Electrical Properties and EPR Analyses of Mn-Doped 67PMN-33PT Piezoceramics

We conducted a study on Mn doping in 67Pb (Mg[Formula: see text]Nb[Formula: see text])O 3 -33PbTiO 3 (67PMN-33PT), which is a ferroelectric material exhibiting a morphotropic phase boundary (MPB). The samples were doped with MnO 2 at mass ratios ranging from 0.5 to 5.0[Formula: see text]wt.% and subsequently sintered at temperatures ranging from 1200 to [Formula: see text]C. Experimental analysis of electrical properties was performed within the temperature range of [Formula: see text]–[Formula: see text]C. Electron paramagnetic resonance (EPR) testing was conducted on these samples to investigate Mn solubility in PMN-PT ceramics and their existence in different valence states. The results indicate that at a doping ratio of 0.5[Formula: see text]wt.% and sintering temperature of 1220–1240 ∘ C, Mn ions achieved a homogeneous dispersion within the crystal lattice, leading to the enhanced electromechanical [Formula: see text] factor (510) and the reduced dielectric loss tan [Formula: see text] to minimum (0.30%) compared to the no doping Mn, however, as the Mn ions dopant content increase higher than 1.0[Formula: see text]wt.% and sintering temperatures 1200–1260 ∘ , the unexpected results have been observed that both [Formula: see text] and tan [Formula: see text] are enhanced to about 1200, 0.87 up to 1.5[Formula: see text]wt.% MnO 2 , and then, [Formula: see text] decreases to 510, but tan [Formula: see text] increases to 3.78% for 5 wt.% MnO 2 . The machinal [Formula: see text] and dielectric loss can be understood by the (Mn-Vo) defect dipoles in lattice, domain wall and grain-bounary, together with the increasing of the MnO 2 , Mn 2 O 3 or their mixed phase of Mn 3 O 4 in the grain boundary.