Glasses, Optical Materials, and their Functional Applications: Current Issues in Science & Technology: Advanced Characterizations and Functional Applications
Sponsored by: ACerS Glass & Optical Materials Division
Program Organizers: Jincheng Du, University of North Texas; S. K. Sundaram, Alfred University
Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 15
Location: MS&T Virtual
Session Chair: S. K. Sundaram, Alfred University; Jincheng Du, University of North Texas
2:00 PM Invited
Glasses beyond Megabar Pressures: Sung Keun Lee1; 1Seoul National University
We provide an overview of the recent experimental progress and insights by X-ray Raman scattering (XRS) into structures of oxide glasses under compression above megabar pressures. A densification of amorphous oxides under extreme compression is dominated by reorganization of oxygen during compression. XRS spectra for SiO2 glass up to 1.6 Mbar reveal the evolution of heavily contracted oxygen environments characterized by a decrease in average O..O distance and the emergence of quadruply coordinated oxygen. Our results also yield the predictive relationship between the density and partial density of state of oxides above megabar pressures. The extreme densification paths with densified oxygen in amorphous oxides shed light upon the possible existence of stable melts in the planetary interiors [Lee.et al., Phys. Rev. Lett., 123 235701 (2019); PNAS 115, 5855 (2018); Kim et al. Geophy. Res. Lett., 46 13756 (2019)].
2:40 PM Invited
Terahertz Time-domain Spectroscopy of Glasses: S. K. Sundaram1; 1Alfred University
Terahertz (THz) spectroscopy captures molecular and vibrational spectra over 10 GHz-10 THz. In the time domain, access to complex refractive indices makes it a versatile tool. THz time-domain spectroscopy (THz-TDS) has been used to study major glass families. The THz-TDS directly measures the THZ wave’s temporal electric field. Fourier transforms of the time-domain data yield the amplitude and phase of the wave pulse and the real and imaginary parts of the dielectric constant. An overview of the tool and its application to study selected model glass systems, e.g., silica, alkali borate, silicates, and tellurite and nonoxide systems will be presented. Our recent results show a linear correlation between refractive index measurements in visible and terahertz frequencies with systematic rare-earth ion inclusions in aluminosilicate glasses. In addition, our results demonstrate that THz-TDS can be utilized as a means of extending the detectable limits in refractive index measurements of disordered glass structures.
3:10 PM
Effect of Transition Metal Impurities on the Properties of ZnSe Single Crystals: Brett Setera1; Charmain Su1; Fow-Sen Choa1; Bradley Arnold1; Ching Hua Su1; Shruti Singh1; Puneet Gill1; Kamdeo Mandal1; Ian Emge1; Narsingh Singh1; 1University of Maryland, Baltimore County
Zinc selenide (ZnSe) has been investigated for variety of applications including an excellent laser host material for MWIR and LWIR wavelength applications. A large number of papers have been published to grow single crystals and to evaluate suitability of ZnS and ZnSe doped with rare earth and transition metal. These ions have been used as activators in the bulk matrix for lazing. There is a continuous effort to grow better crystals and study effects of vapor transport and fluid flow. Since dopant, ions have different sizes and oxidation states. Because of this reason, point and line defects may be generated which ultimately affect the electrical and optical characteristics. In addition, these ions significantly affect point and line defects during growth by physical vapor transport. We have observed that doping with ions affects the dielectric properties and morphologies, which ultimately affect the performance of doped ZnSe.
3:30 PM
Development of YAG-alumina Composites for the Lightening Applications: Sekyung Chang1; Robert Kusner1; Fritz Grensing1; Wenbo Zhang1; 1Materion Corporation
A cerium doped YAG (Y3Al5O12)-alumina composite was developed by solid state sintering in air. Low grade (3N) yttria and, ceria (or cerium nitrates) powder, and alumina obtained from the alumina grinding media eroded during ball milling of the oxide powder mixture were used as starting materials. With a small amount of silica-based sintering aids, the YAG-alumina composites can be sintered in air to near theoretical density at a temperature as low as 1525oC for 8 hours. The amount of ceria in YAG-alumina composites affects not just the intensity of the light output but also in the densification of the YAG-alumina composites. The optical efficiency of YAG-alumina composites as a function of cerium concentration, sintering temperature as well as the content of alumina phase will be presented.