opXRD: Open Experimental Powder X-ray Diffraction Database. - Daniel Hollarek; Henrik Schopmans; Jona Östreicher; Jonas Teufel; Bin Cao; Adie Alwen; Simon Schweidler; Mriganka Singh; Tim Kodalle; Hanlin Hu; Gregoire Heymans; Maged Abdelsamie; et al. (CoRR, 2025)