AgPO3 Glass Research Articles

Post-glass melting synthesis and photochromic properties of composite AgCl-AgPO3 glasses

We herein present a simple, fast, low-temperature, post-glass melting fabrication protocol in which a photochromic silver cation based modified zone is incorporated within silver metaphosphate glass (AgPO3). The selection of AgPO3 glass is mainly based on its relative “soft” nature (Tg = 192 °C) that enables the integration of silver cations from the surface deposited AgCl layer, while being transparent in most of the visible range, and therefore suitable for smart photochromic window applications. The suggested synthesis procedure permits the controlled formation of a silver cation modified layer within the host glass matrix, while the characteristics of the layer itself can be adjusted correspondingly. Our findings reveal a direct relationship between the developed composite AgCl–AgPO3 glass photochromic response and the morphological features of the integrated layer, i.e., thickness and position. More importantly, the photochromic response time with various UV irradiation doses is also studied, where remarkable response times of several seconds are obtained. Processes and efforts to further enhance the photochromic performance by utilizing the presence of silver nanoparticles within the glass matrix are also presented and discussed.

Study of ionic conduction, dielectric relaxation, optical and electrochemical properties of AgPO3/graphene glasses for magnesium battery applications

Developing suitable cathode material for alkali ion batteries is the most significant challenge facing commercialization. The effect of graphene nanoplatelets (GNP) on the physical and optical properties of AgPO3 glass is demonstrated. For the first time, AgPO3/Graphene glasses have been synthesized by melt-quenching method to assess the physical and the electrochemical performance as a cathode for a Magnesium ion battery. The complex impedance method determines bulk conductivity; the bulk conductivity increases with increasing temperature and graphene content. AgPO3_2 wt%GNP (sample 2) shows the optimum stoichiometric ratio with linear conductivity-temperature growth up to fast-ionic conductivity ∼ 1.79×10−2 (ohm. cm)−1 at 150 °C. The study of frequency dependence of both dielectric constant and dielectric loss have been explained based on ion hopping beside the ionic polarization mechanism. Optical properties such as the refractive index, optical energy gap, molar refractivity, molecular polarizability, dispersion, and oscillator energy of AgPO3 glass with different graphene nanoplatelets are investigated. The data reveal the lowest energy gap for the glass sample (AgPO3/2 wt%GNP). On the contrary, the values of refractive index, dispersion energy, molar refractivity and molecular polarizability are the highest for (AgPO3_2%wt%GNP) sample. The coin cell has been fabricated with the cell configuration Mg//electrolyte//AgPO3 and Mg//electrolyte//AgPO3_2 w%GNP. The cell with AgPO3_2 wt% GNP electrode has a high initial discharge capacity of ∼187 mAh/g compared with AgPO3 electrodes of ∼100 mAh/g.

Structure and dielectric properties in silver phosphate AgPO3 glass–ceramic

Silver phosphate glass 50Ag2O-50P2O5 was elaborated by the conventional quenching method. The glass was found colorless and its amorphous state was verified using X-ray diffraction. Raman spectroscopy is used to characterize the structural approach of this silver phosphate glass. This technique allowed the identification of several structural units of phosphate, mainly metaphosphates. The crystallization behavior of the glass was made by heat treatment to achieve the glass–ceramic. X-ray diffraction (XRD) of the glass–ceramic revealed the formation of AgPO3. Investigation of its dielectric properties is undertaken in the range frequency 1 Hz–1 MHz and at various temperatures.

Erasable and rewritable laser-induced gratings on silver phosphate glass

We herein report on the fabrication of high regularity, erasable and rewritable periodic surface patterns on silver metaphosphate glass (AgPO3) by means of ultrashort pulsed laser processing. The laser-induced periodic surface structures (LIPSS) are formed perpendicular to the laser beam polarization, exhibiting a periodicity similar to the laser wavelength. Notably, the so-formed periodic patterns can be readily erased upon further exposure to femtosecond laser irradiation under controlled conditions. This all-laser inscription and deletion protocol allows the reversible patterning of the phosphate glass surface by employing a single laser beam. Optical and Raman spectroscopy revealed that the formation of the periodic patterns and the erasing process do not cause any phosphate network modifications or structural damage on the glass, and thus, proving that the demonstrated reversible LIPSS process is entirely non-ablative. This remarkable feature could enable infinite cycles of the write/erase/re-write process on the same area of the glassy material, posing the AgPO3 glass as an important candidate for waveguides and optical responsive memory components of advanced photonic applications.

Effects of temperature and frequency on the dielectric properties of AgPO3 glass

The dielectric behavior of AgPO3 glass network was studied at different temperatures and in the frequency range between 50 and 106 Hz using impedance spectroscopy technique. The glassy network was prepared by melting NH4H2PO4 and AgNO3 in the powder form using the mole ratio technique. The measured ac-conductivity shows two distinct regions. Over the whole temperature range, the conductivity is fairly constant at low frequency and a power law dispersive behavior was observed at higher frequency (i.e., f > 104 Hz). The power law exponent (s) was very close to unity while the crossover frequency (ω p) was observed to increase with increasing temperature. The activation energy extracted from the Arrhenius linear plot of the dc-conductivity (σ dc) was found to be E a =0.47 eV.

Dissociation Equilibrium and Charge Carrier Formation in AgI–AgPO3 Glasses

The xAgI–(1 – x)AgPO3 glass system exhibits a wide and well-known range of variation in silver ion conductivity with the AgI molar ratio, x, while the total concentration of Ag+ ions does not change significantly. We propose an interpretation to explain this effect, based on the fact that only a fraction of Ag+ cations are effective charge carriers and that their concentration is determined by a dissociation equilibrium of AgI in the AgPO3 glass. In this case, the ionic conductivity stems from the thermodynamic activity of silver iodide, aAgI, dissolved in the AgPO3 glass. To verify this relationship experimentally, aAgI is determined from electromotive force measurements of solid-state cells in the temperature range of 25–90 °C. Our results reveal a linear dependence of silver ion conductivity on aAgI over 3 orders of magnitude. The substantial variations in aAgI observed with the increase in the AgI molar ratio x are justified assuming a regular solution model for the AgI–AgPO3 mixture.

Superlinear frequency dependence of AC conductivity and its scaling behavior in xAgI-(1 − x) AgPO3 glass superionic conductors

Low temperature AC conductivity studies on melt quenched xAgI-(1−x) AgPO3 glass electrolytes are presented. It is observed that doped glasses show Jonscher power law behavior at all temperatures, however, undoped AgPO3 glass also shows superlinear frequency-dependent conductivity at very low temperatures apart from the usual Jonscher power law behavior. This behavior in undoped AgPO3 glass is not yet reported in literature. The Summerfield scaling law is used to demonstrate that Jonscher power law behavior and superlinear power law behavior have different physical origins as scaling law is not followed in the superlinear regime. Moreover, scaling behavior of AC conductivity also indicates that conduction mechanisms are slightly different in doped and undoped glasses. However, scaling behavior provides only qualitative information about the conduction mechanisms. The conductivity spectra of doped and undoped glasses can be merged into a super-master conductivity curve except in the transition zone (where AC conductivity starts dominating over DC conductivity) where the conductivity master plots of doped and undoped glasses do not merge.

Structural relaxation in AgPO3 glass followed by in situ ionic conductivity measurements

The structural relaxation kinetics of a silver meta-phosphate glass (AgPO3) is investigated using a method based on the isothermal variation of its ionic conductivity over time. Samples of AgPO3 glass from the same batch were pre-annealed at 433K or 418K and then relaxed at different temperatures within this temperature range, which is close to its glass transition temperature measured by differential scanning calorimetry, TgDSC=438K. Ionic conductivity data were continuously collected by impedance spectroscopy during the isothermal relaxation process. The variation of the electrical conductivity over time is well described by the Kohlrausch expression (Φ(t)=exp[−(t/τσK)β]), in which τσK is the characteristic relaxation time and β a stretch exponent. Different values of β were found when the glass structure expanded or contracted during relaxation. In addition, viscosity values calculated by the Maxwell relationship using <τ> from conductivity data and a shear modulus taken from the literature are in accordance with the experimental viscosity measured in the same temperature range, thus validating the use of ionic conductivity to unveil glass structural relaxation.

Silver plasmon resonance effects in AgPO3/silica photonic bandgap fiber.

We report on the application of an external electric field and its tuning effect in the guiding properties of a composite AgPO3/silica photonic bandgap fiber. The application of an electric field leads to the poling of the soft glass inclusion, resulting in the formation of a silver-induced plasmonic band, predominantly affecting the short wavelength guiding regimes while inducing polarization dependent losses. These spectral effects are attributed to the formation of silver nanoparticles within the AgPO3 glass matrix, driven by thermal poling.

Coherent THz wave induced excitation in superionic conductors

Millimeter wave absorption spectra of silver halides doped silver phosphate glasses were measured using an intense coherent transition radiation. Two bands were observed at 8.4cm-1 and 6.3cm-1 in AgI doped AgPO3 glass and 8.7cm-1 and 6.1cm-1 in AgBr doped one. Small difference of peak positions between these glasses suggests that these absorption bands are concerned with a large number of silver ions in dopant molecules.

Small angle neutron scattering experiments on solid electrolyte (AgI) x (AgPO3)1−x

Superionic conductor glasses have generated considerable technological interest in the applications such as batteries, fuel cell, sensors, etc. In AgPO3 glass doped by AgI, (AgI) x (AgPO3)1−x , small size of AgI clusters were formed and dispersed in the AgPO3 glass. The size of clusters in the sample depends on the AgI content and influences the electrical properties of the sample. To understand the microscopic structure, in particular the shape and size of the clusters, a series of small angle neutron scattering experiment on (AgI) x (AgPO3) x with x = 0.0, 0.5, and 0.7 were performed at the Neutron Scattering Laboratory–National Nuclear Energy Agency, Indonesia. By assuming the clusters are spherical, a radius of gyration R g of the clusters was determined from a Guinier plot. As there are different clusters sizes in the samples, a polydisperse model is also used to analyze the data. The results show that the average radius of clusters dispersed in (AgI) x (AgPO3)1−x samples with x = 0.0, 0.5, and 0.7 are around 236.2, 252.6, and 257.5 A, respectively.

Anode and anodic interface dependent conduction of silver metaphosphate glass

The electrical response of an ion-conducting glass to dc biasing was very sensitive to the anode material and anode–glass interface, especially when biasing was made under high electric field at high temperature. The response of the platinum-anoded AgPO3 glass was studied, and was compared with that of the gold-anoded one. Emphasis was laid on the effect of polishing of the glass surface.

Electrolytic conduction of silver metaphosphate glass until dielectric breakdown

Ac/dc bias was applied to gold- or silver-electroded AgPO3 glass samples at ∼150 °C. Dielectric breakdown took place with bias fields of ∼700 V/cm. Depth profiles of silver, gold, oxygen, and phosphorus were measured from the electrode surfaces by x-ray photoelectron spectroscopy. Electrolytic conduction of silver and others and field-induced injection of gold ions into glass from the gold anode were found.

Density fluctuations in the network structure of AgI doped AgPO3 glass: The origin of the phonon-fracton crossover?

Neutron diffraction studies of AgI doped AgPO3 glasses show the growth of a sharp diffraction peak at Q ≈ 0.7 Å −1 with increasing salt content, indicative of a change in intermediate range order. We show that this peak is due to local density fluctuations in the network of PO4 tetrahedra caused by the requirement to maintain connectivity while decreasing the average density. The phosphate backbone shows an inhomogeneous density distribution over regions of diameter ≈ 16 Å within which the number of atoms in a sphere of radius R increases at a rate lower than R3. It is proposed that this local inhomogeneity is related to the observation of a "phonon-fracton crossover" in the dynamics of similar glasses.

Search for Quasielastic Neutron Scattering Components Due to Jump Relaxation in Glass

AbstractA lithium bromide doped lithium borate glass has been studied by neutron scattering experiments and by measurement of the dynamic conductivity. Whereas the dispersion of the dynamic conductivity at lower frequencies can be interpreted in terms of a non‐Debye jump relaxation model, a quasielastic neutron scattering component, as predicted by the model, could not be resolved. However, in some other glassy systems there is evidence of quasielastic components due to jump relaxation processes. This is shown for two examples: the glass forming melt 3KNO3 · 2Ca(NO3)2 and an AgI · AgPO3 glass.

EXAFS study of the coordination of phosphorus in AgPO3 glass

EXAFS at the K edge of phosphorus in the glass AgPO3 has been measured with synchrotron radiation and analysed utilizing c-Ag3PO4 as model compound. Phosphorus is coordinated to 4 oxygens at a mean distance 1.55 Å. EXAFS is also consistent with the hypothesis of two different PO distances at r1 = 1.48 Å, r2 = 1.62 Å, corresponding to the presence of respectively 2 non-bridging and 2 bridging oxygens. No direct evidence of PAg coordination is found.

Electrical relaxation and ageing effect in AgPO3 glass

Abstract The complex relative permittivity of silver phosphate glass has been measured in the temperature range 200–400 K, and frequency range 12–105 Hz. Two relaxation processes occur within the glass. Both are observed in the electrical modulus spectrum but only the low-temperature, or faster, process in the loss spectrum. The faster process is attributed to the motion of Ag+ ions that form ion pairs with the phosphate chains and the slower to the local motions of the chain segments. Both indicate the presence of loosely packed regions in the disordered matrix. Annealing increased the strength of the faster process but decreased that of the slower process in a manner qualitatively similar to that observed on cooling the glass. In molten AgPO3 at 790 K, the faster process has the same rate as the viscoelastic modes of PO− 4 chains and, therefore, only one peak is observed in the Brillouip scattering at 790 K. AgPO3 glass behaves like a weak electrolyte.