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Microstructure Characterization of Metal Mixed Oxides

Published online by Cambridge University Press:  09 November 2017

T. Kryshtab,
H. A. Calderon and
A. Kryvko
T. Kryshtab*
Affiliation:
Instituto Politécnico Nacional, ESFM, Departamento de Física, U.P.A.L.M., Av. IPN S/N, Edif. 9, CP 07738, Ciudad de México, México.
H. A. Calderon
Affiliation:
Instituto Politécnico Nacional, ESFM, Departamento de Física, U.P.A.L.M., Av. IPN S/N, Edif. 9, CP 07738, Ciudad de México, México.
A. Kryvko
Affiliation:
Instituto Politécnico Nacional, ESIME - Zacatenco, Departamento de Sistemas, U.P.A.L.M., Av. IPN S/N, Edif. Z-4, CP 07738, Ciudad de México, México.
*
*(Email: kryshtab@gmail.com)
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Abstract

The microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

Keywords

oxidex-ray diffraction (XRD)transmission electron microscopy (TEM)dislocations

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Articles
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MRS Advances , Volume 2 , Issue 64: International Materials Research Congress XXVI , 2017, pp. 4025 - 4030
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Copyright
Copyright © Materials Research Society 2017 

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References

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