Kenji Uchino

• MS, MBA, Ph.D.
• Managing Director at Pennsylvania State University

When barium titanate (BaTiO 3) is doped with lanthanum at levels less than 0.3 atm%, the ceramic becomes semiconducting with a resistivity in the range of 10 ~ 10 3 ·cm. Moreover, the resistivity is drastically increased, by 3 ~ 5 orders of magnitude, with increasing temperature around the Curie point. This phenomenon was discovered in 1954, and i...

Certain materials produce electrical charges on their surfaces as a consequence of applied mechanical stress. The induced charges are proportional to the mechanical stress. This is called the direct piezoelectric effect and was discovered by Jacques and Pierre Curie in 1880. Materials showing this phenomenon also conversely have a geometric strain...

Certain materials produce electrical charges on their surfaces as a consequence of applied mechanical stress. The induced charges are proportional to the mechanical stress. This is called the direct piezoelectric effect and was discovered by Jacques and Pierre Curie in 1880. Materials showing this phenomenon also conversely have a geometric strain...

This article provides insights into the manuscript submission process for the journal “Current Applied Materials,” published by Bentham Science Publishers. As seen from the Editor-In- Chief’s perspective, we have focused on Contributed and Review/Mini-Review articles.

Nowadays, heat dissipation in electronic devices is one of the serious issues to be resolved in energy and environmental terms. Piezoelectric materials are being utilized in many electronic devices, yet the roadblock toward further miniaturization of piezoelectric devices was identified as heat dissipation. Three types of losses (dielectric, elasti...

Electrostrictive effects in complex-perovskite "relaxor" ferroelectrics exhibit superior performance in comparison with the simple-perovskite normal ferroelectrics, such as giant electrostriction in its paraelectric phase and high electromechanical coupling in its ferroelectric phase. As one of the discoverers, the author will deliver the historica...

Our 21st century will face to a “sustainable society”, which requires (a) usage of non-toxic materials, (b) disposal technology for existing hazardous materials, reduction of contamination gas, (c) environmental safety monitoring, (d) new energy source creation, and (e) energy-efficient device development. Electric components such as motors and tra...

Heat generation is one of the significant problems in piezoelectrics for high-power density applications. In this article, we review the loss phenomenology in piezoelectrics first, including three losses, dielectric, elastic and piezoelectric losses, followed by heat generation analysis in piezoelectric materials for pseudo-DC and AC drive conditio...

In the last decade, an enormous amount of attention has been paid to piezoelectric harvesters due to their flexibility in design and the increasing need for small-scale energy generation. As a result, various energy review papers have been presented by many researchers to cover different aspects of piezoelectric-based energy harvesting, including p...

Multiple poling steps and complex electrode configurations are indispensable for high-performance state-of-the-art piezoelectric devices, yet those create partially poled or utterly unpoled regions that significantly change behaviors of piezoelectric devices. Several studies have dealt with method to obtain elastic compliance, yet little attention...

The IEEE standard to determine physical parameters of piezoceramics has been utilized for decades by many researchers, yet it omits presence of important loss factors and possesses serious deficits that restrict accurate parameter determination. To resolve these issues, the partial electrode (PE) method was previously proposed, though the focus has...

Energy harvesting from wasted or unused power has been a topic of discussion for a long time. We developed ‘damper devices’ for precision machinery and automobile engine mats in the 1980s. However, in the 1990s we realized that electric energy dissipation on its own was useless, and started to accumulate the converted electric energy into a recharg...

This paper presents an advanced characterization method to obtain anisotropic intensive piezoelectric loss for k31, k33 and k15 mode. By redefining half-power bandwidth, new procedure is suggested with effective k31-k15 geometry using crystallographic approach. Without using low capacitance k33 bar structure, the relative error is not worth conside...

In the last decade, an explosive attention has been paid to piezoelectric harvesters due to their flexility in design and increasing need to small-scale energy generation. As a result, many review papers have been presented by many researchers to cover different aspects of piezo-based energy harvesting, including piezomaterials, modeling approaches...

The standard method to determine physical parameters of piezoceramics, established by IEEE, has been utilized for decades by the number of researchers, yet it omits presence of important loss factors and possesses serious deficits that restricts accurate parameter determination. In order to resolve these issues, the partial electrode (PE) method (m...

The bottleneck of the piezoelectric devices in miniaturization is the heat generation owing to the losses. There are three losses in a piezoelectric material; dielectric, elastic and piezoelectric losses. The development of high-power density piezoelectrics is directly relevant to the clarification of the loss mechanisms in such materials. This art...

Physical properties of lead-zirconate-titanate (PZT) ceramics change according to the initial electric poling process and electrical boundary conditions. This paper reports the electrothermal, piezothermal, and piezoelectric coupling phenomena in ferroelectrics from thermodynamics viewpoints, in particular, thermal property differences between unpo...

Even though standard method to determine physical parameters of piezoelectric materials has been set up for several decades, bare attention has been made on loss determination method. Furthermore, several deficits have been recognized in the standard method for k33 mode. In this study, detailed discussion on deficits of IEEE Standard k33 is investi...

Accurate determination of three types of losses (dielectric, elastic, and piezoelectric) in piezoelectric materials is critical, since they are closely related to the performance of high-power piezoelectric devices. The standard k33 mode has a number of serious deficits that hinder researchers from determining accurate physical parameters and losse...

p>Physical properties of polycrystalline lead-zirconate-titanate (PZT) changes according to electrical boundary conditions and poling. This paper reports the thermal properties of poled and unpoled PZT's in the poling direction for open circuit and short circuit conditions. The authors found that the short-circuit condition exhibited the largest th...

The piezoelectric material behavior, including loss mechanism, under external DC electric field and stress biases have been extensively studied in lead zirconate titanate ceramics. However, in order to achieve a better understanding of these effects, development of a comprehensive model is required. The purpose of this paper is to develop a phenome...

p>Piezoelectric actuator developments require interdisciplinary knowledge on materials physics, electrical designing and mechanical engineering. Because of the limited knowledge of newly-involved researchers, they occasionally publish misleading information, some sort of misconceptions, reflected in the delay of innovative developments of the next...

Certain materials produce electric charges on their surfaces as a consequence of applying mechanical stress. The induced charges are proportional to the mechanical stress. This is called the direct piezoelectric effect and was discovered in quartz by Pierre and Jacques Curie in 1880. Materials showing this phenomenon also conversely exhibit a geome...

Heat generation by internal loss factors of piezoelectrics is one of the critical issues for high power density piezoelectric applications, such as ultrasonic motors, piezoelectric actuators and transducers. There are three types of internal losses in piezoelectric materials, namely dielectric, elastic and piezoelectric losses. In this paper, a dec...

Accurate determination of three types of losses (dielectric, elastic and piezoelectric) in piezoelectric materials is critical, since they are closely related to the performance of high-power piezoelectric devices. The Standard k33 mode has a number of serious deficits that hinders researchers from determining accurate physical parameters and losse...

Even though standard method to determine physical parameters of piezoelectric materials has been set up for several decades, bare attention has been made on loss determination method. Furthermore, several deficits have been recognized in the standard method for k33 mode. In this study, detailed discussion on deficits of IEEE Standard k33 is investi...

Ferroelectrics can be utilized in various devices such as high permittivity dielectrics, ferroelectric memories, pyroelectric sensors, piezoelectric devices, electrooptic devices, and PTCR components. However, ferroelectric devices often fail to be commercialized in the cases where competitive materials exist. In the photo‐sensors, for example, sem...

Our 21st century faces to a “sustainable society”, which enhances (a) usage of non-toxic materials, (b) disposal technology for existing hazardous materials, (c) reduction of contamination gas, (d) environmental monitoring system, (e) new energy source creation, and (f) energy-efficient device development in the piezoelectric area. With reducing th...

High power piezoelectric devices are often subjected to external mechanical biases, in applications such as underwater transducers. While the performance of these devices under external pressure has been rather extensively studied, there is a lack of study on the loss mechanism in terms of three dielectric, elastic, and piezoelectric losses. Thus,...

Light Driven Micromachines addresses the fundamental characteristics of light activated and optically powered microstructures, simple mechanisms, and complex machines that perform mechanical work at the micro- and nano-scale. It provides a background for how light can initiate physical movement by inducing material or bending or inducing microforce...

Shear vibration mode of piezoelectric ceramic has been widely used in energy harvesting for its high electromechanical coupling coefficient (k15) and high piezoelectric constant (d15). In this study, the effects of dimensions on the piezoelectric shear performance of PZT-5A type ceramic were initially studied with ATILA/GiD finite element simulatio...

Energy harvesting from wasted or unused power has been the topic of discussion for a long time. This paper focuses on harvesting energy from mechanical vibrations using piezoelectric transducers. We will consider comprehensively three major phases/steps associated with piezoelectric energy harvesting: (i) mechanical-mechanical energy transfer, incl...

We introduced an advanced piezoelectric characterization method with mechanical excitation on partial electrode samples, which can determine additional physical parameters the conventional full-electrode electrical excitation method cannot provide. A non-electrode sample with only 10% electrode at the center of a rectangular k31 piezoelectric plate...

A ultrasonic motor (USM) has been developed to meet the specific demands for compact actuators, which can drive humanoid eyeball to realize multi-degree-of-freedom (MDOF) motions. This USM has a ring shape composite stator, and employs combinations of axial bending mode and in-plane nonaxisymmetric mode to generate three type ellipses at four drivi...

Dielectric, elastic and piezoelectric losses are investigated in soft Pb(Zr,Ti)O3-based piezoelectric ceramics in terms of polarization direction dependence of the properties. The difference of the mechanical quality factor at the resonance and anti-resonance frequencies were obtained by the impedance method. The polarization angle of the samples v...

This paper concludes that the deterioration of the mechanical quality factor Qm when operated under high power, can be recovered by externally applying positive DC bias field. Material constants for piezoelectric ceramics are generally characterized under low power conditions. However, high-power properties deviate significantly from the ones measu...