Sc-45 NMR study of the relaxor transition in a lead scandotantalate singlecrystal

The relaxer transition in a disordered lead scandotantalate "virgin" single crystal has been studied by measuring the Sc-45 NMR spectra and spin-latti ce relaxation rates. The observed spectra can be decomposed in a narrow 1/2 --> - 1/2 central part and a broad background due to the satellite transiti ons. The data demonstrate that the macroscopic cubic symmetry is locally br oken and thar the Sc electric quadrupole coupling constant amounts to about 12 MHz. The local polarization distribution function and the temperature d ependence of the Edwards-Anderson order parameter have been determined and can be well described by the recently proposed spherical random bond-random field model.