Micromechanical model for self-organized secondary phase oxide nanorod arrays in epitaxial YBa₂Cu₃O_7−δ films

Abstract

A micromechanical model based on the theory of elasticity has been developed to study the configuration of self-assembled secondary phase oxide nanostructures in high-temperature superconducting YBa₂Cu₃O_7−δ films. With the calculated equilibrium strain and elastic energy of the impurity doped film, a phase diagram of lattice mismatches vs. elastic constants of the dopant was obtained that predicts the energetically preferred orientation of secondary phase nanorods. The calculation of the nanorod orientation and the film lattice deformation has yielded excellent agreement with experimental measurements.

Keywords:

• cuprate superconductors
• micromechanics
• nanocomposites
• nanostructured thin films
• strain
• structural transitions
• YBCO

Acknowledgments

This work is supported by NSF and ARO under contract Nos. NSF-DMR-0803149, NSF-DMR-1105986, NSF EPSCoR-0903806, and ARO-W911NF-0910295.