Three-dimensional characterization of BaHfO3 precipitates in GdBa2Cu3O7-y flim using STEM tomography

Area of Science:

• Materials Science
• Superconductivity
• Nanotechnology

Background:

• Rare earth barium copper oxide (REBCO) superconductors, particularly GdBa2Cu3O7-y (GdBCO), are promising for power cables due to high critical temperature (Tc) and critical current density (Jc).
• Minimizing Jc anisotropy in magnetic fields is crucial for GdBCO applications.
• BaHfO3 (BHO) precipitates have shown effectiveness as artificial pinning centers (APCs) in GdBCO films.

Purpose of the Study:

• To investigate the three-dimensional morphologies and dispersion of BaHfO3 (BHO) precipitates within GdBCO films.
• To understand the role of BHO precipitate characteristics in enhancing superconducting properties.

Main Methods:

• Fabrication of BHO-dispersed GdBCO films on Hastelloy C-276TM substrates using pulsed laser deposition (PLD).
• Preparation of cross-section TEM specimens using focused ion beam (FIB) milling.
• Three-dimensional characterization of BHO precipitate morphology and dispersion via scanning transmission electron tomography (STEM-HAADF).

Main Results:

• 3D reconstruction revealed fine, rod- and plate-like BHO precipitates with homogeneous dispersion in the GdBCO matrix.
• Precipitates exhibited diverse growth directions relative to the GdBCO growth direction.
• Homogeneous dispersion and varied precipitate orientations are likely contributors to enhanced Jc anisotropy.

Conclusions:

• The study provides critical 3D insights into the microstructural features of BHO precipitates in GdBCO.
• Understanding precipitate morphology and dispersion is key to optimizing GdBCO for high-performance superconducting applications.
• The findings support the use of BHO as effective APCs for improving GdBCO superconducting characteristics.