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Ambient temperature synthesis of polycrystalline thin films of lithium cobalt oxide with controlled crystallites orientations

Published online by Cambridge University Press:  10 February 2011

R.B. Goldner
Affiliation:
Tufts University Electro-Optics Technology Center, 4 Colby St., Medford, MA 02155
P. Zerigian
Affiliation:
Tufts University Electro-Optics Technology Center, 4 Colby St., Medford, MA 02155
T.Y. Liu
Affiliation:
Tufts University Electro-Optics Technology Center, 4 Colby St., Medford, MA 02155
N. Clay
Affiliation:
Tufts University Electro-Optics Technology Center, 4 Colby St., Medford, MA 02155
F. Vereda
Affiliation:
Tufts University Electro-Optics Technology Center, 4 Colby St., Medford, MA 02155
T.E. Haas
Affiliation:
Tufts University Electro-Optics Technology Center, 4 Colby St., Medford, MA 02155
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Abstract

Polycrystalline thin films of lithium cobalt oxide (nominally LiCo02) have been deposited by a process which we have named, ion beam directed assembly (IBDA). It is similar to ion assisted deposition (IAD) or ion beam assisted deposition (IBAD), but the major difference is that in IBDA the ion beam directs, via the vector momenta of the ions, rather than merely assists, the growth. Hence, we also term the process directed assembly to distinguish it from self assembly. Also, in directed assembly the ions may or may not become an integral part of the film's composition.

In this paper we wish to show that the IBDA process may be capable of controlling microstructure, e.g., in the case of polycrystalline films, control the orientations of the crystallites. For LiCoO2 we have observed this in two ways - by X-ray analysis, and electrochemically, by lithium diffusivity measurements. In particular, we have observed increased lithium diffusivities (≥ 10−8 cm 2/s) in IBDA deposited films as compared to that found for rf sputter deposited films (z 10−10 cm2/s). In addition, the coulometric titration characteristics of an IBDA deposited Lil−yCoO2 are very similar to those of sputtered deposited films (for lithium extraction/insertion, y ≤0.5, and for quasi-equilibrium voltages up to 4.2 volts).

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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