First Principle Calculations for Silver Halides AgBr, AgCl, and AgF

Density functional theory (DFT) coupled with ) method are carried out to calculate the electronic structures of AgX (X; Br, Cl, and F). The effect of hybridizing between 4d orbital of Ag element and the p orbitals of the X in the valence band plays a very important role in the total density of states configuration. The electronic structure has been studied and all results were compared with the experimental and theoretical values. The importance of this work is that there is insufficient studies of silver halides corresponding the great importance of these compounds. Almost all the results were consistent with the previous studies mentioned here. We found the band gap of AgX to be 2.343 eV, 2.553 eV, and 1.677 eV for AgBr, AgCl, and AgF respectively which are in good agreement with the experimental results.

Synthesis and Characterisation of Photocatalyst Silver/Silver Halide Nanocomposites

<p>The photochemical activity of silver halides forms the basis of photography and latent image formation. More recently it has been used to create hybrid silver/silver halide nanoparticles. These are formed through partial reduction of Ag⁺ to Ag⁰ by a photochemical self-sensitisation when irradiated with light. This gives the silver/silver halide nanoparticles interesting photocatalytic properties. As such, these silver/silver halide nanoparticles have seen to be part of group of photocatalysts known as plasmonic photocatalysts. Where, the photocatalytic mechanism is enhanced by the surface plasmon resonance of noble metal nanodomains on the surface of the silver halide nanoparticle. The silver/silver halide nanoparticles of Cl⁻, Br⁻ and I⁻ were synthesised and characterised. Silver/silver halide nanoparticles were then incorporated into porous support materials creating silver/silver halide nanocomposite materials. This was through a straight forward aqueous synthesis method, where silver halide nanoparticles precipitated from solution, and nanoparticle size, shape and stabilisation was controlled by the porous support material. Silver/silver halide nanocomposite samples using Cl⁻, Br⁻ and I⁻ were synthesised using wool fibres, kraft paper fibres and nanostructured calcium silicate as supports. UV/Vis and XRD showed Ag⁰ nanodomains were formed during the self-sensitisation process. SEM showed the morphology of the nanocomposites and that the nanoparticles were distributed within the nanocomposite matrix, not deposited on the surface. Preliminary photocatalytic activity of Ag/AgCl nanoparticles and nanocomposites was evaluated through the degradation of methylene blue when irradiated with light. All samples showed increased photocatalytic activity with the Ag/AgCl nanoparticles.</p>

Synthesis and Characterisation of Photocatalyst Silver/Silver Halide Nanocomposites

<p>The photochemical activity of silver halides forms the basis of photography and latent image formation. More recently it has been used to create hybrid silver/silver halide nanoparticles. These are formed through partial reduction of Ag⁺ to Ag⁰ by a photochemical self-sensitisation when irradiated with light. This gives the silver/silver halide nanoparticles interesting photocatalytic properties. As such, these silver/silver halide nanoparticles have seen to be part of group of photocatalysts known as plasmonic photocatalysts. Where, the photocatalytic mechanism is enhanced by the surface plasmon resonance of noble metal nanodomains on the surface of the silver halide nanoparticle. The silver/silver halide nanoparticles of Cl⁻, Br⁻ and I⁻ were synthesised and characterised. Silver/silver halide nanoparticles were then incorporated into porous support materials creating silver/silver halide nanocomposite materials. This was through a straight forward aqueous synthesis method, where silver halide nanoparticles precipitated from solution, and nanoparticle size, shape and stabilisation was controlled by the porous support material. Silver/silver halide nanocomposite samples using Cl⁻, Br⁻ and I⁻ were synthesised using wool fibres, kraft paper fibres and nanostructured calcium silicate as supports. UV/Vis and XRD showed Ag⁰ nanodomains were formed during the self-sensitisation process. SEM showed the morphology of the nanocomposites and that the nanoparticles were distributed within the nanocomposite matrix, not deposited on the surface. Preliminary photocatalytic activity of Ag/AgCl nanoparticles and nanocomposites was evaluated through the degradation of methylene blue when irradiated with light. All samples showed increased photocatalytic activity with the Ag/AgCl nanoparticles.</p>

Creating nanoscale luminescence centres in silver halides suitable for infrared application

This study shows the possibility of creating luminescence centres in silver halide media using substances based on rare-earth elements such as neodymium, ytterbium and dysprosium. These luminescent substances in the form of fine particles of both nanoscale and microscale dimensions can be introduced into the AgCl0.25Br0.75 ceramic matrix highly transparent in the spectral range of 0.5–35 μm. Our theoretical and experimental studies showed that the introduction of luminescent nanoparticles or microparticles at the amount of 0.5 wt.% into AgCl0.25Br0.75 ceramics neither reduces the level of its transmission in the MIR region nor shortens the range of transmission. What is more, we proved that the luminescent properties of nanoparticles remain well preserved after doping silver halide ceramic media with them. Therefore, silver halides doped with rare-earth elements in question can be used for developing the sources of coherent middle infrared radiation, with appropriate energy levels being excited by optical radiation or pulsed electric field.

Tilting and rotational motions of silver halide crystal with diffracted X-ray blinking

The dynamic properties of crystalline materials are important for understanding their local environment or individual single-grain motions. A new time-resolved observation method is required for use in many fields of investigation. Here, we developed in situ diffracted X-ray blinking to monitor high-resolution diffraction patterns from single-crystal grains with a 50 ms time resolution. The diffraction spots of single grains of silver halides and silver moved in the θ and χ directions during the photolysis chemical reaction. The movements of the spots represent tilting and rotational motions. The time trajectory of the diffraction intensity reflecting those motions was analysed by using single-pixel autocorrelation function (sp-ACF). Single-pixel ACF analysis revealed significant differences in the distributions of the ACF decay constants between silver halides, suggesting that the motions of single grains are different between them. The rotational diffusion coefficients for silver halides were estimated to be accurate at the level of approximately 0.1 to 0.3 pm2/s. Furthermore, newly formed silver grains on silver halides correlated with their ACF decay constants. Our high-resolution atomic scale measurement—sp-ACF analysis of diffraction patterns of individual grains—is useful for evaluating physical properties that are broadly applicable in physics, chemistry, and materials science.

Synthesis, crystal chemistry, and optical properties of two methylammonium silver halides: CH3NH3AgBr2 and CH3NH3Ag2I3

Two novel ternary compounds from the pseudobinary CH3NH3X–AgX (X = Br, I) phase diagrams are reported. CH3NH3AgBr2 and CH3NH3Ag2I3 were synthesized via solid state sealed tube reactions and the crystal...