Temperature calibration for high-temperature MAS NMR to 913Â K: 63Cu MAS NMR of CuBr and CuI, and 23Na MAS NMR of NaNbO3

► We collected 63Cu and 23Na MAS NMR spectra to 926 K on CuBr, CuI, and NaNbO3. ► Easily observed phase transitions serve as useful temperature calibration points. ► Large temperature effects on 63Cu shifts can also be useful for such calibrations.