• Title/Summary/Keyword: Temperature coefficient of resonance frequency

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The Effect of Poling Strength on Temperature Dependence of Resonance Frequency of PZT Ceramics Near the Morphotropic Phase Boundary (분극전계가 모포트로픽 상경계 부근의 PZT 세라믹스의 공진주파수의 온도의존성에 미치는 영향)

  • Yang, Jung-Bo;Yang, Wan-Seok;Lee, Gae-Myoung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.7
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    • pp.1213-1217
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    • 2008
  • Poling is an important process in fabricating PZT ceramic devices such as filters and resonators and activates piezoelectricity to sintered PZT ceramics. Tolerance of the operating frequency of these devices is tightly required in applications. And a factor to attribute the tolerance is the temperature dependence of the resonance frequency of PZT ceramics. In this paper the relationship of poling strength and temperature dependence of resonance frequency of PZT specimens was studied. The $Pb(Zr_{0.53}Ti_{0.47})O_3$ ceramics were fabricated and the poling strengths were chosen to be 0.5, 1.5, 2.5 and 3.5 [kV/mm]. The dielectric constant of the specimen poled in poling strength 0.5 [kV/mm] was less than that of unpoled specimen and the specimen poled in higher electric field had the higher dielectric constant. (002) peak in X-ray diffraction patterns of the specimens increased as poling strength increased. And the change of resonance frequency of the specimens according to the variation of temperature was measured. Resonance frequency of all specimens increased as the temperature increased. The specimen poled in higher electric field had the smaller positive temperature coefficient of resonance frequency. The effect that temperature coefficient of resonance frequency becomes smaller is obtained when Zr mole in PZT composition equation increase. Controlling the poling strength is believed to be a method to adjust the temperature stability of resonance frequency of the PZT ceramic devices.

Nondestructive bending Strength Evaluation of Woodceramics Using Resonance Frequency Mode (I) - Carbonizing Temperature -

  • Byeon, Hee-Seop;Ahn, Sang-Yeol;Oh, Seung-Won;Piao, Jin-Ji
    • Journal of the Korean Wood Science and Technology
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    • v.32 no.3
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    • pp.8-14
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    • 2004
  • Nondestructive evaluation (NDE) technique method using a resonance frequency mode was carried out for woodceramics produced at different carbonizing temperatures (600℃, 800℃, 1000℃, 1200℃, 1500℃) at the phenol resin impregnation rate of 70%, for three kinds of species (Pinus densifora, Pinus koraiensis, Larix leptolepis), respectively. There was a poor relationship between density and static bending MOR. However, close correlations were found between dynamic MOEd and static bending MOR, and between static MOEs and MOR. Especially, the correlation coefficient was highest between MOEd and static bending MOR. Therefore, the MOEd using the resonance frequency mode is useful as a NDE method for predicting the MOR of woodceramics produced at different carbonizing temperatures.

The Accurate design of a Temperature stable Dielectric Stepped-Impedance Resonator (온도 변화에 안정한 유전체 Stepped-Impedance Resonator의 정확한 설계)

  • 임상규;김덕환안철
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.625-628
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    • 1998
  • This paper presents the design method of a temperature stable stepped-impedance resonator using composite material. In this method temperature coefficient of dielectric constant $(\tau\varepsilon)$ and thermal expansion coefficient $(\alpha1)$ of dielectric material were considered. Ba(Zn1/3Nb2/3)O3 and CaZrO3 as composite material having opposite signs of temperature coefficient of dielectric constant were selected. The length of this resonator for the temperature stability of resonance frequency was calculated at 900MHz, 1.4㎓ and 1.9㎓. It was found that the ratio of the length of positive $\tau\varepsilon$ materal to the length of negative $\tau\varepsilon$ material is constant at various resonance frequencies.

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The Microwave Dielectric Properties of $BiNbO_4$ as The Addition of $MoO_3$ ($MoO_3$첨가에 따른 $BiNbO_4$의 마이크로파 유전특성)

  • 박영순;김덕규;김규도;박춘배
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.232-235
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    • 1999
  • In this paper, We described the effect of $MoO_3$ Addition and firing temperature on the microwave dielectric properties of $BiNb0_4$ ceramics. The specimens prepared by conventional mixed method was addicted by 0 - 0.03 wt% $MoO_3$ and fired at 860 - $950^{\circ}$ for 3hr. Density increased when $MoO_3$ is below O.Olwt% but decreased when over O.Olwt%. $BiNb0_4$ ceramics addicted with CuO 0.03wt % and $MoO_3$ 0.01 wt% showed microwave dielectric properties, Dielectric constant 37.5, Quality factor[Qx$f_0$]5500, Temperature coefficient of resonance frequency 15ppm/$^{\circ}$

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Effect of Ca Contents and Sr Substitutions on Microwave Characteristics of Mg-Ca-Sr-Ti-O System Ceramics (Ca 함량 및 Sr 치환량의 변화에 따른 Mg-Ca-Sr-Ti-O계 세라믹스의 마이크로파 특성)

  • Ryu, Heon-Wi;You, Whan-Sik;Jung, Ha-Chang;Kim, Bae-Yeon
    • Journal of the Korean Ceramic Society
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    • v.43 no.5 s.288
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    • pp.284-292
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    • 2006
  • $MgTiO_3{\cdot}CaTiO_3{\cdot}SrTiO_3$ system ceramics (MCST) were synthesized to study the effect of Ca addition amount and Sr substitution on temperature coefficient of resonance sequency. Temperature coefficient of resonance frequency was slightly increased by small amount ($i.e.{\sim}5%$) of Sr substitution. In case of 50% to 75% addition amount of $MgTiO_3$, decrease of quality factor was not observed with increasing dielectric constant.

The Effects of (Ba0.4Ca0.6)SiO3 Nano Spheroidization Glass Additives on the Microstructure and Microwave Dielectric Properties of Ba(Zn1/3Ta2/3)O3 Ceramics

  • Choi, Cheal Soon;Kim, Ki Soo;Rhie, Dong Hee;Yoon, Jung Rag
    • Journal of Electrical Engineering and Technology
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    • v.9 no.5
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    • pp.1719-1723
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    • 2014
  • In this study, the microwave dielectric properties of nano spheroidization glass powders added $Ba(Zn_{1/3}Ta_{2/3})O_3$ ceramics prepared by solid state reaction have been investigated. Adding $(Ba_{0.4}Ca_{0.6})SiO_3$ nano spheroidization glass powders could effectively promote the densification even in the case of decreasing the sintering temperature. When the glass frit is 0.3 wt% and sintering is carried out at a temperature of $1500^{\circ}C$ for 6 hr, a temperature stable microwave dielectric ceramic could be obtained, which has a dielectric constant (${\varepsilon}_r$) of 30.2, a quality factor ($Q{\times}f_0$) of 124,000 GHz and a temperature coefficient of resonance frequency (${\tau}_f$) of $2ppm/^{\circ}C$.

Resonance of Natural Convection and Heat Transfer inside a Square Cavity due to a Vibrating Wall (사각 공동구의 벽면 가진에 의한 자연 대류 유동의 공진 현상 및 열전달에 관한 연구)

  • Hur, N.;Kim, Y.;Kang, B.
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.483-488
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    • 2001
  • In the present study a numerical simulation is performed on a natural convection inside a square cavity with a vibrating wall. The study has been conducted varying the heat transfer rate, wall excitation frequency and also the orientation of the cavity. The temperature and velocities inside the cavity was observed and also, the heat transfer coefficients on the heating wall was seen. From the results, it can be seen that the temperature inside the cavity decreases when excited with the proper frequency and the heat transfer coefficient increased with cavity inclination angle, ${\theta}$. It is also found from the results that flow resonance is occurred near the inclination angle ${\theta}=90^{\circ}$.

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Effect of Mn Dopping on the Microwave Dielectric Properties of 0.17($Ba_{0.53}$, $Pb_{0.47}$)0-$0.16Nd_2O_3$-$0.67TiO_2$ Ceramics (0.17($Ba_{0.53}$, $Pb_{0.47}$)0-$0.16Nd_2O_3$-$0.67TiO_2$ 세라믹스의 고주파 유전특성에 미치는 Mn 첨가의 영향)

  • 윤중락;이헌용;김경용
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.05a
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    • pp.292-294
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    • 1996
  • Dielectric properties were investigated at Mn doped 0.17($Ba_{0.53}$, $Pb_{0.47}$)0-$0.16Nd_2O_3$-$0.67TiO_2$ system in microwave frequency. It was observed that dielectric constant of 90.1, quality factor of 1320 (at 3.8GHz) and temperature coefficient of resonance frequency 2.3 ppm/$^{\circ}C$ for 0.5wt% Mn doped 0.17($Ba_{0.53}$, $Pb_{0.47}$)0-$0.16Nd_2O_3$-$0.67TiO_2$ system in sintering condition $1290^{\circ}C$/2hr. The quality factor increase due to the compensation effect of Mn ions yp to 0.5wt% and the decrease due to the interface relaxation effect. The temperature coefficient of resonance frequency increases to negative direction with increasing the amounts of Mn.

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Nondestructive Bending Strength Evaluation of Ceramics Made from Miscanthus sinensis var. purpurascens Particle Boards - Effect of Resin Impregnation Ratio -

  • Byeon, Hee-Seop;Won, Kyung-Rok;Oh, Seung-Won
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.2
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    • pp.130-137
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    • 2014
  • Nondestructive evaluation (NDE) method by using a resonance frequency mode was carried out for ceramics made from particle boards with different phenol resin impregnation ratios (30, 40, 50, 60%) at carbonizing temperature of $800^{\circ}C$. The material for ceramics was Miscanthus sinensis var. purpurascens board. Dynamic modulus of elasticity increased with increasing impregnation ratio. There was a close relationship of dynamic modulus of elasticity and static bending modulus of elasticity to modulus of rupture (MOR). However, the result indicated that correlation coefficient is higher in dynamic modulus of elasticity to MOR than that in static modulus of elasticity to MOR. Therefore, the dynamic modulus of elasticity using resonance frequency by free vibration mode is more useful as a nondestructive evaluation method for predicting the MOR of ceramics made from Miscanthus sinensis var. purpurascens particle boards by different phenol resin impregnation ratios.