Glasses, Optical Materials, and Devices: Current Issues in Science & Technology: Advanced Characterizations of Glasses and Glass-ceramics
Program Organizers: Jincheng Du, University of North Texas; S. Sundaram, Alfred University

Monday 8:00 AM
September 30, 2019
Room: A106
Location: Oregon Convention Center

Session Chair: S. K. Sundaram, Alfred University; Sabyasachi Sen, University of California, Davis

8:00 AM  Invited
Advanced Nanoscale Characterization of Buried Glass Interfaces by Atom Probe Tomography: Daniel Schreiber1; Daniel Perea1; Karen Kruska1; Matthew Olszta1; Josef Matyas1; Joseph Ryan1; 1Pacific Northwest National Laboratory
    A buried interface is oftentimes the dominant structural feature that controls the behavior of a material system. Conversely, detailed nanoscale characterization of these buried interfaces gives vital clues to the fundamental atomistic processes directing this behavior. In this talk, I will discuss how atom probe tomography (APT) in providing new insights into interfacial phenomena in glass science. APT provides a unique 3D elemental map of materials with sub-nm spatial resolution, and nominally equal sensitivity to all elements in the periodic table. An overview will be provided of the technique, including sample preparation requirements, and how it complements more conventional high-resolution analytical techniques such as transmission electron microscopy and secondary ion mass spectrometry. Examples will be presented from ongoing research on the corrosion of model nuclear waste forms and glass/ceramic composites.

8:40 AM  Invited
Pentacoordinated Silicon in Alkali Silicate Glasses: Pressure, Temperature and Compositional Effects and Analogies to Borate and Germanate Systems: Jonathan Stebbins1; Saurav Bista1; 1Stanford University
    Small concentrations of SiO5 can be measured in high pressure, and even in ambient pressure, potassium silicate glasses by 29Si NMR. This species is more abundant at higher pressure and higher fictive temperature. As K2O is added to silica, SiO5 first increases, then decreases, in a pattern remarkably similar to known trends in alkali borates and germanates, although there the concentrations of higher-coordinated cations (BO4 and GeO5/GeO6) are orders of magnitude higher. A reaction involving non-bridging oxygens to increase network cation coordination is probably common to all three systems. A simple model of non-ideal mixing of NBO roughly predicts the systematics observed in silicates, borates, and germanates, indicating an underlying, fundamental similarity. A practical prediction is that physical properties of silicate liquids at high pressure should be highly non-linear with composition.

9:10 AM  Invited
Total Scattering Studies of Deformation Behavior of Bulk Metallic Glasses: Dong Ma1; 1Oak Ridge National Laboratory
    Neutron and synchrotron total scattering techniques have been used to investigate deformation behavior of bulk metallic glasses (BMGs) upon uniaxial compression or bending. Reciprocal-space analyses of the total scattering data reveal distinct behaviors of short-range order (SRO) and medium-range order (MRO) in response to uniaxially applied stresses in the apparently elastic regime, indicative of inhomogeneous deformation behavior at multiple length scales. In situ diffraction studies of local elastic strain fields of elastically and plastically bent BMG thin plates are consistent with our stress analysis, which has important implications in designing and manipulating internal strain fields in BMGs for the purpose of ductility enhancement.

9:40 AM  
Scattering of Visible Light by Crystalline Particles in Glass: Mackenzie Stevens1; Shannon Rogers1; Hyojin Lee1; Bill Carty1; 1Alfred University
    It is well known that the presence of crystalline particles in glass scatters light and, if the quantity of particles is sufficient, the glass is opaque. This study determines translucency as a function of the volume fraction of particles, up to the point of opacity. Results demonstrate that volume fraction of particles necessary to create opacity can be below the detection limit of X-ray diffraction. Samples were prepared by introducing crystalline powders (Al2O3, ZrO2, SiO2 (quartz), SiC, Si3N4, etc.) to borosilicate glass frits, mixed by milling, compacting the sample, and sintering in a vacuum furnace. Variables that contributed to volume fraction of crystalline particles necessary for opacity included particle size and refractive index difference between particle and glass. Results also showed that as particle size decreased, opacity scaled with number of scattering sites (i.e., a lower volume concentration of smaller particles equates to a higher volume fraction of larger particles).

10:00 AM Break

10:20 AM  Invited
Structures and Properties of New Sodium Thioborosilicate Glasses: Steve Martin1; Brittany Curtis1; Steven Kmiec1; 1Iowa State University of Science and Technology
    Sodium borosilicate glasses are perhaps among the most widely studied of all oxide glasses. However, it appears that there has never been a detailed study of the sulfide analogue of this series, the sodium thioborosilicate glasses made based upon Na2S + B2S3 + SiS2. In this very first study of this system, we report on one mixed glass former series in this system, 0.60Na2S + 0.4[xBS3/2 + (1-x)SiS2]. We find that glasses can be easily prepared for all 0 x 1once high purity staring materials can be prepared. This series corresponds to the compositional line B0 to Si1 where the superscript defines the number of bridging sulfurs on the glass former. Rather than a simple mixing of 0.4x moles of B0 and 0.4(1-x) moles of Si1 units, the system exhibits significant disproportionation where charge is move to the Si units to form Si0 and B1 and B2 units. We will describe the full structural evolution of this system and some of the physical properties of these glasses in this series.

10:50 AM  
Threshold Detection of Crystalline Particles in Glass by X-ray Diffraction: Shannon Rogers1; Mackenzie Stevens1; Hyojin Lee1; William Carty1; 1Alfred University
    It is relatively common to refer to glass samples as “completely amorphous” when the correct term should be “X-ray amorphous” meaning that crystalline particles were not detectable by X-ray diffraction. The threshold detection limit of crystalline material in a glass is dependent on a number of variables including the particle size, molecular weight of the glass, and the diffraction efficiency of the crystalline particle. Several powders, including Al2O3, ZrO2, SiO2 (quartz), SiC, and Si3N4, were mixed (via milling) with commercial glass frits ranging from 0.1 to 10 volume percent and then measured with X-ray diffraction. The particle size of the crystalline powders was varied while keeping the volume fraction similar. The results show that the average atomic number of the glass frit contributes to X-ray scattering significantly reducing the threshold detection limit for crystalline particles.

11:10 AM  
Influence of Local Structure of the CaO-BO1.5-AlO1.5 Melts on Their Thermal Conductivity: Hodaka Aoki1; Sakae Shirayama1; Kazuki Morita1; 1The University of Tokyo
    In order to obtain the desirable thermal conductivity by designing the mold flux composition for the continuous casting in the steelmaking processes, thermal conductivity of the CaO-BO1.5-AlO1.5 melts at above 1473 K and its local structure have been investigated in our previous work. Results of Raman spectroscopy have suggested the possibility that AlB3O7 structure increased the thermal conductivity. In this study, local structure of the quenched CaO-BO1.5-AlO1.5 glasses was investigated by 11B and 27Al MAS-NMR for more quantitative evaluation. Probability of formation of AlB3O7 structure was calculated by the relative fraction of 4-coordinated B and 4-coordinated Al. As a result, the higher probability of formation of AlB3O7 structure corresponded to the higher thermal conductivity when the concentration of CaO was higher than 25mol%. On the other hand, increment in thermal conductivity at lower CaO content was found to be due to the increase in bridging oxygen.

11:30 AM  
Synthesis and Electrical Conductivity of a Novel, Vanadium Containing, Mixed Conductor Glass: Swati Soman1; Mohit Yadav1; Ajit Kulkarni1; 1Indian Institute of Technology Bombay
    Combining the electrochemical advantage of fluoride phosphate based materials and structural, compositional, synthesis advantages of glasses, we have fabricated new vitrified compositions in narrow compositional range of LiF‒Al(PO₃)₃ system with addition of Vanadium oxide. Homogeneous glasses are obtained by melt quench method over a wide range of Vanadium oxide content, from 2 to 70 mol%. IR spectra reveal that Vanadium acts as network modifier or as second network former depending on its concentration. Changes in glass structure correlate with their measured properties. Glass transition temperature, Tg varies between 250‒350⁰ C, reducing with increasing Vanadium content, due to decreasing rigidity of glass matrix as it transforms from metaphosphate to vanadophosphate network. Total room temperature dc conductivity varies from ~10-⁰ S/cm to ~10-⁶ S/cm. Impedance measurements reveal ionic to mixed conduction with changing composition, rendering them as promising glassy cathode material.