Raman and FTIR spectra of iron phosphate glasses containing cerium

The present work critically reviews the scientific and patent literature on low melting bismuth based oxide glass frits in materials for electronics, sensors and related applications such as sealing glasses, solar cells, architectural and automotive glass, the main motivation being to replace lead based materials by environmentally more benign ones. Due to similar glass forming properties of Bi and Pb, Bi based glasses are the closest ‘drop-in’ alternative for lead bearing formulations, and are therefore actually replacing them in many applications, helped also by previous experience with Bi containing materials in thick film technology and component metallisations. The outstanding issues are discussed, e.g. matching the lowest processing temperatures achieved by the classical lead based glasses without sacrificing durability and stability, as well as stability versus chemical reduction. Finally, consideration is also given to special ‘heavy’ glasses (often containing Bi and Pb together) that are ...

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Review of Bi2O3 based glasses for electronics and related applications

In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.

https://iopscience.iop.org/article/10.1088/0957-4484/21/18/185102/pdf

Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent

IR, DSC, density and molar volume, and dc conductivity of the glasses in V2O5–Fe2O3–TeO2 system were reported. The network structure for the glass compositions with 65 and 62.5 mol%, V2O5 is built up of VO5 polyhedra, while the other glass compositions consist of VO4 polyhedra. Density and glass transition temperature were observed to decrease with an increase in V2O5 content. The glasses had conductivities ranging from 3.31 × 10−3 S m−1 to 2.88 × 10−2 S m−1 at 400 K for V2O5 = 50–65 mol%. The electrical conductivity was confirmed to be due to adiabatic small polaron hopping. The hopping carrier mobility varied from 0.587 × 10−5 cm2 V−1 s−1 to 6.904 × 10−5 cm2 V−1 s−1 at 400 K. The carrier density was evaluated to be 2.997 × 1019–7.298 × 1019 cm−3. The conductivity was primarily determined by hopping carrier mobility.

Characterization and transport properties of V2O5-Fe2O3-TeO2 glasses

Ternary semiconducting glasses in the CuO–V 2 O 5 –TeO 2 system have prepared by the press-quenching technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), infrared (IR) spectra, density ( d ) and oxygen molar volume ( V m ) and dc conductivity ( σ ) of these glasses were reported. The overall features of XRD curves confirm the amorphous nature of the present glasses. SEM exhibits a surface without any presence of microstructure which is a characteristic of the amorphous phase. Density was observed to decrease with an increase in V 2 O 5 content. The network structure for the glass compositions with 57.5 mol% V 2 O 5 is built up of the VO 5 polyhedra, while the other glass compositions consist of VO 4 polyhedra. The temperature dependence of the conductivity data has been analyzed in terms of different polaronic models. In high-temperature region above θ D /2 the Mott model of SPH between nearest neighbors is consistent with the conductivity data, while at intermediate temperature the Greaves VRH (variable-range hopping) model was found to be appropriate. The conduction was confirmed to obey the adiabatic SPH and was mainly due to electronic transport between V ions. The dominant factor determining conductivity was the hopping carrier mobility in these glasses.

Structural and Polaronic transport properties of semiconducting CuO–V2O5–TeO2 glasses

The dc electrical conductivity of (100−x)Na2B4O7−xWO3 (x = 5, 15, 20 and 30 mol%) glasses is reported in the temperature range 323–473 K. The density and molar volume for these glasses are consistent with the ionic size, atomic weight and amount of different elements in the glasses. At high temperatures the Mott model of phonon-assisted small polaron hopping between nearest neighbours is consistent with conductivity data, while at intermediate temperatures the Greaves variable-range hopping model is found to be appropriate. The estimated model parameters such as number of ions per unit volume, hopping distance, polaron radius and activation energy are found to be consistent with the formation of localized states in these glasses. The electrical conduction of these glasses is confirmed to be that of non-adiabatic small polaron hopping. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Non-adiabatic small polaron hopping conduction in sodium borate tungstate glasses

Structural and other physical properties of barium vanadate glasses

Nanostructural behavior and electrical properties of BaTiO 3 -(100− x )V 2 O 5 glasses (where x =35, 40, 45 and 50 mol%) and their corresponding nanocrystalline glass–ceramics were studied. Scanning electron microscopy (SEM) of quenched glasses, confirm the amorphous nature of the glasses present. Also, the overall features of X-ray diffraction (XRD) confirm the amorphous nature of the present glasses. Transmission electron micrograph (TEM) and XRD of the corresponding heat treated sample indicate nanocrystals with a particle size of 20–35 nm. It was found that density ( d ) increases gradually with the increase of the BaTiO 3 content in the nanocrystalline glass–ceramics. It is observed that the conductivity of the nanocrystalline glass–ceramics is higher than that of the corresponding glassy phase. The high conductivity of these nanocrystalline glass–ceramics is considered to be due to the presence of nanocrystals with a particle size of 20–35 nm. This is attributed to the formation of extensive and dense network of electronic conduction paths which are situated between V 2 O 5 nanocrystals and on their surface. The electrical conductivity of this system can be fitted with Mott's model of nearest neighbor hopping at high temperature. From the best fits, reasonable values of various small polaron hopping (SPH) parameters are obtained. From dielectric permittivity of the as-cast glass samples, no ferroelectric behavior can be observed. Also, the dielectric permittivity ( e ) values of these glasses are found to be very high compared to familiar vanadium containing glasses. By annealing the glass system around 450 °C for 1 h in air, nanocrystalline BaTiO 3 phase precipitates and the corresponding nanocrystalline glass–ceramics showed average broad peak around 352 K in the dielectric permittivity ( e ). It is interesting to note that pure nanocrystalline BaTiO 3 phase with average particle size less than 100 nm also shows ferroelectric phase transition around this temperature as predicted from the dielectric permittivity measurements. This observation of these glass–ceramics nanocrystals can be utilized to control BaTiO 3 particle size and hence transition temperature by proper adjustment of annealing time and BaTiO 3 content. Such a feature can be used for industrial applications where the shape of the application article is a necessary requirement.

Study of nanostructural behavior and transport properties of BaTiO3 doped vanadate glasses and glass–ceramics dispersed with ferroelectric nanocrystals

Several properties of semiconducting Fe 2 O 3 –Bi 2 O 3 –Li 2 B 4 O 7 glasses have been investigated. These properties include Mossbauer, differential scanning calorimeter (DSC), density, thermoelectric power and DC conductivity. Mossbauer spectroscopy results revealed that the relative fraction of Fe 2+ increases with an increasing Fe 2 O 3 content. Density was observed to decrease with an increase in Fe 2 O 3 content. The glasses are n-type semiconducting. The experimental data have been analyzed in the light of theoretical models. It has been observed that the general behavior of electrical conductivity is similar for all glass compositions. The high-temperature conductivity data are consistent with Mott's models of phonon-assisted polaronic hopping in the non-adiabatic regime. The physical parameters obtained from the best fits of these models are found reasonable and consistent with glass compositions. The conductivity was primarily determined by carrier mobility.

Iron doping of semiconducting bismuth alkali borate glasses

Theelectricalconductivityofmixed-alkali,lithiumandsodium,ironphosphateglasseshasbeenstudiedinthefrequencyrangefrom0.2to200kHzandoveratemperaturerangefrom323to493K.TheACconductivityasafunctionoftemperaturewasdividedintotwodomains,onewheretheabsolutemagnitudeoftheACconductivitywasclosetotheDCconductivityandanotherwhereitwaslargerthantheDCconductivity.TheDCconductivityforthemixed-alkali,lithiumandsodium,ironphosphateglassesisindependentoftheLi/Naratioandthereisnoevidenceofanymixed-alkalieffect.Thelithiumandsodiumionshavesuchalowmobilityinbothsingle-andmixed-alkaliironphosphateglassesthattheymakenodetectablecontributiontothetotalconductivitythatisofelectronicorigin.Mo¨ssbauerspectralanalysisindicatesthepresenceofbothFe 2+ andFe 3+ ions.r 2005ElsevierB.V.Allrightsreserved. PACS: 72.80.Ng;72.60.+g;66.30.Ed;61.40Keywords: Mixedalkalieffect;Electronic-Ionicconductivity;Conductivityrelaxation;Activationenergy 1. IntroductionSomeglassescontainingtransitionmetalions,suchasiron,vanadiumandtungsten,areelectro-nically conductive [1–6]. The semiconductingbehaviorisduetothetransitionmetalionsbeinginmorethanonevalencestate[7,8].AnexampleofthistransitionofFe

A. Al-Shahrani

Papers

Non-adiabatic small polaron hopping conduction in sodium borate tungstate glasses

Structural and other physical properties of barium vanadate glasses

Study of nanostructural behavior and transport properties of BaTiO3 doped vanadate glasses and glass–ceramics dispersed with ferroelectric nanocrystals

Iron doping of semiconducting bismuth alkali borate glasses

Electrical relaxation in mixed lithium and sodium iron phosphate glasses