Time filter

Source Type

Tenan, South Korea

Rhim S.,Humanscan Co. | Jung H.,Humanscan Co. | Kim D.,Humanscan Co. | Lee H.-Y.,Ceracomp Co. | Kim J.S.,GE Ultrasound Korea
IEEE International Ultrasonics Symposium, IUS | Year: 2011

This paper introduces single crystal transducer using high mechanical quality factor material for Elastography application. This new type transducer shows better sensitivity and reliability when it is used for imaging application not only using normal pulse driving but also long pulse driving. © 2011 IEEE. Source

Rajapurkar A.,Pennsylvania State University | Ural S.O.,Pennsylvania State University | Zhuang Y.,Pennsylvania State University | Lee H.-Y.,Ceracomp Co. | And 2 more authors.
Japanese Journal of Applied Physics | Year: 2010

Lead magnesium niobate-lead titanate (PMN-PT) single crystals are a suitable replacement over conventional PZT-based ceramics in transducer applications because of their large electromechanical coupling factors (k > 0:90) and piezoelectric constants (d >1000 pC/N). For single crystals, it is possible to modify the performance by suitable selection of the orientation, and appropriate composition changes or doping can be utilized to improve the mechanical quality factor Qm. In this research, we report the piezoelectric loss performance in PMN-PT single crystals as a function of orientation, doping and vibration mode. The loss characteristics are based on mechanical quality factor Qm as well as the Q values at resonance (QA) and anti-resonance (QB). The Mn-doping resulted in almost twice the enhancement of the mechanical quality factor Qm and the maximum vibration velocity in comparison with the undoped samples. © 2010 The Japan Society of Applied Physics. Source

Sherlock N.P.,Pennsylvania State University | Zhang S.,Pennsylvania State University | Luo J.,TRS Technologies | Lee H.-Y.,Ceracomp Co. | And 2 more authors.
Journal of Applied Physics | Year: 2010

The use of single crystals based on the solid solution (1-x) Pb (Mg1/3 Nb2/3) O3 -x PbTiO3 (PMNT) has been demonstrated in many piezoelectric devices, but the low mechanical quality factor has limited its use in high power projector applications. In this work, 33-mode properties of PMNT single crystals with various modifications were evaluated to see if self-heating may be reduced by decreasing the mechanical and electrical losses within the active material. Three modifications were evaluated: incorporating ternary components, adding acceptor dopants, or orienting the crystal along different crystallographic directions. The electromechanical properties of these modified crystals were evaluated under increasing levels of dynamic strain. The results suggest that modified single crystal PMNT may improve the source level from a projector while reducing thermal effects from self-heating, making them appropriate for high power applications. © 2010 American Institute of Physics. Source

Erturk A.,Virginia Polytechnic Institute and State University | Lee H.-Y.,Ceracomp Co. | Inman D.J.,Virginia Polytechnic Institute and State University
ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2010 | Year: 2010

Piezoelectric materials have received the most attention for vibration-to-electricity conversion over the last decade. Harmonic excitation is the most commonly investigated form of excitation in piezoelectric energy harvesting and it can be divided into two subgroups as resonant and off-resonant excitations. Although resonant excitation is preferred for extracting the maximum electrical power output from the device, there are several practical cases where it is not possible to excite the energy harvester at its resonance frequency (e.g. varying frequency excitations or very low frequency excitations where the input frequency is much lower than the fundamental resonance frequency). Several researchers have used soft piezoceramics (e.g. PZT-5A and PZT-5H) for power generation under resonant excitation. Typically, these soft piezoceramics have larger piezoelectric strain constant and larger elastic compliance compared to hard piezoceramics (e.g. PZT-4 and PZT-8). However, it is known that hard piezoceramics can have an order of magnitude larger mechanical quality factor compared to soft piezoceramics. Consequently, hard piezoceramics can generate more power under resonant excitation even though researchers have mostly focused on the soft piezoceramics. On the other hand, soft piezoceramics can generate more power for low frequency excitation below the resonance frequency due to their large effective piezoelectric stress constants. This difference is also the case for soft and hard single crystals (e.g. soft PMN-PZT versus hard PMN-PZT-Mn). In addition, single crystals can generate more power than ceramics at low off-resonant frequencies due to their large dynamic flexibilities (which is related to their large elastic compliances). This work investigates the specific advantages of soft and hard piezoceramics and single crystals for vibration-based energy harvesting. An experimentally validated piezoelectric energy harvester model is used to compare the power generation performances of soft and hard ceramics as well as soft and hard single crystals. The soft and the hard piezoceramics considered in this work are PZT-5H and PZT-8, respectively, while the soft and the hard single crystals considered here are PMN-PZT and PMN-PZT-Mn, respectively. Copyright © 2010 by ASME. Source

Lee J.-Y.,Ceracomp Co. | Oh H.-T.,Ceracomp Co. | Lee H.-Y.,Sun Moon University
Journal of the Korean Ceramic Society | Year: 2014

Orthorhombic Ba(Ti0.94Zr0.06)O3 single crystals are fabricated using the cost-effective solid-state single crystal growth (SSCG) method; their dielectric and piezoelectric properties are also characterized. Measurements show that (001) Ba(Ti0.94Zr0.06)O3 single crystals have an electromechanical coupling factor (k33) higher than 0.83, piezoelectric charge constant (d33) of about 400 [pC/N], and piezoelectric voltage constant (g33) higher than 50 [x10 -3 Vm/N]. The transition temperature (TOT) of the (001) Ba(Ti0.94Zr0.06)O3 single crystals between orthorhombic and tetragonal phases is also observed to be about 61 ° C. Because their electromechanical coupling factor (k33) and piezoelectric voltage constant (g33) are higher than those of soft PZT ceramics, it is expected that (001) Ba(Ti0.94Zr0.06)O3 single crystals can be used as "lead-free" piezoelectric materials in many piezoelectric applications. Source

Discover hidden collaborations