Deuteron magnetic resonance study of the antiferroelectric phase of ND4D2PO4

Abstract
The O–D ⋯ O deuteron quadrupole coupling tensors have been determined in the antiferroelectric phase of ND4D2PO4. The results show that the antiferroelectric phase transition in ND4D2PO4 is connected with an order‐disorder transition of the deuterons in the O–D ⋯ O bonds and that the Nagamiya model of hydrogen ordering is correct.