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백종후,임은경,이미재,지미정,최병현,김세기,Paik, Jong-Hoo,Lim, Eun-Kyeong,Lee, Mi-Jae,Jee, Mi-Jung,Choi, Byung-Hyun,Kim, Sei-Ki 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.1
The microwave dielectric properties and their related structural characteristics in solid solutions of (1-$\chi$) Ba($Mg_{1/3}$Nb$_{2/3}$) $O_3$-$\chi$La(Mg$_{2/3}$Nb$_{1}$3) $O_3$(BLMN) have been investigated by measuring the dielectric constant($\varepsilon$r), Q value and temperature coefficient of resonant frequency($\tau$f) and by observing the crystal structure using high resolution transmission electron microscopy (HRTEM). Microwave dielectric properties showed characteristic features for specific composition. Dielectric constant($\varepsilon$$_{r}$) showed maximum value at the composition which corresponds to the phase boundary between 1 : 2 ordered and 1 : 1 ordered structure. The increase in $\varepsilon$$_{r}$ may be caused by the rattling of ions by incorporating smaller ions and the disordered structure. The variation of temperature coefficient of resonant frequency($\tau$$_{f}$) was investigated in terms of oxygen octahedra tilting.dra tilting.
백종후,이미재,최병현,지미정,임은경,남산,Paik, Jong-Hoo,Lee, Mi-Jae,Choi, Byung-Hyun,Jee, Mi-Jung,Lim, Eun-Kyeong,Nahm, Sahn 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.7
Crystal structure of $(Ba-{1-x}La_x)[Mg_\frac{1+x}{3}}Nb_\frac{{2-x}{3}}]O_3$ (BLMN) ceramics with 0\leq1x \geq was investigated using synchrotron X-ray powder diffraction (XRD) and high reso(B $a_{l-x}$L $a_{x}$)[M $g_{(1+x)}$3/N $b_{(2-x)/3}$] $O_3$lution transmission electron microscopy (HRTEM). When the La content, x, is above 0.1, the 1:2 ordered hexagonal structure found in Ba($Mg_\frac{1}{3}Nb_\frac{2}{3}})O_3$(BMN) was transformed into 1:1 ordered cubic structure. The 1:1 ordered cubic structure was maintained up to x=0.7. When x exceeded 0.7, however, BLMN was transformed into 1:1 ordered structure which has cation displacement and in-phase and anti-phase tilt of octahedra.
백종후,임은경,김창일,이미재,지미정,최병현,김세기,Paik Jong-Hoo,Lim Eun-Kyeong,Kim Chang-il,Lee Mi-Jae,Jee Mi-Jung,Choi Byung-Hyun,Kim Sei-Ki 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.3
RAINBOW(Reduced And Internally Biased Oxide Wafers) are a new class of high-displacement, piezoelectric actuator produced by selectively removing oxygen from one surface of ceramic using a high-temperature chemical reduction process. In this paper, RAINBOW actuator materials of $0.4Pb(Ni_{1/3}Nb_{2/3})O_3-0.6Pb(Zr_{x}Ti_{1-x})O_3$ ceramics were prepared. Its dielectric and piezoelectric properties were investigated in the vicinity of MPB. The piezoelectric properties showed the maximum value of ${\epsilon}r$ = 4871, $d_{33}$ = 610 ($10^{-12}$ m/V), $d_{31}$ = -299 ($10^{-12}$ m/V), $k_{33}$ = $71\%$, Qm = 70, in $0.4Pb(Ni_{1/3}Nb_{2/3})O_{3}-0.6Pb(Zr_{405}Ti_{595})O_3$ composition sintered at $1250^{\circ}C$. The strain - electric field characteristics of RAINBOW actuator were significantly improved comparison with the conventional bulk actuator. The prepared RAINBOW actuator showed about $390\;{\mu}m/100\;V$ displacement.
Mg 결핍에 따른 Ba(Mg<sub>1/2</sub>Nb<sub>2/3</sub>)O<sub>3</sub> 세라믹스의 마이크로파 유전특성
백종후,이미재,최병현,김효태,지미정,임은경,남산,이학주,Paik, Jong-Hoo,Lee, Mi-Jae,Choi, Byung-Hyun,Kim, Hyo-Tae,Jee, Mi-Jung,Lim, Eun-Kyeong,Nahm, Sahn,Lee, Hwack-Joo 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.4
Crystal structure and microwave dielectric properties of Ba(Mg1/3Nb2/3) $O_3$ (BMN) ceramics were investigated. Ba(Mg1/3Nb2/3) $O_3$ has the 1:2 ordered hexagonal structure. The 1:2 ordering and relative density of specimens increased with small Mg deficiency(x). The variation of Q${\times}$ $f_{0}$ with Mg deficiency is very similar to that of 1:2 ordering and relative density. The highest Q${\times}$ $f_{0}$ achieved in this investigation is about 96,000 for Ba(Mg1/3Nb2/3) $O_3$. The improvement of Q${\times}$ $f_{0}$ with Mg-deficiency is related to the increase of degree of ordering and relative density of the specimen.
Class I Flextensional 변환기의 주파수 특성 변화
강국진,백종후,이영진,Kang, Kook-Jin,Paik, Jong-Hoo,Lee, Young-Jin 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.2
We constructed a Class I flextensional transducer, and analyzed the variation of the resonance frequency of the transducer in relation to its structural and material variables. We used the FEM for the analysis. Total length of the transducer, thickness and material properties of the shell have large effects on the resonance frequency. While outer radius of the ceramic stack and material properties of the ceramic stack have no effect on the resonance frequency. In addition, the validation of the FE model was verified by manufacturing and comparison of the impedance analysis. Results of the present work can be utilized to design a Class I flextensional transducers of various resonance frequency.
BT-BNT계에서 (Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub> 첨가에 따른 효과
이미재,백종후,김세기,김빛남,이우영,이경희,Lee, Mi-Jai,Paik, Jong-Hoo,Kim, Sei-Ki,Kim, Bit-Nam,Lee, Woo-Yong,Lee, Kyung-Hee 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.1
Lead free positive temperature coefficient of resistivity (PTCR) ceramics based on $BaTiO_3-(Bi_{0.5}Na_{0.5})TiO_3$ solid solution were prepared by a conventional solid state reaction method. The phase structure was showed single phase with perovskite structure regardless calcinations temperature and $Ba_{1-x}(Bi_{0.5}Na_{0.5})_xTiO_3$ structure was transformed from tetragonal to orthorhombic phase at $x{\geq}0.15$ mole. The XRD peaks with $45^{\circ}{\sim}46^{\circ}$ shifted in right the influence of crystal structure change and the intensity of peak was decreased with additive $(Bi_{0.5}Na_{0.5})TiO_3$. The curie temperature risen with additive $(Bi_{0.5}Na_{0.5})TiO_3$ but disappeared for $(Bi_{0.5}Na_{0.5})TiO_3$ addition more than 0.15 mole in TMA. In relative permittivity, the curie temperature by the transform of ferroelectric phase risen with additive $(Bi_{0.5}Na_{0.5})TiO_3$ but decreased in relative permittivity. Also, the peak of new curie temperature showed the sample containing $0.025{\sim}0.045$ mole of $(Bi_{0.5}Na_{0.5})TiO_3$ near $70^{\circ}C$ caused by phase transform from ferroelectric to ferroelectric and the peak of new curie temperature disappeared at 0.045 mole of $(Bi_{0.5}Na_{0.5})TiO_3$. In our study, it was found that the PTCR in $BaTiO_3-(Bi_{0.5}Na_{0.5})TiO_3$ system was possible for $0{\sim}0.025$ mole of $(Bi_{0.5}Na_{0.5})TiO_3$ and the maximum curie temperature by phase transition showed about at $145^{\circ}C$.
TiN 기판 위에 성장시킨 비정질 BaSm<sub>2</sub>Ti<sub>4</sub>O<sub>12</sub> 박막의 구조 및 전기적 특성 연구
박용준,백종후,이영진,정영훈,남산,Park, Yong-Jun,Paik, Jong-Hoo,Lee, Young-Jin,Jeong, Young-Hun,Nahm, Sahn 한국재료학회 2008 한국재료학회지 Vol.18 No.4
The structural and electrical properties of amorphous $BaSm_2Ti_4O_{12}$ (BSmT) films on a $TiN/SiO_2/Si$ substrate deposited using a RF magnetron sputtering method were investigated. The deposition of BSmT films was carried out at $300^{\circ}C$ in a mixed oxygen and argon ($O_2$ : Ar = 1 : 4) atmosphere with a total pressure of 8.0 mTorr. In particular, a 45 nm-thick amorphous BSmT film exhibited a high capacitance density and low dissipation factor of $7.60\;fF/{\mu}m2$ and 1.3%, respectively, with a dielectric constant of 38 at 100 kHz. Its capacitance showed very little change, even in GHz ranges from 1.0 GHz to 6.0 GHz. The quality factor of the BSmT film was as high as 67 at 6 GHz. The leakage current density of the BSmT film was also very low, at approximately $5.11\;nA/cm^2$ at 2 V; its conduction mechanism was explained by the the Poole-Frenkel emission. The quadratic voltage coefficient of capacitance of the BSmT film was approximately $698\;ppm/V^2$, which is higher than the required value (<$100\;ppm/V^2$) for RF application. This could be reduced by improving the process condition. The temperature coefficient of capacitance of the film was low at nearly $296\;ppm/^{\circ}C$ at 100 kHz. Therefore, amorphous BSmT grown on a TiN substrate is a viable candidate material for a metal-insulator-metal capacitor.
이주희,김창일,백종후,조정호,전명표,정영훈,이영진,이정배,이승대,Lee, Joo-Hee,Kim, Chang-Il,Paik, Jong-Hoo,Cho, Jeong-Ho,Chun, Myoung-Pyo,Jeong, Young-Hun,Lee, Young-Jin,Lee, Jeong-Bae,Lee, Seung-Dae 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.3
The osseointegration of dental implant is influenced by many factors such as surface geometry, loading and the amount of bone. Thus, stability of the dental implant should be checked periodically. In order to test the stability of dental implant by using resonance frequency analysis, we designed a structure of transducers and fabricated a piezoelectric devices. Using finite element analysis, the thickness and length of piezoelectric device and transducers were tailorized and the optimized frequency of 10 kHz was obtained. The resonance frequency from simulation analysis and evaluation was estimated to be similar as 10 kHz. The osseointegration was further enhanced with increasing frequency from the evaluation result of the finite element analysis.
ZnO-Zn<sub>2</sub>BiVO<sub>6</sub>-Mn<sub>3</sub>O<sub>4</sub> 바리스터의 미세구조와 전기적 특성
홍연우,하만진,백종후,조정호,정영훈,윤지선,Hong, Youn-Woo,Ha, Man-Jin,Paik, Jong-Hoo,Cho, Jeong-Ho,Jeong, Young-Hun,Yun, Ji-Sun 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.5
This study introduces a new investigation report on the microstructural and electrical property changes of $ZnO-Zn_2BiVO_6-Mn_3O_4$ (ZZMn), where 0.33 mol% of $Mn_3O_4$ and 0.5 mol% of $Zn_2BiVO_6$ were added to ZnO (99.17 mol%) as liquid phase sintering aids. $Zn_2BiVO_6$ contributes to the decrease of sintering temperatures by up to $800^{\circ}C$, and segregates its particles at the grain boundary, while $Mn_3O_4$ enhances ${\alpha}$, the nonlinear coefficient, of varistor properties up to ${\alpha}=62$. In comparison, when the sintering temperature is increased from $800^{\circ}C$ to $1,000^{\circ}C$, the resistivity of ZnO grains decreases from $0.34{\Omega}cm$ to $0.16{\Omega}cm$, and the varistor property degrades. Oxygen vacancy ($V_o^{\bullet}$) (P1, 0.33~0.36 eV) is formed as a dominant defect. Two different kinds of grain boundary activation energies of P2 (0.51~0.70 eV) and P3 (0.70~0.93 eV) are formed according to different sintering temperatures, which are tentatively attributed to be $ZnO/Zn_2BiVO_6$-rich interface and ZnO/ZnO interface, respectively. Accordingly, this study introduces a progressive method of manufacturing ZnO chip varistors by way of sintering ZZMn-based varistor under $900^{\circ}C$. However, to procure a higher reliability, an in-depth study on the multi-component varistors with double-layer grain boundaries should be executed.
유한요소법을 이용한 고온용 초음파 유량센서의 설계 및 평가
이주희,김창일,백종후,조정호,정영훈,이영진,남산,Lee, Joo-Hee,Kim, Chang-Il,Paik, Jong-Hoo,Cho, Jeong-Ho,Jeong, Young-Hun,Lee, Young-Jin,Nahm, Sahn 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.11
An operation temperature of $Pb(Zr,Ti)O_3$ based piezoelectric ultrasonic flowmeter was generally restricted to below 200$^{\circ}C$ due to a low depoling temperature of its ceramic material. Thus, a new designed piezoelectric ultrasonic flowmeter was fabricated in order to protect from the extremely hot fluid. Its structure is optimized by a finite element method to effectively stop heat flowing along a waveguide. Various materials such as Cu, Al, SUS were examined as a multi-plate radiation shield to enhance the performance of piezoelectric ultrasonic flowmeter. The SUS was evaluated as the most effective material to enhance the performance of piezoelectric ultrasonic flowmeter. As the number of plates of the radiation shield increased, the temperature at piezoelectric transducer away from the hot fluid was constantly decreased with a ratio of 3.12$^{\circ}C$ per the plate number.