Silver Phosphate Glasses Research Articles

Postmelting Encapsulation of Glass Microwires for Multipath Light Waveguiding within Phosphate Glasses.

Glass waveguides are the fundamental component of advanced photonic circuits and play a pivotal role in diverse applications, including quantum information processing, light generation, imaging, data storage, and sensing platforms. Up to date, the fabrication of glass waveguides relies mainly on demanding chemical processes or on the employment of expensive ultrafast laser equipment. In this work, we demonstrate an advanced, simple, low-temperature, postmelting encapsulation procedure for the development of glass waveguides. Specifically, silver iodide phosphate glass microwires (MWs) are drawn from splat-quenched glasses. These MWs are then incorporated in a controlled manner within transparent silver phosphate glass matrices. The judicious selection of glass compositions ensures that the refractive index of the host phosphate glass is lower than that of the embedded MWs. This facilitates the propagation of light inside the encapsulated higher refractive index MWs, leading to the facile development of waveguides. Importantly, we substantially enhance the light transmission within the MWs by leveraging the plasmon resonance effects due to the presence of silver nanoparticles spontaneously generated owing to the silver iodide phosphate glass composition. Employing this innovative approach, we have successfully engineered waveguide devices incorporating either one or two MWs. Remarkably, the dual MW devices are capable of transmitting light of different colors and in multipath direction, rendering the developed waveguides outstanding candidates for extending the functionalities of diverse photonic and optoelectronic circuits, as well as in intelligent signaling applications in smart glass technologies.

Field Study of Activity of Antimicrobial Polypropylene Textiles

In this work, an in situ study is presented of the impact of textile materials used in healthcare facilities on microbial colonization of textile surfaces. The available literature describes antimicrobial active textiles and their effectiveness in laboratory conditions. However, the quantification of the impact on the microbiome of healthcare facilities has not been investigated so far. Polypropylene yarns doped with silver phosphate glass and zinc pyrithione were prepared and used for the production of bed sheets and clothing for healthcare personnel. Subsequently, measurements of airborne particles and viable microorganisms on given textiles were conducted in a private surgery clinic for 3 weeks, comparing the counts of viable microorganisms before and after replacing staff clothing and bedding on examination and the surgical bed with said polypropylene cloth. A significant reduction in airborne particles and viable microorganisms was expected based on previous studies on the use of polypropylene textiles in operating rooms. In this study, a significant reduction in viable airborne fungi and viable microorganisms on monitored textiles was observed by multiple methods. However, the effect on airborne microorganisms seems insignificant in areas with frequent patient traffic. The textile described here represents a new additional way of protecting patients and medical personnel from healthcare-associated infections while using a modification of proven production procedures and commercially usable materials without legislative restrictions.

Microstructure, electrical, optical and electrochemical characteristics of silver phosphate glasses cathode for magnesium battery applications

The realization of a practical magnesium battery is combined with the development of a high kinetic cathode and compatible electrolyte to facilitate the redox process. For this reason, silver phosphate glasses in the binary system (Fe2O3–AgPO3) are prepared using the conventional quenching method. The glasses were defined in the form [Fe2O3] x [AgPO3](100−x) and the composition with 0 ⩽ x ⩽ 40 wt. %. The molar volumes and densities were measured. These glass systems were characterized using x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV–Vis–NIR spectrophotometer, electrochemical procedures and impedance spectroscopy. X-ray diffraction revealed that pristine AgPO3 sample was formed in a glassy state, whereas two crystalline phases (AgFeP2O7 and Fe2O3) were formed after the incorporation of Fe2O3 by different concentrations. Bond assignments associated with different functional groups were investigated by an FT-IR spectroscopy. The values of the band gap were decreased with the increase of Fe2O3 content. The effect of grains and grain boundaries in a heterostructure made up of Fe2O3 and AgFeP2O7 crystallites grown in silver phosphate glasses was studied using impedance spectroscopy. The complex impedance, electrical conductivity, and complex electric modulus were measured in terms of frequency and temperature dependency in [Fe2O3] x –[AgPO3](1−x). In the studied glass systems, non-Debye relaxation was observed. Under a variable regime, σ ac conductivity follows a modified Jonscher’s law Arrhenius fitting of multiple relaxation processes in the material yielded activation energy of (0.12 eV–0.271 eV) which support a Maxwell–Wagner relaxation model in the heterostructure glasses at high temperatures and low frequencies. The dc conductivity decreases with iron rate and follows the Arrhenius law with very low activation energy (0.12–0.27 eV. Mg//electrolyte//Glass coin cells are assembled and show an initial discharge capacity of up to ∼564 mAh g−1. These materials are attractive for application in modernistic electrochemical devices because of their great compositional and preparation variety which enables tuning the types and techniques of electrical conduction in the material.

Tailored Additives for Incorporation of Antibacterial Functionality Into Laser Sintered Parts

Infectious disease is a major cause of death worldwide, and novel methods capable of controlling the spread of disease are in high demand. This research presents a method of producing antimicrobial microcomposites by exploiting the powder-based nature of the Laser Sintering Additive Manufacturing process, via the incorporation of silver-containing additives. Silver phosphate glass additives in different formulations were designed to determine the effect of dissolution rate on the antimicrobial efficacy. These were characterised and successfully incorporated into polyamide 12 parts, without affecting the mechanical properties. The printed microcomposite parts displayed both bactericidal and antibiofouling effects against Gram-positive and Gram-negative bacteria in nutrient-poor conditions, with the efficacy found to be more sensitive to silver content than degradation rate.

Weathering and Antimicrobial Properties of Laminate and Powder Coatings Containing Silver Phosphate Glass Used as High-Touch Surfaces

Increasing the use of hygienic high-touch surfaces with antimicrobial properties in health care and public spaces is one way to hinder the spread of bacteria and infections. This study investigates the antimicrobial efficacy and surface reactivity of commercial laminate and powder coated surfaces treated with silver-doped phosphate glass as antimicrobial additive towards two model bacterial strains, Escherichia coli and Bacillus subtilis, in relation to surface weathering and repeated cleaning. High-touch conditions in indoor environments were simulated by different extents of pre-weathering (repeated daily cycles in relative humidity at constant temperature) and simplified fingerprint contact by depositing small droplets of artificial sweat. The results elucidate that the antimicrobial efficacy was highly bacteria dependent (Gram-positive or Gram-negative), not hampered by differences in surface weathering but influenced by the amount of silver-doped additive. No detectable amounts of silver were observed at the top surfaces, though silver was released into artificial sweat in concentrations a thousand times lower than regulatory threshold values stipulated for materials and polymers in food contact. Surface cleaning with an oxidizing chemical agent was more efficient in killing bacteria compared with an agent composed of biologically degradable constituents. Cleaning with the oxidizing agent resulted further in increased wettability and presence of residues on the surfaces, effects that were beneficial from an antimicrobial efficacy perspective.

Laser-Induced Erasable and Re-Writable Waveguides within Silver Phosphate Glasses.

Femtosecond direct laser writing is a well-established and robust technique for the fabrication of photonic structures. Herein, we report on the fabrication of buried waveguides in AgPO3 silver metaphosphate glasses, as well as, on the erase and re-writing of those structures, by means of a single femtosecond laser source. Based on the fabrication procedure, the developed waveguides can be erased and readily re-inscribed upon further femtosecond irradiation under controlled conditions. Namely, for the initial waveguide writing the employed laser irradiation power was 2 J/cm2 with a scanning speed of 5 mm/s and a repetition rate of 200 kHz. Upon enhancing the power to 16 J/cm2 while keeping constant the scanning speed and reducing the repetition rate to 25 kHz, the so formed patterns were readily erased. Then, upon using a laser power of 2 J/cm2 with a scanning speed of 1 mm/s and a repetition rate of 200 kHz the waveguide patterns were re-written inside the glass. Scanning electron microscopy (SEM) images at the cross-section of the processed glasses, combined with spatial Raman analysis revealed that the developed write/erase/re-write cycle, does not cause any structural modification to the phosphate network, rendering the fabrication process feasible for reversible optoelectronic applications. Namely, it is proposed that this non-ablative phenomenon lies on the local relaxation of the glass network caused by the heat deposited upon pulsed laser irradiation. The resulted waveguide patterns Our findings pave the way towards new photonic applications involving infinite cycles of write/erase/re-write processes without the need of intermediate steps of typical thermal annealing treatments.

Silver-phosphate glass matrix for iodine conditioning: From sorbent design to vitrification

A new route for the synthesis of silver-phosphate based sorbent beads as precursors of final iodine waste form is proposed here. This sorbent is used to entrap gaseous iodine produced during the reprocessing of spent nuclear fuels and to be directly transformed into materials composed of a silver phosphate glass phase considered as high efficient iodine containment matrix for long-term storage in deep geological repository. Using sacrificial organic template method (alginate) and well controlled calcination of the obtained silver phosphate grains materials, this innovative synthesis makes in-situ formation of metallic silver inside them. Ag0 then can easily entrap iodine when in contact with gaseous iodine. The obtained sorbent were tested for iodine trapping in static conditions. They showed great performances with a catch rate of 480 mg.g−1. The iodine-loaded sorbent were finally heat treated at 650 °C with an iodine loss lower than 3% wt. The resulted materials shows the presence of the expected silver phosphate glass matrix with a great iodine incorporation of 9% mol.

Chemical durability evaluation of silver phosphate–based glasses designed for the conditioning of radioactive iodine

Silver phosphate glasses have been investigated for the conditioning of radioactive iodine 129. Their disposal in a deep geological repository requires high chemical durability, and to improve this property, two crosslinking agents were examined here: Nb2O5 and Bi2O3. In addition, for some of these glasses, 50 % of phosphorus was replaced by molybdenum to assess the role of glass former entities. The effect of these modifications on the glass chemical durability was studied in pure water, at 50°C. Given the very long half-life of iodine 129 (15.7 × 106 years), only long-term alteration tests were carried out, in order to check if a passivating alteration layer could be formed in these conditions. Alteration rates were then calculated following various methods and compared. Results showed that the use of elemental releases in solution alone leads to an underestimation of the alteration rate, as there is no tracer element in the glass composition. For phospho-molybdate glasses, the addition of Nb2O5 had a significant effect on their chemical durability, i.e. their ability to form a passivating layer that retains most of the elements that are part of the pristine glass. For phosphorus, the more mobile element, release rates decreased by two orders of magnitude compared to phosphate-only glasses, and this trend depends on the Nb2O5 concentration.

Antimicrobial effectiveness of beverage containers made of silver doped PET

Active packaging based on a release of silver ions (Ag+) has become a focus of increasing interest. However, applications are rare for beverages in particular, and the question remains whether the amount for antimicrobial effectiveness is below the migration limit of 0.05 mg Ag/kg food proposed by the EFSA. Experiments were performed using E. coli (106 cfu/mL) in distilled water and Z. bailii (<10 cfu/mL) in iced tea by directly adding AgNO3 at concentrations of 0.015 and 0.05 mg/L Ag, and by using manufactured PET bottles containing silver phosphate glass enabling these concentrations to be reached by a release of Ag+ into the medium. The results showed that these Ag concentrations can inhibit bacteria in distilled water, as well as in iced tea. Ag concentrations of 0.05 mg/L reduced E. coli in distilled water by 105 cfu/mL and 0.015 mg/L by 102 cfu/mL. Z. bailii population was significantly reduced by 0.05 mg/L Ag, but cells started to grow again.

Effect of AgI doping on electrical conductivity and dielectric relaxation in silver phosphate glass nanocomposite systems

A series of ternary silver iodide (AgI)-doped glassy samples of xAgI–(1-x)(0.35P2O5–0.65Ag2O) composition with x = 0.1, 0.2, 0.3 and 0.4 have been processed by well-accepted melt quench technique. The composition-dependent thermal properties of the glassy systems have been analyzed by differential scanning calorimetric (DSC) results. Both density and thermal stability of the nanocomposites increases with the inclusion of AgI content (x). The diminishing nature of ac and dc activation energy enhances ac and dc conductivity with rising AgI content (x). The falling response of the inter-nuclear spacing of Ag+ ion (RAg) is responsible for the enhancement of ionic conductivity. The dielectric constant (ε/) and dielectric loss (ε//) values expand with increasing temperature and reduce with rising frequency. The scaled spectra of complex electric modulus (M/ and M//) indicate that conductivity or dielectric relaxation mechanism is not Debye type, as β < 1 and temperature independent, whereas composition dependent.

Influence of niobium oxide content on the structural features of silver phosphate glasses and their corresponding glass-ceramics

Silver phosphate glasses in the Ag2O-Nb2O5-P2O5 ternary system were prepared using the conventional quenching method. The glasses were defined by the 50Ag2O-xNb2O5-(50-x)P2O5 composition with 0 ≤ x ≤ 25 mol %. They were found coloured. Their density and molar volume values are examined. The X-ray diffraction analysis was confirmed their amorphous state. The glass-ceramics were achieved by performing heat treatments of the elaborated glasses. To highlighting the impact of replacing P2O5 by Nb2O5 on the structural properties of the elaborated glasses and glass-ceramics, Raman analysis was carried out. This technique permitted the identification of various structural units of phosphate, mainly metaphosphates and pyrophosphate, and revealed that niobium adopts an octahedral oxygen environment. The controlled crystallization of the glasses leads to the formation of an orthorhombic silver niobate phase AgNbO3 mixed with a secondary phase Ag4P2O7 for glasses with high niobium content (x ≥ 15 mol%) and AgPO3 for glasses with low niobium concentration (x ≤ 15 mol%).

Effect of heat-treatment on the upconversion of NaYF4:Yb3+, Er3+ nanocrystals containing silver phosphate glass

Novel NaYF4:Yb3+, Er3+ nanocrystals containing phosphate glass with composition 83.25NaPO3–9.25NaF-5ZnO-2.5Ag2O (in mol%) was prepared by adding the NaYF4:Yb3+, Er3+ nanocrystals in the glass using the direct doping method. The optical and luminescence properties of this new glass are presented and discussed. The newly developed glass exhibits visible emission under 980 nm pumping with high intensity confirming the presence of the NaYF4:Yb3+, Er3+ nanocrystals in the glass. From the absorption spectrum of the as-prepared glass, it is showed that the as-prepared glasses contains already Ag nanoparticles which are thought to precipitate due to the decomposition of some of the NaYF4:Yb3+, Er3+ nanocrystals occurring during the glass preparation. A heat treatment of the glass was found to lead to the migration of Ag species at the surface of the glass as evidenced using SEM and to a decrease of the intensity of the upconversion mostly due to an increase of the inter defects in the NaYF4:Yb3+, Er3+ nanocrystals due to the heat treatment.

Release of silver from silver doped PET bottles

• Production of silver-doped PET containers. • Release of Ag + from them was depended on percentage of antimicrobial filler, temperature and acidic strength of simulant. • Ag + release into distilled water was not detected for nanosilver-doped PET containers. • Diffusion coefficients of Ag + in PET were observed to be between 3.2 × 10 −17 and 1.7 × 10 −15 cm 2 /s. • By enhancing the ratio of surface to filling volume, a higher silver content in the solution was achieved. Development of active packaging based on polymers doped with silver has gained increasing interest. PET bottles were produced by injection and stretch blow molding under addition of silver phosphate (Ag 3 PO 4 ) glass at 3 % and 10 % (w/w) and of AgPURE masterbatch at 10 % (w/w) which contained 6500 ppm silver nanoparticles (AgNPs). These bottles underwent release tests. Silver released into distilled water, 0.5 % and 3 % (w/w) acetic acid was quantified using inductively coupled plasma mass spectrometry (ICP-MS). The amount of silver released ranged from 2 μgL −1 to 72 μgL −1 after 10 days at either 21 °C or 43 °C. For PET bottles containing AgNPs no release of silver was detected. Release was dependent on percentage of antimicrobial filler in the polymer, temperature, and acidic strength. Diffusion coefficients of silver ion (Ag + ) in PET were observed to be between 3.2 × 10 −17 and 1.7 × 10 −15 cm 2 /s. Bottles containing 3% (w/w) did not exceed the proposed specific migration level of 0.05 mg Ag per kg food, whereas bottles containing 10 % (w/w) did.

Micro-CT for analysis of laser sintered micro-composites

PurposeX-Ray-computed micro-tomography (micro-CT) is relatively well established in additive manufacturing as a method to determine the porosity and geometry of printed parts and, in some cases, the presence of inclusions or contamination. This paper aims to demonstrate that micro-CT can also be used to quantitatively analyse the homogeneity of micro-composite parts, in this case created using laser sintering (LS).Design/methodology/approachLS specimens were manufactured in polyamide 12 with and without incorporation of a silver phosphate glass additive in different sizes. The specimens were scanned using micro-CT to characterise both their porosity and the homogeneity of dispersion of the additive throughout the volume.FindingsThis work showed that it was possible to use micro-CT to determine information related to both porosity and additive dispersion from the same scan. Analysis of the pores revealed the overall porosity of the printed parts, with linear elastic fracture mechanics used to identify any pores likely to lead to premature failure of the parts. Analysis of the additive was found to be possible above a certain size of particle, with the size distribution used to identify any agglomeration of the silver phosphate glass. The particle positions were also used to determine the complete spatial randomness of the additive as a quantitative measure of the dispersion.Practical implicationsThis shows that micro-CT is an effective method of identifying both porosity and additive agglomeration within printed parts, meaning it can be used for quality control of micro-composites and to validate the homogeneity of the polymer/additive mixture prior to printing.Originality/valueThis is believed to be the first instance of micro-CT being used to identify and analyse the distribution of an additive within a laser sintered part.

Highly luminescent and ultrastable cesium lead bromide perovskite patterns generated in phosphate glass matrices.

Owing to their exceptional optoelectronic properties, all-inorganic lead halide perovskites offer enormous potential for next generation photonic, light-emitting, and optoelectronic devices. However, their usage is significantly limited by their poor stability upon moisture exposure and lead toxicity issues. Moreover, many of the aforementioned applications rely on the development of confined perovskite patterns of various shapes and periodicities. Here we report a simple and low-temperature method enabling the controlled incorporation of photoluminescent all-inorganic metal halide PNCs into a silver phosphate glass (AgPO3) matrix which is transparent in most of the visible range. The developed fabrication protocol is based on a simple melting encapsulation process in which pre-synthesized perovskite crystals are inserted in the glass matrix, following the initial glass quenching. Using this novel approach, two types of composite perovskite glasses are prepared, one that hosts perovskite isles and the second in which a thin perovskite layer is embedded beneath the glass surface. Both types of composite glasses exhibit remarkable photoluminescence stability when compared to the ambient air-exposed perovskite crystals. More importantly, by means of a simple and fast cw-laser processing technique, we demonstrate the development of encapsulated dotted perovskite micropatterns within the composite perovskite glass. The ability of the proposed system to resolve stability and lead toxicity issues, coupled with the facile formation of highly luminescent perovskite patterns pave the way towards the broad exploitation of perovskite crystals in photonic applications.

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.

Niobium- and bismuth-silver phosphate glasses for the conditioning of radioactive iodine

Iodine 129 is a radioactive waste produced by the nuclear industry. Due to its high volatility, it cannot be vitrified in conventional borosilicate glasses. This paper investigates the feasibility of iodine conditioning using a glass matrix intended for long-term storage in a geological repository. Silver phosphate glasses, which can incorporate high amounts of iodine and can be synthesized at low temperature, were chosen for this study. In order to increase their chemical durability, the glasses were cross-linked by niobium and bismuth oxides. Niobium and bismuth incorporation limits were determined for an iodine amount of 12 wt% and ranged from 1.6 mol% to 4.0 mol%, depending on the Ag2O/P2O5 ratio. The glass structures were investigated using 31P MAS NMR, RAMAN spectroscopy and X-ray absorption spectroscopy. The iodine local environment was determined by EXAFS at iodine K-edge. Structural investigations showed that the introduction of these crosslinking reagents induces a significant increase in the polymerization degree of the glasses. However despite this higher connectivity, the two crosslinking reagents have a low impact on the glass transition temperature after iodine addition.

Decoupling mobility and charge carrier concentration in AgR-AgPO3 glasses (R = Cl, Br, I)

Halide-containing silver phosphate glasses have been used as model systems for the study of the ionic conductivity of oxide glasses for the past 50 years, mostly due to the massive increase in conductivity observed as the halide concentration is increased, even if the molar ratio of silver is kept constant. Furthermore there is still no consensus if the increased conductivity is due to an enhancement of the number of effective charge carriers (glass as a weak electrolyte) or a higher charge carrier mobility (glass as a strong electrolyte). In this work we investigate the electrical properties of silver-halide-containing silver metaphosphate glasses through Impedance Spectroscopy. We find the glasses to follow the “canonical scaling”, which coupled with the diffusional nature of the conductivity allows us to show that the number of effective charge carriers remains constant with increasing halide concentration, and that the conductivity follows the same scaling as the ionic mobility.

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.

Glass-forming compositions and physicochemical properties of degradable phosphate and silver-doped phosphate glasses in the P2O5–CaO–Na2O–Ag2O system

Phosphate and silver-doped phosphate glasses are potential candidates for use as degradable biomaterials and as antibacterial materials as well. The present investigation explores the glass-forming compositions (GFC), physical properties and degradation rates of both phosphate glasses in the P2O5–CaO–Na2O ternary system and silver-phosphate glasses derived from it by introducing Ag2O in replacement of Na2O. The glasses were prepared using the traditional melting–annealing technique applied in glass making industry. Bulk glasses were prepared without using any special precautions or specific conditions (contrary to previous studies) which can prevent crystallization or segregation of silver particles from the melt. A wide glass formation domain with ≥40mol% P2O5 was determined in the ternary P2O5–CaO–Na2O system. However, up on Ag2O addition, the amount of Ag2O that can exist in the glass and remains amorphous was limited to 2mol% as ensured from X-ray diffraction (XRD). The compositions with ≥60mol% P2O5 and 0.5, 1 or 2mol% Ag2O formed transparent and colorless silver phosphate glasses. Whereas, the compositions with ≤55mol% P2O5 did not form glasses and showed immediate partial crystallization and separation of silver particles. Thereafter, the structure of representative glasses was studied by FT-IR and UV–vis absorption spectroscopy. Finally, as silver ions function as antibacterial metal ions, the amounts of silver ions released from silver phosphate glasses were measured by atomic absorption spectrometry (AAS).