Crystal Habit Modification of Agel by Impurities Determining the Solvation

Claes, F.H.; Libeer, J.; Vanassche, W.

doi:10.1080/00223638.1973.11737712

Cited by 12 publications

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“…Furthermore, in view of the easy formation of octahedral AgBr prepared at pBr <2.5, the actual deems to be much lower than the theoretical = 188 mJ m -2 , since the difference between the theoretical and (=109 mJ m -2 ) is too large to form the octahedral shape, even if we take into account that the growth form of microcrystals is not necessarily determined only by the energetic requirement, , to say nothing of the small effect of the halide adsorption on the reduction of γ, as will be shown in part 4. Since the shape of AgCl particles in the same fcc crystal system is always cubic under any preparation conditions unless some specific adsorptives are used, , it is likely that of AgBr is reduced by some electronic relaxation of the open sites of the {111} faces or depolarization between cationic and anionic sites, due to the greater covalent nature of AgBr than AgCl. If such a , considerably lowered but still significantly higher than , contributes to raising the overall γ 0 of AgBr particles, the greater temperature dependence of γ 0 is expected, as a sign of such an effect is observed in the experimental γ for AgBr in Table .…”

Section: Discussionmentioning

confidence: 99%

A New Approach to Interfacial Energy. 3. Formulation of the Absolute Value of the Solid−Liquid Interfacial Energy and Experimental Collation to Silver Halide Systems

Sugimoto

Shiba

1999

J. Phys. Chem. B

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A new theoretical formula for the absolute value of the interfacial energy of the solid−liquid interface has been derived on the basis of the fundamental theory of interfacial energy described in J. Colloid Interface Sci. 1996, 181, 259; 1996, 183, 299. Namely, the intrinsic specific interfacial energy of a solid−liquid interface without adsorption is given by γ = −N σλkT ln x ( ∞ ), where N σ is the surface density of the surface monomers of the solid, λ is the ratio of the number of open bonding sites of a surface monomer to that of a free monomer, k is the Boltzmann constant, T is the absolute temperature, and x ( ∞ ) is the solubility of the bulk solid in terms of mole fraction of the monomers in the liquid phase against the total mole numbers of the solution components including the solvent molecules. Here, “monomer” refers to the minimum subunit of the solid such as AgCl, AgBr, etc. The formula has been collated to the experimental results of γ for AgCl, AgBr, and AgI, determined by potentiometric measurement of the size-dependent solubilities of these silver halide particles with the Gibbs−Thomson equation. The experimental results were in excellent agreement with the theoretical values for the silver halides. Also, some fundamental problems were found to be involved in Tolman's theory for size dependence of γ, and it has been deduced that γ must be independent of particle size, as has been confirmed by experiment.

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Section: Discussionmentioning

confidence: 99%

A New Approach to Interfacial Energy. 3. Formulation of the Absolute Value of the Solid−Liquid Interfacial Energy and Experimental Collation to Silver Halide Systems

Sugimoto

Shiba

1999

J. Phys. Chem. B

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“…Electron microscopic studies of the development of emulsions with microsystems "non-silver coresilver halide shell" in methylhydroquinone developer showed that the developed emulsion lacks "silver mustache" and on the surface of the nucleus formed particles of quasi-spherical silver nanometer size [42,43], responsible for the optical density of the emulsion. For this reason, photographic layers based on microsystems "non-silver coresilver halide shell" with low silver content give quite good optical densities [44][45][46]. To confirm this conclusion, an experiment was conducted in which the emulsion with microsystems "core 𝐶𝑎𝐹 2shell 𝐴𝑔𝐵𝑟" was compared with an emulsion containing homophase 𝐴𝑔𝐵𝑟 microcrystals, which was obtained 𝐴𝑔𝐵𝑟 under the same synthesis conditions as the shell 𝐶𝑎𝐹 2 .…”

Section: Properties and Spectral Sensitization Of Emulsions Containin...mentioning

confidence: 99%

Three-Dimensional Holographic Optical Elements Based on New Microsystems

Tyurin,

Zhukov,

Akhmerov

2024

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The origination and improvement of holographic methods, as well as technical equipment for their implementation [1–3] revived interest in light diffraction in three-dimensional periodic structures [4]. This is due to the fact that holographic methods allow to create a relatively simple and affordable technology for the manufacture of three-dimensional diffraction structures for both transmitted and reflected electromagnetic radiation of the visible range of the spectrum. Previously, light diffraction was used only in two-dimensional periodic diffraction structures, the manufacture of which was possible by other methods (chemical, photographic, mechanical, etc.) [5]. Diffraction in three-dimensional periodic structures for transmitted radiation has become widespread only for X-rays, for which a crystal lattice of various substances could be used as a three-dimensional periodic structure [6]. The use of diffraction of electromagnetic radiation of the visible spectrum on holographic three-dimensional structures (holograms) for practical purposes allows to create optical elements and optoelectronic devices of a fundamentally new class based on them, which have the widest range of applications [7–13]. For the first time the basic principles of obtaining three-dimensional diffraction structures for both transmitted and reflected electromagnetic radiation of the visible range of the spectrum by holographic optics (transmitting and reflecting holograms) were formulated by Denisyuk Yu.N. in 1962 [14]. The basis of this technology was a three-dimensional light-sensitive environment that provides registration (recording) of the interference pattern in its entirety. In order for the three-dimensional properties of diffraction (reading) on such a hologram to be most pronounced, the thickness of the hologram should be ≈100 μm or more [15], and diffraction should be carried out not only by changing the absorption coefficient of light-sensitive layer, as in traditional silver containing photoemulsions (amplitude hologram), but also as a result of changes in the refractive index of the layer (phase hologram). In the case of pure phase hologram light losses at diffraction should be minimal and diffraction effectiveness may reach 100% [16]. In the development of light-sensitive carriers, there are two approaches to three-dimensional holograms, which provide diffraction when reading in transmitted light, as well as preservation at room temperature and diffraction in the absence of recording light. The first of them is a two-stage process [17–20]. In the first stage – exposure at room temperature – the recording medium plays a passive role, memorizing the distribution of intensities of beams passing through it, in the second stage, using various chemical and photographic treatments, also at room temperature, this distribution is amplified and fixed. The use of silver halide compounds [21] provides a two-step process, both of which are realized at room temperature, an important advantage, such as high (boundary) sensitivity to hologram recording. But dividing possibility of such holograms with high diffractive effectiveness did not exceed 1000 lines/mm [22]. The second way is to move to non-silver environments [23–26]. The most promising from this point of view are photochromic systems based on colored alkaline halide crystals (AHS) and chalcogenide glassy semiconductors (CGS) 27–32. These materials do not require any intermediate work and change their optical characteristics directly under the action of radiation, forming in the volume of the medium at elevated temperatures amplitude-phase hologram, which provides diffraction in light, as modulation of the absorption coefficient and refractive index. When cooled to room temperature, they are resistant to reading with high diffraction efficiency and angular selectivity [8, 31]. For such holograms, the stages of formation (at elevated temperatures) and fixation (by cooling to room temperature) are inextricably linked and occur simultaneously, and the process of recording-fixation can be considered as one-stage. The main disadvantage of such environments is the need for elevated temperatures and low sensitivity in rather narrow range (400650 nm) of optical radiation, under the action of which a three-dimensional diffractive structure is formed. In this paper, for the registration of three-dimensional transmitting holograms at room temperature, we proposed an emulsion containing a heterophase microsystem "core CaF_2 – shell AgBr", which provides recording of holograms with high resolution and diffraction efficiency; high (boundary) sensitivity and wide spectral range (4001000 nm) optical radiation, under the action of which a three-dimensional hologram is formed. We also consider our proposed applications of holographic optical elements based on three-dimensional transmitting diffraction structures to solve some practical problems. Photochemical transformations in monolithic CGSs of As-S composition corresponding to holographic recording are considered. When using photochromic systems based on colored alkali-halide crystals and chalcogenide glassy semiconductors for the registration of three-dimensional transmitting holograms at elevated temperatures, we proposed spatial stabilization of the recording interference pattern, which achieves optimal characteristics of the recorded holograms. We also consider our proposed applications of optical elements based on three-dimensional transmitting diffraction structures to solve some practical problems.

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“…For example, silver chloride, which under most conditions grows with cubic structure (45), can be prepared with octahedral and dodecahedral morphologies if habit modifiers are used (46). Figure 5 shows electron micrographs of cubic, octahedral, and tabular silver bromide grains.…”

Section: Techniques Of Crystal Growthmentioning

confidence: 99%

Photography

Locker¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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PHOTOGRAPHYThe unique light-sensing properties of silver halide crystals have been recognized since the 1500s. In spite of many technical advances in nonsilver halide (eg, electronic) technologies, chemically based silver halide systems continue to dominate in the ability to record images (1-3) of superb image quality and archival characteristics. Photochemical reduction in which the silver ion, Ag + , in the ionic silver halide crystal is reduced to elemental silver, Ag 0 (4-7) was first observed by the alchemist Fabricius in 1556. As photochemical reduction continues, elemental silver atoms aggregate and grow into clusters of a colloidal size sufficient to scatter light and produce hue shifts. The science of photography uses this photochemical property of silver halide to form images and record scenes. One of the earliest researchers to produce such a photochemical image was Schultze in 1727 (8). In these experiments, solutions of silver nitrate and white chalk were photochemically reduced to produce metallic silver images when the solutions were exposed through stencils.The daguerreotype process, prepared by Daguerre in 1837, and the calotype process, produced by Talbot in 1841, were among the first photographic techniques to produce continuous-tone images as reproductions of scenes (9, 10). The steps of a typical daguerreotype process include polishing and cleaning a silver-plated copper plate; treating the silver side of the plate with iodine vapors to convert silver into light-sensitive silver iodide [7783-96-2], AgI; exposing the plate through the optics of a camera that projects and focuses a scene on the plate, ie, where light strikes these plates, silver ions are photochemically reduced to silver metal; and treating the exposed plate with mercury. The mercury reacts with silver metal to produce a silver amalgam.White silver amalgam appears in areas of the plate exposed by light; the unexposed areas remain dark, thereby producing a positive image.Daguerrotype images were produced primarily by the action of light. For the production of satisfactory images, long exposures to light, on the order of minutes, were required because many absorbed photons were necessary to reduce photochemically enough silver ions to silver metal for visible imaging. In 1841, Talbot announced the calotype process, which could reduce exposure times to seconds and produce visible images without dependence on the action of light (11). In the calotype process, the exposure of silver halide produced an invisible latent image that was composed of only trace amounts of reduced silver. This acted as a catalyst for subsequent chemical reduction, ie, a nonphotochemical continuation of the light-initiated reduction process that eventually produced a visible silver image. In addition to being sensitive to much lower light levels, the calotype process was less expensive than the daguerreotype process and provided a negative-positive system that could generate several positive copies from a single negative original. The use of chemical amplif...

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Crystal Habit Modification of Agel by Impurities Determining the Solvation

Cited by 12 publications

References 0 publications

A New Approach to Interfacial Energy. 3. Formulation of the Absolute Value of the Solid−Liquid Interfacial Energy and Experimental Collation to Silver Halide Systems

A New Approach to Interfacial Energy. 3. Formulation of the Absolute Value of the Solid−Liquid Interfacial Energy and Experimental Collation to Silver Halide Systems

Three-Dimensional Holographic Optical Elements Based on New Microsystems

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