An in-situ X-ray and neutron diffraction investigation of Bi-2212 in multifilamentary wires during thermal treatment

TL;DR

This study uses in-situ synchrotron X-ray and neutron diffraction to analyze the structural evolution of Bi-2212 wires during heat treatment, providing new insights into phase formation and texture development to improve superconductor performance.

Contribution

First in-situ analysis during actual heat treatment of Bi-2212 wires, revealing structural and phase evolution critical for optimizing fabrication processes.

Findings

Identification of phase changes during heat treatment

Insights into texturing and secondary phase formation

Discussion on the role of oxygen in structural evolution

Abstract

Significant insights for critical current density (Jc) improvement in Bi-2212 super- conductor wires can be obtained by an accurate analysis of the structural and mi- crostructural properties evolving during the so-called partial-melt process, a heat treatment needed to improve grain connectivity and therefore gain high Jc. Here, we report an in-situ analysis by means of synchrotron X-ray and neutron diffraction performed, for the first time, during the heat treatment carried out with the very same temperature profile and reacting oxygen atmosphere in which the Bi-2212 wires are usually treated for practical applications. The obtained results show the thermal evolution of the Bi-2212 structure, focusing in particular on texturing and secondary phases formation. The role of the oxygen is discussed as well. Hence, the present investigation marks a significant advance for the comprehension of the phenomena involved in the wire fabrication process and provides useful insights for the process optimization as well.