Piezoelectric energy harvesting technologies, which can be used to convert the electricity from the mechanical energy, have been developed in order to assist or power the wearable electronics. To realize non-toxic and biocompatible electronics, the lead-free (Ba_0.85Ca_0.15)(Ti_0.90Zr_0.10)O₃ (BCTZ) nanoparticles (NPs) are being studied with a great attention as flexible energy harvesting device. Herein, piezoelectric hybrid nanocomposites were fabricated using BCTZ NPs-embedded poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] matrix to improve the performance of flexible energy harvester. Output performance of the fabricated energy device was investigated by the well-optimized measurement system during the periodically bending and releasing motions. The generated open-circuit voltage and the short-circuit current of the piezoelectric hybrid nanocomposite-based energy harvester reached up to ~15 V and ~1.1 μA, respectively; moreover, the instantaneous power of 3.5 μW is determined from load voltage and current at the external load of 20 MΩ. This research is expected to cultivate a new approach to high-performance wearable self-powering electronics.

In this study, to develop low temperature sintering capacitor composition ceramics with the good dielectric properties, (Ba0.86Ca0.14)(Ti0.85Zr0.12Sn0.03)O3 (BCTZ) ceramics were prepared by the conventional solid-state reaction method. The effects of B2O3 addition on the dielectric properties and microstructure was investigated. The XRD patterns demonstrated that all the specimens showed Perovskite phase, and secondary phases are indicated in the measurement range of XRD. And also, temperature coefficient of capacitance(TCC) of all the specimen sintered at 1,180℃ showed +3∼-56% except for x=0.006. For all the specimens, observed one peak was tetragonal cubic difuse phase transition temperature(Tc), which is located in the vicinity of room temperature.

In this study, in order to develop the capacitor composition ceramics with the good dielectric properties, (Ba0.86Ca0.14)(Ti0.85Zr0.12Sn0.03)O3+ xCuO (x= 0.006~0.010) ceramics were prepared by the conventional solid-state reaction method. The effects of CuO addition on the microstructure and dielectric properties was investigated. All specimens indicated rhombohedra1 phase without any secondary phase. As CuO addition increased, the variation width of TCC was increased at more than 40°C. Also, the specimen with x=0.007 sintered at 1,250°C showed the high dielectric constant of 9,632 in spite of low temperature sintering temperature.

We investigated the dielectric relaxation properties 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics with CuO addition. With increasing CuO addition, the lattice parameter was increased by substitution of small amount Cu2+ ion in B-site of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics. Also the grain size and the maximum dielectric constant of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics was decreased with increasing amounts of CuO addition. Moreover, the diffused phase transition properties (γ) of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics was increased by compositional fluctuation with increasing of CuO amount, changed from 1.45 at 1 wt% CuO addition to 1.94 at 7 wt% CuO addition.

In this study, in order to develop the capacitor composition ceramics with the good dielectric properties, (Ba1-xCax)(Ti0.85Zr0.12Sn0.03)O3 (abbreviated as BCTZ) ceramics were prepared by the conventional solid-state reaction method. The effects of Ca substitution on the microstructure and dielectric properties was investigated. The X-ray diffraction patterns demonstrated that all the specimens showed perovskitephase, and secondary phases are indicated in the measurement range of X-ray diffraction. Also, all the specimens indicated an rhombohedron phase structure. It was identified from the X-ray diffraction patterns that the secondary phase formed in grain boundaries and then decreased the dielectric properties. For all the specimens, observed one peak was tetragonal cubic phase transition temperature(TC),which is located in the vicinity of room temperature.

(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3+0.04wt% CeO2 lead-free ceramics were prepared by conventional oxide-mixed method and the effect of sintering temperature on microstructure, dielecrric and piezoelectric properties were investigated. Improved piezoelectric properties have been observed at 1,400℃ sintering temperature which show the optimal electrical properties, kp~0.412, d33~316 Pc/N, Qm~144, ~3,345 and Tc~85℃. These results show that the sintering temperature plays an important role in piezoelectric properties.

(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 + 0.04 wt% CeO2 lead-free ceramics were synthesized by conventional sintering process and the effect of calcination temperature on microstructure, dielectric and piezoelectric properties were investigated. Improved piezoelectric properties have been observed at 1,125℃ calcination temperature which show the optimal electrical properties, kp∼0.457, d33∼367 pC/N, Qm∼158 and Tc∼85℃. These results show that the piezoelectric properties can be improved by appropriate calcination temperature.