• Title/Summary/Keyword: Perovskite Phase

Search Result 524, Processing Time 0.022 seconds

Phase Formation and Proton Conduction of La0.6Ba0.4In1-yMyO3-δ(M=Ga3+ , Sc3+, Yb3+) System (La0.6Ba0.4In1-yMyO3-δ(M=Ga3+ , Sc3+, Yb3+)계 조성의 상생성과 Proton 전도)

  • Kim, Hye-Lim;Kim, Shin;Lee, Hong-Lim
    • Journal of the Korean Ceramic Society
    • /
    • v.39 no.6
    • /
    • pp.610-615
    • /
    • 2002
  • Phase formation and proton conduction of L $a_{0.6}$B $a_{0.4}$I $n_{1-y}$ $M_{y}$ $O_{3-{\delta}}$(M=G $a^{3+}$, S $c^{3+}$, Y $b^{3+}$) system were studied. A cubic perovskite structure with a single phase was formed in all of the compositions of this work except for the composition off=G $a^{3+}$ with y=0.5, viz,L $a_{0.6}$B $a_{0.4}$I $n_{1-y}$G $a_{0.5}$ $O_{3-{\delta}}$ For the compositions of M=S $c^{3+}$and Y $b^{3+}$with y=0.25, proton conduction occurred in wet $N_2$ atmosphere(P $h_{H_2O}$=6.1hPa).X>/=6.1hPa).Pa).

Peculiarities of SHS and solid state synthesis of $ReBa_{2}Cu_{3}O_{7-x}$ materials

  • Sho, Dea-Wha;Li, Yingmei;Cho, Yong-Joon;Kim, Tae-Wan;Korobova, N.;Isaikina, O.;Mansurov, Z.;Baydeldinova, A.;Ksandopoulo, G.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2001.07a
    • /
    • pp.620-623
    • /
    • 2001
  • The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid state phase synthesis for production of high temperature superconductor materials are discussed. Oxide superconductors with general formula $ReBa_2$$Cu_3$$O_{7-x}$ (Re= Y, Yb, Sm, Nd) have been made with using barium oxide initial powder instead of traditional barium carbonate. X-ray powder diffraction showed a single phase orthorhombic perovskite structure was produced in all reactions. Phenomena observed during the grinding of the reactant mixture are presented. Mechano-chemical activation - as a pretreatment of the reactant mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.

  • PDF

Variation of Dielectric Constant with the Volume Fraction of Pyrochlore Phae in the PMN-Polychlore Diphasic System ; Application of General Effective Media Equation (Pyrochlore상의 부피분율에 따른 PMN-Pyrochlore 2상 혼합체의 유전율변화;General Effective Media식의 적용)

  • 허강일;김정주;김남경;김진호;조상희
    • Journal of the Korean Ceramic Society
    • /
    • v.30 no.1
    • /
    • pp.78-84
    • /
    • 1993
  • In PMN-pyrochlore phase mixtures, dielectric constant was measured as a function of the volume fraction of pyrochlore phase and considered with general effective media(GEM) equation. For the application of GEM equation to this system, the critical volume fraction(Vc) where connectivity between the perovskite PMN and pyrochlore phase changed from 0-3 to 3-3, was determined based on the each particle size ratio of two phases with microstructural observation. And then the t value was determined from modified percolation powder-law dependence ( K-Kc (V-Vc)t). In the case of applying such values of t and Vc to the GEM equation, which provided a reasonable fit to the measured dielectric constant within the experimental error range.

  • PDF

Magnetism in the Layered Structure Compound (C_18H_37NH_3)_2 MNCL_4

  • Lee, K. W.;Lee, C. H.;C. Rhee;Lee, Cheol-Eui;J. K. Kang;Lee, K.-S.
    • Journal of Magnetics
    • /
    • v.2 no.4
    • /
    • pp.126-129
    • /
    • 1997
  • We have studied magnetostructural phase transitions in the perovskite-type layered structure compound (C18H37NH3)2 MnCl4 by means of electron paramagnetic resonance (EPR) and superconducting quantum interference device (SQUID) measurements. Distinct slopes were observed in the linear temperature dependences of the Mn++ EPR linewidth in the low and high temperature phases. Besides, linewidth anomalies at the transition temperatures sensitively reflect the magnetic changes arising from the MnCl6 octahedra.

  • PDF

Preparations of PZT Ceramic by Solution Combustion Synthesis (용액연소합성방법에 의한 PZT세라믹의 제조)

  • 이상진;윤존도;권혁보;전병세
    • Journal of the Korean Ceramic Society
    • /
    • v.39 no.1
    • /
    • pp.74-78
    • /
    • 2002
  • In this study, the solution combustion method was employed to synthesize perovskite PZT ceramics. Multicomponent oxides can be prepared by the solution combustion synthesis using redox exothermic reaction of precursor solutions. The results of DTA/TG showed exothermic peaks in 214$^{\circ}C$ and 350$^{\circ}C$. Those were caused by the differences of the thermal decomposition behavior of oxidizer and fuel. The combustion reaction was completed at 370$^{\circ}C$ during heating procedure, but the product was not transformed into perovskite. The thermal decomposition behavior of both oxidizer and fuel were considered during solution combustion process at 600$^{\circ}C$, which showed tetragonal single phase PZT ceramics with 50 nm crystalline size. The lattice constant a was 3.997 ${\pm}$ 0.001 ${\AA}$ and the lattice constant c was 4.147${\pm}$0.001 ${\AA}$.

Preparation of $Pb_{1-x}La_x(Zr_{1/2}Ti_{1/2})_{1-{x/4}}O_3$ thin films by a sol-gel method using a polypropanediol (Polypropanediol을 이용한 sol-gel법에 의한$Pb_{1-x}La_x(Zr_{1/2}Ti_{1/2})_{1-{x/4}}O_3$박막의 제조)

  • 김태희;박경봉;김찬규
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.12 no.4
    • /
    • pp.178-183
    • /
    • 2002
  • The PLZT (x/50/50, x = 1, 2, 5, 7) thin films have been prepared by a sol-gel method using polypropanediol as a solvent, and their dielectric properties have been investigated. The prepared sol was coated 10 times on $Pt/Ti/SiO2_2$/Si wafer. After post-annealing at 560~$600^{\circ}C$ for 10 min, the 600 nm-thick PLZT (x/50/50) thin films were formed with pure perovskite phase. Grain size of the PLZT (x/50/50) thin films was increased with increasing the amount of La. For all the compositions, dielectric properties such as dielectric constant and remnant polarization were enhanced with increasing annealing temperatures. As the amount of La was increased, the remnant polarization, coercive field and dielectric constant of the PLZT (x/50/50) thin films fired at $600^{\circ}C$ were decreased.

Characteristics of SrCo1-xFexO3-δ Perovskite Powders with Improved O2/CO2 Production Performance for Oxyfuel Combustion

  • Shen, Qiuwan;Zheng, Ying;Luo, Cong;Zheng, Chuguang
    • Bulletin of the Korean Chemical Society
    • /
    • v.35 no.6
    • /
    • pp.1613-1618
    • /
    • 2014
  • Perovskite-type oxides are promising oxygen carriers in producing oxygen-enriched $CO_2$ gas stream for oxyfuel combustion. In this study, a new series of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ (x = 0.2, 0.4, 0.6, 0.8) was prepared and used to produce $O_2/CO_2$ mixture gas. The phase, crystal structure, and morphological properties of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ were investigated through X-ray diffraction, specific surface area measurements, and environmental scanning electron microscopy. The oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ was studied in a fixed-bed reactor system. Results showed that the different x values of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ have no obvious effects on crystalline structure. However, the oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ is improved by Co doping. Moreover, $SrCo_{0.8}Fe_{0.2}O_{3-{\delta}}$ synthesized via a new EDTA method has a larger BET surface area ($40.396m^2/g$), smaller particle size (48.3 nm), and better oxygen production performance compared with that synthesized through a liquid citrate method.

Structural and Electrical Properties of (Ba,Sr,Ca)TiO3 Thick Films doped with Dy 2O3 (Dy2O3를 첨가한 (Ba,Sr,Ca)TiO3 후막의 구조 및 전기적 특성 연구)

  • Noh, Hyun-Ji;Park, Sang-Man;Yun, Sang-Eun;Lee, Sung-Gap
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.20 no.8
    • /
    • pp.680-684
    • /
    • 2007
  • In this study, we investigated the effects of structural and electrical properties of $(Ba_{0.6},\;Sr_{0.3},\;Ca_{0.1})TiO_3$ thick films with variation $Dy_2O_3$ contents. $(Ba_{0.6},\;Sr_{0.3},\;Ca_{0.1})TiO_3$ powders, prepared by the sol-gel method, were mixed organic vehicle. The BSCT thick films doped with 0.1, 0.3, 0.5, 0.7 mol% $Dy_2O_3$ were fabricated by the screen-printing techniques on the alumina substrates and the structural and dielectric properties were investigated with variation of $Dy_2O_3$ doping contents. All BSCT thick films were sintered at $1420^{\circ}C$, for 2hr. In the TG-DTA analysis, the formation of the polycrystalline perovskite phase was observed at around $670 ^{\circ}C$. In the XRD analysis, all BSCT thick films showed the cubic perovskite structure. The average thickness of BSCT thick films was approximately $65{\mu}m$. The Curie temperature decreased with increasing $Dy_2O_3$ amount. The relative dielectric constant and dielectric loss of BSCT thick films doped with $Dy_2O_3$ 0.1 mol% were 6267 and 2.6 %, respectively.

Microstructure Observations in Complex Perovskite $(Na_{1/2}Pr_{1/2})TiO_3$ (Complex Perovskite $(Na_{1/2}Pr_{1/2})TiO_3$의 미세구조 관찰)

  • Lee, Hwack-Joo;Ryu, Hyun;Park, Hyun-Min;Cho, Yang-Koo;Nahm, Sahn
    • Applied Microscopy
    • /
    • v.32 no.2
    • /
    • pp.157-162
    • /
    • 2002
  • Microstructural investigations of $(Na_{1/2}Pr_{1/2})TiO_3$ (NPT) complex perovskite compounds were carried out using X-ray diffractometry and transmission electron microscopy. NPT had not 1:1 chemical ordering of Asite cations but had the antiphase and inphase tilting of oxygen octahedron and the antiparallel shift of cations. Both the antiphase boundaries and the ferroelastic domains were not present in the microstructure. Unidentified second phase was found in the microstructure. The measured dielectric properties were ${\varepsilon}_r=99.6,\;Q\;{\Large f}_o=1124\;GHz,\;{\tau}_{f}=-233.64ppm/^{\circ}C$.