• Journal of Ceramic Processing Research
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• v.20 no.3
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• pp.222-230
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• 2019

Microwave hydrothermal-assisted sol-gel method was employed to synthesize the Fe doped TiO2 photocatalyst. The morphological analysis suggests anatase phase nanoparticles of ~20 nm with an SBET area of 283.99 ㎡/g. The doping of Fe ions in TiO2 created oxygen vacancies and Ti3+ species as revealed through the XPS analysis. The reduction of the band gap (3.1 to 2.8 eV) is occurred by doping effect. The as-prepared photocatalyst was applied for removal of NOx under solar light irradiation. The doping of Fe in TiO2 facilitates 75 % of NOx oxidation efficiency which is more than two-fold enhancement than the TiO2 photocatalyst. The possible reason of enhancement is associated with high surface area, oxygen vacancy, and reduction of the band gap. Also, the low production of toxic intermediates, NO2 gas, is further confirmed by Combustion Ion Chromatography. The mechanism related NOx oxidation by the doped photocatalyst is explained in this study.

• Analytical Science and Technology
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• v.8 no.4
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• pp.669-674
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• 1995

The preparation and characterization of photosemiconductive electrodes of GaAs and of $Fe_2O_3$ doped with MgO or CaO were investigated. The doped $Fe_2O_3$ photosemiconductive electrodes were prepared from thin films sintered at temperatures from 1,100 to $1,450^{\circ}C$, and rapidly quenched in distilled water. The surfaces of the electrodes containing both corundum structure of $Fe_2O_3$ and spinel structure of $Mg_xFe_{3-x}O_4$ or $Ca_xFe_{3-x}O_4$ were analyzed by X-ray diffraction and scanning electron microscopy. The cathodic and anodic photocurrents on these electrodes indicated a critical doping amount of 5-11 wt. %. The photocurrents were enhanced when GaAs electrodes were treated with methylene violet the anodic photo-currents were temporarial enhanced and changed to the cathodic ptotocurrents after the surface was dryed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.463-470
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• 1996

Ceramic membrane consisting of an ${\alpha}-Al_{2}O_{3}$ support and Fe doped $TiO_{2}$ top layer was prepared by the sol-gel method. The supported Fe doped $TiO_{2}$ top layer was made by dip coating the support in a mixed sol. The microstructure of the composite membranes was studied by SEM after calcination at $550~850^{\circ}C$. After sintering at $650^{\circ}C$ for 1 hr., the average particle diameter of the Fe doped $TiO_{2}$ top layer was ~40 nm. The supported Fe doped $TiO_{2}$ composite membranes exhibited much higher heat resistance than the $TiO_{2}$ membrane. The Fe doped $TiO_{2}$ composite membrane retained a crack-free microstructure and narrow particle size distribution even after calcination up to $650^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.222-231
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• 2001

The material properties of $SnO_2$ were investigated as a function of the amount of $Fe_2O_3$, the partial pressure of oxygen, the concentration of CO gas, and temperature. $Fe_2O_3$-doped $SnO_2$ thick films were prepared by the screen printing technique on alumina substrate. The specimens sintered at $700^{\circ}C$ for 6 hours showed little difference of the grain size and narrow distribution with the content of $Fe_2O_3$. The electrical conductance of undoped $SnO_2$ is high at low firing temperature and at low partial pressure of oxygen. The electrical conductance of $Fe_2O_3-$-doped $SnO_2$ is increased with measurement temperature, but decreased with the content of $Fe_2O_3$. The dependence of oxygen partial pressure is decreased with dopant addition. The highest sensitivity and the good properties of response speed and repeatability for CO gas were observed on the specimen with 0.1 mol% $Fe_2O_3$ at $350^{\circ}C$.

• Journal of the Korean Vacuum Society
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• v.11 no.4
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• pp.240-248
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• 2002

$Fe_xTi_{l-x}O_2$ films (x=0.07 and 0.16) were grown by oxygen-plasma-assisted molecular beam epitaxy on rutile $TiO_2$(110). The same growth conditions were applied for both films in order to determine surface characteristics of grown films as a function of Fe composition. The films were characterized by several surface analysis techniques. The oxidation states of Ti and Fe in $Fe_xTi_{l-x}O_2$ films were found to be +4 and a mixture of +2 and +3, respectively. More $Fe^{3+}$ species exist in higher Fe doped film of $Fe_{0.16}Ti_{0.84}O_2$. The morphology of $Fe_{0.07}Ti_{0.93}O_2$ film shows tall rectangular and cylinderical islands growth on flat substrate-like surface. On the other hand, $Fe_{0.16}Ti_{0.84}O_2$ film consists of round shaped small islands showing somewhat rougher surface compared to the surface of $Fe_{0.16}Ti_{0.84}O_2$ film.

• Journal of the Korean Ceramic Society
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• v.46 no.4
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• pp.350-356
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• 2009

Perovskite codoped with chromium and iron have been studied. Samples with $YAl_{0.96}(Cr_{0.04-x}Fe_x)O_3$(x=0.01, 0.02, 0.03, 0.04) were prepared by solid state reaction at $1450^{\circ}C$ for 6 h and were characterized by XRD, FT-IR, Raman spectroscopy, SEM and UV-vis spectrophotometer. The color of the synthesized pigments were from red to dark brown(in bulk). Up to 0.02 mole $Fe_2O_3$ for substituting $Cr_2O_3$ development of color in lime-glaze gives good red color but as increasing amount of $Fe_2O_3$ and decreasing $Cr_2O_3$ proportionally produce from brownish red to brown. Increasing $Fe_2O_3$ amount lead to weaken crystal field relatively due to have smaller ionic radius than $Cr_2O_3$ ionic one. The UV-vis peaks were shifted to lower wavelength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.95-95
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• 2009

Lead-free $(K_{0.5}Na_{0.5})(Nb_{0.96}Sb_{0.04)O_3$ + 1.2 mol% $K_4CuNb_8O_{23}$ + x mol% $Fe_2O_3$ ceramics were manufactured by a conventional solid state reaction method. And then, their piezoelectric and dielectric properties were investigated. At the 0.2 mol% $Fe_2O_3$ doped ceramics, the values of Kp=0.436 and Qm=696.36 were obtained, respectively, which were suitable for piezoelectric transformer application.

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.05a
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• pp.95-95
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• 2001

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.5
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• pp.447-453
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• 1999

Congruent $LiNbO_3$ crystals with doped Mg and codoped with Mn or Fe were grown by the Czochralski method. It is known that the physical properties of $LiNbO_3$ depend strongly on the addition of Mg and transition metals. This is established by studying the following properties; XRD patterns, the phase transition temperature, energy of the fundamental absorption edge, the shape of the absorption band of the $OH^-$ vibration and lines of the ESR of $Fe^{3+},\; Mn^{2+}$. The position of the UV absorption edge and the shape and peak point of the absorption band of the $OH^-$ vibrational band changed monotonously up to a critical concentration of $Mg^{2+}$ ions. The mechanism of the incorporation of Mg ions changes at this concentration. The transition temperature was estimated by measuring the dielectric temperature behavior up to $1230^{\circ}C$ in a frequency range of 100Hz to 10MHz. EPR of $Mn^{2+}\;and\; Fe^{3+}$ ions were employed to investigated the Mg doping effects in the $LiNbO_3$ crystal. The increase of linewidths and the asymmetry of signals were observed in all crystals. New signals of $Fe^{3+}$ arising from the new centers were observed I the heavily Mg-doped crystals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1883-1889
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• 2013

Although Fe-Si based alloy has lower figure of merit than Si-Ge alloy applied for space probe, its low cost related to abundant raw material, rather simple processing, high temperature resistance and reliability up to $800^{\circ}C$ made it one of the most promising middle temperature thermoelectric generation materials. The effect of particle size and additive on the thermoelectric properties of p-$FeSi_2$ prepared by a RF inductive furnace was investigated. The electrical conductivity increased slightly with decreasing particle size and hence better grain-to-grain connectivity due to the increase of density. The Seebeck coefficient exhibited the maximum value at about 600~800K and decreased slightly with increasing particle size. This must be due to the amount of residual metallic phase ${\varepsilon}$-FeSi. $Fe_2O_3$ and/or $Fe_3O_4$-doped specimens showed the higher electrical conductivity and the lower Seebeck coefficient due to increase of the metallic phase and Si-vacancy. On the other hand, $SiO_2$-doped specimen showed the higher electrical conductivity and the higher Seebeck coefficients.