Influence of Morphology and Processing on XPS Characterisation of SrO-Ca-ZnO-SiO2 Glass

A study was conducted to demonstrate the influence of morphology and processing on X-ray photoelectron spectroscopic (XPS) characterization SrO-Ca-ZnO-SiO2 glass. The glass formulation being investigated was originally synthesized for developing a novel glass polyalkenoate cement (GPC). High resolution photoelectron spectra of Zn 2p, Ca 2p, Sr 3d, Si 2p, O 1s, and C 1s were recorded for the different forms of glass. It was observed that there was preferential enrichment of Zn2+ with an increase in the proportion of NBO for the investigated BT101 glass. The relative atomic concentration of Zn in BT101 glass was high and resulted in a steeper diffusion gradient. Zn2+ Zn2+ was small as compared to Ca2+, revealing that smaller cations migrated and enriched the surface

Comparison of a SiO2-CaO-ZnO-SrO Glass Polyalkenoate Cement to Commercial Dental Materials: Glass Structure and Physical Properties

Glass polyalkenoate cements (GPCs) have previously been considered for orthopedic applications. A Zn-GPC (BT 101) was compared to commercial GPCs (Fuji IX and Ketac Molar) which have a setting chemistry analogous to BT 101. Handling properties (working, Tw and setting, Ts times) for BT 101 were shorter than the commercial GPCs. BT 101 also had a higher setting exotherm (Sx - 34 °C) than the commercial GPCs (29 °C). The maximum strengths for BT 101, Fuji IX, and Ketac Molar were 75, 238, and 216 MPa (compressive, σc), and 34, 54, and 62 MPa (biaxial flexural strengths, σf), respectively. The strengths of BT 101 are more suitable for spinal applications than commercial GPCs. © 2012 Springer Science+Business Media New York

The Structural Role of Titanium in Ca-Sr-Zn-Si/Ti Glasses for Medical Applications

Glasses for medical applications are used in particulate form or as a cement component. This work was undertaken to determine structural changes in 0.48SiO2-0.36ZnO-0.12CaO-0.04SrO glass when the SiO2 is substituted with 5 mol% increments of TiO2. X-ray Diffraction (XRD) was used to determine the presence of crystallinity. This occurred after additions of 20 mol% TiO2. Differential Thermal Analysis (DTA) and Network connectivity (NC) calculations determined that by increasing the TiO2 content, the Tg and NC reduced (Tg 670 °C to 632 °C, NC 1.83 to -1.14) suggesting that TiO2 acts as a modifying oxide. X-ray Photoelectron Spectroscopy (XPS) was used to determine the glass composition and the relative fraction of Bridging Oxygens (BO) to Non-Bridging Oxygens (NBO). XPS revealed that by increasing the concentration of TiO2, the NBO concentration increases, further suggesting the modifying role of Ti. The NBO/BO ratio was found to increase from 1.2 to 9.0 as the TiO2 content increased from 0 to 20 mol% additions. Raman spectroscopy was used to determine the Q-Structure of the glass series and found that the addition of TiO2 reduced the Raman shift from containing predominantly Q1/Q2 units when no Ti was present to Q0/Q1 with TiO2 additions. © 2010 Elsevier B.V. All rights reserved

The Bioactivity and Ion Release of Titanium-Containing Glass Polyalkenoate Cements for Medical Applications

The ion release profiles and bioactivity of a series of Ti containing glass polyalkenoate cements. Characterization revealed each material to be amorphous with a Tg in the region of 650-660°C. The network connectivity decreased (1.83-1.35) with the addition of TiO2 which was also evident with analysis by X-ray photoelectron spectroscopy. Ion release from cements were determined using atomic absorption spectroscopy for zinc (Zn2+), calcium (Ca2+), strontium (Sr2+), Silica (Si4+) and titanium (Ti4+). Ions such as Zn2+ (0.1-2.0 mg/l), Ca2+ (2.0-8.3 mg/l,) Sr2+ (0.1-3.9 mg/l), and Si4+ (14-90 mg/l) were tested over 1-30 days. No Ti4+ release was detected. Simulated body fluid revealed a CaP surface layer on each cement while cell culture testing of cement liquid extracts with TW-Z (5 mol% TiO2) produced the highest cell viability (161%) after 30 days. Direct contact testing of discs resulted in a decrease in cell viability of the each cement tested. © 2010 Springer Science+Business Media, LLC

The Effect of Glass Synthesis Route on Mechanical and Physical Properties of Resultant Glass Ionomer Cements

Glass ionomer cements (GICs) have potential orthopaedic applications. Solgel processing is reported as having advantages over the traditional melt-quench route for synthesizing the glass phase of GICs, including far lower processing temperatures and higher levels of glass purity and homogeneity. This work investigates a novel glass formulation, BT 101 (0.48 SiO2-0.36 ZnO-0.12 CaO-0.04 SrO) produced by both the melt-quench and the solgel route. The glass phase was characterized by X-ray diffraction (XRD) to determine whether the material was amorphous and differential thermal analysis (DTA) to measure the glass transition temperature (Tg). Particle size analysis (PSA) was used to determine the mean particle size and X-ray photoelectron spectroscopy (XPS) was used to investigate the structure and composition of the glass. Both glasses, the melt-quench BT 101 and the solgel BT 101, were mixed with 50 wt% polyacrylic acid (Mw, 80,800) and water to form a GIC and the working time (Tw) and the setting time (Ts) of the resultant cements were then determined. The cement based on the solgel glass had a longer Tw (78 s) as compared to the cement based on the melt derived glass (19 s). Ts was also much longer for the cement based on the solgel (1,644 s) glass than for the cement based on the melt-derived glass (25 s). The cements based on the melt derived glass produced higher strengths in both compression (σc) and biaxial flexure (σf), where the highest strength was found to be 63 MPa in compression, at both 1 and 7 days. The differences in setting and mechanical properties can be associated to structural differences within the glass as determined by XPS which revealed the absence of Ca in the solgel system and a much greater concentration of bridging oxygens (BO) as compared to the melt-derived system. © 2009 Springer Science+Business Media, LLC

Characterisation of Ga2O3-Na2O-CaO-ZnO- SiO2 Bioactive Glasses

The structural role of Gallium (Ga) is investigated when substituted for Zinc (Zn) in a 0.42SiO2-0.40-xZnO-0.10Na2O-0.08CaO glass series, (where x = 0.08). Each starting material was amorphous, and the network connectivity (NC) was calculated assuming Ga acts as both a network modifier (1.23), and also as a network former. Assuming a network forming role for Ga the NC increased with increasing Ga concentration throughout the glass series (Control 1.23, TGa-1 2.32 and TGa-2 3.00). X-ray photoelectron spectroscopy confirmed both composition and correlated NC predictions. Raman spectroscopy was employed to investigate Q-structure and found that a shift in wavenumbers occurred as the Ga concentration increased through the glass series, from 933, 951 to 960 cm-1. Magic angle spinning nuclear magnetic resonance determined a chemical shift from -73, -75 to -77 ppm as the Ga concentration increased, supporting Raman data. These results suggest that Ga acts predominantly as a network former in this particular Zn-silicate system. © 2013 Springer Science+Business Media New York

Titania-silver and alumina-silver composite nanoparticles: novel, versatile synthesis, reaction mechanism and potential antimicrobial application

Titania–silver (TiO2–Ag) and alumina–silver (Al2O3–Ag) composite nanoparticles were synthesised by a simple, reproducible, wet chemical method under ambient conditions. The surface of the oxides was modified with oleic acid, which acted as an intermediate between the oxide surface and the silver nanoparticles. The resulting composite nanoparticles were thoroughly characterized by XRD, TEM, XPS, FTIR and TGA to elucidate the mode of assembly of Ag nanoparticles on the oxide surfaces. Epoxy nanocomposites were formulated with TiO2–Ag and Al2O3–Ag to examine potential applications for the composite nanoparticles. Preliminary results from disk diffusion assays against Escherichia coli DH5α and Staphylococcus epidermidis NCIMB 12721 suggest that these TiO2–Ag and Al2O3–Ag composite nanoparticles have potential as antimicrobial materials

Synthesis and energy modelling studies of titanium oxy-nitride films as energy efficient glazing

Films of titanium oxynitride are assessed for their potential as energy saving coatings on window glass. The coatings are deposited from the atmospheric pressure chemical vapour reaction of TiCl4 and ammonia. Film microstructure and composition was analysed using scanning electron microscopy, X-ray diffraction, pulsed RF GD OES and X-ray photoelectron spectroscopy. Transmission and reflectance spectroscopy were used to investigate the optical properties of the films. In this study optical data is used in building simulations to predict the savings made by these novel thin films compared to standard products, for locations with different climates. The results suggest that such glazing can have a significant energy saving effect compared to current approaches across a wide range of climate types

The bioactivity and ion release of titanium-containing glass polyalkenoate cements for medical applications

The ion release profiles and bioactivity of a series of Ti containing glass polyalkenoate cements (GPCs). Characterization revealed each material to be amorphous with a Tg in the region of 650-660ºC. The network connectivity decreased (1.83-1.35) with the addition of TiO2 which was also evident with analysis by X-ray Photoelectron Spectroscopy (XPS). Ion release from cements were determined using Atomic Absorption Spectroscopy (AAS) for zinc (Zn2+), calcium (Ca2+), strontium (Sr2+), Silica (Si4+) and titanium (Ti4+). Ions such as Zn2+ (0.1-2.0 mg/L), Ca2+ (2.0-8.3 mg/L,) Sr2+ (0.1-3.9 mg/L), and Si4+ (14-90 mg/L) were tested over 1-30 days. No Ti4+ release was detected. Simulated body fluid (SBF) revealed a CaP surface layer on each cement while cell culture testing of cement liquid extracts with TW-Z (5 mol% TiO2) produced the highest cell viability (161%) after 30 days. Direct contact testing of discs resulted in a decrease in cell viability of each cement tested

High density growth of indium seeded silicon nanowires in the vapor phase of a high boiling point solvent

peer-reviewedHerein, we describe the growth of Si nanowires (NWs) in the vapor phase of an organic solvent medium on various substrates (Si, glass, and stainless steel) upon which an indium layer was evaporated. Variation of the reaction time allowed NW length and density to be controlled. The NWs grew via a predominantly root-seeded mechanism with discrete In catalyst seeds formed from the evaporated layer. The NWs and substrates were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The suitability of the indium seeded wires as anode components in Li batteries was probed using cyclic voltammetric (CV) measurements. The route represents a versatile, glassware-based method for the formation of Si NWs directly on a variety of substrates.ACCEPTEDpeer-reviewe