• 제목/요약/키워드: BaO3-PbO3

검색결과 222건 처리시간 0.031초

비스무스 층구조형 페로브스카이트 SrBi2Nb2O9 강유전체의 이온 치환 효과 (Ionic Doping Effect in Bi-layered Perovskite SrBi2Nb2O9 Ferroelectrics)

  • 박성은;조정아;송태권;김명호;김상수;이호섭
    • 한국재료학회지
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    • 제13권12호
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    • pp.846-849
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    • 2003
  • Doping effect of various ions in Bi-layered ferroelectric $SrBi_2$$Nb_2$$O_{9}$ (SBN) ceramics was studied. Undoped SBN ceramic and SBN ceramics doped with $Ba^{2+}$, $Pb^{2+}$,$ Ca^{2+}$ , $Bi^{3+}$ , $La^{3+}$ , $Ti^{4+}$ , $Mo^{6+}$ , and $W^{6+}$ ions were made by a solid state reaction. Dielectric constants were measured with temperature. Ferroelectric transition temperature decreased with $Pb^{2+}$ , $Ba^{2+}$ , $La^{3+}$ doping, but the transition temperature increased with $Ca^{2+}$ , $Bi^{3+}$ , $Ti^{4+}$, $Mo^{6+}$ , or$ W^{6+}$ ionic doping. These results show that the ion size plays an important role in the ferroelectricity of SBN ceramic.

RF Power에 따른 PZT/BST 이종층 박막의 구조 및 유전 특성 (The Structural and Dielectric Properties of the PZT/BST Heterolayered Thin Films with RF Power)

  • 이상철;남성필;이성갑;이영희
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제54권1호
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    • pp.13-17
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    • 2005
  • The Pb(Zr/sub 0.52/Ti/sub 0.48/)O₃/(Ba/sub 0.6/Sr/sub 0.4/)TiO₃[PZT/BST] heterolayered thin films were deposited on Pt/Ti/SiO₂/Si substrates by using the RF sputtering method with different RF power. The PZT/BST heterolayered thin films had the tetragonal structure of the PZT phase and BST phase. Increasing the RF power. the intensity of the PZT (100), (110) peaks and BST (111) peaks were decreased and the intensity of the BST (100), (110) peaks were increased. The thickness ratio of the top layered BST thin film and the bottom layered PZT thin film was 2 to1. The atomic concentration of the Ba, Sr, Pb. Zr, Ti atoms were constant in the PZT thin films and BST thin films, respectively. The Pt atom was diffused to the PZT region in the PZT/BST heterolayered thin films deposited at condition of 60[W] RF power. Increasing the frequency, dielectric constant and loss of the PZT/BST heterolayered thin films were decreased. The dielectric constant and loss of the PZT/BST heterolayered thin films deposited with RF power of 90[W] were 406 and 3%, respectively.

입도분포에 따른 하상퇴적물의 지구화학적 분산 및 부화 (Geochemical Dispersion and Enrichment of Fluvial Sediments Depending on the Particla Size Distribution)

  • 이현구
    • 자원환경지질
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    • 제32권3호
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    • pp.247-260
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    • 1999
  • Geochermical characteristics of the fluvial sediments deprnding on particle size distribution size were investigated in the respect of majir, minor and rare eath element chemisitry. Ratios of $Al_{2}O_{3}/Na_{2}O$ and $K_{2}O/Na_{2}O$ of the sediments show the homogeneous valus, and partly positive correlation with $SiO_{2}/Al_{2}O_{3}$, respecively. Characteristics of minor element ratios (V/Ni, Cr/V, Ni/Co and Zr/Hf)are within the lower and narrow range. Thesesuggested that sediment sources may be acidic to intermediate granitic rock, and may be explained by simple weathering and sedimentation. With increasing SiO2 contents, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO and MgO decreased, but those of $K_{2}O$ and $Na_{2}O$ increased, Concentrations of Ba, Be, Cs, Cu, Li, Ni, Sr, V and Zr show comparatively normal negative and some positive trends. Compared with the mean composition of granite, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, MnO, CaO and MgO in the sediments of the study area were highly enriced. Among some minor and rare earth elements, concentrations of As, Cd, Cu, and V were enriched, but those of Be, Ce, Rb, Sc, Sr and Zn were depleted when compared with average composition of granite. By decreasing of particle size fractions, SiO2, Rb and Sr conterts decreased, but concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO, MgO, $TiO_{2}$, MgO, $P_{2}O_{5}$, Be, Cu, Hf, Pb, V and Zr increased. From the correlations between particle size fractions and element concenreations, some elements of $Fe_{2}O_{3}$, CaO, MgO, $P_{2}O_{5}$, Cu, Ni, Zn and Zr showed typical trends in the secondary contramination sediments. These trends are typically shown under 100 mesh fractions. It indicates that the fraction of minus 100 mesh is the optimum size fraction for geochemical and environmental survey.

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산화물계 초전도체의 고변이 송도부근의 곡출과 이의 성분 분석에 관한 연구 (Isolation and Analysis of Micro-Regions Having Possibly Higher Tc in Oxide Superconductors)

  • 이규용
    • 수산해양기술연구
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    • 제25권3호
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    • pp.143-153
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    • 1989
  • 산화물 초전도체에 있어서 고천이 임계온도를 갖는 미소영역을 추출하여 이를 분석하기 위하여 La-Ba-Cu-O 계, Y-Ba-Cu-O 계 및 Bi-Pb-Sr-Ca-Cu-O 계의 초전도체를 고상법 및 nitrate solution method로 제조하였다. 제조된 시료들에 대해서 x선회절분석과 저항을 측정하였다. 이들 시료 중에서 고천이온도를 나타내는 미소부분을 Meissner효과를 이용한 추출법으로 분리 해내고 EDAX로 이를 분석하였으며, 이들 결과를 요약하면 다음과 같다. nitrate solution method를 적용하면 YBCO계에 있어서 비교적 단시간에 치밀한 미세조직을 갖는 천이 온도 90K의 초전도체를 제조할 수 있다. Meissner효과를 이용하여 고천이온도에서 추출해낸 미소영역의 EDAX분석 결과는 고상법을 사용한 YBCO-23S와 nitrate solution method으로 제조한 YBCO-23N 및 YBCO-36N 에서는 초기의 조성과 거의 같았으며, 고천이 온도에서 추출된 미소영역은 조성보다는 산소 결함의 차이에 기인한 것으로 생각된다. 공침법으로 제조한 YBCO-23NA 에서는 과도한 Ba의 조성을 보였으며, 천이온도 100K 인 Bi계에서는 약한 반자성효과 때문에 추출이 불가능하였다.

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강유전체를 적용한 무기전계발광소자의 광전특성연구 (The Study of opto-electrics characteristics of Inorganic EL(Electro luminescent) Device with combination of high dielectric constant layer)

  • 이건섭;이성의
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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    • pp.407-407
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    • 2008
  • 무기EL 디스플레이는 고체재료에 전계를 가했을 때 발광하는 현상을 이용한소자로서, 급속도로 발전을 거듭하고 있으나, 유전체층에 강한전계를 가하여 발광하여야 하므로 낮은 Breakdown voltage와 효율의 한계로 인하여 휘도가 낮고 풀 컬러화 디스플레이 등 의 응용에는 적용되고 있지 못하는 실정이다. 본 연구에서는 강유전체 Perovskite 구조를 가지는 ABO3 물질 중 PMN(Lead Magnesium niobate) 과 PZT (Lead Zirconate titanate) 후막을 제조하여 Inorganic EL(Electro Luminance)에 적용하고 소자의 광전특성을 평가하였다. 소자에 사용된 기판은 고온소성에 알맞은 알루미나(Al2O3)기판을 채택 하였으며, 그 위 하부전극으로는 고온소성에 따른 화학적 안정성이 우수한 Au전극을 Screen Printing 하였다. 제조 되어진 PMN후막 페이스트는 PMN(Pb(Mg1/2 Nb2/3)O3) + Glass Frit(Pb-Zn-B) + BaTiO3(99.99%) 로 합성되었으며 하부전극위에 인쇄하였다. 그 다음 PZT sol-gel을 Spin coating으로 도포 하였다. 형광체로 ZnS:Cu.Cl 을 Screen Printing을로 형성하였으며, 평탄화를 위하여 유기물 충을 Screen Printing 공정으로 성막 하였다. 상부전극으로는 DC sputter로 ITO를 증착하여 EL소자 완성 후 Spectro - Chroma meter로 소자특성을 측정하였다. 평탄화를 통한 유기물층에 변화되는 Capacitance를 Oscilloscope로 전압 전류 pulse의 변화에 따른 opto-electronic 특성을 평가하였다.

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스크린 프린팅 공법을 통한 방사선 무연 차폐 시트에 관한 연구 (The Study on Filling Factor of Radiation Shielding Lead-free Sheet Via Screen Printing Method)

  • 강상식;정아림;이수민;양승우;김교태;허예지;박지군
    • 한국방사선학회논문지
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    • 제12권6호
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    • pp.713-718
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    • 2018
  • 많은 선행 연구에서는 무연 차폐재를 제작하기 위하여 몬테카를로 시뮬레이션을 통해 방사선 차폐 능력과 경량화에 대한 가능성을 제시하고 있다. 하지만, 이는 바인더 및 미세 기공에 대한 구현이 어렵기에 제품화 공정에 필요한 정보를 충분히 제공하지 못하는 실정이다. 이에 본 연구에서는 제품화 공정에 요구되는 겔 페이스트에 대한 정보를 사전에 제공하기 위하여 스크린 프린팅 공법을 활용하여 충전율에 따른 방사선 차폐 능력에 대한 결과를 제시하였다. 본 연구에서는 방사선 차폐 능력을 평가하기 위해 IEC 61331-1: 2014와 KS A 4025에 부합하도록 실험 환경을 설계하였으며, 방사선 조사 조건은 KS A 4021 규격을 준용하여 총 여과 2.0 mmAl로 여과된 100 kVp를 이용하였다. 본 연구 결과, TVL를 기준으로 Pb $1270{\mu}m$, $BaSO_4$ $3035{\mu}m$, $Bi_2O_3$ $1849{\mu}m$, $WO_3$ $2631{\mu}m$에서 근사한 값으로 분석되었다. 또한, 충전율은 $BaSO_4$ 38.6%, $Bi_2O_3$ 27.1%, $WO_3$ 30.15%로 분석되었다. 하지만, 차후 저온고압 성형을 적용한다면 충전율을 높이면서도 기공률을 낮춤으로서 방사선 차폐 능력의 개선이 충분히 가능할 것으로 기대된다.

Modified Mixed Oxide 방법에 의한 PMN-PT-BT 분말 합성 및 그의 물성에 미치는 Ag의 영향 (Preparation of PMN-PT-BT Powder by Modified Mixed Oxide Method and Effect of Ag on Dielectric Properties)

  • 임경란;정순용;김창삼
    • 한국세라믹학회지
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    • 제39권2호
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    • pp.159-163
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    • 2002
  • Relaxor 유전체 물질인 PMN-PT-BT를 modified mixed oxide 공정과 단일 하소로 페로브스카이트 단일상으로 제조할 수 있는 공정을 시도하였다. PbO, Nb2O5, BaCO3 와 $TiO_2$ 대신 $Ti(OC_3H_7)_4$를, MgO 대신 $Mg(NO_3)_2$을 사용하여 볼밀로 혼합한 후 건조된 분말을 900$^{\circ}C$/2시간 하소하고, 이어서 1100$^{\circ}C$/2시간 열처리하여 얻은 소결체는 소결 밀도 7.83 g/$cm^3$, 실온 유전율 22000, 유전손실 2.5%의 우수한 유전 특성을 나타내었다. 소결조제로 Ag을 $AgNO_3$로 1.0 몰%(0.3wt%) 첨가한 경우 550$^{\circ}C$/2시간 하소한 분말은 900$^{\circ}C$/2시간 열처리로 소결밀도 7.88 g/$cm^3$, 실온 유전율 20000, 유전손실 2.4%을 나타내었다.

Structural, Dielectric and Field-Induced Strain Properties of La-Modified Bi1/2Na1/2TiO3-BaTiO3-SrZrO3 Ceramics

  • Hussain, Ali;Maqbool, Adnan;Malik, Rizwan Ahmed;Zaman, Arif;Lee, Jae Hong;Song, Tae Kwon;Lee, Jae Hyun;Kim, Won Jeong;Kim, Myong Ho
    • 한국재료학회지
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    • 제25권10호
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    • pp.566-570
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    • 2015
  • $Bi_{0.5}Na_{0.5}TiO_3$ (BNT) based ceramics are considered potential lead-free alternatives for $Pb(Zr,Ti)O_3$(PZT) based ceramics in various applications such as sensors, actuators and transducers. However, BNT-based ceramics have lower electromechanical performance as compared with PZT based ceramics. Therefore, in this work, lead-free bulk $0.99[(Bi_{0.5}Na_{0.5})_{0.935}Ba_{0.065}]_{(1-x)}La_xTiO_3-0.01SrZO_3$ (BNBTLax-SZ, with x = 0, 0.01, 0.02) ceramics were synthesized by a conventional solid state reaction The crystal structure, dielectric response, degree of diffuseness and electric-field-induced strain properties were investigated as a function of different La concentrations. All samples were crystallized into a single phase perovskite structure. The temperature dependent dielectric response of La-modified BNBT-SZ ceramics showed lower dielectric response and improved field-induced strain response. The field induced strain increased from 0.17%_for pure BNBT-SZ to 0.38 % for 1 mol.% La-modified BNBT-SZ ceramics at an applied electric field of 6 kV/mm. These results show that La-modified BNBT-SZ ceramic system is expected to be a new candidate material for lead-free electronic devices.

Synthesis and Comparative Analysis of Crystallite Size and Lattice Strain of Pb2Ba1.7Sr0.3Ca2Cu3O10+δ Superconductor

  • Hasan, Maher Abd Ali;Jasim, Kareem Ali;Miran, Hussein Ali Jan
    • 한국재료학회지
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    • 제32권2호
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    • pp.66-71
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    • 2022
  • In this article, Pb2Ba1.7Sr0.3Ca2Cu3O10+δ superconductor material was synthesized using conventional solid-state reaction method. X-ray diffraction (XRD) analysis demonstrated one dominant phase 2223 and some impurities in the product powder. The strongest peaks in the XRD pattern were successfully indexed assuming a pseudo-tetragonal cell with lattice constants of a = 3.732, b = 3.733 and c = 14.75 Å for a Pb-Based compound. The crystallite size and lattice strain between the layers of the studied compound were estimated using several methods, namely the Scherrer, Williamson-Hall (W.H), size-strain plot (SSP) and Halder Wagner (H.W) approach. The values of crystallite size, calculated by Scherrer, W.H, SSP and H.W methods, were 89.4540774, 86.658638, 87.7555823 and 85.470086 Å, respectively. Moreover, the lattice strain values obtained by W.H, SSP and H.W methods were 0.0063240, 0.006325 and 0.006, respectively. It was noted that all crystallite size results are consistent; however, the best method is the size-strain plot because it gave a value of R2 approaching one. Furthermore, degree of crystallites was calculated and found to be 59.003321%. Resistivity analysis suggests zero-resistance, which is typical of superconducting materials at critical temperature. Four-probe technique was utilized to measure the critical temperature at onset Tc(onset), zero resistivity Tc(off set), and transition (width ΔT), corresponding to temperatures of 128 K, 116 K, and 12 K, respectively.

Temporal variation of magma chemistry in association with extinction of spreading, the fossil Antarctic-Phoenix Ridge, Drake Passage, Antarctica

  • Choe, Won-Hie;Lee, Jong-Ik;Lee, Mi-Jung;Hur, Soon-Do;Jin, Young-Keun
    • 한국지구과학회:학술대회논문집
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    • 한국지구과학회 2005년도 추계학술발표회 논문집
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    • pp.136-141
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    • 2005
  • The K Ar ages, whole rock geochemistry and Sr Nd Pb isotopes have been determined for the submarine basalts dredged from the P2 and P3 segments of the Antarctic-Phoenix Ridge (APR), Drake Passage, Antarctica, for better understanding on temporal variation of magma chemistry in association with extinction of seafloor spreading. The fossilized APR is distant from the known hot spots, and consists of older N-MORB prior to extinction of spreading and younger E-MORB after extinction. The older N-MORB (3.5-6.4 Ma) occur in the southeast flank of the P3 segment (PR3) and the younger E-MORB (1.4-3.1 Ma) comprise a huge seamount at the P3 segment (SPR) and a big volcanic edifice at the P2 segment (PR2). The N-type PR3 basalts have higher Mg#, K/Ba, and CaO/Al2O3 and lower Zr/Y, Sr, and Na8.0 with slight enrichment in incompatible elements and almost flat REE patterns. The E-type SPR and PR2 basalts are highly enriched in incompatible elements and LREE. The extinction of spreading occurring at 3.3 Ma seems to have led to a temporal magma oversupply with E-MORB signatures. Geochemical signatures such as Ba/TiO2, Ba/La, and Sm/La suggest heterogeneity of upper mantle and formation of E-MORB by higher contribution of enriched materials to mantle melting, compared to N-MORB environment. E-MORB magmas beneath the APR seem to have been produced by low melting degree (up to 1% or more) at deeper low-temperature regime, where metasomatized veins consisting of pyroxenites have preferentially participated in the melting. The occurrence of E-MORB at the APR is a good example to better understand what kinds of magmatism would occur in association with extinction of spreading.

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