AgBr Research Articles

Influence of interfacial water layer on surface properties of silver halides: Effect of pH on the isoelectric point

The hypothesis that pH dependent charge of interfacial water affects electrokinetic charge and electrokinetic potential of hydrophobic colloids, but not the (inner) surface potential was tested. It was found that isoelectric points of silver chloride, bromide and iodide shift to the higher pAg values in the acidic solutions, but that surface potential did not depend on pH. Isoelectric points of water at inert surfaces lie in the range 2<pH<4. In the neutral environment around pH≈7, the interfacial water is negatively charged due to preferential accumulation of OH− ions, with respect to H+ ions, thus increasing the negative electrokinetic charge of silver halide particles. In the acidic region, the isoelectric points of silver halides were shifted to the higher pAg values by 0.5–1.0pAg units depending on the type of silver halide, as well on the ionic strength of the solution. At pH≈3, the interfacial water is almost uncharged so that electrokinetic charge of silver halide particles is due to adsorption of silver and halide ions only. The conclusion was supported by mass titration experiments. Consequently, the electroneutrality points of silver halide surfaces correspond to values obtained in the acidic media. For silver chloride, pAgeln=5.3; for silver bromide, pAgeln=5.5; and for silver iodide, pAgeln=4.8.

Fine-tuning longitudinal plasmon resonances of nanorods by thermal reshaping in aqueous media

Metallic nanoparticles that support surface plasmons are potential building units for future nanophotonic circuits, metamaterials, high-density optical data storage, etc. Many of these applications require the ability to ‘dial-up’ the desired plasmonic resonance modes and frequencies with high precision. Here, we demonstrate a thermal reshaping route that can be used to tailor longitudinal plasmon resonance energies of gold nanorods almost continuously from ∼800 to ∼560 nm. The longitudinal plasmon resonance wavelength exhibits an exponential decay function of the thermal annealing time at a given temperature. This correlates with the transmission electron microscopy characterization (TEM) which showed that the nanorod aspect ratio decreases exponentially with time, accompanying a gradual shape transformation from rod to sphere. The exponential decay half-time decreases with increasing annealing temperatures, with a value of 1.43 × 105 s at 50 °C down to 0.02 × 105 s at 100 °C. Our experimental results show that the shape transformation could be attributed to desorption of silver ions and side facet-binding Ag–Br–CTA ligands, which therefore promote the side growth leading to nanorod fattening. Compared to other synthetic methodologies to tune plasmonics, our thermal reshaping approach presents a straightforward paradigm for precisely tailoring plasmon resonance energy with a single parameter.

Ultrasound-assisted coating of polyester fiber with silver bromide nanoparticles

The growth of silver bromide nanoparticles on polyester fiber was achieved by sequential dipping steps in alternating bath of potassium bromide and silver nitrate under ultrasound irradiation. The effects of ultrasound irradiation, concentration and sequential dipping steps in growth of the AgBr nanoparticles have been studied. Particle sizes and morphology of nanoparticle are depending on power of ultrasound irradiation, sequential dipping steps and concentration. These systems depicted a decrease in the particles size accompanying an increase in the sonication power. Results suggest that an increasing of sequential dipping steps and concentration led to an increasing of particle size. The physicochemical properties of the nanoparticles were determined by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Hydroquinone Synthesis of Silver Nanoparticles from Silver Bromide Suspensions

The results of research into the preparation of silver nanoparticles using photoreduction in the presence of hydroquinone as the reductant were discussed. Substrates for the synthesis of silver nanoparticles were ultrafine crystalline gelatine-stabilised aqueous suspensions of silver bromide. The influence of the reductant to substrate molar ratio and the medium’s pH to the ecient production of silver nanoparticles were studied. The properties of resultant silver particles were examined using UV-Vis spectroscopy. Transmission electron microscopy was used for the photomicrography of silver nanoparticles suspensions.

Synthesis of Silver Halide Nanosols

The aim of this work was to establish the average size of silver halide nanosols. The method applied was based on the optical turbidance measurements in real time of crystallization process. Dilute turbid suspensions of silver bromide, chloride and iodide stabilized by excess of halide ions and gelatin were measured over wavelength range from 450 nm to 600 nm. Experimental results were compared with the scattering theory of Rayleigh. Relation between dosing rate of reactants to dispersion system and size of obtained silver halide crystals was investigated. Interest in crystalline gelatine-stabilised aqueous suspensions of silver halide is due to their application as a substrate for the synthesis of silver nanoparticles.

Nanohybrids based on polymeric ionic liquid prepared from functionalized MWCNTs by modification of anionically synthesized poly(4-vinylpyridine)

We report the synthesis of a composite material comprised of poly(4-vinylpyridine) (P4VP) grafted on multiwall carbon nanotubes (MWCNTs) and the preparation of a nanohybrid via quaternization of the nitrogen atom per monomeric unit of the polymer chains. 4-Vinylpyridine was polymerized anionically using high vacuum techniques and was reacted with MWCNTs under vacuum to be grafted on the polymer segments. The composite material was soluble in common solvents and the dispersion of the carbon nanotubes was improved after quaternization due to the formation of polymeric ionic liquid (PIL) of the MWCNTs-g-[P4VP-r-poly(4ViEtPy+Br-)] type. The successful synthesis was confirmed with Fourier-transform infrared and Raman spectroscopies, whereas differential scanning calorimetry was adopted to verify the stability of the polymer's glass transition temperature before and after grafting on the MWCNTs. Moreover, thermogravimetric analysis was used for examining the thermal stability and the PIL formation of the composite. Energy dispersive spectroscopy measurements confirm the precipitation of silver bromide when the MWCNTs-g-[P4VP-r-poly(4ViEtPy+Br-)] is reacted with silver nitrite indicating the successful quaternization and formation of the appropriate PIL. High temperature size exclusion chromatography was used for the determination of the molecular characteristics (average molecular weight by number , polydispersity I) of the homopolymer obtained from the filtration of the composite material. Finally, field-emission scanning electron microscopy was used to verify the successful grafting of the polymer to the MWCNTs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Synthesis, Characterization and Luminescence of Silver(I) and Gold(I) Complexes Bearing a Diethyl Acetal Functionalized N-Heterocyclic Carbene

1-(2,2ʹ-Diethoxyethyl)-3-methyl-imidazolium bromide, 1, has been prepared and used as a precursor for the synthesis of the corresponding silver bromide complex [(NHC)2Ag][AgBr2], 2. Transmetallation of 2 with (tht)AuBr (tht = tetrahydrothiophene) yields (NHC)AuBr, 3. The solid-state structures of 2 and 3 have been determined by single-crystal X-ray diffraction revealing a loose aggregation of the complexes by weak metal-metal interactions. Due to the presence of these contacts, both complexes are emissive in the solid state.

Molecular dynamics simulation of silver bromide nanostructures in single-walled carbon nanotubes

Nanostructures formed upon filling single-walled carbon nanotubes of different diameters (ranging from 11.5 to 17.6 A) with silver bromide have been investigated using the molecular dynamics method. The results of molecular dynamics computer simulation have demonstrated that, in such tubes, AgBr nanotubes in the form of rolled-up two-dimensional crystalline networks (including structures both with a trigonal coordination and with a tetragonal coordination of ions) can be produced as well as fragments of the NaCltype structure, which is typical of bulk AgBr crystals. In the initial stage of their filling, the carbon nanotubes in the silver bromide melt are deformed, on average, to a greater extent than those in a similar system with AgI. After taking out from the melt, the degree of deformation of the nanotubes decreases and, in the majority of cases, AgBr nanotubular structures based on a hexagonal network are formed inside them.

Growth Kinetics of Silver Bromide Nanoparticles in Aqueous Nonionic Surfactant Solutions

The synthesis of silver bromide nanoparticles has been studied by many researchers because of their wide ranges of applications. This article reports on the growth kinetics of silver bromide nanoparticles in the presence and absence of aqueous nonionic surfactant media. The effects of different parameters such as the reactant concentration, the temperature, and the presence of a nonionic surfactant have also been studied. It was found that these parameters have significant effects on the process of growth kinetics, as well as on the equilibrium particle size. In pure aqueous media, the particle size decreases with increasing reactant concentration. The presence of nonionic surfactant (TX-100) significantly lowers the AgBr particle size compared to that obtained in pure aqueous media.

Photo-induced chemical reduction of silver bromide to silver nanoparticles

AbstractThis paper discusses the experimental results of the production of nanocolloidal silver using photoreduction method. Ultrafine crystalline gelatine-stabilised aqueous suspensions of silver bromide were used as a substrate for the synthesis of silver nanoparticles (Ag NPs). The influences of the reductant to substrate molar ratio, the medium’s pH, the type of the source of actinic radiation and the time of exposure to the efficient production of the Ag NPs were studied. A typical reaction was suggested, which involves the photo-induced reduction of silver bromide nanocrystals in the presence of ascorbic acid under specified physicochemical conditions. The properties of resultant silver particles were examined using UV-Vis spectroscopy and Dynamic Light Scattering (DLS). In addition, Transmission Electron Microscopy (TEM) was used for imaging the silver nanoparticle suspensions.

AgBr粒子による2, 2'-キノシアニンの吸着とその脱着

AgBr粒子による2, 2'-キノシアニンの吸着とその脱着

臭化銀, 硫化銀, 銀に対するシアニン色素の吸着におよぼす硝酸銀, 臭化カリウムの影響

臭化銀, 硫化銀, 銀に対するシアニン色素の吸着におよぼす硝酸銀, 臭化カリウムの影響

Preparation of silver nanostructure from silver(I) coordination polymer and fabrication of nano silver(I) bromide by reverse micelles technique

A new one-dimensional silver(I) coordination polymer, [Ag(μ-bpfb)(NO 3)] n ( 1); bpfb = N,N′-bis(4-pyridylformamide)-1,4-benzene, has been synthesized and characterized by IR, 1H NMR and 13C NMR spectroscopy. The single crystal X-ray data show that the silver(I) 1D coordination polymer grows into a three-dimensional network by hydrogen bonding and π–π stacking interactions. Compound 1 with nanorod morphology was also prepared by sonochemical method. The cetyltrimethylammonium bromide (CTAB) as a cationic surfactant was used in reverse micelles technique to obtain spongy silver(I) bromide nanoparticles from compound 1. Also, different silver nanoparticles have been prepared via direct calcination at 673 K and thermal decomposition in oleic acid from compound 1. The nanostructures of [Ag(μ-bpfb)(NO 3)] n ( 1), silver and silver(I) bromide were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDAX) analysis. Thermal stability of compound 1 in both bulk and nano-sized form was studied by thermal gravimetric (TG) and differential thermal (DT) analyses.

Studies on the adsorption of 125I on bromide coated silver rods for the preparation of 125I-seeds for brachytherapy applications

This paper describes a method for the preparation of 125I brachytherapy sources. The process consist of surface oxidation of a silver rods [0.5 mm (ϕ) × 3 mm (1)], formation of a thin silver bromide over layer and finally replacement of bromide ions by 125I− ions. The effect of various parameters such as 125I feed activity, iodide carrier concentration and reaction time were examined and optimized for maximum impregnation of 125I activity on the substrate. Sources containing 74–111 MBq (2–3 mCi) 125I on a silver matrix could be prepared and encapsulated in titanium capsules [0.8 mm (ϕ) × 4.75 mm (1)] using Nd: YAG laser. Quality assurance tests to ensure nonleachability, uniform distribution of activity and leak tightness that are necessary before application were evaluated.

Cover Picture: ZAAC ‐ Journal of Inorganic and General Chemistry 6/2011

The cover picture shows the octaanion of the salt [Et3MeN]8[{AgCl(GeB11H11)}4]. This silver chloride adduct was synthesized by reacting the silver halide with an equimolar amount of the nucleophile germa‐closo‐dodecaborate [Et3MeN]2[GeB11H11]. The Ag‐X heterocubane compound was also isolated and characterized in the case of silver bromide. Both silver halide adducts show germanium‐silver coordination and crystallize in the monoclinic space group C2/c with half of the octaanions in the asymmetric unit lying on a twofold axis of rotation. More details are discussed in the Short Communication by L. Wesemann et al. on pp. 643ff.

Two-Step Preparation of Silver Nanoparticles

The silver colloidal dispersions were obtained by two-step preparation method. The first step was based on preparation of the colloidal dispersions of silver bromide nanoparticles (NPs), which were reduced by sodium borohydride in the second step. The effective diameters of silver bromide nanoparticles and silver nanoparticles were determined by using of dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques. The colloidal dispersions of silver bromide nanoparticles were prepared by the reaction of silver nitrate and potassium bromide solutions mixed in various ratios. The influence of KBr/AgNO3 ratio to particle size was verified by using of two preparation ways. The first preparation way was based on using of the various concentration of potassium bromide and constant concentration of silver nitrate in the reaction systems. In the second case, the various concentration of silver nitrate and constant concentration of potassium bromide in the reaction systems were used. The KBr/AgNO3 ratios were 2, 5, 10, 20 and 50 in the both cases to easy comparison of obtained results. Synthesized silver bromide nanoparticles were reduced by sodium borohydride to silver nanoparticles with size between 29 and 50 nm.

Well-defined N-heterocyclic carbene silver halides of 1-cyclohexyl-3-arylmethylimidazolylidenes: synthesis, structure and catalysis in A3-reaction of aldehydes, amines and alkynes

Structurally well-defined N-heterocyclic carbene silver chlorides and bromides supported by 1-cyclohexyl-3-benzylimidazolylidene (CyBn-NHC) or 1-cyclohexyl-3-naphthalen-2-ylmethylimidazolylidene (CyNaph-NHC) were synthesized by reaction of the corresponding imidazolium halides with silver(I) oxide while cationic bis(CyBn-NHC) silver nitrate was isolated under similar conditions using imidazolium iodide in the presence of sodium nitrate. Single-crystal X-ray diffraction revealed a dimeric structure through a nonpolar weak-hydrogen-bond supported Ag-Ag bond for 1-cyclohexyl-3-benzylimidazolylidene silver halides [(CyBn-NHC)AgX](2) (X = Cl, 1; Br, 2) but a monomeric structure for N-heterocyclic carbene silver halides with the more sterically demanding 1-cyclohexyl-3-naphthalen-2-ylmethylimidazolylidene ligand (CyNaph-NHC)AgX (X = Cl, 4; Br, 5). Cationic biscarbene silver nitrate [(CyBn-NHC)(2)Ag](+)NO(3)(-)3 assumed a cis orientation with respect to the two carbene ligands. The monomeric complexes (CyNaph-NHC)AgX 4 and 5 showed higher catalytic activity than the dimeric [(CyBn-NHC)AgX](2)1 and 2 as well as the cationic biscarbene silver nitrate 3 in the model three component reaction of 3-phenylpropionaldehyde, phenylacetylene and piperidine with chloride 4 performing best and giving product in almost quantitative yield within 2 h at 100 °C. An explanation for the structure-activity relationship in N-heterocyclic carbene silver halide catalyzed three component reaction is given based on a slightly modified mechanism from the one in literature.

Hologram Recording Using Photothermographic Materials

Holograms were formed on a silver halide photothermographic material without carrying out wet treatment. Amplitude holograms whose gratings consist of rows of developed silver grains were formed, and the maximum diffraction efficiency of the gratings was almost 1.5%. When the amplitude holograms were bleached using bromine gas, they were converted to phase holograms, and the diffraction efficiency increased to a maximum of 6%. All areas turned yellow in color because of the formation of silver bromide. The mechanism of formation of gratings after bleaching has not yet been established. The authors propose that stripes of silver bromide, developer, toner, or other components may be formed by thermal development and subsequent bleaching. These stripes are transparent but have different diffraction indices, and this leads to the formation of gratings.

Silver halide planar waveguides and grating couplers for middle infrared integrated optics

We fabricated silver bromide (AgBr) planar waveguides with a thickness of ≈20 μm and designed reflective grating couplers for coupling the radiation of a tunable CO2 laser into these waveguides. We found that the attenuation was 6–9 dB/cm. The waveguides were used as attenuated total reflection elements for the sensing of hazardous pesticides in water in concentrations higher than 25 ppm. This work will pave the way for developing integrated optical elements and circuits which are based on silver halides and which operate in a broad spectral range in the mid-IR. These will be useful as chemical sensors and as spatial elements in nulling interferometry.

LARGE-SCALE SYNTHESIS OF UNIFORM SILVER BROMIDE NANOWIRES USING ION TRACK MEMBRANE AS TEMPLATE

Silver bromide (AgBr) nanowires were grown in the pores of ion track membrane. Simple chemical reaction technique was used where pores in the membrane act as reactors. Uniform morphology of nanowires was found using scanning electron microscopy (SEM). An X-ray diffraction (XRD) study shows the crystalline structure. Energy dispersive X-ray fluorescence (EDXRF) technique was used to study the composition of AgBr nanowires. Optical band gap of AgBr nanowires determined using absorption spectra was found to be higher than the bulk.