Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

Journal Article · 23 February 2018 · Ultramicroscopy

DOI: https://doi.org/10.1016/j.ultramic.2018.02.007 · OSTI ID:1431039

Mangum, John S. ^[1]; Chan, Lisa H. ^[2]; Schmidt, Ute ^[3]; Garten, Lauren M.  ^[4]; Ginley, David S. ^[4]; Gorman, Brian P. ^[1]

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1. Colorado School of Mines, Golden, CO (United States)
2. TESCAN USA Inc., Warrendale, PA (United States)
3. WITec GmbH, Ulm (Germany)
4. National Renewable Energy Lab. (NREL), Golden, CO (United States)

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Next Generation of Materials by Design: Incorporating Metastability (CNGMD)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1431039
• Report Number(s): NREL/JA-5K00-71234
• Journal Information: Ultramicroscopy, Vol. 188, Issue C; ISSN 0304-3991
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English