• Title/Summary/Keyword: $TiO_2$powder

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수산염법에 의한 $Ba_2Ti_9O_{20}$의 합성과 유전특성에 미치는 $ZrO_2$ 첨가의 영향 (Effect of $ZrO_2$ Addition on the Synthesis and Microwave Dielectric Properties of $Ba_2Ti_9O_{20}$ Fabricated by Oxalate method)

  • 박재원;이헌식;이병하
    • 한국세라믹학회지
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    • 제31권8호
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    • pp.835-840
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    • 1994

  • In this study, the synthesis of Ba2Ti9O20 powder having chemically homogeneous and highly pure fine particle size distribution was attempted by the oxalate method. And the effects of ZrO2 addition was investigated. The four compositions (X=0, 0.028, 0.048, 0.068) of Ba2(Ti9-x, Zrx)O20 were prepared by precipitation reaction of BaCl2, TiCl4, and ZrOCl2, with oxalic acid and NH4OH acting as a precipitating agent and a pH regulator respectively, in aqueous solution. In case of 4.8 mol% ZrO2 addition, the single phase Ba2Ti9O20 was obtained at 120$0^{\circ}C$ and its dielectric properties was excellent showing K=40.5, Q=4621 at 5.4 GHz.

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Pt/TiO2의 HS 산화반응 및 SO2 피독과 재생 방안 연구 (A Study on the H2 Oxidation over Pt/TiO2, SO2 Poisoning and Regeneration)

  • 이동윤;김성수
    • 공업화학
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    • 제30권6호
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    • pp.731-736
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    • 2019

  • 본 연구에서는 Pt/TiO2를 파우더 및 허니컴 형태로 제조하고, 촉매의 피독 물질인 SO2에 대한 영향과 재생 방안을 연구하였다. 이에 따라 Pt/TiO2의 SO2 노출 전·후 촉매 활성을 비교하였다. Pt/TiO2의 초기 활성은 주입되는 H2 농도(1~5%)에 비례하며, 촉매의 온도와 H2 전환율이 각각 최대 183 ℃와 95%로 나타났다. 2,800 ppm SO2를 파우더 및 허니컴 Pt/TiO2에 노출시켰고, 이때 성능이 나타나지 않았고 촉매 표면에 0.69%의 황(S)이 잔류함을 확인하였다. 피독 촉매에 대한 세척 및 열처리 결과, 파우더 촉매는 세척에 의해 96% 이상의 H2 전환율을 나타냈고 허니컴 촉매는 H2 또는 air 분위기의 열처리를 통해 촉매 활성이 재생되어 95% 이상의 H2 전환율이 확인되었다.

  • https://doi.org/10.14478/ace.2019.1093 인용 PDF KSCI

고상반응법을 이용한 BaTiO3 합성 및 특성 평가 (Synthesis and Characterization of BaTiO3 Powder by Solid State Method)

  • 김용진;최문희;신효순;주병권;전명표
    • 한국전기전자재료학회논문지
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    • 제33권6호
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    • pp.483-489
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    • 2020

  • BaTiO3 powder was synthesized by a solid-state reaction using BaCO3 and TiO2. Different calcination temperatures (800℃, 850℃, 900℃, and 950℃) were set to investigate their effects on the properties of BaTiO3 powder. The synthesized BaTiO3 phase was confirmed to be a single phase by XRD, and the tetragonality (c/a) and crystallite size were calculated. Thereafter, each calcinated BaTiO3 was sintered at five different sintering temperatures (1,100℃, 1,150℃, 1,200℃, 1,250℃, and 1,300℃), and the tetragonality, density, porosity, dielectric constant, and grain size were measured. As the calcination temperature increased, the tetragonality and crystallite size also increased, to 1.008 and 66 nm, respectively, at 950℃. Moreover, most pellets showed increased density, dielectric constant, and tetragonality as the sintering temperature increased up to 1,250℃; the same parameters slightly decreased at 1,300℃. It is noteworthy that the tetragonality of BaTiO3 at 1,250℃ exhibits a very high c/a value of 1.0084. In addition, the grain size and dielectric constant measured near the Curie temperature increased as the sintering temperature increased.

  • https://doi.org/10.4313/JKEM.2020.33.6.483 인용 PDF KSCI

BaTiO3-Poly Vinylidene Fluoride 복합 압전발전기의 출력특성에 미치는 배합비와 분극의 효과 (Effects of Mixing Ratio and Poling on Output Characteristics of BaTiO3-Poly Vinylidene Fluoride Composite Piezoelectric Generators)

  • 김희태;박상식
    • 한국재료학회지
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    • 제33권12호
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    • pp.517-524
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    • 2023

  • BaTiO3-Poly vinylidene fluoride (PVDF) solution was prepared by adding 0~25 wt% BaTiO3 nanopowder and 10 wt% PVDF powder in solvent. BaTiO3-PVDF film was fabricated by spreading the solution on a glass with a doctor blade. The output performance increased with increasing BaTiO3 concentration. When the BaTiO3 concentration was 20 wt%, the output voltage and current were 4.98 V and 1.03 ㎂ at an applied force of 100 N. However, they decreased when the over 20 wt% BaTiO3 powder was added, due to the aggregation of particles. To enhance the output performance, the generator was poled with an electric field of 150~250 kV/cm at 100 ℃ for 12 h. The output performance increased with increasing electric field. The output voltage and current were 7.87 V and 2.5 ㎂ when poled with a 200 kV/cm electric field. This result seems likely to be caused by the c-axis alignment of the BaTiO3 after poling treatment. XRD patterns of the poled BaTiO3-PVDF films showed that the intensity of the (002) peak increased under high electric field. However, when the generator was poled with 250 kV/cm, the output performance of the generator degraded due to breakdown of the BaTiO3-PVDF film. When the generator was matched with 800 Ω resistance, the power density of the generator reached 1.74 mW/m2. The generator was able to charge a 10 ㎌ capacitor up to 1.11 V and turn on 10 red LEDs.

  • https://doi.org/10.3740/MRSK.2023.33.12.517 인용 PDF