Direct Observation and Quantitative Analysis of Anti-ferroelectric Fluctuations in Pb(Mg1/3Nb2/3)O3 Relaxor
Tkachuk, A. · Chen, Haydn
Original · EN
Synchrotron x-ray scattering studies of anti-ferroelectric nanoregions (AFR) as fluctuations, which give rise to 1/2(hk0) superlattice reflections (alpha spots), were systematically performed in Pb(Mg1/3Nb2/3)O3 (PMN) ferroelectric relaxor. Separation of the alpha spots from underlying diffuse scattering background allowed studying them as separate entities for the first time. AFR fluctuations were shown to be different from the chemical nanodomains (CND) and ferroelectric polar nano-regions (PNR). Instead, they are formed by anti-parallel short-range correlated Pb²+ displacements that lead to unit cell doubling in <110> directions, based upon structure factor calculations. Correlation length is only on the 30 Ang scale, which defines the effective average size of the AFR fluctuations. This size remains temperature independent while the total number of AFRs significantly increases near the Vogel-Fulcher freezing temperature of 220 K. Presence of local fluctuations produced by anti-parallel atomic displacements can explain relaxor behavior as a result of competition between ferroelectric and anti-ferroelectrics type polar ordering in the glass-like systems.
English translation
This paper has no Arabic translation yet. Be the first: it takes a few seconds, and the result is stored for every future reader.