Atomistic modeling of diffuse scattering in cubic PbZrO₃

Abstract

We present a joint theoretical and experimental study on diffuse scattering in cubic PbZrO${}_3$. A comprehensive synchrotron data-set reveals $⟨110⟩$-oriented diffuse streaks emanating from Bragg reflections and showing a strong intensity variation in the vicinity of selected $M$ points. The intensity distribution on the $hk\frac{1}{2}$ section reveals another system of weaker but much sharper $q\frac{1}{2}\frac{1}{2}$ -type diffuse lines extended along $⟨100⟩$directions. These lines are slightly bent and intersect the $⟨110⟩$-oriented diffuse streaks a little off the $M$ points of the Brillouin zone. Molecular dynamics simulations with an ab initio derived shell model allow one to assign observed diffuse intensity to correlations coming from different atomic species. It is shown that interactions between the Pb-related modes and the octahedra tilting modes are manifested in subtle diffuse scattering features.

Keywords:

• diffuse scattering
• local structure
• soft modes
• anti-ferroelectricity
• zirconates
• molecular dynamics

Acknowledgments

The computational part of this research was undertaken on the NCI National Facility in Canberra, Australia, which is supported by the Australian Commonwealth Government. We thank P. Marton for fruitful discussions.

Additional information

Funding

This work was supported by the Czech Science Foundation (project no. 13-15110S) as well as by the Australian Research Council through its Discovery Projects program. Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.