• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.9
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• pp.760-765
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• 2011

Znic sulfide (ZnS) thin films were deposited on glass substrates by radio frequency magnetron sputtering. The substrate temperature varied from room temperature (RT) to $500^{\circ}C$. The structural and optical properties of ZnS films were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive analysis of X-ray (EDAX) and UV-visible transmission spectra. The XRD analyses reveal that ZnS films have cubic structures with (111) preferential orientation, whereas the diffraction patterns sharpen with the increase in substrate temperatures. The FESEM images indicate that ZnS films deposited at $400^{\circ}C$ have nano-sized grains with a grain size of ~ 67 nm. Then films exhibit relatively high transmittance of 80% in the visible region, with an energy band gap of 3.71 eV. One obvious result is that the energy band gap of the film increases with increasing the substrate temperatures.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1024-1028
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• 1998

Crystalline structure of the extrudate of high amylose corn starch was studied by X-ray diffractometer and $^{13}C\;NMR$. The X-ray diffraction crystal ratio of the extrudates (barrel temperature $100^{\circ}C$ )of high amylose corn starch slightly increased from 6.08% to 8.37% by increasing feed moisture content from 25% to 45%. But extrudates of high amylose corn starch showed similar crystal ratio on various extrusion conditions. Extrudates of high amylose corn starch (feed moisture content 20%, barrel temp $140^{\circ}C$) showed more enlarged crystal structure than that of non-extrudates. The perpendicular distance of crystal increased by extrusion. Crystal ratio was changed from $6.3{\sim}8.3%$ to $4.5{\sim}5.8%$ during storage at $4^{\circ}C$. Starch configuration was examined with $^{13}C\;NMR$. Double helical content was measured by $^{13}C\;NMR$ method. The highest double helical content (60%) was obtained from high amylose corn starch extrudate (barrel temp.: $100^{\circ}C$, feed moisture content 45%). Double helical contents and resistant starch (RS) yield (pancreatin) were positively correlated. However, double helical content of the extrudates was not changed by the storage at $4^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1242-1246
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• 2012

The Co oxide microfibers were synthesized using the electrospinning process and formed $Co_3O_4$ microfibers after being calcined at high temperatures. The calcination temperature influenced the diameters, morphology, crystalline phase, and chemical environment of the fibers. The surface morphology of the obtained fibers was examined by using the scanning electron microscope (SEM). As the calcination temperatures increased from room temperature to 873 and 1173 K, the diameters of the cobalt oxide fibers decreased from 1.79 to 0.82 and 0.32 mm, respectively. The structure of the fibers was investigated with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The calcined $Co_3O_4$ fibers had crystalline face-centered cubic (fcc) structure. The X-ray photoelectron spectroscopy (XPS) results revealed that increasing the calcination temperature promoted the formation of $Co^{2+}$ and $Co^{3+}$ species.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.55-58
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• 2015

The mesoporous metal organic framework structure Fe-BTC was successfully synthesized by hydrothermal process with noticeable yield. The synthesis operation was conducted at intermediate temperature and for shortened operation time as compared to conventional procedures. This process approach with reduced operating temperature and shortened operation time may open an opportunity window towards process economy with reduction in energy consumption. A simple mathematical approach of diffraction indexing using X-ray diffraction patterns of synthesized powder was employed to confirm its crystalline nature and to investigate its high temperature stability. The crystallite size was calculated by using Debye-Scherrer equation.

• Journal of Korean Vacuum Science & Technology
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• v.4 no.2
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• pp.50-54
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• 2000

We studied the synthesis of S $i_{1-x}$ Cx (x=0.016) epitaxial layer using ion implantation and solid phase epitaxy (SPE). The activation energy Ea was obtained for the loss of substitutional carbon using fourier transform-infrared spectroscopy (FTIR) and high-resolution x-ray diffraction (HR-XRD). In FTIR analysis, the integrated peak intensity was used to quantify the loss of carbon atoms from substitutional to interstitial sites during annealing. The substitutional carbon contents in S $i_{0.984}$ $C_{0.016}$ were also measured using HR-XRD. By dynamic simulations of x-ray rocking curves, the fraction of substitutional carbon was obtained. The effects of annealing temperature and time were also studied by comparing vacuum furnace annealing with rapid thermal annealing (RTA))))))

• Clean Technology
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• v.20 no.1
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• pp.28-34
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• 2014

In this study, we synthesized $TiO_2$ supports with nanosized crystalline structure by solvothermal method and prepared $TiO_2$ supported Pd-Cu catalysts. It was shown that the crystalline size of $TiO_2$ support in the catalyst influenced on the catalytic activity of nitrate reduction in water. The catalyst with the smaller crystalline size of $TiO_2$ support presented faster nitrate reduction rate, but had low nitrogen selectivity due to high pH environment of reaction medium during the reaction. Through injection of carbon dioxide as a pH buffer, the nitrogen selectivity increased by about 60%. Furthermore, we investigated that the relationships between the catalytic performance and the physicochemical properties of the prepared catalysts characterized by $N_2$ adsoprtion-desorption, X-ray diffraction (XRD), $H_2$-temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS).

• Resources Recycling
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• v.3 no.3
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• pp.21-26
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• 1994

In present study an attempt has been made to extract the high purity $Al_2O_3$from domestic aluminous shale. The processes of the salt roasting with ammonium sulfate, extraction with sulfuric acid and calcination were adopted. In the extraction of alumina, the effects of the sulfuric acid concentration, the reaction time and the temperature has been investigated. The reaction products were analyzed by X-ray diffraction, DTA-TG, chemical analysis and SEM. The results are summerized as follows: 1)The pretreatment conditions were 0.6M-$(NH_4)_2SO_4$and $650^{\circ}C$ in sintering temperature. 2) The optimum extraction conditions were $10%-H_2SO_4$ and 240 minutes in acid treating time. 3)Physical properties of sintering materials were confirmed as $\alpha-Al_2O_3$ by X-ray diffraction method and the purity of $\alpha-Al_2O_3$ was 99.23%.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.5
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• pp.706-711
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• 1986

The AgGa1-xInxSe2 films are deposited by a flash evaporation method onto pyrex glass substrates at temperatures between 5\ulcorner and 360\ulcorner. The single crystalline films which have X-ray diffraction peak of only (112) plane are preared at substrate temperature above 360\ulcorner. The prepared AgGa 1-xInxSe2 films are high photosensitive. The temperature coefficients of energy gap are found to be (-1.2~-4.0)x10**4 eV/K and (-3.1~-5.2)x10**-4 eV/K, and that of peak energy of spectral photoresponse curve are found to be (-1.1 ~ -3.0)x10**-4 eV/K(50K~100K) and (-2.4~-5.1)x10**-4 eV/K(100K~300K).

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.600-603
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• 1995

A series of samples in the Sm1-xSrxCoO3-y(x=0.00, 0.25, 0.50, 0.75 and 1.00) system has been prepared at 1200 ℃ under ambient atmosphere. The X-ray diffraction patterns of the samples with x=0.00 and 0.25 are indexed with orthorhombic symmetry like GdFeO3 and x=0.50 appears to be perfectly cubic. In the tetragonal system (x=0.75), the structure is similar to that of SrCoO2.80. The composition of x=1.00, SrCoO2.52, shows the brownmillerite-type structure. The reduced lattice volume is increased with x value in this system. The chemical analysis shows the τ value (the amount of the Co4+ ions in the system) is maximized at the composition of x=0.50. Nonstoichiometric chemical formulas are determined by the x, τ and y values. The electrical conductivity has been measured in the temperature range of 78 to 1000 K. The activation energy is minimum for those of x=0.25 and x=0.50 with metallic behavior. First-order semiconductor-to-metal transition of SmCoO3 is not observed. Instead, a broad, high-order semiconductor-to-metal transition is observed. In general, the effective magnetic moment is increased with increasing τ values at low temperature. At high temperature, the magnetic moment is maximum for that of x=0.00. The 3d-electrons are collective and give ferromagnetism in x=0.50.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.221-223
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• 1999

In this work, samples were manufactured variously by changing conventional calcining and sintering conditions and we tried the utilization by making the heat treatment time, which is demanded to high-Tc phase formation, much shorter. We found out optimal heat treatment conditions with the analysis on formation process at superconducting phase in term of the change of calcining and sintering time and then, examined X-ray diffraction(XRD) patterns, scanning electron microscope(SEM) measurement and energy dispersive X-ray spectrometer(EDX) of the samples manufactured under heat treatment conditions which we suggest here. As a result, 2223 high-$T_c$, phase of (Bi,Pb)SrCaCuO superconductor starting with ($Bi_l$ xPbx,)$_2$$Sr_2$$Ca_2$$Cu_3$$O_y$, composition was formed from 1 hr sintering sample at temperature nearby melting point and also the completed sample with calcining and sintering time of 9 hr was formed high-$T_c$.low-$T_c$ phase appearing in sight above the critical temperature of liquid $N_2$.