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Core-rim structure is the micro-basis of BaTiO3-based MLCC dielectric materials. Its formation and evolution mechanism and the effect on electric properties deserve a closer and more detailed study. Herein, a...

Due to their excellent piezoelectric properties, low dielectric losses, and environmental friendliness, lead-free piezoelectric ceramics are gradually taking the place of lead-based piezoelectric ceramics and widely applied in commercial electronic devices. [1][2][3][4][5][6][7][8] Among the numerous lead-free piezoelectric ceramics, BaTiO 3 (BT) has gained many attentions on account of its low cost, easy processing, and good temperature stability.Whether for the lead-free or lead-based piezoelectric ceramics, an effective method to acquire high piezoelectric properties is to adjust the composition of the material to the vicinity of the phase transition boundaries. [9][10][11][12][13][14] Paraelectric to ferroelectric phase transition or two ferroelectric phase transition could be induced by the compositions, resulting in the instablility of the polarization state. Therefore, the polarization direction could be easily rotated under external stress or electric field, so that high piezoelectric properties could be achieved. [15][16][17][18] As far as pure BT material is concerned, there are four phases as the temperature increases, which are rhombohedral (R), orthorhombic (O), tetragonal (T), and cubic (C) phases, respectively. The stability of domain state in BT depends on the crystal structure. [19] The phase transition temperature and phase boundary type of BT ceramics can be altered by substituting the isovalent cations of Ba or Ti. Ca ions are usually used to lower the O to R phase transition temperature (T O-R ) and the T to O phase transition temperature (T T-O ) by replacing the Ba ions. In contrast, Sn, Zr, and Hf substitutions for Ti ions can increase T O-R and T T-O . [20] The changes of T-O or O-R transition allow to prepare the ceramics, which present high piezoelectric performances, in a wide range of dopants' compositions at room temperature. Ajay Kumar Kalyani et al. revealed that 2 mol% of Sn could stabilize the coexistence of