Crystalline phase of Y2O3:Eu particles generated in a substrate-free flame process--颗粒学报PARTICUOLOGY

Guo, B., Yim, H., Hwang, W., Nowell, M., & Luo, Z. (2011). Crystalline phase of Y2O3:Eu particles generated in a substrate-free flame process. Particuology, 9(1), 24-31. https://doi.org/10.1016/j.partic.2010.07.020

Crystalline phase of Y₂O₃:Eu particles generated in a substrate-free flame process

Bing Guo ^a *, Hoon Yim ^a, Wonjoong Hwang ^a, Matt Nowell ^b, Zhiping Luo ^c

a Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA
b EDAX-TSL, EDAX Inc., Draper, UT 84020, USA
c Microscopy and Imaging Center, Texas A&M University, College Station, TX 77843, USA

10.1016/j.partic.2010.07.020

Volume 9, Issue 1, February 2011, Pages 24-31

Received 2 March 2010, Revised 25 June 2010, Accepted 6 July 2010, Available online 24 November 2010.

E-mail: bguo@tamu.edu

Highlights

Abstract

In this study, factors affecting the crystal structure of flame-synthesized Y₂O₃:Eu particles were investigated, especially the particle size effect and its interaction with Eu doping concentration. Polydisperse Y₂O₃:Eu (size range 200 nm to 3 μm) powder samples with Eu doping concentrations from 2.5 mol% to 25 mol% were generated in either H2/air or H₂/O₂ substrate-free flames. The crystal structure of the powder samples was determined by powder X-ray diffraction (XRD), which was complemented by photoluminescence (PL) measurements. Single particle crystal structure was determined by single particle selected area electron diffraction (SAED), and for the first time, by electron backscatter diffraction (EBSD). H₂/air flames resulted in cubic phase Y₂O₃:Eu particles with hollow morphology and irregular shapes. Particles from H₂/O₂ flames had dense and spherical morphology; samples with lower Eu doping concentrations had mixed cubic/monoclinic phases; samples with the highest Eu doping concentrations were phase-pure monoclinic. For samples generated from H₂/O₂ flames, a particle size effect and its interaction with Eu doping concentration were found: particles smaller than a critical diameter had the monoclinic phase, and this critical diameter increased with increasing Eu doping concentration. These findings suggest that the formation of monoclinic Y₂O₃:Eu is inevitable when extremely hot substrate-free flames are used, because typical flame-synthesized Y₂O₃:Eu particle sizes are well below the critical diameter. However, it may be possible to generate particles with dense, spherical morphology and the desired cubic structure by using a moderately high flame temperature that enables fast sintering without melting the particles.

Graphical abstract

Keywords

Flame synthesis; AerosolSize effect; Crystal structure; Y₂O₃:Eu; Particles

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