• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.189-190
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• 2005

Ploycrystalline $Pb(Zr_{0.5},Ti_{0.5))O_3$ and $BaTiO_3$ powder were prepared by sol-gel process. The alumina substrate were sintered at $1400^{\circ}C$ with bottom electrode of Pt for 2 hours. The Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films with laminating times were fabricated on alumina substrate by screening printing method. The obtained thick films were sintered at $800^{\circ}C$ with upper electrode of Ag paste for 1 hour. Structural properties of Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films were investigated. As a result of the Differential Thermal Analysis(DTA) of Pb(Zr0.5,Ti0.5)O3, exothermic peak was observed at around 650 $^{\circ}C$. The X-ray diffraction (XRD) patterns indicated that BaTiO3 and Pb(Zr0.5,Ti0.5)O3 phases and porosities were formed in the interface of Pb(Zr0.5,Ti0.5)O3 / BaTiO3multilayered thick films.

• Journal of Pharmaceutical Investigation
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• v.17 no.1
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• pp.1-14
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• 1987

To increase the bioavailability of norfloxacin, inclusion complex of antimicrobial agent norfloxacin with ${\beta}-Cyclodextrin$ was prepared and studied by the solubility method, spectrophotometric methods(UV, IR, $^1H-NMR$), differential thermal analysis, powder X-ray diffractometry, the physical properties, the antimicrobial activity, DNA binding and in situ recirculation technique. The conclusions are summerized as following; 1) The inclusion complexation was identified by means of solubility, spectrophotometry(UV, IR, NMR), DTA and X-ray diffraction. 2) The molar ratio of $norfloxacin-{\beta}-cyclodextrin$ complex was 1 : 1. 3) The stability constant of $norfloxacin-{\beta}-cyclodextrin$ complex was $21.5\;M^{-1}$, and both true and apparent partition coefficients of the inclusion complex were larger than those of norfloxacin. 4) The time required to dissolve 60% $(T_{60}%)$ of the inclusion complex was 120 min. in distilled water and in the artificial intestinal juice, while norfloxacin did not reach to 60% dissolution within 120 min. 5) The antimicrobial activity of the inclusion complex against Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus showed no significant difference compared to that of norfloxacin alone. 6) Studies on binding properties between the inclusion complex and norfloxacin alone to DNA according to equilibrium dialysis showed no significant differency. 7) In situ absorption rates (Ka) of inclusion complex and norfloxacin alone were 0.229 and $0.102hr^{-1}$, respectively.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.361-372
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• 1994

Vanadium containing MFI type zeolites have been prepared hydrothermally or by the impregnation method with $NH_4VO_3$ solution after dealumination of HZSM-5. Incorporation of vanadium into the framework of zeolite has been demonstrated by XRD, DTA, FT-IR and ESR analyses. Upon $NH_4VO_3$ impregnation and calcination of dealuminated zeolite, vanadium substitution into the framework could be performed like a hydrothermally synthesized zeolite. Vanadium in zeolite is able to pass redox cycles at high temperatures, and it is shown that vanadium is probably fixed and atomically dispersed in the structure of zeolite. The catalytic benzene hydroxylation, hexanes and alcohols oxidation were used for evaluating the properties of vanadium incorporated MFI zeolite.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.57-59
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• 2005

Ploycrystalline $Pb(Zr_{0.5},Ti_{0.5})O_3$ and $BaTiO_3$ powder were prepared by sol-gel process. The alumina substrate were sintered at $1400^{\circ}C$ with bottom electrode of Pt for 2 hours. The Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films with laminating times were fabricated on alumina substrate by screening printing method. The obtained thick films were sintered at $800^{\circ}C$ with upper electrode of Ag paste for 1 hour. Structural properties of Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films were investigated. As a result of the Differential Thermal Analysis(DTA) of Pb(Zr0.5,Ti0.5)O3, exothermic peak was observed at around $650^{\circ}C$. The X-ray diffraction (XRD) patterns indicated that BaTi03 and Pb(Zr0.5,Ti0.5)O3 phases and porosities were formed in the interface of Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.691-697
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• 1999

TiO2 powder was adsorbed on the surface of mica using the heterocoagulation method in water TiO2 powder was prepared from hydrolysis of titanium-iso propoxide in a mixed solvent of anhydrous ethanol and water. When the molar ratio of water to titanium iso-propoxide was 0.25 monodispersed spherical TiO2 particles were obtained. The prepared TiO2 powder showed anatase phase after heat treatment at 50$0^{\circ}C$ for 2 h and then transformed to rutile phase after heat treatment at 100$0^{\circ}C$ for 2h. The iso-electric points of TiO2 and Mica were pH 3.9 and pH 3.25 respectively which were measured by the Z-potential analysis in water base. The maximum Z-potential difference between two powders was observed in the range of pH 3.6~3.7 TiO2 powder was adsorbed on the surface of mica by heterocoagulation method in pH 3.6~3,7 The properties of prepared TiO2 powder was haracterized by TG-DTA, XRD and SEM The morphology and thermal properties of TiO2-adsorbed mica were examined.

• Journal of the Korean Ceramic Society
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• v.43 no.5 s.288
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• pp.309-314
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• 2006

We synthesized lithium zirconate using solid-state reaction and analyzed thermal properties (TG/DTA) of starting materials and the synthesized one. When $Li_2ZrO_3$ powder was exposed to $CO_2$ environment at $500^{\circ}C$, 93% of the theoretical absorption weight was gained within 280 min with fairly high sorption rate. Almost all the absorbed $CO_2$ was generated by heating the sample to $800^{\circ}C$. We also investigated densification behavior of $Li_2ZrO_3$ under $CO_2$ environment. By sintering $Li_2ZrO_3$ at $760^{\circ}C$ using 2-step process, we obtained dense product, composed mainly of $Li_2ZrO_3\;and\;ZrO_2$, with relative density of 92%.

• Journal of Magnetics
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• v.3 no.4
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• pp.99-104
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• 1998

The $ Sm_2Fe_{17}N_x $materials were prepared by the combination consisting of the HDDR (hydrogenation, disproportionation, desorption, and recombination) process and nitrogenation or by the conventional way consisting of nitrogenation only, and the magnetic and thermomagnetic properties of the materials were investigated. The magnetic characterisation of the prepared $ Sm_2Fe_{17}N_x $ materials was performed using a VSM. Thermal stability of the materials was evaluated using a DTA under Ar gas atmosphere. The thermomagnetic characteristics of the materials were examined using a Sucksmith-type balance. The previously HDDR-treated Sm2Fe17parent alloy was found to be nitrogenated more easily compared to the ordinary $ Sm_2Fe_{17}N_x $alloy. The $ Sm_2Fe_{17}N_x $ material produced by the combination method showed a high coercivity (12.9 kOe) even in the state of coarse particle size (around 60 ${\mu}{\textrm}{m}$). It was also revealed that the $ Sm_2Fe_{17}N_x $ material produced by the material produced by the combination showed an unusual TMA tracing featured with a low and constant magnetisation at lower temperature range and a peak just before the Curie temperature. This thermomagnetic characteristic was interpreted in terms of the competition between two counteracting effects; the decrease in magnetisation due to the thermal agitation at an elevated temperature and the increase in magnetisation resulting from the rotation of magnetisation of the fine grains comparable to a critical single domain size due to the decreased magnetocrystalline anisotropy at an elevated temperature.

• Journal of Magnetics
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• v.18 no.4
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• pp.391-394
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• 2013

In this study, nickel-zinc ferrite nanoparticles, with the chemical formula of $Ni_{0.3}Zn_{0.7-x}Cu_xFe_2O_4$ (where x = 0.1- 0.6 by step 0.1), were fabricated by the sol-gel method. The effect of copper substitution on the phase formation and crystal structure of the sample was investigated by X-ray diffraction (XRD), thermo-gravimetry (TG), differential thermal analysis (DTA), Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD result shows that due to the reduction of Zn content,the crystallite size of the sample increased. The results of the vibration sample magnetometer (VSM) exhibit an increase in saturation magnetization value (Ms) for samples with x ${\leq}$ 0.3 and a linear decrease for samples with x > 0.3. The variation of saturation magnetization and coercivity of the samples were then studied.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.380-387
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• 2017

In this study, unstable CaO was converted into a stable Ca compound by using carbonation in a circulating fluidized bed boiler of fly ash to confirm material usability as cement admixture; also undertaken was carbonation test and mortar to examine chemical and physical change by measuring absorption rate and compressive strength. To investigate the chemical properties of circulating fluidized bed boiler fly ash, XRD and TG-DTA were used to determine how the properties of the reaction product change quantitatively during carbonation. In order to stabilize CaO, carbonation of CaO is considered to be the most desirable process. This is because $CaCO_3$, which is a Ca compound, was produced by carbonate reaction of unstable CaO, and decrease of the absorption rate and improvement of the compressive strength were observed when the carbonated fly ash was replaced with cement.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.375-381
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• 2002

N-type ${\beta}-FeSi_2$ with a nominal composition of $Fe_{0.98}Co_{0.02}Si_2$ powders has been produced by mechanical alloying process and consolidated by vacuum hot pressing. As-milled powders were of metastable state and fully transformed to ${\beta}-FeSi_2$ phase by subsequent isothermal annealing. However, as-consolidated $Fe_{0.98}Co_{0.02}Si_2$ consisted of untransformed mixture of ${\alpha}-Fe_2Si_ 5$ and $\varepsilon$-FeSi phases. Isothermal annealing has been carried out to induce the transformation to a thermoelectric semiconducting ${\beta}-FeSi_2$ phase. The transformation behavior of ${\beta}-FeSi_2$ was investigated by utilizing DTA, a modified TGA under magnetic field, SEM, and XRD analyses. Isothermal annealing at $830^{\circ}C$ in vacuum led to the thermoelectric semiconducting ${\beta}-FeSi_2$ phase transformation, but some residual metallic $\alpha$ and $\varepsilon$ phases were unavoidable even after prolonged annealing. Thermoelectric properties were remarkably improved by isothermal annealing due to the transformation from metallic $\alpha$ and $\varepsilon$ phases to semiconducting phases.