• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.54-58
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• 2002

The present paper is to investigate the phase stability and soft magnetic properties of amorphous CoNbZr films when Pd is added as a substitution for CoNbZr alloys. The films were prepared by a RF magnetron sputtering method. The CoNbZrPd films deposited on Si wafers exhibited amorphous structures being independent upon the amount of Pd added in the films. On the addition of 4.34% Pd, the excellent soft magnetic characteristics of the films were observed with a coercive force of 0.54 Oe and an anisotropy field of 11 Oe, whereas a coercive force of 1 Oe and an anisotropy field of 3.5 Oe were shown in the film without the addition of Pd. The increased anisotropy field and low coercive force of the films may be attributed to the occupancy of Pd in the preferred sites parallel to the external magnetic field applied on the deposition process. A permeability of about 1100 was kept constant in the operation frequency ranging up to 100 MHz, which can be explained by the Landau-Lifshitz formula.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.173-173
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• 1999

The initial growth mode of Nb on Ag(110) in sub-monolayer region is studied using Scanning Tunneling microscopy. E-beam evaporated Nb is deposited onto the substrate at RT, and STM measurements are carried out at RT and 78K. With Nb being immiscible in bulk Ag, 3D islands formation begins at early stage and no particular ordered structure is found. At very low coverages, however, many interesting phenomena are observed in association with Nb clusters. Small Nb clusters as deposited displays very strong size dependence against atom-manipulation by the STM tip. In addition, the apparent corrugation of clusters below the critical size exhibits dramatic dependence on the imaging bias, disappearing completely over a wide range of the bias. Possible physical mechanism responsible for such behavior will be discussed.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1043-1047
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• 1998

The effect of CuO and CdO addition on the microwave dielectric properties of $BiNbO_4$, ceramics were investigated. As the content of CdO increased, sintered density and quality factor decreased. With increasing sintering temperature, both the dielectric constant and quality factor increased. In the case of specimen sintered at $960^{\circ}C$ with addition of 0.03 wt% of CuO and CdO, respectively. the microwave dielectric properties obtained were dielectric constant of 41.2, quality factor ($Q{\times}f_0$) of 6,500 (at 5.6GHz), temperature coefficient of resonant frequency of $3ppm^{\circ}C$.

• Nuclear Engineering and Technology
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• v.43 no.5
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• pp.421-428
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• 2011

The out-of-pile mechanical performance and microstructure of recrystallized Zr-1.5 Nb-S alloy was investigated. The strength of the recrystallized Zr-1.5Nb-O-S alloys was observed to increase with the addition of sulfur over a wide temperature range, from room temperature up to $300^{\circ}C$. A yield drop and stress serrations due to dynamic strain were observed at room temperature and $300^{\circ}C$. Wavy and curved dislocations and loosely knit tangles were observed after strained to 0.07 at room temperature, suggesting that cross slip is easier. At $300^{\circ}C$, however, dislocations were observed to be straight and aligned along the slip plane, suggesting that cross slip is rather difficult. At $300^{\circ}C$, oxygen atoms are likely to exert a drag force on moving dislocations, intensifying the dynamic strain aging effect. Oxygen atoms segregated at partial dislocations of a screw dislocation with the edge component may hinder the cross slip, resulting in the rather straight dislocations distributed on the major slip planes. Recrystallized Zr-Nb-S alloys exhibited ductile fracture surfaces, supporting the beneficial effect of sulfur in zirconium alloys. Oxidation resistance in air was also found to be improved with the addition of sulfur in Zr-1.5 Nb-O alloys.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.292-293
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• 2006

$ZnNb_2O_6$ ceramics were sintered under the presence of zinc-borosilicate(ZBS) glass and resultant microwave dielectric properties were investigated with a view to applying the composition to LTCC technology. The addition of 10~30 wt% ZBS glass ensured successful sintering below $900^{\circ}C$. In general, increased addition of ZBS glass increased sinterability but it decreased the dielectric properties significantly due to the formation of an excessive liquid and second phases. The sintered $ZnNb_2O_6$ ceramics at $900^{\circ}C$ with 25 wt% ZBS glass demonstrated 15.8 in dielectric constant(${\varepsilon}_r$), 5,400 in quality factor($Q{\times}f_0$), and $-98\;ppm/^{\circ}C$ in temperature coefficient of resonant frequency(${\tau}_f$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.313-314
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• 2006

$BiNbO_4$ ceramics were sintered under the presence of zinc-borosilicate(ZBS) glass and resultant microwave dielectric properties were investigated with a view to applying the composition to LTCC technology. The addition of 5~20 wt% ZBS glass ensured successful sintering below $900^{\circ}C$. In general, increased addition of ZBS glass increased sinterability and temperature coefficient of resonant frequency(${\tau}_f$), but it decreased the dielectric constant(${\varepsilon}_r$) and quality factor($Q{\times}f_0$) significantly due to the formation of an excessive liquid. The sintered $BiNbO_4$ ceramics at $900^{\circ}C$ with 15 wt% ZBS glass demonstrated 25 in dielectric constant(${\varepsilon}_r$), 3,700 in quality factor($Q{\times}f_0$), and -32 $ppm/{\circ}C$ in temperature coefficient of resonant frequency(${\tau}_f$).

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.432-436
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• 1995

The hydrogen decrepitation behaviour of the $Sm_{2}Fe_{17} alloy containing 4at%Nb was examined by means of DTA and SEM metallography, and the magnetic properties of the alloy were studied by means of VSM or TMA. It has been found that a simple hydrogenation and degassing treatment for the alloy caused a poor hydrogen decrepitation. The cycle treatment consisting of repeated hydrogenation and degassing, however, caused a severe hydrogen decrepitation with a combination of intergranular and transgranular failure. The disproportionation temperature of the hydrogenated $Sm_{2}Fe_{17}-type alloy was enhanced significantly by small addition of Nb. It has also been found that the Curie temperature of $Sm_{2}Fe_{17} matrix phase in the Nb-containing alloy has been enhanced by the hydrogenation, and this was attributed to the increase in interatomic distance between the neighbouring iron atoms caused by the interstitial occupancy of the hydrogen atom into the $Sm_{2}Fe_{17}-type lattice. The magnetisation of the $Sm_{2}Fe_{17} alloy containing Nbwas found to be lower than that of the Nb-free alloy, and this was explained by the dilution effect due to the presence of the paramagnetic $Sm_{2}Fe_{17} phase.

• Korean Journal of Materials Research
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• v.13 no.11
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• pp.761-768
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• 2003

The corrosion resistance and cytotoxicity behavior of Ti alloys were studied as a function of Nb contents(3wt.%Nb, 20wt.%Nb, 40wt.%Nb). Ti-Nb alloys were melted by vacuum arc furnace and then rolled to 50% reduction ratio after homogenized at 105$0^{\circ}C$ for 24hrs. The corrosion resistance of Ti-Nb alloys were investigated by potentiodynamic polarization test in the 0.9% NaCl and 5% HCI solution. Biocompatibility of Ti-Nb alloys was evaluated by cytotoxicity test. The results can be summarized as follows 1) The microstructure change from equiaxial to acicular and the increased $\beta$ phase in Ti-Nb alloys were obtained as the Nb content increased. 2) For the corrosion test in the solution of 0.9% NaCl and 5% HCI, the corrosion behavior of Ti-Nb alloys was similar to ASTM grade 2 CP Ti. 3) For the cytotoxicity test, Ti-Nb alloys showed excellent biocompatibility compared to ASTM grade 2 CP Ti, 316L STS and Co-Cr alloys.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.56-61
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• 2009

STATEMENT OF PROBLEM. The success of titanium implants is due to osseointegration or the direct contact of the implant surface and bone without a fibrous connective tissue interface. PURPOSE. The purpose of this study was to evaluate the osteoblast precursor response to titanium-10 tantalum-10 niobium(Ti-Ta-Nb) alloy and its sputtered coating. MATERIAL AND METHODS. Ti-Ta-Nb coatings were sputtered onto the Ti-Ta-Nb disks. Ti6-Al-4V alloy disks were used as controls. An osteoblast precursor cell line, were used to evaluate the cell responses to the 3 groups. Cell attachment was measured using coulter counter and the cell morphology during attachment period was observed using fluorescent microscopy. Cell culture was performed at 4, 8, 12 and 16 days. RESULTS. The sputtered Ti-Ta-Nb coatings consisted of dense nanoscale grains in the range of 30 to 100 nm with alpha-Ti crystal structure. The Ti-Ta-Nb disks and its sputtered nanoscale coatings exhibited greater hydrophilicity and rougher surfaces compared to the Ti-6Al-4V disks. The sputtered nanoscale Ti-Ta-Nb coatings exhibited significantly greater cell attachment compared to Ti-6Al-4V and Ti-Ta-Nb disks. Nanoscale Ti-Ta-Nb coatings exhibited significantly greater ALP specific activity and total protein production compared to the other 2 groups CONCLUSIONS. It was concluded that nanoscale Ti-Ta-Nb coatings enhance cell adhesion. In addition, Ti-Ta-Nb alloy and its nanoscale coatings enhanced osteoblast differentiation, but did not support osteoblast precursor proliferation compared to Ti-6Al-4V. These results indicate that the new developed Ti-Ta-Nb alloy and its nanoscale Ti-Ta-Nb coatings may be useful as an implant material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.208-209
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• 2006

Sinterability and microwave dielectric properties of the $Zr1-x(Zn_{1/3}Nb_{2/3})xTiO_4$(x=4, 6) system ceramics have been investigated as functions of zinc-borosilicate(ZBS) glass contents and amount of $Zn_{1/3}Nb_{2/3}O_2$ substitution with a view to applying the composition to LTCC technology. The addition of 25 wt% ZBS glass ensured successful sintering below $925^{\circ}C$. With increasing ZBS glass and $Zn_{1/3}Nb_{2/3}O_2$ contents increased dielectric constant and sinterability but addition ZBS glass decreased the quality factor significantly due to the formation of an excessive liquid and second phases. The sintered $Zr4(Zn_{1/3}Nb_{2/3})6TiO_4$ system ceramics at $925^{\circ}C$ with 25 wt% ZBS glass demonstrated 27.7 in dielectric constant (${\varepsilon}_r$), 3,850 m quality factor($Q{\times}f_0$), and +6 ppm/$^{\circ}C$ in temperature coefficient of resonant frequency($\tau_f$).