• Title/Summary/Keyword: %24TiO_2%24

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Microwave dielectric properties of 0.96Mg$TiO_3$-0.04Sr$TiO_3$ ceramics with $V_2O_5$ ($V_2O_5$ 첨가에 따른 0.96Mg$TiO_3$-0.04Sr$TiO_3$ 세라믹스의 마이크로파 유전특성)

  • Nam, Gyu-Bin;Lee, Moon-Kee;Kim, Kang;Ryu, Ki-Won;Lee, Young-Hie
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1485-1487
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    • 2002
  • The 0.96Mg$TiO_3$-0.04Sr$TiO_3$ ceramics with $V_2O_5$(5wt%) were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature by XRD and SEM. According to the X-ray diffraction patterns of the 0.96Mg$TiO_3$-0.04Sr$TiO_3$ceramics with $V_2O_5$(5wt%), the ilmenite $MgTiO_3$ and perovskite $SrTiO_3$ structures were coexisted and secondary phase $MgTi_2O_5$ were appeared. Increasing the sintering temperature, the grain size was increased and three types of grains were exhibited: larger circular grain, small square grain and lapth-shaped grain. In the case of 0.96Mg$TiO_3$-0.04Sr$TiO_3$ ceramics with $V_2O_5$(10wt%), dielectric constant, quality factor and temperature coefficient of resonant frequency were $15.24{\sim}18.55$, $22,890{\sim}42,100$GHz, -24.5${\sim}$+2.414ppm/$^{\circ}C$, respectively.

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Effect of Prefiring Time on Epitaxy and crystallinity of Pb(Zr, Ti)O$_3$ Thin Films in Low Temperature Pyrolysis (저온도포열분해에 의해 제조된 Pb(Zr, Ti)O$_3$ 박막의 에피탁시와 결정화도에 미치는 전열처리 시간의 영향)

  • 황규석;이형민;김병훈
    • Journal of the Korean Ceramic Society
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    • v.35 no.9
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    • pp.969-973
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    • 1998
  • Pb(Zr, Ti)O3 (PZT) (Zr:Ti= 52: 48) thin films were prepared on MgO(100) substrates by dipping-py-rolysis process using metal naphthenates as starting materials. Thin films were fabricated by spin coating technique and the precursor films were prefired at 20$0^{\circ}C$ in air for 0.5, 1, 2, 3, and 24 h followed by final heat treatment at 75$0^{\circ}C$ for 30min. Film prefired for 24 h lost orientational properties and pole figure analysis showed the lost of the epitaxial relationship between the films and substrate while highly a/c-axis oriented thin films were obtained for the samples prefired for 1, 2, and 3h.

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Synthesis and Sintering of Nanostructured Mg4Al2Ti9O25 by High-Frequency Induction Heating and Its Mechanical Properties (고주파 유도 가열에 의한 나노구조 Mg4Al2Ti9O25 합성 및 소결과 기계적 성질)

  • Kang, Hyun-Su;Doh, Jung-Mann;Yoon, Jin-Kook;Shon, In-Jin
    • Korean Journal of Materials Research
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    • v.24 no.2
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    • pp.67-72
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    • 2014
  • Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties, including high strength, high hardness, excellent ductility and toughness. In this study, nanopowders of $Al_2O_3$, MgO and $TiO_2$ were prepared as starting materials by high energy ball milling for the simultaneous synthesis and sintering of the nanostructured compound $Mg_4Al_2Ti_9O_{25}$ by high-frequency induction heating process. The highly dense nanostructured $Mg_4Al_2Ti_9O_{25}$ compound was produced within one minute by the simultaneous application of 80MPa pressure and induced current. The sintering behavior, grain size and mechanical properties of the $Mg_4Al_2Ti_9O_{25}$ compound were evaluated.

A Study on the Characteristics of Dye Sensitized Solar Cells with TiO2 Thickness and Sintering Temperature (TiO2 두께 및 소성온도에 따른 염료감응 태양전지 특성에 관한 연구)

  • Lee, Young-Min;Lee, Don-Kyu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.9
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    • pp.1233-1238
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    • 2014
  • In this thesis, it is investigated the characteristics of Dye Sensitized Solar Cell (DSSC) according to variation of $TiO_2$ thickness (6, 12, 18, and $24{\mu}m$) and three distinct $TiO_2$ sintering temperatures (350, 450 and $550^{\circ}C$) by XRD, SEM, I-V and UV-Vis spectrophotometer. According to sintering temperature, $TiO_2$ was transformed into the anatase structure at $350^{\circ}C$, rutile structure at $550^{\circ}C$ and further into the two structure at $450^{\circ}C$. With increasing thickness up to $18{\mu}m$ and sintering temperature up to $450^{\circ}C$, respectively, the irradiance rate increased in the range of 9~26 percent and 2.80~5.10 percent. Whereas a further increase to $24{\mu}m$ and $550^{\circ}C$, the irradiance rate decrease in the range of 4~11 percent and 30~47 percent. The conversion efficiency increased in the range of 2.80~5.01 and 3.03~5.01 with increasing thickness up to $18{\mu}m$ and sintering temperature up to $450^{\circ}C$. By contrast, increase to $24{\mu}m$ and $550^{\circ}C$, the conversion efficiency decreased in the range of 3.31~5.01 and 2.80~3.89, respectively. The DSSC that thickness of $TiO_2$ were $18{\mu}m$ and sintered at $450^{\circ}C$ exhibited the most excellent characteristics, in which open-circuit voltage, short-circuit current, Fill Factor and conversion efficiency are 0.69 V, $11.4mA/cm^2$, 0.64 and 5.01%, respectively.

A Study on the Piezoelectric Properties of the Pb($Zn_{1/3}Nb_{2/3})O_3-Ba(Zn_{1/3}Nb_{2/3})O_3-PbTiO_3$ (Pb($Zn_{1/3}Nb_{2/3})O_3-Ba(Zn_{1/3}Nb_{2/3})O_3-PbTiO_3$ 세라믹의 압전특성에 관한 연구)

  • 박혜옥;박인길;이성갑;이영희
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1989.06a
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    • pp.70-73
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    • 1989
  • (1-x-y)Pb($Zn_{1/3}Nb_{2/3})O_3-Ba(Zn_{1/3}Nb_{2/3})O_3-PbTiO_3(0.12{\leq}x{\leq}0.21, 0.24{\leq}y{\leq}0.33$) ternary compound ceramics were fabricated by the mixed oxide method. The sintering temperature and time were 1050 [$^{\circ}C$], 2[hr]. Morphotropic phase boundary region was chosen for the composition. 0.55 PZN-0.21 BZN-0.24 PT specimen had the highest value of relative dielectric constants, 5353. The curie temperature of specimens were increased linearly with PT content. Near the morphotropic phase boundary, electro-mechanical coupoling factor and mechanical quality factor of the specimens had the highest values.

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Synthesis of Fe-Doped TiO2/α-Fe2O3 Core-Shell Nanowires Using Co-Electrospinning and Their Magnetic Property (복합 전기방사법을 이용한 Fe-doped TiO2/α-Fe2O3 이중구조 나노와이어의 합성 및 자성 특성)

  • Koo, Bon-Ryul;Ahn, Hyo-Jin
    • Korean Journal of Materials Research
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    • v.24 no.8
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    • pp.423-428
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    • 2014
  • We synthesized Fe-doped $TiO_2/{\alpha}-Fe_2O_3$ core-shell nanowires(NWs) by means of a co-electrospinning method and demonstrated their magnetic properties. To investigate the structural, morphological, chemical, and magnetic properties of the samples, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used, as was a vibrating sample magnetometer. The morphology of the nanostructures obtained after calcination at $500^{\circ}C$ exhibited core/shell NWs consisting of $TiO_2$ in the core region and ${\alpha}-Fe_2O_3$ in the shell region. In addition, the XPS results confirmed the formation of Fe-doped $TiO_2$ by the doping effect of $Fe^{3+}$ ions into the $TiO_2$ lattice, which can affect the ferromagnetic properties in the core region. For comparison, pure ${\alpha}-Fe_2O_3$ NWs were also fabricated using an electrospinning method. With regard to the magnetic properties, the Fe-doped $TiO_2/{\alpha}-Fe_2O_3$ core-shell NWs exhibited improved saturation magnetization(Ms) of approximately ~2.96 emu/g, which is approximately 6.1 times larger than that of pure ${\alpha}-Fe_2O_3$ NWs. The performance enhancement can be explained by three main mechanisms: the doping effect of Fe ions into the $TiO_2$ lattice, the size effect of the $Fe_2O3_$ nanoparticles, and the structural effect of the core-shell nanostructures.

Atmosphere Effects in Low Temperature Pyrolysis of Chemical Solution Derived Pb(Zr, Ti) O3 Films

  • Hwang, Kyu-Seog;Lee, Hyung-Min;Kim, Byung-Hoon
    • The Korean Journal of Ceramics
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    • v.4 no.3
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    • pp.199-203
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    • 1998
  • $Pb(Zr, Ti)O_3$ (Pb:Zr:Ti=1:0.52:0.48) thin films were prepared on single crystal MgO(100) substrates by dipping-pyrolysis process using a solution of constituent metal naphthenates as starting materials. The solution was spin-coated onto substrate and the precursor films were pyrolyzed at $200^{\circ}C$ in air or at $200^{\circ}C$ in argon for 1, 2, 5 and 24h, followed by final heat treatment at $750^{\circ}C$. For all the films, highly (h00)/(00l)-oriented Pb$Pb(Zr, Ti)O_3$ thin films with smooth surfaces and crack-free were obtained, whereas thin film pyrolyzed in air for 24 h exhibited polycrystalline character. According to the pole-figure analysis, epitaxy of the product films was found to depend on pyrolysis atmosphere.

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Characterization of Hydrogen Gas Sensitivity of TiO2 Thin Films with Electron Beam Irradiation (전자빔 열처리에 따른 TiO2 박막의 수소가스 검출 특성 연구)

  • Heo, S.B.;Lee, H.M.;Jung, C.W.;Kim, S.K.;Lee, Y.J.;Kim, Y.S.;You, Y.Z.;Kim, D.
    • Journal of the Korean Society for Heat Treatment
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    • v.24 no.1
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    • pp.31-36
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    • 2011
  • $TiO_2$ films were deposited on a glass substrate with RF magnetron sputtering and then surface of $TiO_2$ films were electron beam irradiated in a vacuum condition to investigate the effect of electron bombardment on the thin film crystallization, surface roughness and gas sensitivity for hydrogen. $TiO_2$ films that electron beam irradiated at 450eV were amorphous phase, while the films irradiated at 900 eV show the anatase (101) diffraction peak in XRD pattern. AFM measurements show that the roughness is depend on the electron irradiation energy. As increase the hydrogen gas concentration and operation temperature, the gas sensitivity of $TiO_2$ and $TiO_2$/ZnO films is increased proportionally and $TiO_2$ films that electron beam irradiated at 900 eV show the higher sensitivity than the films were irradiated at 450eV. From the XRD pattern and AFM observation, it is supposed that the crystallization and rough surface promote the hydrogen gas sensitivity of $TiO_2$ films.

A Study of PTCR Effects in Semiconducting BaTiO3 Prepared by Direct Wet Process (습식 직접합성법에 의한 반도성 BaTiO3의 PTCR 효과에 관한 연구)

  • 이경희;이병하;정연식
    • Journal of the Korean Ceramic Society
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    • v.24 no.2
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    • pp.111-116
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    • 1987
  • By the method of direct wet process which has been developed in our laboratory, the high purity BaTiO3 powders could be synthesized from the room temperature to 90$^{\circ}C$ according to particle sizes. For to detect the PTCR effects, Sb2O3 wasdoped in the BaTiO3 powders which had been prepared on above method. As the results, the PTCR effects were in creased with the decreasing grain size of BaTiO3 powders.

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