• The Journal of Korean Academy of Prosthodontics
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• v.45 no.1
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• pp.85-97
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• 2007

Statement of problem: Recently, anodic oxidation of cp-titanium is a popular method for treatment of titanium implant surfaces. It is a relatively easy process, and the thickness, structure, composition, and the microstructure of the oxide layer can be variably modified. Moreover the biological properties of the oxide layer can be controlled. Purpose: In this study, the roughness, microstructure, crystal structure of the variously treated groups (current, voltage, frequency, electrolyte, thermal treatment) were evaluated. And the specimens were soaked in simulated body fluid (SBF) to evaluate the effects of the surface characteristics and the oxide layers on the bioactivity of the specimens which were directly related to bone formation and integration. Materials and methods: Surface treatments consisted of either anodization or anodization followed thermal treatment. Specimens were divided into seven groups, depending on their anodizing treatment conditions: constant current mode (350V for group 2), constant voltage mode (155V for group 3), 60 Hz pulse series (230V for group 4, 300V for group 5), and 1000 Hz pulse series (400V for group 6, 460V for group 7). Non-treated native surfaces were used as controls (group 1). In addition, for the purpose of evaluating the effects of thermal treatment, each group was heat treated by elevating the temperature by $5^{\circ}C$ per minute until $600^{\circ}C$ for 1 hour, and then bench cured. Using scanning electron microscope (SEM), porous oxide layers were observed on treated surfaces. The crystal structures and phases of titania were identified by thin-film x-ray diffractmeter (TF-XRD). Atomic force microscope (AFM) was used for roughness measurement (Sa, Sq). To evaluate bioactivity of modified titanium surfaces, each group was soaked in SBF for 168 hours (1 week), and then changed surface characteristics were analyzed by SEM and TF-XRD. Results: On basis of our findings, we concluded the following results. 1. Most groups showed morphologically porous structures. Except group 2, all groups showed fine to coarse convex structures, and the groups with superior quantity of oxide products showed superior morphology. 2. As a result of combined anodization and thermal treatment, there were no effects on composition of crystalline structure. But, heat treatment influenced the quantity of formation of the oxide products (rutile / anatase). 3. Roughness decreased in the order of groups 7,5,2,3,6,4,1 and there was statistical difference between group 7 and the others (p<0.05), but group 7 did not show any bioactivity within a week. 4. In groups that implanted ions (Ca/P) on the oxide layer through current and voltage control, showed superior morphology, and oxide products, but did not express any bioactivity within a week. 5. In group 3, the oxide layer was uniformly organized with rutile, with almost no titanium peak. And there were abnormally more [101] orientations of rutile crystalline structure, and bonelike apatite formation could be seen around these crystalline structures. Conclusion: As a result of control of various factors in anodization (current, voltage, frequency, electrolytes, thermal treatment), the surface morphology, micro-porosity, the 2nd phase formation, crystalline structure, thickness of the oxide layer could be modified. And even more, the bioactivity of the specimens in vitro could be induced. Thus anodic oxidation can be considered as an excellent surface treatment method that will able to not only control the physical properties but enhance the biological characteristics of the oxide layer. Furthermore, it is recommended in near future animal research to prove these results.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1388-1390
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• 2013

Macroporous $SnO_2$ foam was successfully synthesized via a simple soft-chemical route by hybridization between alkylamine and tin(IV) oxide. According to X-ray diffraction (XRD) analysis, the as-prepared $SnO_2$ foam had a highly ordered lamella structure along the crystallographic c-axis, which transformed to a rutile phase after thermal treatment at $300^{\circ}C$. X-ray absorption spectroscopy (XAS) at the Sn K-edge revealed that $SnO_2$ particles in the hybrid material maintained their nanosized structure after hybridization with alkylamine. Scanning electron microscope (SEM) images clearly showed that the as-prepared $SnO_2$ foam had a macroporous structure. This synthetic route can be extended to the development of open frameworks with good electrochemical properties in battery applications.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.3
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• pp.91-94
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• 2007

Single-crystalline $SnO_2$ nanowires were successfully grown on Si(001) substrates via vapor-liquid-solid mechanism in a thermal chemical vapor deposition. Large quantity of $SnO_2$ nanowires were synthesized at temperature ranges of $950{\sim}1000^{\circ}C$ in Ar atmosphere. It was found that the grown $SnO_2$ nanowires are of a tetragonal rutile structure and single crystalline by diffraction and transmission electron microscopy measurements. Broad emission located at about 600 m from the grown nanowires was clearly observed in room temperature photoluminescence measurements, indicating that the emission band originated from defect level transition into $SnO_2$ nanowires.

• Applied Microscopy
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• v.49
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• pp.1.1-1.10
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• 2019

Joints of three-dimensional (3D) rutile-type (r) tin dioxide ($SnO_2$) nanowire networks, produced by the flame transport synthesis (FTS), are formed by coherent twin boundaries at $(101)^r$ serving for the interpenetration of the nanowires. Transmission electron microscopy (TEM) methods, i.e. high resolution and (precession) electron diffraction (PED), were utilized to collect information of the atomic interface structure along the edge-on zone axes $[010]^r$, $[111]^r$ and superposition directions $[001]^r$, $[101]^r$. A model of the twin boundary is generated by a supercell approach, serving as base for simulations of all given real and reciprocal space data as for the elaboration of three-dimensional, i.e. relrod and higher order Laue zones (HOLZ), contributions to the intensity distribution of PED patterns. Confirmed by the comparison of simulated and experimental findings, details of the structural distortion at the twin boundary can be demonstrated.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.209-215
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• 2005

Titanium dioxide films $(TiO_2)$ doped cobalt transition metal were prepared on titanium metal by water spray pyrolysis technique. Micro-morphology, crystalline structure, chemical composition and binding state of sample groups were evaluated using field emission scanning microscope(FE-SEM), X-ray diffractometer(XRD), Raman spectrometer, X-ray photoelectron spectrometer(XPS). $TiO_2$ films of rutile structure were predominately formed on all sample groups and $Ti_2O_3$ oxide was coexisted on the surface of cobalt doped-sample groups. The optical absorption peaks measured by using UV-VIS-NIR spectrophotometer were observed at specific wavelength region in sample groups doped cobalt ion. This result could be analyzed by introducing crystal field theory.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1982-1988
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• 2009

$TiO_2$ films are fabricated using silk printing method. Heat treatment temperature of films is 600[$^{\circ}C$]. From the analysis of microstructure, grain size of $TiO_2$ films is about $0.2{\sim}0.3[{\mu}m]$. Thickness of films is 30.19[${\mu}m$] and surface uniformity of films is good. From the analysis of crystalline structure, $TiO_2$ films transform anatase phase to rutile phase. Capacitance of films increases according to increase relative humidity and decrease measuring frequency. Hysteresis characteristics of capacitance and impedance are best at 45[%RH] and 75[%RH] respectively. Impedance of films increases according to decrease measuring frequency.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.36.2-36.2
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• 2011

Titanium and its alloys have been widely used for orthopedic implants because of their good biocompatibility. We have previously shown that the crystalline titania layers formed on the surface of titanium metal via anodic oxidation can induce apatite formation in simulated body fluid, whereas amorphous titania layers do not possess apatite-forming ability. In this study, hot water and heat treatments were applied to transform the titania layers from an amorphous structure into a crystalline structure after titanium metal had been anodized in acetic acid solution. The apatite-forming ability of titania layers subjected to the above treatments in simulated body fluid was investigated. The XRD and SEM results indicated hot water and/or heat treatment could greatly transform the crystal structure of titania layers from an amorphous structure into anatase, or a mixture of anatase and rutile.The abundance of Ti-OH groups formed by hot water treatment could contribute to apatite formation on the surface of titanium metals, and subsequent heat treatment would enhance the bond strength between the apatite layers and the titanium substrates. Thus, bioactive titanium metals could be prepared via anodic oxidation and subsequent hot water and heat treatment that would be suitable for applications under load-bearing conditions.

• Journal of the Korean Applied Science and Technology
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• v.25 no.2
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• pp.130-136
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• 2008

$xTiO_2$-$ySiO_2$ system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area were measured. Considering the efficiency of the ethanol and phenol degradation using the catalyst, the conclusions were obtained as follows: By means of X-ray analysis of $xTiO_2$-$ySiO_2$ powder that is obtained from Titanium and Silicon alkoxide by sol-gel process, it is shown that crystal structure of anatase type is a dominating structure and, on the other hand, the structure of rutile also partly exists. The increase of $SiO_2$ contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. It is shown that more than 90% of ethanol and phenol are degraded when reaction time is about three and an hours, and the maximum degradation rate of ethanol and phenol is shown in $60TiO_2$-$40SiO_2$ catalyst.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.213-213
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• 2009

Titanium dioxide ($TiO_2$) thin films were prepared on glass substrates by ion-assisted electron-beam evaporation with 200nm thickness and subsequently crystallized by rapid thermal annealing at the rage of $200{\sim}700^{\circ}C$ in flowing $N_2$ gas. The crystal structure of the films were examined by X-ray diffractometer. As-deposited $TiO_2$ films were amorphous. After annealing, anatase and rutile phase of $TiO_2$ films were observed together.

• Analytical Science and Technology
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• v.19 no.5
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• pp.376-382
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• 2006

In this work, pitch/activated carbon/$TiO_2$ composite were prepared by $CCl_4$ solvent method with different mixing ratios. The BET surface area of pitch/activated carbon/$TiO_2$ composite has a significantly increase with increasing activated carbon content in pitch/activated carbon/$TiO_2$ composite. The surface structure and elemental compositions of the composite were studied by SEM and EDX, respectively. The SEM results were presented to the characterization of porous texture on the pitch/activated carbon/$TiO_2$ composite. And EDX data was shown the presence of C, O, S, Ti and other elements. The structural properties of the composite were studied in XRD measurements. The $TiO_2$ crystal phases of the pitch/activated carbon/$TiO_2$ composite had lots of rutile-type structure which transforms from anatase-type with a little of anatase-type structure. The photocatalytic activities of the composite were evaluated using a photo-decomposition method under UV lamp. The pitch/activated carbon/$TiO_2$ composites were observed better photocatalytic activity than that of pristine $TiO_2$.