12th International Symposium on Green and Sustainable Technologies for Materials Manufacturing and Processing: Sustainable Manufacturing of Ceramics II
Sponsored by: ACerS Engineering Ceramics Division
Program Organizers: Surojit Gupta, University of North Dakota; Rajiv Asthana, University of Wisconsin; Mritunjay Singh, Ohio Aerospace Institute; Tatsuki Ohji, AIST; Enrico Bernardo, University of Padova; Zhengyi Fu, Wuhan University of Technology; Hisayuki Suematsu, Nagaoka University of Technololgy; Tatami Junichi, Yokohama national university; Yiquan Wu, Alfred University; Allen Apblett, Oklahoma State University
Tuesday 2:00 PM
November 3, 2020
Room: Virtual Meeting Room 20
Location: MS&T Virtual
Session Chair: Tatami Junichi, Yokohama National University; Yiquan Wu, Alfred University; Eva Hemmer, University of Ottawa
2:00 PM
Solid State Single Crystal Growth of YAG by SPS Sintering: Iva Milisavljevic1; Yiquan Wu1; 1Alfred University
Technologies which are currently used for the production of single crystals are accompanied by many problems, such as high costs of production. However, recently it has been shown that many of the challenges associated with the growth of single crystals can be overcome by solid-state single crystal growth (SSCG) from polycrystalline materials. In this work, Y3Al5O12 (YAG) single crystals were grown by the SSCG method using spark plasma sintering (SPS). The powder containing the seed crystal was sintered using SPS and the single crystal was grown through the conversion of the polycrystalline matrix. XRD analysis showed that the polycrystalline matrix had a single cubic YAG phase. From the SEM images, large areas without grain boundaries and small porosity, described as single crystals, could be observed. Furthermore, the growth kinetics and mechanisms of SSCG of YAG prepared by SPS was discussed.
2:20 PM Invited
Microwave-assisted Synthesis of Lanthanide-based Nano- and Microscale Materials: Ilias Halimi1; Nan Liu1; Nikita Panov1; Emille Rodrigues1; Eva Hemmer1; 1University of Ottawa
Lanthanide-based fluorides (MLnF4, M = alkali metal, Ln = lanthanides/Yttrium) have been suggested for a wide range of applications, e.g. in biomedicine, optoelectronics, and solar energy conversion. Among the popular synthesis methods are hydrothermal, co-precipitation and thermal decomposition. The conventional decomposition approach allows for some phase- and size-selectivity, while limitations remain. The need for reaction temperatures of 300 °C and times of several hours constitutes further drawbacks. Conversely, microwave radiation provides faster and more homogeneous heating, resulting in shorter reaction times and possible decrease of temperature. We here report the development of two microwave-assisted synthesis methods towards MLnF4 at the nano- and microscale. The first employs various precursor chemistries and provides rapid access to small (sub-10 nm) Er3+/Yb3+-doped NaGdF4 nanoparticles. The second yields Ln3+-doped LiYF4 microcrystals. Salient characteristics of this approach are the reduced reaction duration and use of inexpensive and more environmentally benign solvents, i.e., ethanol and water.
2:40 PM
Microwave-assisted Pretreatment of Coal Fly Ash for Enhanced Recovery of Rare-Earth Elements: Gunes Yakaboylu1; Daniel Baker1; Katarzyna Sabolsky1; John Zondlo1; Christina Wildfire2; Edward Sabolsky1; 1West Virginia University; 2US DOE-National Energy Technology Laboratory & Leidos
Coal fly ash solid waste is a promising source for extraction of the critical rare-earth elements due to increasing demand and need for green and sustainable technologies (e.g. hybrid vehicles, batteries). However, rare-earth elements are mostly isolated within aluminosilicate fly ash particles, which makes their recovery highly limited even using aggressive acid solutions. In this study, a microwave-assisted pretreatment technique was developed as an economic and sustainable approach to improve the enrichment and extraction of the rare-earth elements from coal fly ash. The mixtures of coal fly ash and carbon were pretreated under microwave irradiation at various conditions (e.g. power, time, mode) under argon. Ultra-high heating rates, high temperatures and drastic temperature changes resulted in compositional changes and microstructural defects, which highly enhanced the penetration of acid leaching solutions into aluminosilicate fly ash particles. The leaching efficiency of the total rare-earth elements thereby increased from 21.7 to 54.9-83.4%.