Amorphous Materials: Common Issues within Science and Technology: Glass Technology
Sponsored by: MS&T Organization
Program Organizers: Pierre Lucas, University of Arizona
Thursday 11:00 AM
October 20, 2011
Room: C211
Location: Greater Columbus Convention Center
Session Chair: S. Sundaram, Alfred University
11:00 AM
Bioactive Glass Nanoparticles with Negative Zeta Potential: Ali Doostmohammadi1; Ahmad Monshi1; Mohammad Hossein Fathi1; 1Isfahan University of Technology
This work aimed at preparation and characterization of SiO2–CaO–P2O5 bioactive glass nanoparticles. X-ray fluorescence spectroscopy (XRF) confirmed the preparation of the 63S bioglass with 62.17% SiO2, 28.47% CaO and 9.25% P2O5 (in molar percentage). The in vitro apatite forming ability of the glass particles was evaluated by Fourier transform infrared spectroscopy (FTIR) after immersion in simulated body fluid. The result showed that crystalline hydroxyapatite can form on glass particles. By the BET method, particle specific surface area and theoretical particle size were 223.6±0.5 m²/g and ~24 nm, respectively. Laser dynamic light scattering (DLS) indicated that particles were mostly agglomerated and had an average diameter between 100 to 500 nm. Finally, using laser Doppler electrophoresis (LDE), the zeta potential of bioglass nanoparticles was determined and it was negative for different pH values. The nanometric particle size, bioactivity and negative zeta potential make this material a possible candidate for bone tissue engineering.
11:20 AM
Quantitative Evaluation of Dissolved H2 Concentration in Silica Glass by Thermal Desorption Spectrometry (TDS) in Ultra-High Vacuum: Yuko Tachibana1; Masaaki Takata1; Yasuyuki Takimoto1; Tsuguhide Isemura1; Kiyoshi Yamamoto1; Shinya Kikugawa1; 1Asahi Glass Co., Ltd.
Hydrogen is one of the fundamental gaseous impurities in silica glass which affects on the optical property. In 1986, Khotimchenko proposed the equation to calculate the H2 concentration from the normalized intensity of H2 vibration in Raman scattering (RS) spectroscopy on the basis of calibration by evaluation from mass spectrometry. Whereas this equation is widely used now, mass spectrometry and vacuum technique have been remarkably progressed after the Khotimchenko’s work. In this work, we made the quantitative evaluation of the H2 concentrations in silica glasses by thermal desorption spectrometry (TDS) in ultra-high vacuum with the measurement of the standard sample implanted H+ ions. We also made clear the dissolved H2 release, distinguished from H2 dissociated hydrocarbon surface contamination in ionization process in detection. The relationship between the H2 concentration determined by TDS and the normalized intensity of H2 vibration in RS spectroscopy will be also reported.
11:40 AM
Molecular Dynamics Simulation of the Locations, Atomistic Structures and Properties of Rare-Earth Doped Silicon Oxy-Nitride Intergranular Films in Silicon Nitride: YUN JIANG1; Stephen Garofalini1; 1Rutgers University
Molecular dynamics computer simulations were used to investigate the location, energy, atomistic structure, and fracture behavior of La ions in silicate intergranular films (IGFs) between prism and misoriented silicon nitride crystals. La adsorption at four specific sites on the prism surface is observed as an effect of compositions and thickness in our simulations, at locations precisely consistent with HAADF-STEM results. Results shows sites 1, 2 for almost all the compositions in the ~1.8 nm and ~0.6 nm IGFs, and sites 3 and 4 for specific compositions only in ~1.8 nm IGFs. Increasing N content results in more La ions remaining in the glassy portion of the interior IGF. This is consistent with the change in binding energy of the La ions in the IGF interior in comparison to that at the interfaces, reducing the driving force for segregation and potentially affecting strength and fracture behavior.