• Journal of Magnetics
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• 제16권2호
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• pp.101-103
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• 2011

Solid solutions between $BaTiO_3$ and $LaFeO_3$ have been prepared through a solid state reaction method. The X-ray diffraction results reveal that $Ba_{1-x}La_xTi_{1-x}Fe_xO_3$ ($0.1\;{\leq}\;x\;{\leq}\;0.7$) compounds have a cubic structure, whereas the parent material $BaTiO_3$ has a tetragonal structure. The magnetization measurements indicate that the materials have a magnetic ordering at room temperature and the magnetic properties of the solid solutions depending on the doping amount of $LaFeO_3$. The origin of magnetic behaviors is believed to be from $Fe^{3+}$ ions.

• Journal of Korean Vacuum Science & Technology
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• 제6권1호
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• pp.40-42
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• 2002

TiO$_2$/Fe$_2$O$_3$composite thin films were prepared on common glass substrates by sol-gel processing and dip-drawing method. The effect of Fe$_2$O$_3$content on the photocatalytic and hydrophilic properties of composite films was studied. The results indicate that the photocatalytic activities of composite TiO$_2$films are superior to that of pure TiO$_2$film, and the film containing 0.5% Fe$_2$O$_3$has the best photocatalytic activity. The hydrophilicity is difference with variant Fe$_2$O$_3$content, the films containing 0.05% ~0.1% Fe$_2$O$_3$have the best hydrophilicity and their contact angles are 0。.

• 한국세라믹학회지
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• 제16권4호
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• pp.225-236
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• 1979

The effect of $Ti^{+4}$ addition on the sinterability, microstructure, and temperature dependence of electromechanical coupling factor of magnetostrictive Ni-Cu-Co ferrite was investigated. The density of Ni-Cu-Co ferrite slightly increased by 2.0 mole % addition of either $TiO_2$ or $Fe_2TiO_4$, but tended to decrease by more than 2.0 mole % addition of $TiO_2$ or $Fe_2TiO_4$. As the content of either $TiO_2$ or $Fe_2TiO_4$ increased, the magnetocrystalline anisotropy compensation temperature also increased. Microstructure studies showed the stable grains when Ni-Cu-Co ferrite was sintered above 1, 20$0^{\circ}C$.

• 한국재료학회지
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• 제22권11호
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• pp.615-619
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• 2012

Recently, ultrafine grained (ufg, typically 100 > d > 500 nm) Ti-Fe eutectic materials have been highlighted due to their extraordinarily high strength and good abrasion resistance compared to conventional coarse grained (cg, d > $1{\mu}m$) materials. However, these materials exhibit limited plastic strain and toughness during room temperature deformation due to highly localized shear strain. Several approaches have been extensively studied to overcome such drawbacks, such as the addition of minor elements (Sn, Nb, Co, etc.). In this paper, we have investigated the influence of the addition of Gd and Y contents (0.3-1.0 at.%) into the binary Ti-Fe eutectic alloy. Gd and Y are chosen due to their immiscibility with Ti. Microstructural investigation reveals that the Gd phase forms in the eutectic matrix and the Gd phase size increases with increasing Gd content. The improvement of the mechanical properties is possibly correlated to the precipitation hardening. On the other hand, in the case of Ti-Fe-Y alloys, with increasing Y contents, primary phases form and lamellar spacing increases compared to the case of the eutectic alloy. Investigation of the mechanical properties reveals that the plasticity of the Ti-Fe-Y alloys is gradually improved, without a reduction of strength. These results suggest that the enhancement of the mechanical properties is closely related to the formation of the primary phase.

• 한국광물학회지
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• 제9권1호
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• pp.43-53
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• 1996

The detailed crystal chemistry of ilmenite from the Hadong massif was studied by the EPMA, M ssbauer spectroscopy, and Rietveld structural refinement using X-ray powder diffraction data. The ilmenite-bearing anorthosite shows complicated mineral assemblage which consists of plagioclase, clinopyroxene, hornblende, biotite, chlorite, apatite, allanite, and zircon. Anorthite is andesine in composition (Ab 28-57), and clinopyroxene drops in ferro-hypersthene (Fs 62-70). Ilmenite is trigonal symmetry with R space group, whose structure shows the alternation of Fe2+ (M1 site) octahedral layer and Ti (M2 site) layer along c axis. M ssbauer spectroscopy indicates that there are three doubles which assigned to couple of Fe2+($\delta$=0.812, 0.890mm/sec) and one Fe3+($\delta$=0.303mm/sec) in octahedral sites. Their Fe3+/$\Sigma$Fe is 0.065 and chemical formula is established as Fe2+0.94Fe3+0.07Ti0.97O3 using both EPMA and M ssbauer analysis. Rietveld structural refinement reveals that site occupancies of Fe in M1 and Ti in M2 are 91.2% and 89.4%, respectively. This implies that Ti and Fe2+ are alternatively occupy M1 and M2 sites. In addition, smaller M2 site is more preferable to Fe3+ occupancy over M1.

• 한국세라믹학회지
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• 제15권1호
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• pp.9-15
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• 1978

The possiblity of mullitization from the domestic alunite by adding of $Fe_2O_3-MnO_2$, $Fe_2O_3-MnO_2-TiO_2$, $Fe_2O_3-MnO_2-CaF_2$, and $Fe_2O_3-MnO_2-CaF_2-TiO_2$ mixtures as mineralizers was studied at the temperature range between $1, 250^{\circ}C$~$1, 430^{\circ}C$. The modifying method of domestic alunite was performed by calcination, wet ballmilling, and washing with water. The following results were obtained; 1) When added of 3.0% $Fe_2O_3$ plus 1.0-1.5% $MnO_2$ to modified alunite, the appropriate temperature range of mullite-forming was $1, 350^{\circ}C$-$1, 400^{\circ}C$. 2) When added of $TiO_2$ as mineralizer, the mullite-forming temperature was higher than not added. 3) When added of $CaF_2$ as mineralizer, the synthesized mullite was resolve at the temperature above $1, 350^{\circ}C$.

• 한국세라믹학회지
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• 제45권6호
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• pp.324-330
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• 2008

Activated carbon/$TiO_2$ (AC/$TiO_2$) composites modified with different concentrations of Fe were prepared. The $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine activated carbon. This indicated the blocking of the micropores on the surface of AC, which was further supported by observation via SEM. XRD results showed patterns for the composites and an anatase typed titanium dioxide structure with a small part of rutile in a higher Fe concentration (> 1.0 mol/L). EDX results showed the presence of C and, O, with Ti peaks on the composites of Fe-AC/$TiO_2$ with relatively lower Ti concentration, which may be due to the higher Fe concentration incorporated into the composites. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photodegradation. Especially, the composites modified by Fe revealed enhanced photodegradation behaviors of MB.

• 전기화학회지
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• 제24권3호
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• pp.52-64
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• 2021

Li_1+xFe_xTi_2-x(PO₄)_3-y(BO₃)_y (x = 0.2, 0.5)계 유리에서 Fe doping과 BO₃ 치환이 유리 또는 결정화유리(glass-ceramics) 전해질의 구조적, 열적 및 전기적 특성에 미치는 영향을 조사하였다. 또한, Li_1.5Fe_0.5Ti_1.5(BO₃)₃ 유리분말을 소결하고, 소결 온도에 따른 결정상과 이온전도도 영향도 검토하였다. Li_1+xFe_xTi_2-x(PO₄)_3-y(BO₃)_y 유리에서 Fe²⁺ 및 Fe³⁺ 이온은 network modifier로서 FeO₆ 팔면체를 형성하거나 network former로서 유리망목구조에 들어가 FeO₄ 유사 사면체를 형성하면서 유리의 구조를 변화시키는 것으로 확인되었다. 한편, BO₃는 BO₃ 또는 BO₄ 그룹을 형성하였는데, BO₃ 치환량이 작은 경우 boron은 (PB)O₄ 망목구조를 형성하지만, BO₃ 치환량이 증가하면 붕소이상현상(boric oxide anomaly)이 생겨나면서 BO₄는 BO₃로 변화하고 이로 인하여 비가교산소(non-bridging oxygen)가 증가하였다. BO₃ 치환은 유리전이온도와 결정화 온도를 낮추는 효과가 있으며, Fe 첨가량이 증가하면 Fe³⁺의 일부는 Fe²⁺로 환원되며, 유리전이온도와 연화온도를 낮아지게 하고 결정화온도를 높아지게 하는 것으로 확인되었다. Li_1+xFe_xTi_2-x(PO₄)_3-y(BO₃)_y (x = 0.2, 0.5) 유리에서 BO₃ 함량이 증가함에 따라 이온전도도는 증가하였으며, x = 0.2 및 0.5에서 각각 8.85×10^-4 및 1.38×10^-4S/cm의 이온전도도값을 나타내었다. 본 연구에서 얻어진 높은 이온전도도는 Fe³⁺의 산화상태 변화와 붕소이상현상에 의한 BO₃ 생성 및 이로 인한 비가교산소의 생성에 기인한 것으로 생각된다. Li_1.5Fe_0.5Ti_1.5(BO₃)₃ 유리를 800℃에서 소결한 결과 이온전도도가 급격히 저하되었는데 이는 결정화유리 분말이 고온에서 유리화되었기 때문으로 생각된다. 따라서 유리분말을 800℃에서 소결한 후, 다시 460℃에서 조핵하고, 600℃에서 결정성장을 시킨 결과, 이온전도도가 열처리전과 동등 수준으로 회복되는 것을 확인하였다.

• 마이크로전자및패키징학회지
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• 제12권2호
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• pp.141-147
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• 2005

나노재료 $TiO_2-SiO_2$는 2-prOH(2-propanol)를 용매로 사용하여 가수분해와 축합반응으로 제조하였고, FT-IR, DSC, XRD, FE-SEM을 사용하여 $TiO_2-SiO_2$의 특성을 조사하였다. FT-IR분석으로부터 Ti-0-Si의 흡수피크에 대해 설명하였으며, DSC분석 결과를 Ozawa 방정식에 적용하여, 결정화에 필요한 활성화 에너지를 계산하였다. 결정학적 특징은 XRD를 이용하여 하소 온도의 변화에 따른 시료의 회절패턴과 반가폭의 변화 등에 관련하여 설명하였다. FE-SEM을 통하여 Ti mol$\%$가 증가할수록 입자크기가 커지는 것을 확인 할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.3011-3015
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• 2009

Structural and thermo-analytical studies were carried out to understand the phase formation kinetics of the single phase $Bi_5Ti_3FeO_{15}$ (BTFO) nanocrystals in $Bi_2O_3-Fe_2O_3-TiO_2$, during the polymerized complex (PC) synthesis method. The crystallization of Aurivillius phase $Bi_5Ti_3FeO_{15}$ layered perovskite was found to be initiated and achieved under the temperature conditions in the range of ${\sim}$800 to 1050$^{\circ}C$. The activation energy for grain growth of $Bi_5Ti_3FeO_{15}$ nanocrystals (NCs) was very low in case of NCs formed by PC (2.61 kJ/mol) than that formed by the solid state reaction (SSR) method (10.9 kJ/mol). The energy involved in the phase transformation of Aurivillius phase $Bi_5Ti_3FeO_{15}$ from $Bi_2O_3-Fe_2O_3-TiO_2$ system was ${\sim}$ 69.8 kJ/mol. The formation kinetics study of $Bi_5Ti_3FeO_{15}$ synthesized by SSR and PC methods would not only render a large impact in the nanocrystalline material development but also in achieving highly efficient visible photocatalysts.