Solid-state Optical Materials and Luminescence Properties: Session I
Sponsored by: ACerS Basic Science Division, ACerS Engineering Ceramics Division, ACerS Glass & Optical Materials Division
Program Organizers: Yiquan Wu, Alfred University; Jas Sanghera, Naval Research Laboratory; Akio Ikesue, World-Lab. Co., Ltd; Rong-Jun Xie, Xiamen University; Mathieu Allix, University of Orléans; Kiyoshi Shimamura, National Institute for Materials Science; Liangbi Su, Shanghai Institute of Ceramics; Dariusz Hreniak, Institute of Low Temperature and Structure Research

Wednesday 8:00 AM
October 20, 2021
Room: B232
Location: Greater Columbus Convention Center

Session Chair: Yiquan Wu, Alfred University; Jas Sanghera, Naval Research Laboratory

8:00 AM  Invited
Non Rule-of-mixtures Thermal Expansion in Core-shell Based Nanocrystalline Composite Ceramics: James Wollmershauser¹; Kevin Anderson²; Benjamin Greenberg²; Heonjune Ryou¹; Edward Gorzkowski¹; Boris Feigelson¹; ¹U.S. Naval Research Laboratory; ²National Research Council Postdoctoral Research Fellow sited at U.S. Naval Research Laboratory
    Nanocrystalline ceramics demonstrate property improvements over larger-grain-sized ceramics such as increased hardness, strength, and, in the case of birefringent ceramics, visible light transparency. Modeling has also suggested the possibility to actively modulate visible light transparency when harnessing intrinsic electro-optic effects in fine-grained ceramics. However, when designing optical ceramics for integration into components, other properties such as thermal expansion become important. One avenue to design thermal expansion is through combining materials with different coefficients of thermal expansion into a single composite ceramic. Recent work at NRL has combined particle atomic layer deposition (pALD) with Environmentally Controlled – Pressure Assisted Sintering (EC-PAS) to synthesize dense nanocomposite ceramics from core-shell nanopowders. Limited experiments suggest that CTE of these nanocomposites do not follow a simple rule-of-mixtures law, opening the possibility to design CTE outside of these bounds while potentially harnessing other benefits of nanocrystalline ceramics, such as improved mechanical properties.

8:20 AM
Processing of Rare Earth Doped Ga2O3 Transparent Ceramics: Jiao Li¹; Yiquan Wu¹; ¹Alfred University
    Gallium oxide (Ga2O3) has attracted much attention due to its promising applications in optical and electronic devices. Over the past years, the optical properties of rare earth doped Ga2O3 powders, films, single crystals have been widely explored for phosphors, deep-UV optoelectronics and scintillator applications, which makes it even more attractive to fabricate Ga2O3 transparent ceramics. However, there are few studies about Ga2O3 ceramics and even less on transparent ceramics due to the serious reduction reaction and monoclinic structure of Ga2O3. In this report, we synthesized different rare earth (RE) elements (Er-, Dy-, Tb-) doped Ga2O3 powders via co-precipitation method and prepared RE-doped Ga2O3 transparent ceramics by spark plasma sintering. The phase structures and microstructures of RE-doped Ga2O3 powders and ceramics were characterized by XRD and SEM, respectively. Additionally, the density, transmittance and luminescence performance of the sintered ceramics were studied in details.

8:40 AM  Invited
Additive Manufacturing of Tailored Laser Gain Media: Steve Payne¹; Zachary Seeley¹; Nerine Cherepy¹; Thomas Rudzik¹; Tyler Wineger¹; Ian Phillips¹; Alex Drobshoff¹; Tim Yee¹; ¹Lawrence Livermore Lab
    We have been developing laser gain media with composite structures and concentration gradients by transparent ceramics processing, where the “green body” is made by additive manufacturing (AM) techniques. Work has included laser rods with undoped endcaps and internal concentration gradients, thin disks with tailored gain profiles, and waveguide structures. The AM methods are direct-ink write and materials-jetting. The objective is to improve the overlap of the laser and pump modes, and to improve thermal management. Initial laser results on the manufactured parts will be presented. Our collaborators at Army Research Laboratory (Mark Dubinskiy, Team) and Radiation Monitoring Devices (Mike Squillante, Yimin Wang, Team) are gratefully acknowledged. This work was performed under auspices of US Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52- 07NA27344; and was funded by LLNL’s LDRD program (16-SI-03, 19-ERD-006), Joint Transition Office (17-S&A-0579), and DOE STTR DE-SC0018722. Release number is IM 1032508.

9:00 AM
Optical Basicity of Oxynitrides: Doris Möncke¹; Sharafat Ali²; Bo Jonson²; Efstratios Kamitsos³; ¹Alfred University; ²Linnaeus Univerity; ³National Hellenic Research Foundation
    We apply the concept of optical basicity to oxynitride systems by comparison of nitride systems, either crystalline or glassy, with respective oxides. The optical basicity, Λ, was calculated from the chemical composition or by explotimg the relationship between Λ and anion polarizability. Experimental refractive index and density data of alkaline earth and rare earth silicate oxynitride glasses, as well as literature data of similar systems let us propose a method to separate nitride polarizabilities (α_N) from oxide polarizabilities (α_O) in mixed M-Si-O-N systems with varying N:O and M:Si ratios.We find good agreement with Duffy’s previous work on oxyfluoride glasses as the optical basicity varies for the isoelectronic anions N^3-:O^2-:F^- as follows: Λ(fluoride)=1⁄2Λ(oxide)=1⁄3Λ(nitride). The optical basicity of complex nitrides can therefore be calculated by the same method established for oxides using the equivalent fractions and basicity of the constituent nitrides.

9:20 AM
Highly Transparent MgGa2O4 and Ni Doped MgGa2O4 Semiconducting Ceramics: Guangran Zhang¹; Yiquan Wu¹; ¹Alfred University
    MgGa2O4 is considered as a new wide bandgap transparent semiconducting oxide, with an optical bandgap of 4.9 eV at a room temperature. Growing atmosphere will strongly affect conductivity of fabricated MgGa2O4 single crystals. The presence of oxygen can turn semiconducting MgGa2O4 crystal into an insulator. In addition, Ni-doped MgGa2O4 has been developed as a promising host material for tunable near IR laser applications. Such spinel structured material was fabricated into transparent ceramics by spark plasma sintering in our work for the first time. The highest in-line transmittance achieved in the transparent MgGa2O4 and Ni:MgGa2O4 ceramics is about 73% at a wavelength of 1050nm with a relative density above 99.5%. Photoluminescence and absorption spectrum were characterized to explain transition of octahedral Ni2+ doped in MgGa2O4 and to calculate bandgap of the transparent MgGa2O4 ceramics. Tanabe-Sugano diagram is also plotted for the 1 at% Ni:MgGa2O4 ceramics to explain energy level.

9:40 AM  Invited
A Review of Sharp Indentation to Probe Contact Damage in Glass: Brian Davis¹; Ivar Reimanis¹; Amanda Bellafatto¹; Amber Tremper²; Scott Glaesemann²; ¹Colorado School of Mines; ²Corning Incorporated
    The prediction of strength degradation due to contact damage remains an important challenge in the development of glass in load-bearing applications. A key aspect is to describe how damage under an indent evolves into a crack. A review is provided here beginning with analytical descriptions of contact stress fields developed to capture certain types of cracking behaviors. A widely used analytical model developed by Yoffe is compared with a recently developed finite element model (FEM). It is demonstrated that while the analytical model successfully describes the stress field for a limited number of situations, the results are largely inconsistent with experimentally observed crack systems and with FEM, and are sometimes misleading. The FEM model is extended to examine the importance of indenter geometrical variables for several glasses. Implications on the prediction of pop-in cracking during indentation are discussed.