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IntroductionThe microstructure analysis of thermoelectric oxides like Ca3Co4O9 is fundamental to the research of thermoelectric power generation devices. These devices provide a means of utilizing waste heat to make power; thus, improving the sustainability of energy. Analysis techniques for studying the p-type semiconductor Ca3Co4O9 were explored in this study. Also, β-FeO(OH) was investigated which is useful in magnetic recording media.

Experiment

Synthesis of Iron Powder: • FeCl3 + Urea + H2O • Solution placed in high preactor• Particles centrifuged after

removed from preactor

Determination of appropriate XRD and SEM parameters for analysis:• Adjust XRD scan speed, lens size, and

angle increment• Adjust SEM preparation method,

voltage applied, detector mode, and working distance

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ObjectiveDetermine appropriate XRD settings to get well-defined peaks for Ca3Co4O9 pellet sample and β-FeO(OH) powder sample. Determine appropriate SEM settings to get clear SEM images for β-FeO(OH).

Scan Angles: 5°-62°Increment: 0.05Scan Speed: 16 sec/stepMode: 1DAbsorber: 1

Scan Angles: 5°-80° Increment: 0.05°Scan Speed: 8 sec/stepMode: 0DAbsorber: 1

Scan Angles: 5°-80° Increment: 0.05°Scan Speed: 38 sec/stepMode: 1DAbsorber: 1Lens: 0.2 mm

SEM Images for β-FeO(OH)

Preparation: particles dispersed on double sided copper tape attached to sample mount

Preparation: particles mounted on silicon wafer and coated with platinum

XRD Results for β-FeO(OH)

Scan Angles: 10°-80° Increment: 0.05°Scan Speed: 13 sec/stepMode: 1DAbsorber: 1Lens: 0.1 mm

10µm

Conclusions

1 µm

XRD • Ca3Co4O9 pellets require a scanspeed of 16 sec/step for distinguishable peaks• β-FeO(OH) powder requires a scanspeed of 38 sec/step • Powders require a higher scan speed than pellets• A larger lens size produces higher peaksSEM• β-FeO(OH) powder must be attached to a silicon wafer and coated with a conductive

coating to get clear images• β-FeO(OH) particles were roughly 500 nm with a narrow particle size distribution and

a needle-like shape

XRD Results for Ca3Co4O9

References[1] Michitaka OHTAKI, Recent aspects of oxide thermoelectric materials for power generation from mid-to-high temperature heat source, Journal of the Ceramic Society of Japan, 119 (11), 770-775.[2] Jeffrey W. Fergus, Oxide materials for high temperature thermoelectric energy conversion, Journal of the European Ceramic Society, 32 (2012) 525-540.[3] http://www.sciencedirect.com/science/article/pii/S0010938X03000787[4] http://www.easyfairs.com/de/events_216/labotec-suisse2012_24924/labotec-suisse-2012_24925/visitors_24926/ausstellerkatalog_24937/stand/337587/[5] http://serc.carleton.edu/research_education/geochemsheets/techniques/XRD.html[6] http://www.nanocenter.umd.edu/new_facilities/NispLab.php

[1]

[4]

Acknowledgements• I want to thank Xueyan Song and Maria Alejandra Torres Arango for their assistance as

well as the WVU Shared Facilities for their assistance and access to the XRD and SEM.• This research was sponsored by NSF Divisions of Materials Research and Chemistry

(DMR-1004431).

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SEMHydrothermal Reactor

Thermoelectric Unicouple Ca3Co4O9 crystal structure β-FeO(OH) crystal structure

XRD

[2] [3]

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Laura E. Carpenter, Xueyan Song, and Maria Alejandra Torres ArangoDepartment of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6045

Microstructure Analysis of Ca3Co4O9 and β-FeO(OH) using XRD and SEM