Pb-207 NMR study of the relaxor behavior in PbMg1/3Nb2/3O3 - art. no. 024104

The local structure of the relaxer single crystal PMN has been studied via a measurement of the temperature dependences of the Pb-207 spectra and rela xation times between 450 K and 15 K. The Pb-207 NMR spectra are frequency d istributions which reflect the existence of polar nanoclusters and which ca n be well described by the recently proposed spherical random-bond-random-f ield model. The temperature dependence of the Edwards-Anderson order parame ter q has been determined together with the random bond coupling and the ra ndom held variance. The results agree with those obtained from the Nb-93 NM R spectra and show that at any given instant of time the crystal consists o f polar clusters with variable orientation and magnitude of the local polar ization. The polar clusters are on the NMR time scale 10(-4)-10(-5) s, dyna mic entities which exist for a certain amount of time, disappear, and then reappear in a different form.