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- Title
Microgravity effects on nonequilibrium melt processing of neodymium titanate: thermophysical properties, atomic structure, glass formation and crystallization.
- Authors
Wilke, Stephen K.; Al-Rubkhi, Abdulrahman; Koyama, Chihiro; Ishikawa, Takehiko; Oda, Hirohisa; Topper, Brian; Tsekrekas, Elizabeth M.; Möncke, Doris; Alderman, Oliver L. G.; Menon, Vrishank; Rafferty, Jared; Clark, Emma; Kastengren, Alan L.; Benmore, Chris J.; Ilavsky, Jan; Neuefeind, Jörg; Kohara, Shinji; SanSoucie, Michael; Phillips, Brandon; Weber, Richard
- Abstract
The relationships between materials processing and structure can vary between terrestrial and reduced gravity environments. As one case study, we compare the nonequilibrium melt processing of a rare-earth titanate, nominally 83TiO2-17Nd2O3, and the structure of its glassy and crystalline products. Density and thermal expansion for the liquid, supercooled liquid, and glass are measured over 300–1850 °C using the Electrostatic Levitation Furnace (ELF) in microgravity, and two replicate density measurements were reproducible to within 0.4%. Cooling rates in ELF are 40–110 °C s−1 lower than those in a terrestrial aerodynamic levitator due to the absence of forced convection. X-ray/neutron total scattering and Raman spectroscopy indicate that glasses processed on Earth and in microgravity exhibit similar atomic structures, with only subtle differences that are consistent with compositional variations of ~2 mol. % Nd2O3. The glass atomic network contains a mixture of corner- and edge-sharing Ti-O polyhedra, and the fraction of edge-sharing arrangements decreases with increasing Nd2O3 content. X-ray tomography and electron microscopy of crystalline products reveal substantial differences in microstructure, grain size, and crystalline phases, which arise from differences in the melt processes.
- Subjects
ATOMIC structure; REDUCED gravity environments; THERMOPHYSICAL properties; EXPANSION of liquids; FORCED convection; CRYSTALLIZATION; NON-equilibrium reactions
- Publication
NPJ Microgravity, 2024, Vol 10, Issue 1, p1
- ISSN
2373-8065
- Publication type
Article
- DOI
10.1038/s41526-024-00371-x