Role of charge compensation mechanism on phase formation, dielectric and ferroelectric properties in aliovalent Gd3+ ion modified PbMg1/3Nb2/3O3 ceramics

Abstract Phase, microstructural, dielectric and ferroelectric properties investigation clearly reveal that the charge imbalance created due to alio-valent Gd3+-ion substitution at the Pb2+-site in lead magnesium niobate (PMN) should be compensated by changing the B-site cation ratio instead of creating the A-site or B-site vacancies. Microstructure analysis along with elemental mapping exhibit segregation of MgO and GdNbO4 phase, which is consistent with the Gd3+-ions solubility limit in the PMN. Gd3+-ion substituted PMN (PGMN) where the charge imbalance is compensated by creating the A-site vacancies leads to formation of large concentration of pyrochlore phase. Fitting of frequency dependent temperature of dielectric constant maximum [Tm(f)] and the Mydosh parameter “K” calculated from the Tm(f) clearly reveals critical slowing down of polar nano-regions (PNRs) dynamics leading to a super-dipolar glass state in PGMN in which the charge imbalance is compensated by changing the B-site cations ratio or by creating the B-site vacancy.