pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2019; 69: 119-123

Published online February 28, 2019 https://doi.org/10.3938/NPSM.69.119

## Neutron Diffraction Studies of the Relaxor Ferroelectric Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$ Ceramic Under an Electric Field

Ilkyoung JEONG*

Department of Physics Education & Research Center for Dielectrics and Advanced Matter Physics, Pusan National University, Busan 46241, Korea

Correspondence to:jeong@pusan.ac.kr

Received: December 5, 2018; Revised: December 24, 2018; Accepted: December 31, 2018

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

### Abstract

We perform neutron diffraction measurements on a Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$ (PMN) ceramic disk under electric fields up to E $\simeq$ 1.2 kV/mm at 300 K and 100 K. The electric field and the temperature dependences of lattice parameter $a(E,T)$ are  obtained from Rietveld refinements. Under the external electric field, the lattice parameter increases as the E-field increases. The E-field dependence is found to be more significant at 100 K, and $a$($E$, 100 K) becomes larger than $a$($E$, 300 K) for E $\geq$ 0.3 kV/mm. To complement the Rietveld refinement, we investigate the local structure of PMN by using the atomic pair distribution function (PDF). Based on the PDF analysis, we study the effects of the external E-field and the temperature on the volume fraction of the polar nanoregions that appear in the average cubic lattice of PMN.

Keywords: Relaxor ferroelectric, Neutron powder diffraction, Atomic pair distribution function, Electric field