• Restorative Dentistry and Endodontics
• /
• v.22 no.1
• /
• pp.228-243
• /
• 1997

The changes of microstructures, morphology of sclerotic dentin and bonding aspects generated by an adhesive resin was investigated. Incisors and premolars showing natural cervical abrasions were collected and conditioned with 10 % phosphoric acid or 10 % maleic acid. The sclerotic dentin specimens were then rinsed and blot-dried and applied with dentin adhesive (All Bond 2) to the conditioned dentin surface. To examine the morphologic change of the sclerotic dentin specimen after etching and bonding procedure, the treated specimens were examined by SEM. To analyze the chemical composition of sclerotic dentin and crystals occluding dentinal tubules, the sclerotic dentin specimen was powdered and examined with X-ray Diffractometer. To investigate the Ca/P weight percent ratio within the dentinal tubules, the sclerotic dentin specimen was fractured perpendicularly to the long axis of the tooth from the center of cervical abrasion lesion and then examined with EDX(Energy Dispersive X-ray) microanalyzer. The results were as follows : 1. The increased width of peritubular dentin and the depositions of the irregular amorphous materials within the dentinal tubules were showed in the sclerotic dentin specimens. 2. After the treatment of sclerotic dentin specimen with 10 % phosphoric acid or 10 % maleic acid, the lateral side of tubules rather than cross-sectional tubule openings was showed exclusively at the incisal and gingival incline of the specimens. 3. After the treatment of sclerotic dentin specimen with 10 % phosphoric acid or 10 % maleic acid, the hybrid layer was not formed evidently and the resin tag was not formed or shortly penetrated into the tubules with the thinner diameter. 4. According to the results of XRD analysis of the sclerotic dentin specimen, Hydroxyapatite and Octacalcium phosphate were predominent, however, Whitlockite crystals were rare. 5. The mean Ca/P weight percent ratio analysed from 5 fractured sclerotic dentin specimens was $2.322{\pm}0.170$ at the intertubular dentin, $1.826{\pm}0.051$ within the dentinal tubule.

• Applied Chemistry for Engineering
• /
• v.17 no.5
• /
• pp.471-475
• /
• 2006

$VO_x$ thin films with the thickness of 450 nm were prepared on a $Pt/Ti/SiO_{2}/Si$ substrate at room temperature by a reactive radio frequency (rf) magnetron sputtering method. The deposition rates of $VO_x$ thin films were investigated as a function of $O_{2}$ concentration and rf power. As the $O_{2}$ concentration in a $O_{2}/Ar$ mixture increased, the deposition rate decreased. However, the deposition rate increased with increasing rf power. The deposited $VO_x$ thin films were annealed at $450^{\circ}C$ for 2, 4, and 6 h in $O_{2}$ and $N_{2}$ ambient. After annealing, the phase changes of $VO_x$ thin films were investigated using X-ray diffraction analysis. The plane and cross-sectional views of $VO_x$ thin films before and after annealing were observed by field emission scanning electron microscopy. The metal-insulator transition (MIT) properties of $VO_x$ thin films were measured using current-voltage measurement. The excellent MIT properties were observed in $VO_x$ thin films annealed in $O_{2}$ ambient.

• Journal of the Korean Electrochemical Society
• /
• v.17 no.3
• /
• pp.149-155
• /
• 2014

In this study, a positive-electrode material in a lithium secondary battery $Li[Ni_{0.575}Co_{0.1}Mn_{0.325}]O_2$ was synthesized as precursor by co-precipitation. Cathode material was synthesized by adding iron. The synthesized cathode material was analyzed by scanning electron microscope and x-ray diffraction. The analysis of x-ray diffraction showed that the a-axis and c-axis is increased by doping iron. And $I_{(003)}/I_{(104)}$ is increased and $I_{(006)}+I_{(102)}/I_{(101)}$ is decreased. Through this result, it was confirmed that the structural stability is improved. And impedance measurements show that the charge transfer resistance ($R_{ct}$) is lowered by doping iron. Consequently, electrochemical properties are improved by doping iron. In particular, the cycle characteristics are improved at a high temperature condition (328 K). Structural stabilities are contributing to the cycle properties.

• Journal of the Microelectronics and Packaging Society
• /
• v.13 no.4
• /
• pp.27-36
• /
• 2006

We fabricated thermally evaporated 10 nm-Ni/(poly)Si, 10 nm-Ni/l nm-Ir/(poly)Si and 10 nm-Ni/l nm-Pt/(poly)Si films to investigate the thermal stability of nickel monosilicides at the elevated temperatures by rapid annealing them at the temperatures of $300{\sim}1200^{\circ}C$ for 40 seconds. Silicides of 50 nm-thick were formed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point tester was used to examine sheet resistance. A scanning electron microscope and field ion beam were employed for thickness and microstructure evolution characterization. An X-ray diffractometer and an Auger depth profiler were used for phase and composition analysis, respectively. Nickel silicides with platinum have no effect on widening the NiSi stabilization temperature region. Nickel silicides with iridium farmed on single crystal silicon showed a low resistance up to $1200^{\circ}C$ while the ones formed on polycrystalline silicon substrate showed low resistance up to $850^{\circ}C$. The grain boundary diffusion and agglomeration of silicides lowered the NiSi stable temperature with polycrystalline silicon substrates. Our result implies that our newly proposed Ir added NiSi process may widen the thermal process window for nano CMOS process.

• Journal of the Korean Chemical Society
• /
• v.36 no.1
• /
• pp.16-23
• /
• 1992

High $T_c$, superconductor $(Y_{1-x}Eu_x)Ba_2Cu_3O_{7-{\delta}}$ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared and the physical properties were observed. XRD analysis showed that the structures of all the specimen were orthorhombic and the lattice parameters a, b and c increased with the increasing x value. Electrical resistivity and magnetization measurements revealed that pure high $T_c$, superconducting phases were formed at above 90 K. The critical temperatures increased with increasing the amount of Eu. From the measurement of magnetization and the size of the grains using SEM micrographs, volume diamagnetic susceptibilities for each specimen were calculated. These values decreased with the increasing x value. The composition of Ba in the lattice site decreased as the concentration of Eu increased, and this was confirmed by EPMA. It was found out that the volume diamagnetic susceptibility of each specimen was directly influenced by the composition of Ba in the lattice site.

• Polymer(Korea)
• /
• v.38 no.5
• /
• pp.656-663
• /
• 2014

Atorvastatin calcium-loaded polyoxalate (POX) microspheres were prepared by an emulsion solvent-evaporation/ extraction method of oil-in-oil-in-water ($O_1/O_2/W$) for sustained release. We investigated the release behavior according to initial drug ratio, molecular weight ($M_w$) and concentration of POX and concentration of emulsifier. The microsphere was characterized on the surface, the cross-section morphology and the behavior of atorvastatin calcium release for 10 days by scanning electron microscopy (SEM) and high performance liquid chromatography (HPLC). The analysis of crystallization was analyzed to use X-ray diffraction (XRD), differential scanning calorimeter (DSC) and Fourier transform infrared (FTIR). These results showed that the release behaviors can be controlled by preparation conditions.

• Journal of the Korean Magnetics Society
• /
• v.19 no.4
• /
• pp.121-125
• /
• 2009

Amorphous $Ge_1$_$_xMn_x$ semiconductor thin films grown by low temperature vapor deposition were annealed at various temperatures from 400 to $700^{\circ}C$ for 3 minutes in high vaccum chamber. The electrical and magnetotransport properties of as-grown and annealed samples have been studied. X-ray diffraction patterns analysis revealed that the samples still maintain amorphous state after annealling at $500^{\circ}C$ for 3 minutes and they were crystallized when annealing temperature increase to $600^{\circ}C$. Temperature dependence of resistivity measurement implied that as-grown and annealed $Ge_1$_$_xMn_x$ films have semiconductor characteristics, the increase of resistivity with annealling temperature was obseved. The $700^{\circ}C$-annealed sample exhibited negative magnetoresistance (MR) at low temperatures and the MR ratio was ${\sim}$8.5% at 10 K. The asymmetry was present in all MR curves. The anomalous Hall Effect was also observed at 250 K.

• Korean Journal of Materials Research
• /
• v.8 no.6
• /
• pp.505-512
• /
• 1998

In this study, two-layer thermal barrier coatings composed of plasma sprayed 0.3mm $ZrO_2(8wt% Y_2o_3)$ ceramic coating layer and O.lmm $NiCrAlCoY_20_3$ bond coating layer on AISI 316 were investigated microstructure of the coating, oxidation of the metallic bond coating and adhesive strength to evaluate the durability of coating layer after cyclic and isothermal test at 90$0^{\circ}C$. And quantitative phase analysis of $ZrO_2(8wt% Y_2o_3)$ ceramic coating was performed as a function of thermal exposure time using XRD technique. The results showed that the amount of m - 2rO, phase in the coating was slightly increased with increasing thermal exposure time at 90$0^{\circ}C$. The c/a ratio of t' - $ZrO_2$ in the as-sprayed coating was 1.0099 and slightly increased to 1.0115 after 100 hours heat treatment. It was believed that $Y_2O_3$ in high yttria tetragonaJ(t') was transformed to low yttria tetragonaJ(t) by $Y_2O_3$ diffusion with increasing thermal exposure time. The adhesive strength was gradually decreased as thermal exposure time increased. After the isothermal test, the failure predominantly occured in ceramic coating layer. On the other hand. the specimens after cyclic thermal test were mostly failed at bond coating/ceramic coating interface. The failure was oeeured by decreasing the bond strength between bond coating and oxide scale which were formed by oxidation of the metallic elements within bond coating and by thermal stress due to thermal expansion mismatches between the oxide scale and ceramic coating.

• Korean Journal of Materials Research
• /
• v.8 no.12
• /
• pp.1170-1175
• /
• 1998

PZT films without lower electrode were deposited on the highly doped Si(100) substrate with MgO buffer layer (Mgo/si) by RF magnetron sputtering method followed by the rapid thermal annealing at $650^{\circ}C$ . We investigated the dependences of the crystalline and electrical properties on the MgO thickness and the RTA post annealing. The PZT films on bare Si (without MgO) showed pyrochlore crystal structure while those on MgO(50 )/Si substrates showed the typical perovskite crystal structures. From SEM and AES analysis, the thickness of PZT films was about 7000 showing relatively smooth interface. The depth profiles indicated that atomic species were distributed homogeneously in the PZT/MgO/Si substrate. The dielectric constant($\varepsilon_{r}$ ) and remanent polarization(2Pr) were about 300 and $14\mu$C/$\textrm{cm}^2$;, respectively. The leakage current was about $3.2\mu$/A$\textrm{cm}^2$.

• Journal of Conservation Science
• /
• v.34 no.2
• /
• pp.87-96
• /
• 2018

This study analyzed the influence of folding time on the forge welded bar and hammer scale produced using the traditional refining and forge welding reproduction experiment. In the case of the forge welded bar, increasing the forging time decreased the percentage of impurities and porosity from 26.09% to 1.8%. Additionally, the hardness increased by an average of 36.88 HV. In other words, the microstructure gradually became more precise. For the hammer scale, the amount of T Fe increased with forging time. X-ray diffraction analysis revealed the presence of quartz, fayalite, $w{\ddot{u}stite$, and magnetite. The amount of quartz decreased as the forging time increased. In addition, as the forging time increased, the granular $w{\ddot{u}stite$ changed into a cohesive, long, white band. The results provide information on the characteristics of the forge welded bar and hammer scale produced in the refining and forging process. This information can be used as technical data for ancient steel making processes as well as for future technological systems.