Data supporting the peer-reviewed article 10.1002/anie.202102073, on the computational identification of a new oxide compound with complex aperiodic structure and low thermal conductivity. The deposit includes experimental data (X-ray and neutron powder diffraction; electron microscopy images, heat capacity measurements, thermal conductivity measurements, Raman measurements), as well as computational data (probe structure calculations, DFT, machine learning models). Please note: ReadMe files are included to explain the contents of individual zip files.