Takuya Hoshina

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The electric transient response method is an effective technique to evaluate material constants of piezoelectric ceramics under high-power driving. In this study, we tried to incorporate nonlinear piezoelectric behaviors in the analysis of transient responses. As a base for handling the nonlinear piezoelectric responses, we proposed an assumption that the(More)
Barium titanate (BaTiO<sub>3</sub>) nanoparticles from 27 to 192 nm were prepared by the 2-step thermal decomposition method from barium titanyl oxalate nanoparticles. These particles were dispersed well into 1-propanol and dence BaTiO<sub>3</sub> nanoparticle sphere arrays without stress-field were prepared by the meniscus method. Temperature dependence of(More)
Almost impurity and defect-free barium titanate (BaTiO<sub>3</sub>) nanoparticles with various sizes from 20 to 430 nm were prepared using 2-step thermal decomposition method. The nano-structures of these particles were analyzed using a synchrotron radiation X-ray diffraction (XRD). As a result, it was found that the BaTiO<sub>3</sub> nanoparticles had(More)
Silver lithium niobate (Ag<sub>1-x</sub>Li<sub>x</sub>NbO<sub>3</sub> ALN) single crystals with Li contents of 10 and 12.5 mol% were successfully grown by a slow cooling method. The high-energy X-ray diffraction measurement revealed that the crystal structures of both ALN10 and ALN12.5 were assigned to the coexistence between orthorhombic Pc2<sub>1</sub>b(More)
The frequency variable microwave microscope was developed to evaluate the dielectric permittivity distribution for dielectrics. The dielectric permittivity and dielectric loss for multi-layer ceramics capacitor were estimated from their microwave reflection intensities at the minimum intensity points. The two dimensional dielectric permittivity image for(More)
A possible power output estimation based on material constants in piezoelectric vibration-based generators is proposed. A modified equivalent circuit model of the generator was built and was validated by the measurement results in the generator fabricated using potassium sodium niobate-based and lead zirconate titanate (PZT) ceramics. Subsequently,(More)
The size effect of BaTiO3 (BTO) is the most important issue to design multilayer ceramic capacitors (MLCCs) with high capacitance. In the size effect of BTO particles, the size dependence of dielectric permittivity related with the complex structure in BTO nano-particles. The grain size dependence of dielectric permittivity in BTO ceramics was due to the(More)
Wideband dielectric spectra from the kilohertz to terahertz range are discussed for BaTiO₃-based ferroelectrics. Ceramics of BaTiO₃ (BT), Ba(0.6)Sr(0.4)TiO₃ (BST-0.6), and BaZr(0.25)Ti(0.75)O₃ (BZT-0.25) were selected as normal ferroelectrics, ferroelectrics with diffuse phase transition (DPT ferroelectrics), and relaxor ferroelectrics, respectively. The(More)
The size effect of BaTiO3 (BTO) is the most important issue to design the high-capacitance MLCCs in the next generation. In the size effect of BTO ceramics and powders, the maxima of the permittivity were observed at certain grain size and the particle size. The permittivity maximum in the ceramics was due to the domain wall contribution, while that in the(More)