Microstructural, vibrational, dielectric and ferroelectric properties correlation in hot-pressed PbMg1/3Nb2/3O3 ceramics

TL;DR

This study investigates the microstructural, vibrational, dielectric, and ferroelectric properties of hot-pressed PbMg1/3Nb2/3O3 ceramics, revealing the formation of chemical ordered regions and relaxor behavior across different sintering temperatures.

Contribution

It provides new insights into the formation and stability of chemical ordered regions in PMN ceramics and their influence on dielectric and ferroelectric properties at various sintering temperatures.

Findings

Presence of chemical ordered regions (CORs) confirmed by superlattice reflections.

Increase in polar nano-size regions indicated by vibrational mode shifts.

Grain size influences dielectric transition temperature and polarization behavior.

Abstract

Microstrctural, vibrational, ferroelectric and dielectric properties investigation reveals non-stoichiometric chemical ordered regions (CORs) and relaxor like dielectric characteristics in lead magnesium niobate (PMN) ceramics uniaxially hot pressed (HP) at 800 oC to 1200 oC. Occurance of (1/2 1/2 1/2) superlattice reflections along <111> in <110> zone axis SAED pattern as well as the presence of bright nano-meter regions in corresponding dark-field images in 800 oC hot pressed PMN demonstrates formation of the CORs as soon as perovskite phase is formed during calcination and remains unaffected with HP sintering tempreature. Separation between two broad peaks of Nb-O-Nb stretching mode and the red-shift of O-B-O bending modes suggest an increase in the polar nano-size regions. Grain size dependence of the em and shifting of the Tm from 278 K to 263 K is explained by the core-shell model. Polarization switching and impedance spectroscopy is observed to be consistent with the grain size analysis.