Diffuse scattering in lead-based relaxors: synchrotron experiments, data, and models

Abstract

Structural disorder is a core of the relaxor behavior and can be probed by measuring diffuse scattering. Here we focus on the experimentation and discuss diffuse scattering data for the PbMg_1/3Nb_2/3O₃ relaxor collected as a function of temperature. Experimental pitfalls such as a resolution in reciprocal space and heating of the crystal by an intense synchrotron beam are discussed together with different presentation of diffuse scattering data. The diffuse scattering is found to be very anisotropic at all temperatures with the main component following q⁻² dependence. A new component with a similar anisotropy and q⁻⁴ decay emerges below the room temperature and in the close neighborhood of the Bragg nodes. A two-term model is proposed for parameterization of the observed patterns.

Keywords:

• diffuse scattering
• relaxor ferroelectrics
• synchrotron radiation

Acknowledgments

The authors would like to thank Sergey Vakhrushev (PTI, St. Petersburg) and Vladimir Dmitriev (SNBL, Grenoble) for many fruitful and stimulating discussions, and also Alexander Popov (ESRF, Grenoble) for invaluable support in the experiment at ID29.