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Polar Nano-Clusters in Relaxors on the Atomic Level

2006; Taylor & Francis; Volume: 330; Issue: 1 Linguagem: Inglês

10.1080/00150190600605353

1563-5112

R. Blinc,

Acoustic Wave Resonator Technologies

207Pb, 93Nb and 45Sc quadrupole pertubed NMR spectra in PMN and PSN relaxor single crystals show that a significant fraction of the polar clusters are static and randomly oriented on the NMR time scale 10−4s even far above the freezing temperature. At the freezing temperature Tf the volume fraction of anisotropic static polar clusters increases and reaches the percolation threshold resulting in the formation of macroscopic ferroelectric domains. The clusters become oriented parallel to the polar ferroelectric direction and an orientational percolation transition takes place in the field cooled case in PMN and even in the zero field cooled case in PSN. The intra—cluster reorientational dynamics of the individual ionic dipoles still persists below Tf though it is biased due to random fields and chemical disorder. * Originally presented at IMF-11, Foz do Iguaçu, Brasil, September 2005. Keywords: RelaxorsNMRnano-clusters Notes * Originally presented at IMF-11, Foz do Iguaçu, Brasil, September 2005.