Bong-Ki Ryu

냉각 방법에 따른 모의 방사성폐기물 유리고화체의 특성평가

In order to examine and compare the characteristics of two vitrified forms (AG8W1 and DG2) simulated for the operation of a commercial vitrification facility being constructed in Ulchin nuclear power plant, the vitrified forms were cooled by the natural cooling and annealing methods, respectively. And the Product Consistency Test (PCT), compressive strength, thermal conductivity, specific heat, phase stability, softening point and Coefficient of Thermal Expansion (CTE) of the vitrified forms were experimented. Consequently, it was shown that there were no significant differences on the physiochemical properties of the vitrified forms performed the natural cooling and annealing.

Effects of substituting B2O3 for P2O5 on the structures and properties of V2O5-P2O5 glass systems

V2O5-B2O3-P2O5 glasses with various compositions were prepared using a normal melt quenching technique, and their characteristics and structural properties were investigated using different techniques. Replacement of P2O5 by B2O3 was found to improve the thermal properties, chemical durability, and room-temperature conductivity. The observed variations in the properties may be correlated with changes in the internal glass network as a result of changes in the chemical composition. Vanadium ions are believed to be present in three possible valence states, namely V3+, V4+, and V5+, and the ratios of these states depend on the glass composition. The observed increases in chemical durability and room-temperature conductivity are assumed to be related to increases in the mean crosslinking density, increases in the number of bridging oxygens, and electron hopping between vanadate ions in different valence states.

Effects of Substitution of K2O for Na2O on the Bioactivity of CaO-Na2O-SiO2-P2O5 glasses

The compositional dependences of bioactivity, thermal properties, atomic structure, and surface morphology have been investigated in the CaO-Na2O-SiO2-P2O5 system; this system is known as a bioglass. 45S5 Bioglass® is known to be a general and highly bioactive material. However, the bioactivity of this glassy material is expected to be improved by modifying the alkali-metal composition. Thermal properties, density, and molar volume were measured to investigate the structural packing. FT-IR spectra and X-ray diffraction were used to confirm the structures of these glasses. The morphology was examined using field emission electron microscopy, and the formation of a Ca-P layer was studied using an energy-dispersive system. This study shows that the tendency to form a calcium phosphate layer is increased with the substitution of K2O for Na2O.

Crystallization behavior of phosphate glasses with hydrophobic coating materials

We analyzed the effect of the addition of Li2O3, TiO2, and Fe2O3 on the crystallization behavior of P2O5-CaO-SiO2-K2O glasses and the effect of the crystallization behavior on the roughness and hydrophobicity of the coated surface. Exothermic behavior, including a strong exothermic peak in the 833-972 K temperature range when Fe2O3, TiO2, or Li2O3 was added, was confirmed by differential thermal analysis. The modified glass samples (PFTL1-3) showed diffraction peaks when heated at 1073 and 1123K for 5 min; the crystallized phase corresponds to Fe3(PO4)2, that is, graftonite. We confirmed that the intensity of the diffraction peaks increases at high temperatures and with increasing Li2O3 content. In the case of the PFTL3 glass, a Li3Fe2(PO4)2 phase, that is, trilithium diiron(III) tris[phosphate(V)], was observed. Through scanning electron microscopy and the contact angles of the surfaces with water, we confirmed that the increase in surface roughness, correlated to the crystallization of the glass frit, increases hydrophobicity of the surface. The calculated values of the local activation energies for the growth of Fe3(PO4)2 on the PTFL1, PTFL2, and PFTL3 glass were 237-292 kJ mol-1, 182-258kJ mol-1, and 180-235kJ mol-1.

Relationship between structure and optical properties in the CdO-B2O3-SiO2 glass system

To study the compositional dependence of the optical properties and atomic structure of glasses, the CdOB2O3-SiO2 ternary glasses, which are known as highly photoconductive glasses, have been investigated. The photoconductivity of glasses containing CdO was investigated in a previous study, because of their potential applications in photoelectronic devices. The thermo-mechanical analysis and the Fourier transform infrared (FT-IR) spectra of the glass samples were measured to determine the structural variation of these glasses. Using transmittance measurements, we calculated the optical energy band gap. This paper presents results for control of the optical energy band gap 3.8 ∼ 3.2 eV in cadmium-borosilicate glass system while the structural properties undergo monotonic changes.

Effect of ZnO content change on the structure and properties of zinc borophosphate glasses

The glass system xZnO-10B2O3-(100 − x)P2O5 was prepared by cooling using the melt-quenching technique in the composition series x from 30 to 60 mol %. The density, thermal expansion coefficient, glass transition temperature, and softening temperature of the glass system were determined. Structural characterization was performed by using a combination of IR and Raman spectroscopy and 11B/31P solid state NMR spectroscopy data. In particular, variations in the phosphate network structure upon the addition of ZnO were investigated. Data analysis indicated that increasing the ZnO content and decreasing the P2O5 content increased the extent of cross-linking between the phosphate and borate units in the glass network; this was because incorporation of ZnO polyhedra into the structural network of ZnO increased the network dimensionality. These structural changes were confirmed by Raman and IR spectroscopy.

Electrical properties of crystallized 30B2O3-70V2O5 glass

Abstract30B2O3-70V2O5 binary-system glass was prepared, and variations in structural and electrical property were examined using crystallization. While different related research studies exist, few have evaluated the variations in the structure and properties with changes in the crystallization rate. 30B2O3-70V2O5 glass was annealed in the graphite mold above the glass transition temperature for 2 h and heat-treated at each crystallization temperature for 3 h. 30B2O3-70V2O5 glass showed predominantly electronic conductive characteristic. FTIR was preferentially used for analyzing the structural changes of B-O bond after crystallization, while XRD was utilized to verify the inferred changes in the structure array (BO3 + V2O5 ↔ BO4 + 2VO2). Structural changes induced by heat treatment were confirmed by analyzing the molecular volume determined from the sample density, and conductance was measured to correlate structural and property changes. Conductivity is discussed based on the migration of vanadate ions with different valence states because of the increase in VO2 crystallinity at 130°C, which, however, was not observed at 170°C. After VO2 structures were reinforced, a 1.8-fold increase in conductance was observed (as compared to the annealed sample) after crystallization at 130°C for 3 h.

Effects of Substituting B 2 O 3 for P 2 O 5 on the Structure and Properties of SnO-P 2 O 5 Glass Systems

The investigation is directed to lead free (Pb-free) frits that can be used for organic light emitting diode, plasma display screen devices and other sealing materials. -SnO system glasses have been prepared for Pb-free low temperature glass frit. Structure and properties of the glasses with the composition SnO- (x

Structure and transmittance behavior of sol–gel silica nanoparticles synthesized using pH-stable alkanolamines

Although sol–gel silica nanoparticles are widely used in academic and industrial applications, only a few studies have focused on amine catalysts other than ammonia to control the particle size. In this study, we systematically investigated how the particle size is affected by various amine catalysts such as ammonia (NH3), ethanolamine (EOA), diethanolamine (DEOA), and triethanolamine (TEOA) in a wide range of catalyst amount. Different amine catalysts had a different effect on the particle size with respect to their content, and it was shown that the pKa and molecular size of the amine catalyst are the main factors controlling the particle size during the sol–gel reactions. It was suggested that the amines behave not only as catalysts, but also as surfactants or dispersants. While the pH of the ammonia solution exhibited a gradual decrease due to the high volatility of NH3, the other types of amines exhibited high pH stability, which is an important aspect for reproducibility and industrial application. After coating the silica nanoparticles on glass substrates, the transmittance was significantly affected by the coating thickness and the type of amine catalyst. TEOA lead to higher transmittance than NH3, which is attributed to the more porous structure of TEOA-catalyzed silica nanoparticles.Graphical abstract

A study of the relationship between structure and properties of cadmium phosphate glasses

It analysed the structure and chemical durability which it follows in CdO content in Cadmium phosphate glasses. We prepared glasses with the composition, xCdO-(100-x)P2O5 (x = 10 mol. % to 50 mol. %), and analyzed their density (ρ), molar volume (VM), glass transition/softening temperature (Tg/Td), thermal expansion coefficient (α), fourier transform infrared spectroscopy, and dissolution rate. All of these of the values were found to vary with the CdO content of the glasses. It is observed that the dissolution rate increase with with CdO contents. This suggests that Cadmium ion breaks the p-o-p bonds.