Deuteron Magnetic Resonance Spectrum and Relaxation in KD2PO4

Abstract

The electric field gradient (EFG) tensor at the site of the deuteron in the hydrogen bond of K${\mathrm{D}}_{2}$P${\mathrm{O}}_{4}$ and the relaxation times of the deuteron have been studied. The measured quadrupole coupling constant is 119 kc/sec, the asymmetry parameter is 0.049, and the major principal axis of the tensor is along the bond direction. None of these features of the EFG tensor change appreciably with temperature over the entire range studied, which range includes the ferroelectric Curie point ${T}_{c}$. An interesting additional splitting in the spectral lines below ${T}_{c}$ is observed however. The thermal relaxation time of the deuteron has been studied carefully only at room temperature. One obtains ${T}_{1}=6.5$ minutes at a particular orientation of the crystal decreasing by a factor of 2 at other particular orientations. ${T}_{2}$ is of the order 5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ second. All deuterons have the same relaxation as a function of crystal orientation although falling into distinct categories from the point of view of relative orientation of electric field gradient tensor and applied magnetic field. This interdependence of deuterons in different environments and the possible causes of relaxation are discussed.