Molten Silver Chloride Research Articles

UV-VIS Absorption Spectra of Molten AgCl and AgBr and of their Mixtures with Group I and II Halide Salts

AbstractThe UV-VIS absorption spectra of (Ag1-X[Li-Cs, Ba]X)Cl and of (Ag1-X[Na, K, Cs]X)Br at 823 K at the concentrations X=0.0, 0.1, 0.2 have been measured. The findings show that on adding the respective halides to molten silver chloride and silver bromide, shifts of the fundamental absorption edge to shorter wavelengths result. A correlation between the observed shifts and the expansion of the silver sub-lattice is found, which is valid for both silver halide systems studied in this work.

The application of LA-ICP-MS in the examination of the thin plating layers found in late Roman coins

During the late Roman period the production of complex copper alloy (Cu–Sn–Pb–Ag) coins with a silvered surface, became common practice. Previous analyses of these coins did not solve key technological issues and in particular, the silvering process. Two methods have been suggested for the production of the thin plating layers in late Roman coins the dipping in molten silver chloride and the use of silvering pastes. However, there are questions about their use. More recent research showed that hot-dipping methods, such as the dipping in molten silver chloride, were not really suitable for mass production. Also, the earliest references to the use of silvering pastes dated to 17th century AD. A review of ancient sources and historic literature indicated silver amalgam plating as the possible method for the production of the plating in late Roman coins. Results derived from non-destructive LA-ICP-MS analysis have demonstrated, for the first time, the presence of Hg in the surface layers of these coins. The optimization of the method and the factors influenced the analyses results, are discussed. The examination of the coins by means of EPMA confirmed the ICP-MS results. The introduction of a new technique for the examination of plating layers, helped in the identification of amalgam silvering as the method used in the production of the coins.

Structure of the molten silver chloride

The structure of molten AgCl has been studied by neutron and X-ray diffractions. Significant differences in the neutron and X-ray total structure factors have been observed, reflecting different contributions of three partial structures Ag–Ag, Ag–Cl and Cl–Cl. By means of the reversed Monte Calro (RMC) structural modeling and analysis, partial structures have been calculated and then compared with the earlier work [J.Y. Derrien and Dupuy, J. Phys. Chem. Liq. 5 (1976) 71]. The results show that Cl–Cl correlations are similar to those for a close packed structure. Ag–Ag correlations are gas-like and the local structure of unlike pairs is similar to those for a rock salt type structure with vacancy sites.

Viscosity, Conductivity and Density of Fused Silver and Copper(I) Chlorides Doped with Group I and II Chlorides in the Mole Fraction Region 0 ≦ xdopant ≦ 0.1

The density, the electrolytic conductivity and the viscosity of molten silver chloride doped with NaCl, RbCl, MgCl2, CaCl2, SrCl2 and CdCl2, and of molten copper chloride doped with NaCl, KC1, CsCl, MgCl2, CaCl2 and BaCl2 have been measured in the concentration range 0 ≦ xdopant ≦ 0.1: the temperature range was 740 K ≦ T ≦ 900 K for silver chloride and 710 K ^ T ^ 850 K for copper chloride. The findings show that the molar conductance in such systems is strongly dependent on the ionic radii o f the cations: the viscosity, on the other hand, is mainly governed by their charge. A strong correlation exists between the formal activation energies o f conductance and viscosity, Ea η/Ea Λ being constant for all types and concentrations of dopant used in this work.

Delta-n control in GRIN glass by additives in AgCl diffusion baths

The uptake of silver from a molten silver chloride bath by an aluminosilicate glass is highly sensitive to the presence of sodium in the salt bath under both equilibrium and nonequilibrium conditions. The delta-n resulting from the silver dopant is reduced by nearly an order of magnitude by the addition of just 5-mol % sodium chloride to the melt. The addition of zinc chloride or lead chloride can be used to maintain high delta-n values in the presence of sodium in the melt.

Viscosity, Conductivity and Density of Fused Silver Chloride Doped with MeCln (Me = Li, K, Cs, Ba) in the Mole Fraction Region 0 ≦xdopant ≦0.1

The density, the electrolytic conductivity, and the viscosity of molten silver chloride doped with LiCl, KCl, CsCl, and BaCl2 have been measured in the concentration range 0 ≦x dopant ≦0.1 and temperature range 740 K ≧ Tm ≦900 K. The molar conductivity, Λ, decreases linearly with x dopant , the curve being independent of the charge of the added cation. Only in the case of LiCl is a very small increase of Λ observed. The viscosity of the melt remains virtually unchanged when doped with alkali halides. Addition of BaCl2 leads to a strong increase of the viscosity. The findings show that for these systems no correlation exists between the conductivity and the viscosity. It is further suggested that there is a strong influence of the long range Coulomb interaction on the viscosity of molten salts.

ChemInform Abstract: THE APPLICATION OF THE RELAXATION METHOD IN THE STUDY OF THE SILVER(I)/SILVER ELECTRODE REACTION IN PURE MOLTEN SILVER CHLORIDE

Chemischer InformationsdienstVolume 16, Issue 15 Physical Inorganic Chemistry ChemInform Abstract: THE APPLICATION OF THE RELAXATION METHOD IN THE STUDY OF THE SILVER(I)/SILVER ELECTRODE REACTION IN PURE MOLTEN SILVER CHLORIDE A. KISZA, A. KISZASearch for more papers by this authorJ. KAZMIERCZAK, J. KAZMIERCZAKSearch for more papers by this author A. KISZA, A. KISZASearch for more papers by this authorJ. KAZMIERCZAK, J. KAZMIERCZAKSearch for more papers by this author First published: April 16, 1985 https://doi.org/10.1002/chin.198515023Read the full textAboutPDF 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 onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue15April 16, 1985 RelatedInformation

The application of the relaxation method in the study of the Ag(I)/Ag electrode reaction in pure molten silver chloride

A new relaxation method developed for the study of fast electrode processes in molten salts has been applied to the system silverpure silver chloride electrode reaction. The cathodic rate constant k * c is of the order 10 5 s −1 and its temperature dependence is given by the equation k * c = 2.7579 × 10 6 exp (−1242.13/ T) with the activation energy 10.37 kJ mol −1.

Electrolytic Conductivity of Pure and Doped Molten Silver Chloride

The electrolytic conductivity of pure molten silver chloride and of molten silver chloride doped with up to 2mole% of CaCl2, CdCl2, CsCl, LiCl has been measured in the temperature range 460°C to 620°C. The changes in the conductivity of silver chloride when doped with ionic salts are found to be analogous to the conductivity changes found in binary alkali halide mixtures.

Structure of molten silver chloride

From neutron elastic scattering measurements using the technique of isotopic enrichment, the parital structure factors of silver chloride are obtained. These show important differences from CsCl, a...

ChemInform Abstract: THE ACTIVITY OF AGCL IN AGCL‐LICL‐KCL MELTS

AbstractDie thermodynamischen Funktionen von AgCl in der im Titel genannten Salzschmelze werden durch Messungen an der Zelle A ermittelt.

The Activity of AgCl in AgCl–LiCl–KCl Melts

Thermodynamic properties of silver chloride in molten silver chloride – lithium chloride – potassium chloride melts were studied using a silver chloride formation cell employing a chlorine electrode of novel design which facilitated measurements in ternary melts. The data were treated by analytical methods resulting in the generation of activity and the partial molar excess free energy at 500 °C.The measured properties were interpreted with the aid of a model which presupposed the existence of free silver ions as well as those "bonded" to adjacent chloride ions. With three adjustable parameters it was possible to account for the thermodynamic behavior of silver chloride.

Gravimetrie Interdiffusion Measurements in Molten Halides at Temperatures up to 1000 °C

Abstract The interdiffusion coefficient of bromide ions at low concentration in molten silver chloride has been measured with the gravimetric technique, and it can be "least-squares" fitted into the equation D23 = 6.58 x 10-4 exp { - (4280 ± 110) / RT) (503-820 °C) where D23 is expressed in cm2 s-1 and RT in cal equiv-1 . Friction coefficients as defined by Klemm do not indicate association between the chloride and bromide ions. The interdiffusion coefficients of potassium ions in molten sodium chloride at 900 °C and of sodium ions in molten potassium chloride at 995 °C, both at low concentration, have been found to be approximately 2 x 10-4 cm2 s-1

Thermodynamics of Molten Silver Chloride‐Alkali Chloride Solutions by Electromotive Force Measurements

Electromotive force measurements have been made using the reversible formation cell Various aspects of the cell design are discussed. Measurements were of sufficient precision to give the concentration dependence and the magnitude of the excess free energies, enthalpies, and excess entropies of mixing in the systems. The results are discussed in terms of covalent bonding in molten silver chloride. A simple semiquantitative “dual bonding” model is developed in which “ionic” and “covalent” silver coexist.

Electron spin resonance of vanadium in silver chloride

Vanadium-doped silver chloride is prepared by dipping vanadium metal into molten silver chloride. The vanadium enters the lattice substitutionally in the doubly ionized state. Silver-ion vacancies are associated with the vanadium ions in next-nearest cation positions at 93 °K. The symmetry of the crystal field at the vanadium ions is tetragonal and the values of the constants in the spin Hamiltonian are D = (557·2 ± 0·9) × 10-4 cm-1, A = (77·7 ± 0·5) × 10-4 cm-1, B = (76·3 ± 0·5) × 10-4 cm-1, g parallel = 1·9657 ± 0·0007 and g perpendicular = 1·9666 ± 0·0007. At 415 °K the vacancies are no longer associated. The field symmetry is octahedral and the values of the constants in the spin Hamiltonian are A = (77·7 ± 0·5) × 10-4 cm-1 and g = 1·9657 ± 0·0007. The situation is similar to that reported by Grossberg and by Daehler for manganese in silver chloride. The temperature variation in the width of lines which constitute the outer fine-structure components of the spectrum gives an activation energy of 0·30 ± 0·05 ev for vacancy motion. Vanadium-doped silver chloride is not found to be noticeably photo-active.

The Electrical Conductivity, and the Thermodynamic and Structural Properties of Molten AgCl ‐ Ag2 S Mixtures: II . Electrical Conductivities

The specific conductivities of molten silver chloride‐silver sulfide mixtures have been determined over the entire composition range. Pure molten silver sulfide is a good electronic conductor having a specific conductivity of 202 , with an almost negligible temperature dependence. The measured specific conductivity of pure molten silver chloride is in very close agreement with previous determinations. Silver chloride has a very low apparent activation energy for conduction. By comparison with the alkali halides, it is shown that the apparent activation energy for conduction of univalent salts is inversely proportional to their lattice energies. Dilute solutions of silver sulfide in silver chloride are ionic conductors. The specific conductivity in this region decreases and the apparent activation energy for conduction increases as the concentration of silver sulfide is increased. Above 20 mole % silver sulfide, the conductivity of the melts increases rapidly with increasing silver sulfide content and increasing temperature, as electronic conduction starts to occur. The activation energy for electronic conduction in this region is shown to be essentially composition and temperature independent. One per cent electronic conduction starts to occur at about 14 mole % silver sulfide at 750°C and at 24.5 mole % silver sulfide at 460 °C. Above 50 mole % silver sulfide the conductivity increases very rapidly, and the temperature dependence of the conductivity becomes negative. Structural changes in these melts appear to influence the electronic conduction markedly.

L'electrode chlore-charbon dans du AgCl fondu

The influence of anodic current density and that of temperature on the potential/time curves on open circuit of the chlorine/carbon electrode in molten silver chloride have been studied. There are two kinds of potential/time curve. When the preliminary polarization is at potentials near to the reversible potential, characteristic ‘flats’ on the open-circuit curves are obtained. These correspond to the desorption and diffusion of chlorine absorbed on the carbon electrode. If the preliminary polarization is at potentials from the reversible potential curves without flats are obtained; here, the depolarization on open circuit is controlled by the discharge of the double layer. Rise of temperature favours the appearance of residual currents. Rate constants and the activation energy of the depolarization process on open circuit have been calculated.

MOLTEN SALTS ELECTRICAL CONDUCTIVITY IN THE SYSTEM SILVER CHLORIDE – SILVER NITRATE

Conductivity and density data have been obtained for the system silver chloride – silver nitrate. The Arrhenius activation energy for electrical migration in molten silver chloride is constant at 1280 cal. mole−1 from 460 to 530 °C.; for silver nitrate there is a variation from 3300 cal. mole−1 at 220 ° to 2700 at 320 °C., which indicates a diminution of structural forces in molten silver nitrate with increase in temperature. The activation energy for binary melts of the two salts at 320 °C. is constant at 2700 cal. mole−1 from 0 to 20 mole % silver chloride; Frenkel's simple equation for the dependence of the activation energy on composition is not supported by this work.

Forest fires in France

During the late Roman period the production of complex copper alloy (Cu–Sn–Pb–Ag) coins with a silvered surface, became common practice. Previous analyses of these coins did not solve key technological issues and in particular, the silvering process. Two methods have been suggested for the production of the thin plating layers in late Roman coins the dipping in molten silver chloride and the use of silvering pastes. However, there are questions about their use. More recent research showed that hot-dipping methods, such as the dipping in molten silver chloride, were not really suitable for mass production. Also, the earliest references to the use of silvering pastes dated to 17th century AD. A review of ancient sources and historic literature indicated silver amalgam plating as the possible method for the production of the plating in late Roman coins. Results derived from non-destructive LA-ICP-MS analysis have demonstrated, for the first time, the presence of Hg in the surface layers of these coins. The optimization of the method and the factors influenced the analyses results, are discussed. The examination of the coins by means of EPMA confirmed the ICP-MS results. The introduction of a new technique for the examination of plating layers, helped in the identification of amalgam silvering as the method used in the production of the coins.

Electromagnetic mechanism, with special reference to telegraphic work

During the late Roman period the production of complex copper alloy (Cu–Sn–Pb–Ag) coins with a silvered surface, became common practice. Previous analyses of these coins did not solve key technological issues and in particular, the silvering process. Two methods have been suggested for the production of the thin plating layers in late Roman coins the dipping in molten silver chloride and the use of silvering pastes. However, there are questions about their use. More recent research showed that hot-dipping methods, such as the dipping in molten silver chloride, were not really suitable for mass production. Also, the earliest references to the use of silvering pastes dated to 17th century AD. A review of ancient sources and historic literature indicated silver amalgam plating as the possible method for the production of the plating in late Roman coins. Results derived from non-destructive LA-ICP-MS analysis have demonstrated, for the first time, the presence of Hg in the surface layers of these coins. The optimization of the method and the factors influenced the analyses results, are discussed. The examination of the coins by means of EPMA confirmed the ICP-MS results. The introduction of a new technique for the examination of plating layers, helped in the identification of amalgam silvering as the method used in the production of the coins.