Y2O3–Al2O3 microsphere crystallization analyzed by electron backscatter diffraction (EBSD)

• Published in: Scientific reports Vol. 10; no. 1; p. 11122
• Main Authors: Wisniewski, Wolfgang, Švančárek, Peter, Prnová, Anna, Parchovianský, Milan, Galusek, Dušan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.07.2020; Nature Publishing Group
• Subjects: 639/301/1023/1024; 639/301/1023/218; Aluminum oxide; Contaminants; Cooling; Crystal growth; Crystallization; Diffraction; Electron microscopy; Growth models; Heat treatment; Heat treatments; Hot pressing; Humanities and Social Sciences; Microspheres; multidisciplinary; Nitrates; Phase transitions; Scanning electron microscopy; Science; Science (multidisciplinary); Scientific imaging; Spectrometry; Temperature
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-67816-7

The crystallization of glass microspheres in the Y 2 O 3 –Al 2 O 3 -system produced from precursor powders of four different nominal compositions via flame synthesis is analyzed in detail by electron microscopy with a focus on electron backscatter diffraction (EBSD). Growth models are formulated for individual microspheres crystallized during flame synthesis as well as after an additional heat treatment step. 16 different types of crystallized bodies are cataloged for future reference. They are presented without regard for their relative occurrence; some are extremely rare but illustrate the possibilities of flame synthesis in the analyzed system. All three phases in the binary Y 2 O 3 –Al 2 O 3 -phase diagram (Y 3 Al 5 O 12 , YAlO 3 and Y 4 Al 2 O 9 ) and α-alumina are located by EBSD. Energy dispersive X-ray spectrometry results obtained from these microspheres show that their chemical composition can deviate from the nominal composition of the precursor powder. The multitude of differing microsphere types showing polygon and dendritic crystal growth as well as phase separation indicate that flame synthesis can lead to a wide variety of parameters during microsphere production, e.g. via irregular flight paths through the flame, contaminants or irregular cooling rates.