Structural fluctuation of Pb(Mg1/3Nb2/3)O3 in the cubic phase

Abstract

To investigate the structural fluctuations of relaxor Pb(Mg1/3Nb2/3)O3 (PMN) in the cubic phase, the probability density function of each atom was determined by high-energy synchrotron radiation X-ray powder diffraction measurements and a Rietveld analysis with anharmonic temperature factors. A rotator-like behavior of the Pb ion was observed in the cubic phase. The off-center behavior along the 1 1 1 directions became pronounced with decreasing temperature. The ferroelectricity of PMN was attributed to a combination of the freezing of the 1 1 1-preferred rotator-like disorder and the ferroelectric distortion of the B-O6 octahedron.