In this study, borate-based and borosilicate glass samples according to the composition of xSiO2-(40-x)B2O320SrO-20Na2O-20CaO where x = 0, 10, and 20 mol% were fabricated, and their in vitro bioactivities were evaluated. Morphological and structural studies of the proposed samples before and after immersion in simulated body fluid (SBF) were performed using physiochemical instruments. The XRD results showed that a crystalline phase was formed after the immersion of the glass samples, confirming the bioactivity of these samples. The SEM results revealed changes in the glass morphology after immersion in the crystalline form. The weight-loss results showed that B40Si0 was superior to B20Si20 and B30Si10. The glass samples showed antibacterial activity against four pathogenic bacterial strains, including two Gram-positive and two Gram-negative bacteria. Finally, based on the bioactivity results, it can be concluded that the new bioactive glass is valid for use as a biomaterial for bone and dental healing.
Oxide glasses exhibit slow crack growth (SCG) behavior in the presence of water vapor. Oxide glasses are generally considered to be perfectly brittle materials exhibiting no plastic deformation at room temperature. The SCG behavior is generally classified into three regions, region I, region II and region III, in the order of increasing crack velocity as a function of increasing stress intensity. In the regions I and II, crack growth rate is affected by water vapor pressure in environment while in the region III, crack growth rate is independent of water vapor pressure. Water was believed to affect mechanical strength through the surface reaction. In recent years, however, it was observed that water enters into glass at the crack. Water entry into a crack tip is expected to modify the glass properties, e.g. lowering elastic modulus with time through internal friction. In this paper, we observed a residual tensile stress at the crack tip of soda-lime silicate glass after crack growth in regions I and II, but not in region III. Furthermore, this residual tensile stress was observed to decrease with time. This behavior is consistent with the internal friction or viscoelasticity of the crack tip, rather than perfectly elastic deformation. This observation indicates a new mechanism of formation of different crack growth regions (Regions I, II and III) in the slow crack glasses of oxide glasses through internal friction of the crack tip.
The Er3+ doped lead-bismuth-gallium oxide glasses were prepared by melt quenching technique. The spectral and luminescent properties were analyzed based on experimental and theoretical calculations. Analysis of Er3+ concentration dependences of density and electronic optical polarizability was carried out. The radiative lifetime values for 4S3/2 and 4F9/2 energy states were calculated using Judd-Ofelt theory. In the glassy system under study, the concentration quenching of state 4S3/2 was discovered at content of erbium ions above 0.869 x 1020 cm 3. It was also shown that 4F9/2 energy state was isolated from concentration effects and showed an increase in luminescence intensity with increasing concentration of activator ions. The luminescence quantum efficiency for transition 4S3/2 -> 4I15/2 was about 40%, which allows us to consider this system as a glassy matrix effective for activation by rare-earth ions.
This research examines the influence of surface roughness and the incorporation of ZnO (0.05–0.20 mol%) on the magnesium sulfate: dysprosium oxide: boron oxide (0.1 < x < 0.5) glass ceramic system for dosimeter applications. The parent glasses were prepared using the melt-quenching technique, with all samples melted at 1350 °C, except for B, which was melted at 700 °C. The crystallization, roughness, and optical properties were further determined using X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), and UV–Visible Spectrophotometry, respectively. The glass ceramics were exposed to 2.97 mGy of X-ray radiation ten cycles to assess specific dosimetric capabilities. Among the doped samples, MgSO4:Dy2O3-(0.2B2O3:0.05ZnO) exhibited the most promising performance as a dosimeter. Notably, the Thermoluminescence Dosimetry (TLD) readings of the pre- and post-polished 0.2MDB were 1041.96 nC and 1278.84 nC, respectively, with roughness values of 1.83 nm and 54.7 nm. Similarly, the TLD readings of the pre- and post-polished 0.05MDBZ were 1888.33 nC and 3262.63 nC, respectively, with roughness values of 17.3 nm and 19.8 nm. This work highlights that surface roughness significantly enhances trapping efficiency, underscoring the importance of dosimeter polishing as a beneficial step in enhancing their performance.
Understanding the phase transition behavior of phase-change (PC) material with respect to the scaling effect is essential for the application of PC materials. Among all the PC materials, SbTe binary plays a significant role in the well-known Ge-Sb-Te system. Here we have used an unconventional and cost-effective method to fabricate a wide range of prototypical Sb2Te3 amorphous nanowires (18–220 nm in diameter) using templated electrodeposition. Compositional, morphological, and structural characterization of the amorphous nanowires were performed, and the crystallization temperature of in-template nanowires was measured using a four-probe resistivity meter. We report that the crystallization temperature of amorphous Sb2Te3 nanowires can be tuned with respect to the diameter of the nanowires and a significant increase was observed for the nanowires with diameters ≤35 nm. Our study sheds light on the size-dependent phase transition behavior of PC NWs with implications for further advancement of the PC memory technology.
