximum refractive index (n = 3.729) and minimum acoustic velocity (V = 2.037 × 103 m/s) appeared in 70GeTe4.3–30AgI glass, thereby resulting in a maximum M2 of 3671 × 10−15 s3/kg at 10.6 μm. The outstandingly high M2 of this vitreous material make it attractive for far-infrared (FIR) AO modulators that require greater diffraction efficiency.

Biomedical Materials Based on Polymer-Colloid Dispersion of Succinamide Chitosan-Sol of Silver Iodide

Polymer-colloid dispersions which are products of interaction of macromolecules with inorganic sol are of special interest among polymeric materials of biomedical function. The water-soluble sodium salt of chitosan suссinamide (SChT) having a complex of unique properties, among which is biocompatibility with body tissues, bacteriostaticity, ability to biodegradation, and so on, has been used as a basis for creation of film composite materials for biomedical purpose. Sol of silver iodide (AgI) known for its bactericidal properties has been used as colloidal dispersion. Microbiological studies have shown that films on the basis of polymer-colloidal dispersion SChT-AgI possess the expressed bactericidal action, while individual sol and individual SChT at the chosen concentration are characterized only by a bacteriostatic effect. It is revealed that polymer-colloidal dispersion SChT-AgI promotes an increase in resistance of components of blood to action of hemolytic agents. It is established that addition of AgI leads to an increase in tensile strength and decrease in elongation fracture. It is shown that the obtained films in all cases destruct much more slowly and to a lesser extent than an initial film of SChT when maintaining good water-absorbing ability.

Silver phosphate glasses for immobilization of radioactive iodine

Management of radioactive 129I is a challenging issue due to its significantly long half-life and negative health effects. In this study, silver iodide (AgI)-incorporated silver phosphate glasses were prepared to immobilize 129I for a long time. A melt-quenching method was employed to synthesize the glasses at 450°C to prevent the evolution of I during the heat treatment. Characterization of the AgI-Ag2O-P2O5 specimens revealed that the addition of AgI was possible up to 60mol% into the glassy matrix although there were some amounts of Ag4I(PO4) and AgI clusters. This result was supported by the structural analysis which showed that the major iodine environment was composed of Ag and O regardless of the specimen compositions. The normalized leaching rates obtained by the 7-day PCT-A test showed that the chemical stability of iodine was satisfactory with the lowest leaching rate of 1.7×10−4gm−2/d. Our findings in this study demonstrate the potential of silver phosphate glass for the immobilization of radioactive 129I.

Chromic Acid Oxidation of Methylaminopyrazole Formamidine in Sulfuric Acid Medium: A Kinetic and Mechanistic Approach

The kinetics of chromic acid oxidation of one of aminopyrazole formamidine derivatives, namely N,N-dimethyl-N’ -(5-methyl-1H-pyrazol-3-yl) formamidine (MAPF)in sulfuric acid solutions has been investigated at constant ionic strength and temperature. The progress of the reaction was followed spectrophotometrically. The reaction showed a first order dependence on [chromic acid] and fractional-first order dependences with respect to [MAPF] and [H+]. Increasing ionic strength and solvent polarity of the reaction medium had no significant effect on the oxidation rate. Addition of AgI, PdII and RuIII catalysts was found to enhance the reaction rate and the order of catalytic efficiency is: AgI > RuIII > PdII. The final oxidation products of MAPF are identified by spectral and elemental analysis as methylaminopyrazole, dimethylamine and carbon dioxide. A spectral evidence for the formation of chromium(III) product was obtained. A reaction mechanism adequately describing the observed kinetic behavior is proposed, and the reaction constants involved in the different steps of the mechanism have been evaluated. The activation parameters with respect to the rate-determining step of the reaction, along with thermodynamic quantities of the equilibrium constants, are presented and discussed.

Formation and properties of chalcogenide glasses based on GeS2–Sb2S3–AgI system

Novel glasses in GeS2–Sb2S3–AgI system have been prepared by melt-quenching method. A large glass-forming region was found in this novel system, in which almost 60mol% AgI has been incorporated. The basic physiochemical properties of glass samples were investigated. With the addition of AgI, redshift of short-wavelength absorption edge and distinct drop of the glass transition temperature (Tg) were observed. In addition, a high Ag+ ion conductivity of 6.37×10−4S/cm at room temperature was obtained in 55(0.6GeS2–0.4Sb2S3)–45AgI sample, indicating that these glasses have potential application as amorphous solid electrolytes.

Mixed glass former effect in AgI doped silver borophosphate glasses

Abstract Mixed glass former effect has been investigated in AgI doped silver borophosphate glasses for the system 0.10AgI–0.90(0.50Ag 2 O–0.50(xB 2 O 3 –(1 − x)P 2 O 5 )). The network structure of these glasses has been investigated by FTIR spectroscopy. It has been observed that the structural evolution of these glasses with increase of B 2 O 3 content is not similar to that of undoped silver borophosphate glasses. The addition of AgI in silver borophosphate glasses affects the mixed glass former effect. FTIR spectra show that the phosphate glass network is continuously modified in the entire compositional range due to incorporation of B 2 O 3 . The network connectivity between the borate and phosphate network depends on the formation of P–O–B linkages and the concentration of three dimensionally connected P 3 and B 4 units. The compositional dependence of the glass transition temperature depends on network connectivity of the mixed glass formers. The electrical conductivity of these glasses depends on the distribution of different types of anionic site in the glass network.

Structure of AgI-doped Ge–In–S glasses: Experiment, reverse Monte Carlo modelling, and density functional calculations

We report an investigation of the structure and vibrational modes of Ge–In–S–AgI bulk glasses using X-ray diffraction, EXAFS spectroscopy, Reverse Monte-Carlo (RMC) modelling, Raman spectroscopy, and density functional theoretical (DFT) calculations. The combination of these techniques made it possible to elucidate the short- and medium-range structural order of these glasses. Data interpretation revealed that the AgI-free glass structure is composed of a network where GeS4/2 tetrahedra are linked with trigonal InS3/2 units; S3/2Ge–GeS3/2 ethane-like species linked with InS4/2− tetrahedra form sub-structures which are dispersed in the network structure. The addition of AgI into the Ge–In–S glassy matrix causes appreciable structural changes, enriching the Indium species with Iodine terminal atoms. The existence of trigonal species InS2/2I and tetrahedral units InS3/2I− and InS2/2I2− is compatible with the EXAFS and RMC analysis. Their vibrational properties (harmonic frequencies and Raman activities) calculated by DFT are in very good agreement with the experimental values determined by Raman spectroscopy.

Effect of AgI on Conduction Mechanism in Silver-Vanadate Superionic Glasses

A quaternary super-ionic glass system xAgI: (95-x) [Ag2O:2V2O5]: 5TeO2, where 40 ≤ x ≤ 65 in steps of 5, has been pre- pared by melt quenching technique. The prepared glass samples are characterized by X-ray, FTIR and DSC studies. As revealed by the FTIR spectra, the oxyanion network is not affected by the addition of AgI. The frequency dependence of the electrical conductivity for various glass compositions at different temperatures has been analyzed in terms of Jon- scher’s universal power law. The measurements reveal that the conductivity increases from σ = 7.62 × 10–7 S/cm to 1.15 × 10–4 S/cm with increasing AgI content. The temperature dependent conductivity obeys the Arrhenius relationship. The impedance and modulus studies indicate the non-debye type of the frequency dispersion for all the glass samples.

Vibrational modes and structure of (AgI) x (GeS 1.5) 100−x chalcohalide glasses

We report a structural investigation of bulk Ge-rich Ge–S–AgI chalcohalide glasses. A vibrational spectroscopic study of the quaternary system (AgI) x (GeS 1.5) 100− x (0 ⩽ x AgI ⩽ 20) has been undertaken using infrared spectroscopy and Fourier transform Raman scattering. It was found that the GeS 1.5 Raman spectrum is compatible with a glass structure composed of corner- and edge-sharing mixed GeS n Ge 4− n ( n = 0–4) tetrahedra where units with n = 2–4 dominate, whilst the fraction of corner-sharing units are significantly lower than the corresponding fraction in the stoichiometric GeS 2 glass. The addition of AgI has revealed a subtle but systematic effect in the structure of the Ge-rich glass matrix, manifested by mild decrease of the ES units and the concomitant increase of complex GeS n I 4− n or GeS n Ge m I 4- n − m tetrahedra whose vibrational modes form a continuum at low frequencies. Although, AgI seems to cause subtle structural changes due to the formation of Ge–I bonds, it is also evident that AgI does not act as a real modifier that would depolymerize appreciably the Ge–S network structure.

Both alcohol and halogenated solvents soluble soft-metal sensor functional phthalocyanines: synthesis, electrochemistry, spectroelectrochemistry

In this study, we report a novel both alcohol and haloganated solvent soluble selective ionophore functional ligand and its β-substituted 2(3),9(10),16(17),23(24)-tetrakis(1-hydroxyhexan-3-ylthio)-phthalocyanines, M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}, (Pc: Phthalocyanine) ( M = Zn , Cu , Co ), where -OH indicates peripheral functionality. Pcs exhibiting both hydrophobic and hydrophilic character were characterized spectroscopically (FT-IR, 1 H and 13 C NMR, MS (MALDI-TOF) and UV-vis), electrochemically and spectroelectrochemically. The complexes were soluble in both polar solvents, such as MeOH and EtOH, and non-polar solvents such as CHCl 3, CH 2 Cl 2, benzene, toluene, and even hexane. Absorption spectral changes of the functional MPcs during addition of AgI and PdII soft-metal ions are evaluated by monomer-oligomer and even polymer formations technique and monitored for in situ monitoring technique in the UV-vis spectroscopy. The binding process results in considerable blue-shift in the absorption spectra of MPcs . According to continuous variation method, the ligand:metal ratio was found ca. 1:1 and 1.5:1 for total concentration of 1.0 × 10-5 M and 7.5 × 10-5 M , respectively. Their electrochemical and spectroelectrochemical studies show that the complexes exhibited stable monoanionic M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}1-, dianionic M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}2- and monocationic M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}1+ species during reduction and oxidation processes.

Appearance of fast ionic conduction in AgI-doped chalcogenide glass powders prepared by mechanical milling

(AgI) x (As 2Se 3) 1− x glass powders were successfully obtained up to 70 mol% AgI content by the mechanical milling method. Electrical conductivities, which show the exponential increase with addition of AgI, are comparable to the values of the corresponding melt-quenched glasses. The conductivity of 60 mol% AgI-doped glass shows great increase at the early period of the milling. A DSC signal for the β–α phases transition of crystalline AgI becomes weak at the medium stage of the milling, whereas glass transition appears clearly. EXAFS measurements at Ag, I, As, and Se K-edges have been carried out for (AgI) 0.6(As 2Se 3) 0.4 glasses with different period of the milling. The amorphization process of (AgI) 0.6(As 2Se 3) 0.4 system was accompanied by a decrease of the nearest neighboring coordination number of Ag at the medium stage of the milling. These results suggest that the structural disordering of AgI units in the glass matrix would be strongly related to the appearance of fast ionic conduction.

Structure and dynamics on superionic conducting phosphate glasses by neutron scattering

Neutron diffraction and inelastic scattering experiments have been performed on superionic conducting phosphate glasses, AgI–AgPO 3 and its undoped glass AgPO 3. In general, the static, elastic and dynamic structure factors S( Q), S( Q, ω=0), S( Q, ω), respectively, exhibit a prepeak at very low Q∼0.7 Å −1 related to the intermediate range order ∼10 Å, but not for the AgPO 3. The low-energy excitation, or Boson peak (BP), at around 2–3 meV appears in all undoped and doped glasses.The amplitude of the BP increases and the position shifts to lower energy with addition of AgI. The inelastic contribution can be expressed in terms of sound waves, Δ S( Q, ω) α Q 2 S( Q), which is consistent with an acoustic mode. The expansion of the phosphate network plays a dominant role on increasing the mobility of the Ag ions, the ionic conductivity, the prepeak and the BP intensities.

Structural characterization of silver thioborosilicate glasses

Fast ion conducting glasses of composition zAgI+(1− z)[0.525Ag 2S+0.475(0.5B 2S 3+0.5SiS 2]), where 0.0⩽ z⩽0.4, have been studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry, and nuclear magnetic resonance (NMR), Raman, and infrared (IR) spectroscopies to investigate their short-range order (SRO) structure. These glasses are of significant interest due to the observation that they exhibit significant non-Arrhenius behavior in their ionic conductivity. A thorough study of the SRO of these glasses is being conducted to determine if there is an underlying structural origin to the non-Arrhenius behavior of the conductivity. The NMR, Raman and IR spectra show that these glasses are comprised primarily of silicon sulfide (Ag 2Si(S 2)S 2/2 and boron sulfide (AgBS 4/2) tetrahedra with small amounts of B 3S 6 thioboroxyl six-membered rings and BS 3/2 trigonal units in the glassy matrix. The addition of AgI appears dissolve into glass interstitially without significant modification of the SRO of the glasses. SEM experiments show the samples are homogeneous with little oxide contamination and the XRD experiments show that the samples are glassy with little evidence of crystallization. As with other AgI-doped glasses, the AgI systematically decreases the glass transition temperature. So far, there is no evidence of significant structural uniqueness at the SRO level to these glasses that would suggest a cause for the non-Arrhenius temperature dependence of the conductivity. More detailed neutron scattering and NMR studies of these glasses are in progress and will be used to determine if the structural origin of this behavior can be found at longer length scales.

Structural and electrical properties of AgI dispersed As-chalcogenide glasses

X-ray diffraction, EXAFS and Raman spectroscopic studies, together with transport phenomena measurements, have been carried out for (AgI) x (As 2Se 3) 1− x glasses in order to investigate the ionic conduction mechanism in AgI doped non-oxide glasses. The addition of AgI into As 2Se 3 glass is responsible for a pronounced increase in the electrical conductivity. Particularly, the ionic component of the electrical conductivity is dominant in highly doped glasses. Results of Raman spectra, EXAFS measurements and least squares fitting analysis for observed X-ray structural functions suggest that the local structure of the present glasses can be described as a pseudo-binary mixture of As–Se networks and fourfold coordinated AgI clusters.

Glass structure of the Ag2O-TeO2-V2O5 system

During the last years the interest to study the silvercontaining glass-forming systems has increased, due to the possibility to obtain materials exhibiting high ion conductivity [1–5]. By now mainly P2O5 and B2O3 have been used as a glass former for the ionic conducting glasses. A few publications are known on the synthesis of ionic conductive tellurite glasses [6–9] and also for V2O5 containing glasses [10–15]. In our previous investigations of the system Ag2OTeO2-V2O5 [16] a wide region of glasses (Fig. 1), which are synthesized in the central part of the system up to 40 mol.% Ag2O, using low cooling rate (≤100 degree/min) has been found. Meanwhile, many glass compositions in this system rich of V2O5 exhibit semiconducting properties [17], but with increasing Ag2O content high ion conductivity [18] is revealed. By the heat treatment of glasses in the 300–350 ◦C range, they easily crystallize with fine microstructure typical for glass-crystalline materials. The phase diagram of the Ag2O-TeO2-V2O5 system was also examined in detail [19, 20]. The fields of primary crystallization of twelve phases were outlined: 2TeO2·V2O5, Ag2O·TeO2, 3Ag2O·V2O5, 2Ag2O·V2O5, Ag2O· V2O5, Ag2O·2V2O5, Ag2O·7V2O5, TeO2, V2O5, Ag2O, Ag2O·3V2O5·6TeO2, and Ag2O·V2O5·2TeO2. In the Ag2O rich area dissociation of Ag2O to elementary silver has been noticed. This variety of crystal phases is a prerequisite for the synthesis of glasses with different structure. The glass structure of some compositions was also investigated. It is proved that the three-dimensional tellurite structure is destroyed and Te-non-bridging oxygen (NBO) bonds are formed with the increase of Agion content in the glasses of the Ag2O-TeO2 system [21]. The increase of Ag2O content up to 30 mol.% leads to the formation of TeO3 groups. S. Rossignol et al. investigate the structure of glasses from the system TeO2-AgO0.5-AgI. These glasses contain deformed TeO4 groups such as TeO3+1 groups. The structure of the tellurite network is not modified by the addition of AgI [7, 9]. Our purpose is to study the thermal stability and modifications of the structure of glasses with increase of silver ions in the glass formation range of the Ag2O-TeO2-V2O5 system. The determination of specific structural units of the glass network is made by IR-spectroscopy in accordance to the concept about the independent vibrations of separate groups in the glasses. They were discussed in detail many years ago by Tarte [22, 23] and Condrate [24, 25]. Glass compositions were chosen with a different Ag2O/TeO2/V2O5 ratio along Ag2O 2TeO2·V2O5 (A) and TeO2 Ag2O·2V2O5 (B) lines (Fig. 1). The choice was made having in mind the previous investigations of the glass forming region and the type of crystal phases, which could separate according to the phase diagram, during the thermal treatment procedure. As initial precursors for the synthesis were used reagent grade TeO2, V2O5 and Ag2O. After homogenization, the bathes were melted in porcelain crucibles at 600– 800 ◦C temperature range. The melts were quenched rapidly between two polished copper plates. A twin roller quenching technique was used for the compositions with high Ag2O content beyond the traditional glass-forming region. The samples were identified by X-ray powder diffractometer Philips APD 15 (Cu Kα radiation). The thermal behavior was investigated using Perkin-Elmer DSC 4 differential scanning calorimeter. The structure of the glasses was investigated by infrared absorption spectroscopy (IR) using SPECORD-M80 spectrometer preparing powder samples dispersed in Nujol. On Fig. 2 are presented DSC-curves and in Table I are summarized some thermal parameters of the glasses along a selected line (A). The glass-forming ability of melts and the thermal stability of glasses are interpreted using some criteria [26, 27]: (Tc− Tg), Tg/Tl,

Photoinduced changes in the optical constants of Ge–Se–AgI thin films

The photoinduced changes in the complex refractive index n = n − ik of thin films from the Ge–Se–AgI system with constant ratio Ge/Se=1/4 and concentrations of AgI of 0, 5 and 10 mol% are studied by real time measurements of reflectance ( R) and transmittance ( T) of the films. The phase delay ( δ) between the components of the transmitted wave, which is proportional to the birefringence of the film, is measured in real time as well. The changes in the average value of the refractive index (Δ n), and in the average value of the absorption index (Δ k) in the imaginary part of n as well as the induced optical anisotropy are estimated by solving the inverse optical problem. It is found that involving small quantities of AgI into a Ge–Se matrix increases the sensitivity of the films, but the anisotropic effects are comparatively weakly in them. The maximum values of changes in the average refractive index (Δ n=0.025) and in the average absorption index (Δ k=−0.03) are obtained in the films, containing 5 and 10 mol% AgI, respectively. Considerable values of the photoinduced anisotropy – birefringence ( Δn a≈−0.002) and dichroism ( ΔD≈0.05, which corresponds to Δk a≈0.035) are observed in films without addition of AgI (“pure” Ge–Se film).

The origins of neutron-scattering prepeaks and conductivity enhancement in AgI-containing glasses

Addition of AgI causes remarkable increases in the Ag +-ion conductivity of glass, and in some cases to the appearance of prepeaks in neutron scattering data (at Q = ca. 0.8 A ̊ −1 ). The origins of these prepeaks are discussed in relation to possible structural models. It is suggested that the enhanced conductivity is related to the formation of AgI clusters, but that local structure in the glass especially at the edge of these clusters is continuously modified by the mobile Ag + ions. According to the dynamic structure model, the mechanism of cation transport in AgI-based glasses therefore resembles that in other cation-conducting glasses.

Effect of tartrate on vanadium-catalysed chlorpromazine–bromate redox reaction and its application to the determination of vanadium in natural waters

The spectrophotometric determination of vanadium using the catalytic oxidation of chlorpromazine (CPH) with bromate was sensitized in the presence of sodium tartrate (TART) as an activator. The red oxidation product of CPH was monitored at 525 nm within a 1 min reaction time. Vanadium was determined by the measurement of its oxidation rate. The detection limit was 0.2 ng cm–3 using optimized reaction conditions of 5 × 10–4 mol dm–3 CPH, 5 × 10–3 mol dm–3 KBrO3, 0.1 mol dm–3 TART and 0.35 or 0.5 mol dm–3 H3PO4 at 25 °C. The calibration graph was linear up to 150 ng cm–3 VV or VIV. The interferences from Br–, I–, S2– and NO2– were eliminated by the addition of AgI and methanol. The proposed method was successfully applied to the determination of vanadium in rain and river waters.

Microscopic structure of doped borate glasses from molecular dynamics simulations

Abstract The structure of four metal-halide-doped borate glasses (MX)x (M2O-2B2O3)1−x (M = Ag, Li; X = I,Cl) was calculated using molecular dynamics. Addition of AgI, x = 0·6, does not affect the local structure of the B-O network; addition of LiCl, x = 0·6, leads to a little more open network and consequently to a decrease of the boron coordination number. Total structure factors of the four glasses have been calculated and compared with the neutron scattering data of Borjesson, Torell and Howells (1989). The comparison is good at high q values, 5 Å−1 < q < 30 Å−1, and confirms the short-range structure of the B-O network found also in other experimental results. As for the low-q region of the structure factors, the results of simulation and neutron scattering agree less satisfactorily for the AgI-rich glass than for the LiCl-doped glass. This study confirms that the ordering of the medium-range structure decreases when LiCl salt is added to the pure binary matrix. The partial radial distribution functions as well as the total radial distribution function have also been calculated. This latter function compares quite well with the Fourier transform of the total structure factor for the AgI-rich glass obtained by neutron diffraction.

ESCA studies of fast ion conducting glasses

The results of the X-ray excited Auger and photoelectron spectra for the AgI-Ag 2O-P 2O 5 glassy system are discussed here. The Ag core electron binding energies of the Ag 2O-P 2O 5 system do not show any appreciable changes with the variation of Ag 2O content whereas the addition of AgI as dopant results in significant changes, the values of which alter within a range limited by the different phases of AgI(α,β). The binding energies of O1s and P2p have not altered with the addition of AgI. The peak synthesis of P2p spectra reveals the abundant presence of different structural unit such as PO − 3 or P 2O 4− 7 or PO 3− 4 when the molar ratio of Ag 2O to P 2O 5 is 1 or 2 or 3 respectively. The values of the Auger parameters for silver and phosphorus indicate that the chemical environments of P and Ag are relatively more polarisable in doped system than in the undoped modified system.