Effect of order-disordered nano-domains on the dielectric and electrical properties of PMNT ceramics

0.9Pb1−xLax(Mg1/3ZnyNb2/3)O3-0.1PbTiO3 relaxor ferroelectric ceramics has been investigated to demonstrate the change of order-disordered nano-domains contributes to the dielectric and electrical properties of PMNT ceramics. Co-doping of the La3+ and Zn2+ was used to adjust the order-disordered nano-domain structure. After co-doping with the La3+ and Zn2+, the degree of order-disorder was remarkably increased. Moreover, an additional dielectric “shoulder” was observed in the temperature dependence of the dielectric constant. With increasing of the degree of order-disorder, the “shoulder” turned stronger and the dielectric peak turned fainter. For these compositions with different order-disordered nano-domains, the relative dielectric constant change with DC bias field was measured. When 2 mol% La3+ and 3 mol% Zn2+ were co-doped, the maximal relative dielectric constant change decreased from 70% to 23% at 1 kHz (1000 V/mm). The reduction of the polar nano-domains and the crystal anisotropy due to the improving of the degree of order-disorder was responsible for the remarkable increase of the electric field stability.