In-Sung Kim

Applications of Self Power Device Using Piezoelectric Triple-Morph Cantilever for Energy Harvesting

In this paper, piezoelectric triple-morph cantilever was manufactured using the PMN-PZT thick film for electric harvesting device. The electrical characteristics of the piezoelectric triple-morph cantilever were investigated under dynamic conditions. The experimental results that piezoelectric triple-morph cantilever with 25 mm length and 5 mm width was operated under force of 100 N. A power of 0.432 mW were generated at the resonance frequency 154 Hz across a 100 kΩ optimal resistance. In order to apply automobile engine, the self-power device was designed using piezoelectric triple-morph cantilever with circuit. The applied result of automobile engine, output voltage was 3.57 Vrms on the running automobile engine.

Piezotransformer with ring-dot-shape for easy heat radiation and high efficiency power

Power of piezoelectric transformer was also limited for higher power application, therefore structures with multilayer and various shapes were researched to increase the output power and decrease heat distribution, but existing problems such as complicated manufacturing process and mechanical durability.

ELECTRIC PROPERTIES OF PIEZOELECTRIC FILM FABRICATED BY ELECTROPHORESIS DEPOSITION METHOD

ABSTRACT This study presents dielectric and piezoelectric properties of piezoelectric thick film processed by electrophoresis deposition method. 1 μm∼200 μm-thick film were fabricated by electrophoresis depostion method. The dielectric constant and piezoelectric property of the piezoelectric film increased as the film become thicker. When an electric field < 3 kV/mm was applied, their dielectric and piezoelectric properties changed with their thickness. At an electric field > 3 kV/mm their properties are constant regardless of their thickness. These changes can be explained by the existence of many void defects to be inevitabley introduced in thick film fabrication process, which can be one of crucial causes of controlling ferrroelectric properties of thick films. The change in dielectric and piezoelectric properties was evaluated by introducing simplified composite concept.

Multilayer piezoelectric ceramic actuator for laser scanner

This work studies the lead magnesium niobate-lead zirconium titanate (PMN-PZT) multilayer ceramic actuators (MLCA) for laser scanner applications. PMN-PZT MLCA was fabricated. 5×5×30 mm3 size MLCA was fabricated by conventional tape casting method. The displacement of the MLCA with 30 mm thickness was ∼30 μm at 150 V Tilt stage consisting of multilayer actuator and two hinge type lever mechanisms was investigated. Circular hinge type mechanism showed translation from linear motion to rotation motion along with stroke amplification. The hinge-based mechanical platform showed one-to-one linear translation with strain amplifier, which is suitable for high precision control system.

Sinterability and Piezoelectric Properties of PMNZT Ceramics with Copper Oxide

The sinterability and piezoelectric properties of the Pb(Mg0.15Nb0.3Zr0.2Ti0.35)O3 ceramics with CuO sintering aid were investigated. The samples were synthesized with the conventional sintering method. The x-ray diffraction patterns indicated that all the samples formed a single-phase perovskite structure. The CuO additions improved the sinterability of the Pb(Mg0.15Nb0.3Zr0.2Ti0.35)O3 ceramics and increased the density and grain size of the samples. Excellent piezoelectric and electromechanical responses of d33 = 657 pC/N and kP = 0.72 were obtained from the high-density samples with 0.2 wt% CuO that were sintered at 1000 °C for 4 h.

PIEZOELECTRIC PROPERTIES BY LITHIUM OXIDE ADDITION IN THE SODIUM—POTASSIUM NIOBATE SYSTEM

ABSTRACT As a candidate for lead-free piezoelectric materials, dense 0.95(Na0.5K0.5)NbO3-0.05LiTaO3 (NKN-5LT) ceramics were developed by conventional sintering process. Sintering temperature was lowered by adding Li2O as a sintering aid. Grain growth behaviors with Li2O addition were explained in terms of the effect of Li2O on interface reaction—controlled grain growth and the critical driving force. The electrical properties of NKN-5LT ceramics were investigated as a function of Li2O concentration., Excellent piezoelectric and electromechanical responses, d33∼ 250 pC/N, k P ∼ 0.37, were obtained for 1 mol% Li2O excess NKN-5LT samples sintered at 1000°C for 4 h in air.

DIELECTRIC PROPERTIES OF ASYMMETRICALLY ANNEALED FERROELECTRIC (Ba,Sr)TiO3:MGO THICK FILMS

ABSTRACT A 20 wt.% of MgO added (Ba0.6Sr0.4)TiO3 (BST:MgO) thick film have been fabricated by a tape casting and firing method for tunable microwave applications. In order to improve ferroelectric properties, the composite BST:MgO thick films have been asymmetrically annealed by a focused beam method. Dielectric constants of BST:MgO films are changed from 1050 to 1300 at 100 kHz after 150 s annealing by the focused beam. Even though it was not observed any prominent changes from the thick films before-and after-annealing in terms of chemical composition and surface morphology, it is clear that the average particle size of the thick films calculated by Scherrers formula were increased by annealing. Furthermore, a strong correlation between particle size and dielectric constant of the BST:MgO has been observed; dielectric constant increases with increased particle size. This has been attributed to the increased volume of ferroelectric domain due to increased particle sizes.

Properties of 0.74BiNaTiO 3 -0.06SrTiO 3 / Bi 0.5 (Na 0.8 K 0.2 ) 0.5 TiO 3 ceramic composite

We investigated the temperature- and frequency-dependent polarization and strain of two Bismuth-based perovskite composites. A matrix material was chosen as 0.74Bi_0.5Na_0.5TiO₃ -0.26SrTiO₃ (BNT-ST) which have a transition point of 60°C from relaxor to ferroelectric phase (T_R-F). An inclusion material was Bi_0.5(Na_0.8K_0.2)_0.5TiO₃ (BNKT) possessing the T_R-F of 120°C. Depending on test temperature, the different polarization and strain behaviors were observed in BN-TST/BNKT composite. At T=25°C, the composite exhibited double-like polarization loop and parabolic strain curves which involve ergodic relaxor-to-normal ferroelectric phase transition with external electric field and the reverse ferroelectric-to relaxor phase transition with removal of the field. When T= 80°C, the BNT-ST/BNKT has very slim polarization and strain of which magnitude are slightly increased values from pure BNT-BT. When T= 120°C, both composites have slim polarization and strain behaviors of which values are almost same as the pure BNT-ST. These high field-induced polarization and strain with respect to temperature for the composites are related to the thermal stability of ferroelectric inclusions, and their nucleation and growth in relaxor matrix.

Variation of Piezoelectric Transformer Electrode by Oxidation in Piezoelectric Inverter with Driving Time

Multi layer piezoelectric transformer has an advantage of the high step-up ratio, high electromechanical coupling coefficient (Kp ) and high mechanical quality factor (Qm ). However, they are subject to the electrode-crack and the need for an increased sintering temperature make the electrodes costly. The electrode-crack correlates to electrode oxidation in multi layer piezoelectric transformers and it is attended with drop-off in efficiency. In this study, high-power Rosen-type piezoelectric transformer were manufactured, and then investigated about electrode oxidation according to lapse of time for 4 month. The basic composition of piezoelectric ceramics consists of ternary 0.01Pb(Ni1/3Nb2/3)O3-0.08Pb(Mn1/3Nb2/3)O3-0.91Pb(Zr0.505Ti0.495)O3.

Preparation of Glass-Coated Cu Electrodes and their Effect on Piezoelectric Device

In this study, a technique to prepare metal powder coated by glass was examined. Specifically, the glass-coating on Cu and its oxidation resistance were investigated. The Cu powder was coated with borosilicate glass via the sol-gel process. Nominal weight ratios of Glass/Cu were controlled to be 2%, 5%, 10% and 20%. The average particle sizes of the as-received and coated Cu powders were 0.59 μm and 0.63∼0.67 μm, respectively. The pastes consisting of coated powder and other conventional organic vehicle were fabricated. The coated Cu paste could be burnt-out at 500°C under air atmosphere, and was then sintered at 1050°C under N2 atmosphere. Using the glass-coated Cu paste and a 0.945(Bi0 . 5Na0 . 5)TiO3–0.055BaTiO3 (BNT-BT) piezoelectric ceramic, the piezoelectric devices were fabricated. Their performances were investigated in comparison with piezoelectric disk devices using BNT-BT base ceramic and Ag electrode.