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The phase transition behavior and piezoelectric properties of (Ba1−xCax)(Zr0.1Ti0.9)O3 and (Ba0.85Ca0.15)(ZryTi1−y)O3 ceramics were investigated in this work to find out the potential factors contributing to large piezoelectricity. It was found that the morphotropic phase boundary (MPB) of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics was closely related to the presence of an intermediate phase (considered as orthorhombic phase in this work) between rhombohedral (R) and tetragonal (T) phases at a narrow region, which could be carefully adjusted by the temperature and contents of Ca and Zr in the composition. In addition, the maximum piezoelectric and electromechanical coupling coefficients (with d33 = 572 pC/N and kp = 0.57) were observed near the MPB region close to T phase side, which might be intimately related to the presence of the intermediate phase. This investigation yielded a new sight to understand the mechanism of enhanced piezoelectricity near the MPB.

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Large energy storage density and high efficiency in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic induced by AgNbO3 doping.

25 h exhibited a giant dielectric constant (1.10 3 10 4 ) and a relatively low dielectric loss (0.033) around room temperature. The samples showed good temperature stability (DC T =C 25 C ¼ À6:7% -9.5%) in the temperature range from À60°C to 125°C at 10 kHz. It was also found that a new dielectric relaxation III appeared at higher temperatures (>200°C). The complex impedance spectroscopy analysis suggested that Y 2/3 Cu 3 Ti 4 O 12 ceramics were electrically heterogeneous, and they consisted of semiconducting grains and insulating grain boundaries, which could be modeled to a first approximation on an equivalent circuit based on two parallel RC elements connected in series. The Cu 2+ /Cu 3+ and Ti 3+ / Ti 4+ aliovalences were observed in Y 2/3 Cu 3 Ti 4 O 12 ceramics. The giant permittivity phenomenon could be explained by internal barrier layer capacitance (IBLC) effect.X. M. Chen-contributing editor Manuscript No. 30429.