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Microstructural Evolution During Epitaxial Growth of Chemically Derived Ba2YCu307-x. Thin Films

Published online by Cambridge University Press:  25 February 2011

Paul C. Mclntyre  and
Michael J. Cima
Paul C. Mclntyre
Affiliation:
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
Michael J. Cima
Affiliation:
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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Abstract

Microstructure development in thin films of Ba2YCu3O7-x (BYC) synthesized on (001) LaA1O3 using an ex situ process was characterized by TEM and STEM examination of specimens quenched from different points in the growth heat treatment. The microchemistry of the growing oxide films was characterized by EDS in STEM. Phase development was also studied by X-ray diffraction. Several investigators have suggested that growth of BYC during ex situ processing occurs by nucleation and growth of BYC into an amorphous precursor film. Our observations indicate that this process involves growth into a substantially crystalline matrix. X-ray diffraction was used to identify three phases, BaF2, BaCuO2, and CuO, which are present prior to BYC nucleation. Nucleation of both c-axis normal and a-axis normal BYC occurred at approximately 760°C during rapid heating to 830°C in the growth heat treatment. Rapid growth of the c-axis normal material parallel to the substrate surface caused this orientation to become dominant in the fully converted films. Chemical microanalysis of the quenched films suggests that the BYC grows into an overlying layer that, after quenching, is composed of relatively large (25–100 nm diameter) yttrium- and copper-rich particles in a nanocrystalline barium-rich matrix.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 280: Symposium B – Evolution of Surface and Thin Film Microstructure , 1992 , 371
Copyright
Copyright © Materials Research Society 1993

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References

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