Electrical conductivity and crystal structure of piperazinium 10-silver 12-iodide·4-dimethylformamide

Crystals of (C₄N₂H₁₂)Ag₁₀I₁₂·4C₃H₇NO contain channels formed by face-sharing iodide tetrahedra. These channels, parallel to the monoclinic $\text{c}$-axis, are isolated from each other by the (C₄N₂H₁₂)²⁺ ions and C₃H₇NO molecules. Electrical measurements along the $\text{c}$-axis of the crystals at 200 psig (argon) indicate that the material does not become a true solid electrolyte below 332 K, the decomposition temperature. Structural considerations show that despite the substantial ratio (3:1) of sites to Ag⁺ ions, the material is not expected to become a solid electrolyte, if it retains its room temperature structure, at any temperature or pressure.     

Synthesis and properties of a zinc cadmium sulfide based low-voltage cathodoluminescent phosphors

This paper describes the fabrication of a red-orange-emitting (Zn,Cd)S:(Ag,In,Sb) cathodoluminescent phosphor which offers enhanced brightness at a low excitation voltage. The effects of antimony and chlorine added to the starting mixture as coactivators are analyzed. The largest brightness gain, observed at C _Sb/C _Ag ≃ 1.3, is probably due to the formation of Ag⁺-Sb³⁺ associates. Increasing the C _Sb/C _Ag ratio to above ≃ 2.2 leads to quenching of luminescence.     

Ionic conductivity of Ag+ exchanged α-zirconium phosphate

The conductivity of silver ion in silver exchanged α-zirconium phosphate, Zr(AgPO₄)₂, was measured in the temperature range 80 to 330°C. The data were found to conform to an Arrehnius type behavior in this temperature range with an activation energy of 0.53eV and ⁰300°C = 1.94 × 10^?4 ohm^?1 cm^?1. The conductivity values for Ag⁺ are higher than the corresponding values obtained for Na⁺ and K⁺ conduction in their respective exchanged forms. This enhancement is attributed to the greater polarizibility of the silver ion.     

Photoluminescence properties and photocatalytic reactivities of Cu/zeolite and Ag/zeolite catalysts prepared by the ion-exchange method

Transition metal ions (Cu⁺, Ag⁺) incorporated within the cavities of zeolites by an ion-exchange method exhibit unique photoluminescence under UV irradiation due to the inner shell type electronic transition (d⁹s¹ → d¹⁰). Detailed photoluminescence investigations revealed that the transition metal ions exist in highly dispersed state with linear 2 coordination sphere and interact with NO_x (NO and N₂O) in their photoexcited states. In fact, Cu⁺ and Ag⁺ ions within zeolites show an efficient and unique photocatalytic performance for the decomposition of NO into N₂ and O₂ at ambient temperature. Detailed studies of the interaction of NO_x with the excited states of these metal ions indicated that an electron transfer from the s orbital of the excited state of Cu⁺ or Ag⁺ ions into the π^* antibonding orbital of NO_x initiates the decomposition of NO_x into N₂ and O₂.     

Metal-Containing Zeolites as Sorbents for Localization of Radioiodine and CsI Aerosols from Vapor-Air and Aqueous Phases

New sorbents for efficient sorption of radioiodine and radiocesium from the vapor-gas phase and aqueous solutions were prepared by treatment of Cu⁺- and Ag⁺-substituted NaX and NaA zeolites with acetylene in aqueous solution. The distribution factor K _d of radioiodine and radiocesium between the modified sorbents and aqueous solutions is higher than 10³-10⁴ ml g^{- 1}. Decontamination factor of the vapor-gas phase with respect to radioiodine and ¹³⁷CsI aerosols exceeds 10²-10³ and 10³, respectively. The sorption properties of the modified sorbents in both aqueous solutions and the vapor-gas phase are better than those of the initial sorbents. However, localization of radioiodine from the vapor-gas phase with the Cu⁺-containing sorbents is less efficient than with the Ag⁺-containing zeolites. At the same time, in aqueous solutions the sorption capacity of the Cu⁺-containing sorbents for radioiodine is appreciably higher than that of the Ag⁺-containing sorbents. The sorption properties of the modified sorbents were studied as influenced by various factors. Paracomplexes of univalent copper and silver with C₂H₂, H₂O, and anions present in the solution are probably formed during modification of the metal-containing zeolites. The dependence of K _d of radioiodine on the metal concentration in the sorbent, the free pore volume of the sorbent, and the anion nature was revealed.     

Phase diagram study of the formation and crystallization of Ge-metal amorphous alloy films

The Ge-Au and Ge-Ag alloy films were deposited in vacuum at room temperature and then systematically observed in the TEM. The maximum metallic concentrations in the alloy films,C _max, which form the stable amorphous alloy phases of germanium with gold and silver, were obtained. The annealed crystallization temperatureT _c, which falls with increasing metallic content in these films was also found. The structures of these films and their annealed specimens were also studied. There are various factors which influence the formation of amorphous alloy films deposited in vacuum for Ge-metal systems. A new formula forC _max has been derived. The annealed crystallization character has been explained by means of the variation of the free energy and the activation energy of crystallization. The activation energy of crystallization,E _a, can be obtained from the data values ofT _c. For Ge-Au films,E _a (Au)=E _a ^o /(–18.66C _Au ² +16.83C _Au+1)±3.3 (kcal mol^–1); for Ge-Ag films,E _a (Ag)=E _a ^o /(–2.754C _Ag ² +3.815C _Ag+ 1)±2.6 (kcal mol^–1). In order to explain all these results, two kinds of phase diagram for the alloy films have been introduced. One is the three-dimensional relationship diagrams of phase formation in semiconductor-metallic alloy films; it was introduced to explain the influencing factors. The other is the three-dimensional phase diagrams of annealed semiconductor-metallic films systems. From this diagram all the phase transitions can be found.     

Structural and electrical studies on thin films of solid electrolyte Ag6I4WO4

An electrolytic method of preparation of thin films of solid electrolyte Ag₆I₄WO₄ on a silver substrate is described. Films of different quality were obtained when the electrolysis was carried out at different temperatures and current densities. X-ray diffraction studies were carried out to confirm the compound formation. Scanning electron micrographs were taken in order to study the surface characteristics of these films. Investigations on the a.c. electrical conductivity of films prepared at different electrolysis temperatures (10 to 80° C) and two current densities (2 and 10 mA cm^–2) are also reported in the temperature range 30 to 130° C. The films deposited at 65° C gave values of room temperature conductivity and the activation energy for Ag⁺ ion conduction as 0.04 ^–1 cm^–1 and 0.132 eV, respectively.     

Les composes Ag7AsS6 et Ag7AsSe6 etude des proprietes thermiques,cristallographiques et electriques

The preparation and the partial phase diagrams Ag₂X“As₂X₅” (X = S or Se) are described. Peritectic decompositions occur at 560°C for Ag₇AsS₆ and 360°C for Ag₇AsSe₆. Phase changes are observed at 250°C for Ag₇AsS₆ and 150°C for Ag₇AsSe₆. For each compound, the low temperature form is cubic P2₁3, and the high temperature form has the Ag₈GeTe₆ structural type, F$\text{4}$3m. The high temperature forms are not quenchable. Ionic and electronic conductivity have been measured in Ag₇AsS₆ and Ag₇AsSe₆. Ionic conductivity was measured using RbAg₄I₅ as a blocking electrode for electronic conduction. Electromotive force measurements confirm transference numbers. At room temperature, ionic conductivities were 1,5.10^?6 (Ω.cm)^?1 and 0,08 (Ω.cm)^?1 for Ag₇AsS₆ and Ag₇AsSe₆ respectively.     

Palm‐Sized Ag+ Ion Emission Gun Operated at Room Temperature in Non‐Vacuum Atmosphere

Ion implantation is an effective method for changing surface properties and inducing various functionalities. However, a high vacuum is generally necessary for ion implantation, which limits the range of applications. Here, we describe a palm‐sized Ag⁺ ion emission gun produced using a solid electrolyte. AgI–Ag₂O–B₂O₃ glass, known as a super‐ion‐conducting glass, has a Ag⁺ ion conductivity higher than 5 × 10^?3 S cm^?1 at room temperature. In addition, the melted glass has suitable viscous flow, and a sharp glass‐fiber emitter with a pyramid‐like apex can be obtained. Ag⁺ ion emission is observed from the tip of the glass fiber at accelerating voltages corresponding to electric fields above 20 kV cm^?1, even at room temperature in a non‐vacuum atmosphere. Ag nanoparticles of size 50–350 nm are precipitated on a Si target substrate. Other glass components such as boron and iodine are not detected. Electrochemical quartz crystal microbalance (EQCM) measurements show that the mass of Ag nanoparticles estimated from the emission current using Faraday's law of electrolysis is in good agreement with that estimated from the QCM frequency shift.

     

Mild and facile synthesis of Ag2S nanowire precursor using mercaptoacetic acid as a reductant/stabilizer and its subsequent conversion to Ag2S or CdS nanowires

Silver sulfide nanowire precursor was prepared at room temperature by simple mixing of mercaptoacetic acid (MAA) and silver nitrate solutions for 10–20 min duration. The MAA concentration in the chemical reaction bath was varied from 1 to 10 mM to afford nanowire precursors ranging in length from 800 nm to 42 μm and diameters ranging from 53 to 210 nm. The chemical identity of the precursor was established as a Ag⁺–⁻SCH₂COOH complex by a variety of spectroscopic probes. It could be converted into crystalline Ag₂S nanowires (with no alteration in nanowire dimensions) by a thermal anneal at ∼300 °C. Reverse cation exchange of the Ag₂S nanowire precursor in a Cd²⁺-containing medium afforded CdS nanowires (with some alterations in morphology) whose chemical identity was confirmed by Raman spectroscopy and photoluminescence. Finally the dual role of MAA as a capping agent and reducing agent in the formation of the Ag₂S nanowire precursor complex is briefly discussed.     

Tunable Color Temperatures and Efficient White Emission from Cs2Ag1−xNaxIn1−yBiyCl6 Double Perovskite Nanocrystals

Recently, Bi‐doped Cs₂Ag_0.6Na_0.4InCl₆ lead‐free double perovskites demonstrating efficient warm‐white emission have been reported. To enable the solution processing and enrich the application fields of this promising material, here a colloidal synthesis of Cs₂Ag_1?xNa_xIn_1?yBi_yCl₆ nanocrystals is further developed. Different from its bulk states, the emission color temperatures of the nanocrystal can be tuned from 9759.7 to 4429.2 K by Na⁺ and Bi³⁺ incorporation. Furthermore, the newly developed nanocrystals can break the wavefunction symmetry of the self‐trapped excitons by partial replacement of Ag⁺ ions with Na⁺ ions and consequently allow radiative recombination. Assisted with Bi³⁺ ions doping and ligand passivation, the photoluminescence quantum yield of the Cs₂Ag_0.17Na_0.83In_0.88Bi_0.12Cl₆ nanocrystals is further promoted to 64%, which is the highest value for lead‐free perovskite nanocrystals at present. The new colloidal nanocrystals with tunable color temperature and efficient photoluminescence are expected to greatly advance the research progress of lead‐free perovskites in single‐emitter‐based white emitting materials and devices.     

Synthesis and physical properties of new oxide AgMnO<Subscript>2</Subscript>

A novel oxide AgMnO₂ was prepared from LiMnO₂ via Ag⁺ → Li⁺ exchange in the eutectic melt AgNO₃-KNO₃. It crystallizes in a monoclinically distorted unit cell (SG C2/m) caused by the Jahn-Teller (J-T) ion Mn³⁺ (3d ⁴). The structure was refined by isotypy with the crednerite CuMnO₂. There are two long axial Mn–O of 264.2(0) pm and four equatorial bonds of 192.7(3) pm and Mn–O–Mn adjoining (83.07°) are bent below the ideal angle. The thermal variation of the magnetic susceptibility (χ/T ⁻¹) obeys a Curie-Weiss law with manganese in a trivalent, high spin (HS) state accommodated in elongated MnO₆ octahedra (14.8%). Direct coupling between Mn³⁺ involves negative exchange interactions through long-range antiparallel moments with a temperature θ _p = −436 K and a magnetic moment of 5.26 μ_B/Mn³⁺ slightly larger than the spin only moment. The title oxide is stable in air up to ∼680 °C before it decomposes into metal silver. It displays a semi-conducting behavior with an activation energy of ∼0.45 eV, characteristic of a conduction by low mobility polarons between Ag^+/2+ where nearly all polarons are bonded. The photoelectrochemical properties of AgMnO₂ have been investigated by photocurrent technique in 1 M KOH. The cathodic photocurrent J _ph provides unambiguous evidence of p-type character attributed to oxygen insertion (0.025 oxygen by formula unit) as required by the charge compensating mechanism. The valence band is made up of Ag−4d wave functions positioned at ∼5.14 eV below vacuum. A comparison with CuMnO₂ was also reported.     

Charakterisierung von ferrocen-FeOCl-intercalat-phasen durch tieftemperatur-Mössbauerspektroskopie

Fe (C₅H₅)₂⁺ (6FeOC1) · e^? intercalation phases were studied by Mössbauer spectroscopy at 4 K. The absorption lines of the guest and host iron components are clearly separated. The isomer shift of the Fe (C₅H₅)⁺₂ guest species relative to α-Fe metal lies between δ = 0.44 ? 0.48 mm/sec. When prepared at room temperature, the intercalated compound represents, at 4 K, a single phase with a paramagnetic and an antiferromagnetic component, as expected for Fe (C₅H₅)₂⁺ (6FeOC1) · e^?. In preparations at higher temperature however, two magnetically ordered systems are revealed at 4 K, both of which differ in their magnetic and quadrupol data from the previously mentioned phase.     

Electrical properties of (K0.5Na0.5)1? x Ag x NbO3 lead-free piezoelectric ceramics

(K_0.5Na_0.5)_1−x Ag _x NbO₃ lead-free piezoelectric ceramics have been fabricated by an ordinary ceramic technique. The results of XRD reveal that Ag⁺ diffuses into the K_0.5Na_0.5NbO₃ lattices to form a new solid solution with an orthorhombic perovskite structure and the solubility of Ag⁺ into A-sites of K_0.5Na_0.5NbO₃ is about 0.20. The ceramics can be well-sintered at 1,100–1,110 °C. The partial substitution of Ag⁺ for A-site ion (K_0.5Na_0.5)⁺ decreases slightly both paraelectric cubic-ferroelectric tetragonal (T _C) and ferroelectric tetragonal-ferroelectric orthorhombic phase transition temperatures (T _O−T). The ferroelectricity of the ceramics becomes weak at high Ag⁺ concentration. The ceramic with x = 0.10 possesses optimum electrical properties: d ₃₃ = 135 pC/N, k _P = 0.43, k _t = 0.46, ε _r = 470, tanδ = 3.39%, and T _C = 394 °C.     

Structural,magnetic and electrical study of CoMnAlO4

A spinel CoMnAlO₄ has been synthesised by the oxide method. It has a tetragonal structure withA=8.10 A andC=8.22 A. A break is found in the plot of logρ against 1/T at 573°K when activation energy changes from 0.62 eV to 0·52 eV. The electrical properties show that it can be regarded as a properly substituted CoMn₂O₄ by Al⁺³ ions. It is paramagnetic withC _M = 4.72 and ϑ _a = −298°K. These results show the ionic configuration of the compound as Co⁺² [Mn⁺³ Al⁺³]O₄.     

An analysis of the electrical conductivity in BaSO4-added Ag2SO4 solid electrolyte system

The compositions (1 −x)Ag₂SO₄−(x)BaSO₄, wherex=0·01 to 0·6, were prepared by slow cooling of the melt. The extent of the solid solubility of Ba²⁺ in Ag₂SO₄ was determined by X-ray powder diffraction and scanning electron microscopy. The bulk conductivity of each sample was obtained using a detailed impedance analysis. The partial substitution of Ba²⁺ results in the enhancement of conductivity in compliance with the classical aliovalent doping theory. A simplistic model based on lattice distortion (expansion) due to partial substitution of Ag⁺ by the bigger Ba²⁺ has been considered to explain enhanced conductivity. Beyond solid-solubility limit (5·27 mole%) the BaSO₄-dispersed Ag₂SO₄ conductivity follows the usual trend seen in binary systems. An increase in conductivity in this case is discussed in the light of interfacial reactions and surface defect chemistry. The maximum conductivity in 20 mole% BaSO₄ dispersed Ag₂SO₄ is due to percolation threshold.     

Conductivite ionique de l'argent dans le compose Ag14Sb12O36F2 etude comparative avec la phase pyrochlore AgSbO3

The compound Ag₁₄Sb₁₂O₃₆F₂, with a desordered KSbO₃ cubic structure, is obtained by an ion exchange method. The conductivity of the silver ions in both Ag₁₄Sb₁₂O₃₆F₂ and AgSbO₃ pyrochlore compounds is investigated by measurement of complex impedance. The e.m.f. measurement and curves i vs. E show that the conduction is essentially assumed by Ag⁺ ions. This study confirms that the cubic KSbO₃ framework structures are good candidates for ionic conductors.     

Structural,thermal and transport studies on Ag1 − x Cuxl (0.05 ⩽ x ⩽ 0.25) solid electrolyte

Preparation and characterization studies on polycrystalline samples of Ag_{1 – x}Cu_xl wherex=0.05, 0.1, 0.15, 0.2 and 0.25, respectively, have been reported. Samples were analysed using powder X-ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques in order to identify the compositions and phase transition temperatures. A.c. electrical conductivity studies were carried out on pelleted specimens of various compositions in the frequency range 65.5 kHz to 1 Hz and over the temperature range 293–412 K. DSC results obtained in the temperature range 373–473 K have shown that the ß- to -phase transition temperature is enhanced from 426 K to 438 K whenx is increased from 0.05 to 0.25. XRD results have indicated that there is a shift ind-spacing when the Cul content is increased, suggesting changes in the crystal structure. Typical XRD patterns recorded for the composition Ag_0.95Cu_0.05l at three different temperatures (room temperature, 373 and 473 K, respectively) have confirmed that both face-centred cubic and hexagonal phases would be present at room temperature and at 373 K as well, whereas at 473 K the structure would be purely body-centred cubic in nature. A.c. impedance analysis of the above samples appears to suggest that their electrical conductivity, predominantly due to the migration of Ag⁺ ions, lies in the order of 10^–4S cm^–1 at room temperature.     

Preparation and photovoltaic properties of anodically grown Ag2O films

The semiconducting and photovoltaic properties of p-type Ag₂O films grown anodically on silver electrodes were studied, in view of possible applications in solar energy conversion. Films were grown in different alkaline solutions; the best results were obtained for 0.02M Ag₂SO₄ + 0.17M NH₄OH + 5.7 × 10^–3M Ba(OH)₂ saturated with Ag₂O powder, stirred mechanically at room temperature. Film thicknesses of up to 10m were thus obtained for the first time in anodically grown Ag₂O. Photovoltaic spectra taken at 300 K give a bandgap ofEg = 1.42 ± 0.04 eV. Evaporated gold on Ag₂O appears to be ohmic while aluminium and platinum are rectifying. The barrier height of Ag/Ag₂O is 0.90 ± 0.02 eV, that of Al/Ag₂O is 0.93 ± 0.02 eV, and that of platinum 0.94 ± 0.02 eV. The best cells give an open-circuit voltage,V _oc, of over 150 mV, and a short circuit current,I _sc = 100A cm^–2 under 50 mW cm^–2 illumination.     

Kinetics of Pu(IV) Reduction with Butanal Oxime

The reduction of Pu(IV) with butanal oxime in nitric acid solution in the presence of excess reductant follows the equation 4Pu^{4 +} + 2C₃H₇CHNOH + H₂O = 4Pu^{3 +} + 2C₃H₇CHO + N₂O + 4H⁺, and its rate is given by the equation -d[Pu(IV)]/dt = k[Pu(IV)]²[C₃H₇CHNOH]/{[Pu(III)][H⁺]}. The rate constant is k = 3.65±0.14 min^{- 1} at 20.2°C and the solution ionic strength = 2. The activation energy is E = 88.8±10.3 kJ mol^{- 1}. The probable reaction mechanism is discussed.