A combined ultra-wideline solid-state NMR and DFT study of 137Ba electric field gradient tensors in barium compounds

► Ultra-wideline 137Ba solid-state NMR obtained from five Ba-containing materials with highly asymmetric barium environments. ► The WURST-QCPMG sequence and magnetic field of 21.1 T greatly reduce experimental time. ► One of two resolved sites in α-Ba2P2O7 shows a CQ of 42.3 ± 0.3 MHz, the largest obtained for 137Ba in a powder. ► The experimental quadrupolar parameters are in excellent agreement with the DFT calculations.