AgCl Crystals Research Articles

Luminescence centres in pure AgCl crystals

The temperature dependence and the influence of pressure on band width of blue-green luminescence were measured in pure AgCl crystals. The comparison of results obtained with other published data support the existence of two luminescence centres (in the temperature ranges between 130–160°K and between 20–30°K).

Diffusion of Mn2+ in AgCl and AgBr Crystals

AbstractThe diffusion of Mn2+ in undoped and Mn‐doped AgBr and AgCl crystals is measured in dependence on temperature with the aid of radioactive tracers (Mn54). For AgBr:Mn the concentration dependence of the diffusion coefficient D is determined, there is a qualitative correspondence to the assumption of Mnc □c associates and a migration of the foreign ions via cation vacancies. The enthalpies for association (Ha = 0.22 eV for AgBr and 0.28 eV for AgCl) and for migration (Hm = 0.74 eV for AgBr and 0.56 eV for AgCl) are approximatively determined from the temperature dependence of D.

Phonon Scattering by Point‐Defect Aggregates in AgCl Crystals

Phonon Scattering by Point‐Defect Aggregates in AgCl Crystals

Detection of Ag2+ in doped AgCl crystals by ESR

physica status solidi (b)Volume 25, Issue 1 p. K55-K57 Short Note Detection of Ag2+ in doped AgCl crystals by ESR M. Höhne, M. Höhne Institut für Kristallphysik der Deutschen Akademie der Wissenschaften zu BerlinSearch for more papers by this authorM. Stasiw, M. Stasiw Institut für Kristallphysik der Deutschen Akademie der Wissenschaften zu BerlinSearch for more papers by this author M. Höhne, M. Höhne Institut für Kristallphysik der Deutschen Akademie der Wissenschaften zu BerlinSearch for more papers by this authorM. Stasiw, M. Stasiw Institut für Kristallphysik der Deutschen Akademie der Wissenschaften zu BerlinSearch for more papers by this author First published: 1968 https://doi.org/10.1002/pssb.19680250160Citations: 16AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume25, Issue11968Pages K55-K57 RelatedInformation

ESR Detection of Self‐Trapped Holes in AgCl

AbstractAg2+ centres are produced in doped and appropriately treated AgCl crystals by irradiation with blue light at 20 °K. It is shown that the only purpose of the preceding treatment is to create a high concentration of electron traps. In chalcogen doped crystals (AgCl:S, Se, Te) electron traps are formed by pre‐irradiation with blue light above 120 °K; in iron doped crystals the incorporated Fe2+ ions are converted to Fe3+, acting as traps, either by irradiation at 20 °C or by annealing in chlorine gas. As the paramagnetic data of the localized Ag2+ centres are independent of the kind of the impurity, one must conclude that the hole is trapped in the undisturbed lattice.

ESR Study of Cu2+ in AgCl Crystals Additionally Doped with Se or S

physica status solidi (b)Volume 27, Issue 1 p. K77-K80 Short Note ESR Study of Cu2+ in AgCl Crystals Additionally Doped with Se or S D. Schwarz, D. Schwarz Institut für Kristallphysik der Deutschen Akademie der Wissenschaften zu BerlinSearch for more papers by this author D. Schwarz, D. Schwarz Institut für Kristallphysik der Deutschen Akademie der Wissenschaften zu BerlinSearch for more papers by this author First published: 1968 https://doi.org/10.1002/pssb.19680270167Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume27, Issue11968Pages K77-K80 RelatedInformation

Tracks of charged nuclear particles in AgCl crystals

The effects of alpha particles in AgCl crystals which lead to tracks which can be rendered visible by `decoration' techniques have been found to have in some cases a very short lifetime which is a function of the structural properties of the crystals and the doping materials used. The formation of visible tracks therefore depends on the time interval between irradiation and decoration. This property could be made use of for the triggered recording of tracks.

Optical Absorption and Luminescent Emission of theI−Center in AgCl

The optical absorption and luminescent emission of AgCl crystals doped with small concentrations of AgI have been investigated. In such crystals, a narrow absorption band with intensity proportional to the iodide content can be resolved from the AgCl lattice absorption at low temperatures. Excitation in this (3.13-eV) band at low temperatures produces a distinct emission band peaking at 2.67 eV. The oscillator strength is found to be low (4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$), whereas the radiative lifetime is rather long (6 \ensuremath{\mu}sec). A model is proposed in which the excited electronic states for absorption and emission are effective-mass states resulting in small overlap with the closed-shell ground state.

Nonlinear Transport Phenomena in AgCl and AgBr at High Electric Field

The mobility of electrons in zone-refined and impurity-doped AgCl and AgBr crystals at high electric fields has been investigated over the temperature range from $T={4}^{\ensuremath{\circ}}$ K to 77\ifmmode^\circ\else\textdegree\fi{}K in order to examine the energy-momentum relation and to clarify the scattering mechanisms of slow and fast electrons in ionic crystals. The highest-purity crystals were obtained from ingots zone-refined 300 times in halogen atmospheres. Several crystals containing known amounts of iron impurity were also investigated. A fast-pulse technique was used to observe both the transient photoconductivity and the Hall mobility of the photo-electrons. The electrode geometry of Redfield was used in the Hall-mobility measurements. At high electric fields, the photocurrent $Q(T,E)$ was found to be proportional to the square root of the electric field $E$ in pure AgCl and AgBr crystals at low temperatures. The Hall mobility ${\ensuremath{\mu}}_{H}(T,E)$ of fast electrons in pure crystals at low temperatures was observed to be a decreasing function of the electric field, thus explaining the $Q(T,E)$ data. Such nonlinear behavior is weaker in the impurity-doped crystals and gradually disappears even in pure crystals as the temperature rises, for the same range of the electric fields. These results are discussed in terms of the hot-electron theory. An energy-dissipation mechanism similar to the scattering due to the acoustical mode of lattice vibrations is suggested as effective for fast electrons in ionic crystals.

The influence of an ultrasonic field on the conductivity of AgCl crystals

The influence of an ultrasonic field on the conductivity of AgCl crystals

Electroluminescence of AgCl Crystals Excited by Short Field Pulses

AbstractAn investigation is made of the electroluminescence excited by short electric field pulses in pure and doped (0.01 mol% TlCl or 0.01 mol% MnCl2) AgCl crystals. The majority of the results obtained (dependence of electroluminescence on voltage and pulse duration; threshold exciting voltage) are similar to electroluminescence phenomena in ZnS. Illumination of the electroluminescence cell by red light, and by UV light, respectively decreases and increases the electroluminescence brightness. Attempts to interpret the data in terms of a bipolar field emission model prove satisfactory under the assumption that the luminescence centres are cation vacancies.

Indirect Optical Absorption of AgCl-AgBr Alloys

High-resolution measurements of the optical absorption edge of pure crystals of AgBr and AgCl are in good agreement with the theory of phonon-assisted indirect transitions. The indirect optical absorption of AgCl-AgBr mixed crystals has been studied between 4.2 and 77\ifmmode^\circ\else\textdegree\fi{}K. At 4.2\ifmmode^\circ\else\textdegree\fi{}K, the addition of AgBr to AgCl causes the absorption edge to shift continuously from the pure AgCl threshold at 3.252 eV to the pure AgBr threshold at 2.691 eV. Above 5.7 mole% AgBr in AgCl, the absorption coefficient increases steeply to values considerably greater than that of pure AgBr at the same wavelength. The effect of the alloying on the pure-crystal absorption spectra is somewhat different for the two extremes of mixing. In AgBr-rich mixed crystals (>90 mole% AgBr in AgCl), a temperature-independent component with a sharp threshold is observed at an energy precisely halfway between the indirect phonon-emission and phonon-absorption thresholds (which still appear with phonon energy 0.0082 eV as in pure AgBr). This suggests that nonvertical transitions can occur in the alloy without the aid of phonons to conserve crystal momentum. The zero-phonon threshold is not so evident for dilute concentrations of AgBr in AgCl, where a weak shoulder and tail extends approximately 0.07 eV to longer wavelengths. Some comparison with theory is given, but present understanding of the band structure of alloys is rather incomplete.

Pulse measurements of thermostimulated currents in AgCl crystals

The course of thermostimulated currents in AgCl crystals was measured in a temperature region between 200‡ and 300‡K. Maxima at 240‡, 275‡ and 290‡K were observed on the curves obtained.

Light‐Induced Dispersal of Cu2+ Precipitates in AgCl Crystals

AbstractIn order to investigate changes in the Cu2+ center in AgCl due to dark storage and subsequent exposure or thermal treatment, exposed samples and halogen‐treated samples of copper‐doped AgCl were studied by electron spin resonance (ESR) and optical techniques. The results show that the precipitation of Cu2+ ions during dark storage can be reversed by exposure to light. Evidence is presented to support the hypothesis that both electronic and ionic steps are involved. The effect of the thermal treatment of exposed samples is also discussed.

ELectron traps in silver chloride crystals

The photoelectret state has been examined for AgCl crystals after treatment with heat and light; it is found that there are shallow electron trapping levels, whose ionization energy ɛ1 is about 0.2 eV and whose concentration n1 is about 1017 cm−3. These appear to be due to inherent defects in the lattice of AgCl.

The embrittlement of single crystals and bicrystals of agcl in aqueous salt solutions

The degree of embrittlement of bicrystal AgCl deformed in aqueous NaBr was studied as a function of the orientation of adjacent grains that make up a boundary and the angle that the grain boundary makes with the tensile axis. Embrittlement was observed when the angle between slip directions in adjacent grains exceeded about 20°. The degree of embrittlement was insensitive to variations in grain boundary angle to the tensile axis except for a boundary completely parallel to the tensile axis. It was concluded that the stress concentration at the head of a slip band with the aid of the environment causes initiation of cracks and that the resolved normal stress is active in propagating these cracks to cause intergranular failure. The embrittlement of notched single crystals of AgCl is attributed to the combined effects of stress concentration at the notch root, environment and the applied normal stress since crack propagation always occurred perpendicular to the applied tensile stress.

Note on the indirect absorption of pure and mixed crystals of AgCl and AgBr

Note on the indirect absorption of pure and mixed crystals of AgCl and AgBr

Tetrahedral ferric complexes in silver halides

Single crystals of AgCl and AgBr which contained iron impurity in the ferrous state were annealed in chlorine and bromine gas at about 350°C for approximately one half hour. An investigation by e.s.r. methods, after quenching to room temperature, showed that a portion of the iron impurity was oxidized to the ferric state. The stability of the ferric state at room temperature is dependent on the dislocation content of the crystals. It is suggested that the ferric ions are present interstitially in the crystal forming a complex which may be described as (Fe X 4) − where X is a halogen; the model in the case of AgCl requires association of the ferric ion with four nearest neighbour silver ion vacancies.

Electron Spin Resonance and Optical Studies on Copper-Doped AgCl

Upon exposure at room temperature, large, strain-free AgCl crystals containing up to ${10}^{17}$ cuprous ions per ${\mathrm{cm}}^{3}$ show a stable darkening (print-out) and an electron spin resonance (ESR) absorption which is characteristic of cupric ions. The intensity of the print-out band and of the ESR signal are proportional. Essentially all the cuprous ions are converted to cupric ions by prolonged exposure. For well-annealed crystals, the cupric ESR signal is stable below 180\ifmmode^\circ\else\textdegree\fi{}C in exposed samples and stable below 280\ifmmode^\circ\else\textdegree\fi{}C in halogenated samples, showing that the cuprous ion is a deep hole-trap at room temperature. When the samples are deliberately strained, there are rapid decays in the ESR signal at room temperature. Evidence from ESR suggests that such decays are related to coagulation of cupric ions. Exposure at -180\ifmmode^\circ\else\textdegree\fi{}C converts some cuprous to cupric ions without associated vacancies. Total conversion of cuprous to cupric ions by exposure at room temperature is not obtained in samples containing higher copper concentrations. It is suggested that, at sufficiently high concentrations, cupric ions can compete with intrinsic electron traps, thereby limiting the maximum ESR signal and darkening produced by exposure to smaller values than those expected on the basis of studies of samples with low copper concentration.

A note on the formation of etch pits on deformed AgCl crystals

A note on the formation of etch pits on deformed AgCl crystals