PA-TIO/RQD: A Theoretical Framework for Enhancing Grain-Boundary Critical Current Density in Polycrystalline Superconductors

This preprint presents an independent theoretical framework addressing the 30-year grain-boundary weak-link problem in polycrystalline superconductors. The work distinguishes two physically distinct grain-boundary barriers—geometric misorientation (Layer 1) and electronic structure discontinuity (Layer 2)—and proposes a pressure-assisted thermally induced ordering (PA-TIO) followed by rapid quench-depressurization (RQD) methodology to simultaneously reduce both. A two-layer Jc suppression model, Ginzburg-Landau phase-slip energy barrier analysis, DFT electronic structure calculations (VASP), and TDGL simulations support the theoretical predictions of significant Jc enhancement in FeSe and MgB₂. A four-phase experimental validation protocol with clear falsification criteria has been designed. This preprint establishes academic priority. The full technical report with detailed process parameters, DFT data, and simulation results is available upon request to the author.