Sang-hyeok IM | Pnu - Academia.edu (original) (raw)
Papers by Sang-hyeok IM
Thin Solid Films, 2010
In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[T... more In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[Ti(OC 2 H 5 ) 4 ] and ferric nitrate[Fe(NO 3 ) 3 •9H 2 O] were used as precursors to make the Fe-TiO 2 sol. The samples for measurement were prepared on a glass substrate using the sol-gel dip coating method. The annealing temperature (T a ) was varied in the range of 673.15-873.15 K in intervals of 50 K. The cut-off points of the samples were increasingly red-shifted with increasing Fe content. Simultaneously, the optical band gap decreased from 4.03 to 3.64 eV. A change of the crystalline phase as the Fe content increased was observed from the X-ray diffraction measurements. Combined with the X-ray diffraction analysis, the observed variations in both the cut-off points and optical band gap were directly correlated with the structural change of the composite films.
Thin Solid Films, 2010
In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[T... more In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[Ti(OC 2 H 5 ) 4 ] and ferric nitrate[Fe(NO 3 ) 3 •9H 2 O] were used as precursors to make the Fe-TiO 2 sol. The samples for measurement were prepared on a glass substrate using the sol-gel dip coating method. The annealing temperature (T a ) was varied in the range of 673.15-873.15 K in intervals of 50 K. The cut-off points of the samples were increasingly red-shifted with increasing Fe content. Simultaneously, the optical band gap decreased from 4.03 to 3.64 eV. A change of the crystalline phase as the Fe content increased was observed from the X-ray diffraction measurements. Combined with the X-ray diffraction analysis, the observed variations in both the cut-off points and optical band gap were directly correlated with the structural change of the composite films.
Thin Solid Films, 2010
In the present work, ZnO-Bi 2 O 3 -P 2 O 5 glasses were studied to examine the effect of the Bi 2... more In the present work, ZnO-Bi 2 O 3 -P 2 O 5 glasses were studied to examine the effect of the Bi 2 O 3 composition on the structure and properties of the phosphate glass system. Glasses with the compositions, I: (50 − 2x)ZnO-xBi 2 O 3 − (50 + x)P 2 O 5 and II: (50 − x)ZnO-xBi 2 O 3 -50P 2 O 5 (x = 0− 20 mol%) were prepared. To investigate the relation between the structural change and compositional change, the structure was measured by FT-IR analysis and the density, glass transition temperature (T g ) and chemical properties of the glasses were measured. The T g and chemical properties (water-resistant qualities) increased with increasing metaphosphate phase in the glasses, due to the increase in the number of bridging oxygens. The glass properties were dependent on the O/P ratio. The compositional variations that changed the dominant phosphate structure from a metaphosphate to a pyrophosphate were accompanied by the transformation in the dominant Bi coordination, complicating the effect that Bi 2 O 3 has on the glass properties. Bi 3+ cations were incorporated into the glass network and difference in the Bi-O bonding state in the glasses.
Advanced Materials Research, 2010
Electronic Materials Letters, 2010
Glasses in the system xB2O3−(60−x)P2O5−40Na2O (x = 0 mol. %, 10 mol. %, 20 mol. %, 30 mol. %, 40 ... more Glasses in the system xB2O3−(60−x)P2O5−40Na2O (x = 0 mol. %, 10 mol. %, 20 mol. %, 30 mol. %, 40 mol. %) were prepared and characterized by measuring their density (ρ), molar volume (V M), glass transition/ softening temperature (T g/Td), thermal expansion coefficient (α) and chemical durability (DR). All of these values were found to vary with the B2O3 content of the glasses. The results were interpreted on the basis of the structural data. The Raman and infrared spectra confirmed these structural changes.
Journal of The Korean Physical Society, 2010
Electronic Materials Letters, 2010
This study looks at crystallization and sintering behavior in B2O3 containing Li2O-Al2O3-SiO2 gla... more This study looks at crystallization and sintering behavior in B2O3 containing Li2O-Al2O3-SiO2 glass powder. The sintered sample was produced with glass powders measuring 44 μm. The relative density and transmittance of the sintered samples showed the highest value at the temperature of 650°C. At temperatures higher than 650°C, crystal growth occurred to decrease the densification of B2O3-Li2O-Al2O3-SiO2 (BLAS) glass powder. The main crystalline phase in the glass powder was â-spodumene. From non-isothermal differential thermal analysis, the crystallization of particles (Φ = 44 μm) was observed at 640°C to 684°C with respect to the heating rate. The activation energy of crystallization (EC) and the Avrami constant (n) calculated by Kissinger and Ozawa equations indicated that the surface and the bulk crystallization occurred simultaneously in the glass. The optimum sintering temperature of this glass powder was 650°C without crystal growth of β-spodumene, although nucleation or nano-crystal growth occurred.
Thin Solid Films, 2010
In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[T... more In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[Ti(OC 2 H 5 ) 4 ] and ferric nitrate[Fe(NO 3 ) 3 •9H 2 O] were used as precursors to make the Fe-TiO 2 sol. The samples for measurement were prepared on a glass substrate using the sol-gel dip coating method. The annealing temperature (T a ) was varied in the range of 673.15-873.15 K in intervals of 50 K. The cut-off points of the samples were increasingly red-shifted with increasing Fe content. Simultaneously, the optical band gap decreased from 4.03 to 3.64 eV. A change of the crystalline phase as the Fe content increased was observed from the X-ray diffraction measurements. Combined with the X-ray diffraction analysis, the observed variations in both the cut-off points and optical band gap were directly correlated with the structural change of the composite films.
Thin Solid Films, 2010
In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[T... more In this study, the optical and structural properties of an Fe-TiO 2 sol were investigated. TEOT[Ti(OC 2 H 5 ) 4 ] and ferric nitrate[Fe(NO 3 ) 3 •9H 2 O] were used as precursors to make the Fe-TiO 2 sol. The samples for measurement were prepared on a glass substrate using the sol-gel dip coating method. The annealing temperature (T a ) was varied in the range of 673.15-873.15 K in intervals of 50 K. The cut-off points of the samples were increasingly red-shifted with increasing Fe content. Simultaneously, the optical band gap decreased from 4.03 to 3.64 eV. A change of the crystalline phase as the Fe content increased was observed from the X-ray diffraction measurements. Combined with the X-ray diffraction analysis, the observed variations in both the cut-off points and optical band gap were directly correlated with the structural change of the composite films.
Thin Solid Films, 2010
In the present work, ZnO-Bi 2 O 3 -P 2 O 5 glasses were studied to examine the effect of the Bi 2... more In the present work, ZnO-Bi 2 O 3 -P 2 O 5 glasses were studied to examine the effect of the Bi 2 O 3 composition on the structure and properties of the phosphate glass system. Glasses with the compositions, I: (50 − 2x)ZnO-xBi 2 O 3 − (50 + x)P 2 O 5 and II: (50 − x)ZnO-xBi 2 O 3 -50P 2 O 5 (x = 0− 20 mol%) were prepared. To investigate the relation between the structural change and compositional change, the structure was measured by FT-IR analysis and the density, glass transition temperature (T g ) and chemical properties of the glasses were measured. The T g and chemical properties (water-resistant qualities) increased with increasing metaphosphate phase in the glasses, due to the increase in the number of bridging oxygens. The glass properties were dependent on the O/P ratio. The compositional variations that changed the dominant phosphate structure from a metaphosphate to a pyrophosphate were accompanied by the transformation in the dominant Bi coordination, complicating the effect that Bi 2 O 3 has on the glass properties. Bi 3+ cations were incorporated into the glass network and difference in the Bi-O bonding state in the glasses.
Advanced Materials Research, 2010
Electronic Materials Letters, 2010
Glasses in the system xB2O3−(60−x)P2O5−40Na2O (x = 0 mol. %, 10 mol. %, 20 mol. %, 30 mol. %, 40 ... more Glasses in the system xB2O3−(60−x)P2O5−40Na2O (x = 0 mol. %, 10 mol. %, 20 mol. %, 30 mol. %, 40 mol. %) were prepared and characterized by measuring their density (ρ), molar volume (V M), glass transition/ softening temperature (T g/Td), thermal expansion coefficient (α) and chemical durability (DR). All of these values were found to vary with the B2O3 content of the glasses. The results were interpreted on the basis of the structural data. The Raman and infrared spectra confirmed these structural changes.
Journal of The Korean Physical Society, 2010
Electronic Materials Letters, 2010
This study looks at crystallization and sintering behavior in B2O3 containing Li2O-Al2O3-SiO2 gla... more This study looks at crystallization and sintering behavior in B2O3 containing Li2O-Al2O3-SiO2 glass powder. The sintered sample was produced with glass powders measuring 44 μm. The relative density and transmittance of the sintered samples showed the highest value at the temperature of 650°C. At temperatures higher than 650°C, crystal growth occurred to decrease the densification of B2O3-Li2O-Al2O3-SiO2 (BLAS) glass powder. The main crystalline phase in the glass powder was â-spodumene. From non-isothermal differential thermal analysis, the crystallization of particles (Φ = 44 μm) was observed at 640°C to 684°C with respect to the heating rate. The activation energy of crystallization (EC) and the Avrami constant (n) calculated by Kissinger and Ozawa equations indicated that the surface and the bulk crystallization occurred simultaneously in the glass. The optimum sintering temperature of this glass powder was 650°C without crystal growth of β-spodumene, although nucleation or nano-crystal growth occurred.