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Characterization and Physical Properties of Ba<SUB>0.9</SUB>Sb<SUB>0.1</SUB>TiO₃ Solid Solution
Yeon Jung Kim 한국진공학회(ASCT) 2019 Applied Science and Convergence Technology Vol.28 No.2
BaTiO₃ is known to be an environmentally friendly electronic material with a phase transition temperature that can be controlled through the substitution of an appropriate additive. Physical changes of grain growth in Ba0.9Sb0.1TiO₃ were analyzed by adding a small amount of antimony to pure BaTiO₃. The Ba0.9Sb0.1TiO₃ solid solution with antimony substitution was prepared under various calcination and sintering conditions. The optimal conditions for sintering were confirmed and the grain growth process was clearly understood. As a result, the relationship between the dielectric properties and the polycrystalline structure of Ba0.9Sb0.1TiO₃ substituted with antimony was confirmed. The maximum dielectric constant of the Ba0.9Sb0.1TiO₃ solid solution was found to exceed about 5500 and the dielectric constant at room temperature reached nearly 4000. The transition temperature of Ba0.9Sb0.1TiO₃ was shifted closer to room temperature than that of pure BaTiO₃. Unlike the phase transition behavior of pure BaTiO₃, the dielectric constant curve, which is a function of temperature for all samples, showed a very gradual change.
LiFe<SUB>0.9</SUB>Mn<SUB>0.1</SUB>PO<SUB>4</SUB> 물질의 결정구조 및 뫼스바우어 분광 연구
권우준(Woo Jun Kwon),이인규(In Kyu Lee),이찬혁(Chan Hyuk Rhee),김삼진(Sam Jin Kim),김철성(Chul Sung Kim) 한국자기학회 2012 韓國磁氣學會誌 Vol.22 No.1
The olivine structured LiFe<SUB>0.9</SUB>Mn<SUB>0.1</SUB>PO<SUB>4</SUB> material was prepared by solid state method, and was analyzed by x-ray diffractometer(XRD), superconducting quantum interference devices (SQUID) and Mossbauer spectroscopy. The crystal structure of LiFe<SUB>0.9</SUB>Mn<SUB>0.1</SUB>PO<SUB>4</SUB> was determined to be orthorhombic (space group: Pnma) by Rietveld refinement method. The value of Neel temperature (T<SUB>N</SUB>) for LiFe<SUB>0.9</SUB>Mn<SUB>0.1</SUB>PO<SUB>4</SUB> was determined 50 K. The temperature dependence of the magnetization curves showed magnetic phase transition from paramagnetic to antiferromagnetic at T<SUB>N</SUB> by SQUID measurement. Mossbauer spectra of LiFe<SUB>0.9</SUB>Mn<SUB>0.1</SUB>PO<SUB>4</SUB> showed 2 absorption lines at temperatures above T<SUB>N</SUB> and showed asymmetric 8 absorption lines at temperatures below T<SUB>N</SUB>. These spectra occurred due to the magnetic dipole and electric quardrupole interaction caused by strong crystalline field at asymmetric FeO<SUB>6</SUB> octahedral sites.
Influence of Bismuth Oxide on Dielectric Properties of Barium Titanate Solid Solution
Yeon Jung Kim 한국진공학회(ASCT) 2021 Applied Science and Convergence Technology Vol.30 No.4
A Ba0.9Bi0.1TiO₃ solid solution was prepared by substituting 0.1 mole % Bi₂O₃ at the Ba<SUP>2+</SUP> sites in BaTiO₃, and its dielectric properties were investigated. The Ba0.9Bi0.1TiO₃ solid solution was sintered at 1310 ℃ for 5 h. The stable formation of the perovskite structure was confirmed through X-ray diffraction, energy-dispersive X-ray spectroscopy, and field emission scanning electron microscopy. Unlike pure BaTiO₃, pyrochlore Bi₂Ti₂O7 was observed in Ba0.9Bi0.1TiO₃ at approximately 27.1º. Overall, the perovskite structure was well formed. The Ba0.9Bi0.1TiO₃ solid solution showed typical dielectric properties and followed the modified Curie–Weiss law. In addition, the curve of the dielectric constant vs. temperature showed an extremely gradual change compared to the phase transition behavior of BaTiO₃.
신미연,권대규,유창호 제어로봇시스템학회 2019 제어로봇시스템학회 각 지부별 자료집 Vol.2019 No.1
In this paper, Zr0.9Ti0.1Cr0.6Fe1.4 and Zr0.9Ti0.1Cr0.7Fe1.3 were selected as Metal-Hydride(MH) alloys for driving the rehabilitative system. The MH alloys were fabricated by Arc-melting and the compositions of its were analyzed by Field Emission Scaning Electron Microscope(FE-SEM), Energy Dispersive X-ray Spectroscopy(EDS), X-Ray Diffractometry(XRD) and Inductively Coupled Plasma(ICP). As a result of the analysis, the alloys were nonuniform in composition although it was prepared as a single phase of hexagonal structure. In the future, the hydrogen storage capacity of the MH alloys will be evaluated by producing P-C-T diagram of each MH alloys. And MH alloys will be used at driving actuation system for confirming its actual performance.
나노분말 CoGa<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O₄의 Mössbauer 분광학적 연구
이승화(Seung Wha Lee) 한국자기학회 2006 韓國磁氣學會誌 Vol.16 No.2
CoGa<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O₄ nanoparticles have been prepared by a sol-gel method. The structural and magnetic properties have been investigated by XRD, SEM, VSM and Mossbauer spectroscopy. CoGa<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O₄ powder that was annealed at 250℃ has spinel structure and behaved superparamagnetically. The estimated size of superparammagnetic CoGa<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O₄ nanoparticle is around 10 ㎚. The hyperfine fields at 4.2 K for the A and B patterns were found to be 518 and 486 kOe, respectively. The bl℃king temperature (TB) of superparammagnetic CoGa<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O₄ nanoparticle is about 250 K. The magnetic anisotropy constant of CoGa<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O₄ nanoparticle was calculated to be 3.0×10<SUP>5</SUP> erg/㎤. CoGa<SUB>0.1</SUB>Fe<SUB>1.9</SUB>O₄ nanoparticle was annealed at 250℃ will be used to candidate for biomedicine applications as magnetic carriers.
Sagar M. Mane,Sachin A. Pawar,Dipali S. Patil,Seong Hun Lee,Jae Cheol Shin 한국진공학회(ASCT) 2020 Applied Science and Convergence Technology Vol.29 No.2
Composites constructed by combining ferroelectric and ferromagnetic materials are of significant interest owing to their multifunctional features and potential applications in multifunctional devices. Herein, the magnetodielectric effect of a composite containing ferroelectric Ba0.8Sr0.2TiO₃ (BST) and ferrite Co0.9Ni0.1Fe₂O₄ (CNFO) phases is investigated. This ferroelectric and ferrite composite is synthesized using the co-precipitation method followed by microwave sintering. The tetragonal crystal structure of BST and cubic structure of CNFO are confirmed using X-ray diffraction. All composite samples are characterized using nanoparticle tracking analysis. The measurements of dielectric constant (room temperature) and loss tangent as a function of frequency show an increase in the dielectric constant with an increase in the CNFO phase. The highest value of magnetodielectric coefficient, -40.13 %, is observed for the 60BST-40CNFO composite at 100 Hz, which decreases with an increase in the applied frequency.