• 제목/요약/키워드: temperature hysteresis

검색결과 499건 처리시간 0.03초

Dielectric Characteristics of PbSc1/2Nb1/2O3 Prepared by Using the One-step Solid State Reaction

  • Kim, Yeon Jung
    • Applied Science and Convergence Technology
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    • 제25권4호
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    • pp.77-80
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    • 2016
  • The $PbSc_{1/2}Nb_{1/2}O_3$ ceramics at a relatively low temperature of $1300^{\circ}C$ was successful synthesized. Solid state reaction of two-step process is not necessary. The dielectric constant, dielectric loss and admittance of ceramic samples were determined. The pyroelectric characteristics are in good agreement with the dielectric properties. Ferroelectric properties of well-formed the $PbSc_{1/2}Nb_{1/2}O_3$ ceramics are in agreement with broad distribution of relaxation phenomenon. Relatively strong frequency dependent of dielectric constant is observed at about $110^{\circ}C$. The distinct thermal hysteresis was observed in the measurement of the dielectric constant and dielectric loss. The critical exponents of during cooling and heating measurements in the $PbSc_{1/2}Nb_{1/2}O_3$ ceramics were 1.14 and 1.59 at 1 kHz, respectively.

Magnetic Properties of Nano-Sized CuNi Clusters

  • Jo, Y.;Jung, M.H.;Kyum, M.C.;Park, K.H.;Kim, Y.N.
    • Journal of Magnetics
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    • 제11권4호
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    • pp.156-159
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    • 2006
  • We have studied the magnetic properties of the CuNi nanoparticles for three different sizes prepared by plasma and chemical techniques. The magnetization is enormously enhanced with decreasing the nanoparticle size. This enhanced magnetic moment shows almost inversely linear temperature dependence, which could be interpreted by the Langevin-type superparamagnetism. The field dependence exhibits ferromagnetic-like behavior with weak hysteresis, which could described in terms of uncompensated spin and/or surface anisotropy. In addition, the magnetic data suggest that the CuNi nanoparticles produced by the plasma method result in significantly less oxidized metallic nanoparticles than those prepared by other techniques.

p-n 접합에 있어서의 비등방성 응력효과 (Anisotropic stress Effects in p-n junction)

  • 손병기;이건일
    • 대한전자공학회논문지
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    • 제11권3호
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    • pp.22-26
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    • 1974
  • The effects of anisotropic mechanical stress applied normal to the surface of p-n junctions have been investigated. As the stress increased, the breakdown voltage was decreased and the breakdown mode became softer. Within a certain limitation in the applied stress, the above phenomena werw reversibbe, though relaxation and hysteresis phenomena were observed. The time constant of relaxation depended upon the shape of the stressing tip, but for the given tip and device a unique time constant was obtained. The stress.dependence of breakdown voltage showed a good linearity up to about 3.0${\times}10^4$ kgw/$\textrm{cm}^2$, when the flat tip of radius 15$\mu$ was used, and the temperatere-dependence of breakdown voltage under the stress also showed a good linearity in the temperature range of 100 to $300^{\circ}K$.

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(Pb, Ba) (Zr, Ti)O3계의 확산된 상전이에 있어서 Strain Energy의 역할 (Role of the Strain Energy in Diffuse Phase Transition of (Pb, Ba)(Zr, Ti)O3)

  • 이재찬;주웅길
    • 한국세라믹학회지
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    • 제24권6호
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    • pp.586-592
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    • 1987
  • The role of the strain energy and phase stability in the diffuse phase transition have been investigated in the highly disordered solid solution, (Pb1-xBax)(Zr0.4Ti0.6)O3 (0.2 x 0.4). X-ray diffraction analysis indicates that tetragonality (c/a) decreases with the increasing Ba content. Also as the Ba content increases, phase transition becomes more diffuse and at the same time dielectric relaxation as a function of measured frequencies in the 1KHz-10MHz range occurs very pronouncedly. In the Ba content range, 0.2 x 0.35, hysteresis loops are routinely observed and the loop is observed to narrow shape as the Ba content increases but becomes very slim at 40mol% Ba content. Moreover thermal analysis shows that there is no abrupt change in the thermal expansion coefficient below the apparent transition temperature at which dielectric constant becomes maximum. From the above results, it has been concluded that creation of the strain energy due to the distorthion that occurred during the phase transition suppresses diffuse phase transition.

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코디에라이트-티탄산알루미늄 복합체의 제조 및 특성 (Preparation and Properties of Cordierite Aluminium Titanate Composites)

  • 송휴섭;김상우;장성도;손용배
    • 한국세라믹학회지
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    • 제27권3호
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    • pp.345-354
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    • 1990
  • The densification behaviro and resulting properties of cordierite-aluminium titanate composites containing 5 to 40wt.% aluminium titanate were investigated. Compared with cordierite monolithics a substantial increase of sintering temperature range for composites was observed, which was due to the formation of cordierite and glass phase at relatively low temperatures. The bending strength of composites showed its maximum at 30wt.% aluminium titanate content, which was about 50% increase relative to the cordierite monolithics, then decreased by a small amount at 40wt.% aluminium titanate content. The decrease was explained by the increase of microcracks whose presence was confirmed by the hysteresis of thermal expansion curve of composites. However, the microcracks formed was not severe enough to produce a significant decrease in strength, which was also evidenced by the continuous increase of thermal expansion coefficient up to 40wt.% aluminium titanate content.

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Iodine-doped PPA 박막의 감습특성 (Humidity Sensing Properties of Iodine-doped PPA Thin Films)

  • 민남기;강현식;김태윤;김석기;홍석인
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 하계학술대회 논문집 D
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    • pp.1561-1563
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    • 1998
  • A capacitive humidity sensor is used as a test device to characterize the performance of iodine doped polyphenylacetylene(PPA) thin films in relative humidity sensing application In comparison with undoped PPA thin films. the iodine doped PPA films showed higher sensitivity(0.19pF/%RH), better linearity(4.2%FS), much lower hysteresis and lower temperature coefficients(0.043 $\sim$ 0.067pF/$^{\circ}C$) over a wide range of relative humidity.

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PMN - PT - PZ 계 세라믹스를 이용한 압전 엑츄에이터의 제작 및 변위 특성 (The fabrication and strain properties of piezoeletric ceramic actuator using PMN - PT -PZ system)

  • 지승한;이능헌;이덕출;김호기
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1993년도 춘계학술대회 논문집
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    • pp.15-18
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    • 1993
  • Piezoelectric Actuator and electrostrictive Actuator samples were fabricated using PMN-PT-PZ system ceramics with Barium substitution, and the strain properties of them investigated. The largest Piezoelectric coefficient and electromechanical coupling coefficient were observed at sintering temperature $1250^{\circ}C$, Barium 0.05 mol %. The strain of poled samples is observed twice highly then unpoled ones, and the former showed larger hysteresis in strain then the latter, too. Poled multilayered actuator samples showed considerable strain.

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Magnetically Soft Nanomaterials Obtained by Devitrification of Metallic Glasses

  • Kulik, Tadeusz;Ferenc, Jaroslaw;Kowalczyk, Maciej;Xiubing, Liang;Nedelko, Natalya
    • Journal of Magnetics
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    • 제9권2호
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    • pp.65-68
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    • 2004
  • Magnetically soft nanomaterials obtained by controlled crystallisation of metallic glasses are the newest group of materials for inductive components. In particular, research is carried out in the field of alloys for high temperature applications. This kind of materials must meet two basic requirements: good magnetic properties and stability of properties and structure. In the present work the magnetic properties and structure of Fe-Co-Hf-Zr-Cu-B (HIDTPERM-type) alloys were investigated, as well as their stability. Differential thermal analysis, (DTA), X-ray diffractometry (XRD), transmission electron microscopy (TEM), magnetometry (VSM) and quasistatic hysteresis loop recording were used to characterise structure and properties of the alloys investigated. Optimisation against properties and their stability was performed, resulting in formulation of chemical composition of the optimum alloy, as well as its heat treatment.

스파타가공법을 이용한 스트레인 게이지의 개발 및 특성에 관한 연구 (A Study on the Development and Characteristics of Strain Gauge using Sputter Machining)

  • 한응교;노병옥;이명호
    • 비파괴검사학회지
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    • 제9권2호
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    • pp.50-60
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    • 1989
  • The control of resistance of foil strain gauge is accomplished by means of etching technique. Thus, there is an irregularity in metal foil. In order to solve this problem, ion sputter machining method has been used to make strain gauge in this study and the characteristics of this strain gauge are investigated. As the result of this study, it was possible to make a flexible strain gauge which can be used to measure the stress. The strain gauge made by authors shows superior characteristics in creep, O point variance, hysteresis and nonlinearity by surrounding temperature.

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The magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects

  • Lee, C.W.;Shim, S.Y.;Ha, D.H.;Kim, D.H.;Lee, T.W.
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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    • pp.103-106
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    • 2000
  • We have studied the magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects using micro Hall-probe array. We found that fold profiles inside sample were similar to the Bean's critical state model from the magnetic hysteresis measurement. In the magnetic relaxation measurement, the normalized relaxation rates were maximum near the center and decreased toward the edge of the sample expect zero gauss. The relaxation rates as a function of the temperature were maximum near the 40K and rapidly decreased both sides of the peak.

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