• Journal of Powder Materials
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• v.25 no.1
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• pp.48-53
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• 2018

One-dimensional rutile $TiO_2$ is an important inorganic compound with applicability in sensors, solar cells, and Li-based batteries. However, conventional synthesis methods for $TiO_2$ nanowires are complicated and entail risks of environmental contamination. In this work, we report the growth of $TiO_2$ nanowires on a Ti alloy powder (Ti-6wt%Al-4wt%V, Ti64) using simple thermal oxidation under a limited supply of $O_2$. The optimum condition for $TiO_2$ nanowire synthesis is studied for variables including temperature, time, and pressure. $TiO_2$ nanowires of ${\sim}5{\mu}m$ in length and 100 nm in thickness are richly synthesized under the optimum condition with single-crystalline rutile phases. The formation of $TiO_2$ nanowires is greatly influenced by synthesis temperature and pressure. The synthesized $TiO_2$ nanowires are characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM).

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.267-270
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• 2003

수용성 양이온 안료인 RhB를 대상으로 분말 $TiO_2$와 고정화 $TiO_2$를 이용하여 색도제거실험을 수행한 결과 다음과 같은 결론을 얻었다. 1) 분말 $TiO_2$의 최적 투입량은 0.2 g/L였으며, 대부분 광촉매 반응에 의하여 제거되었다. 고정화 $TiO_2$의 최적 투입량은 210.7 g/L이었고, 광촉매와 흡착에 의해 제거되었다. Langmuir - Hinshelwood 식으로 표현되지 못하였다. 2) 고정화 $TiO_2$를 이용하여 Rhodamine B를 제거할 경우 광촉매 분리 문제는 해결할 수 있으며, 광 투과율을 증가시킬 수 있으나 같은 제거율을 얻기 위해 투입량이 분말에 비해 매우 높은 것이 문제점으로 나타났다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11b
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• pp.295-299
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• 2003

1. 고정화 $TiO_2$의 경우도 분말을 이용한 것과 같이 최적 광촉매 투입량이 나타났으며, 최적 투입량은 33.8 g/L이었고, 분말 $TiO_2$를 이용한 경우보다 빠른 초기반응속도를 보였으며, 최종반응시간도 빠른 것으로 나타났다. 2. 수용액에서 빠른 초기 제거속도의 1차적인 기작은 고정화 $TiO_2$ 표면으로의 흡착 때문이었으며, 빠른 흡착으로 인해 수용액 중의 RhB 농도가 빠르게 감소하여 광 투과율이 증가하므로 전체 반옹속도가 빠른 것으로 사료되었다. 3. 고정화 $TiO_2$를 이용한 유동층 반응기의 경우 최적 공기 공급량은 의한 Rhodamine B의 초기 제거속도는 분말보다 빠르지만 전체적인 제거시간은 흡착된 Rhodamine B의 분해 때문에 분말 $TiO_2$보다 느린 것으로 나타났다.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.97-104
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• 1997

Hydrothermal synthesis of PbZ1-xTixO3 has been investigated. Syntheses were performed using lead acetate triphdrate as Pb source, Ti/Zr gel by hydrolizing Ti-isopropoxide as Tiand Zr source and Zr-propoxide and KOH (0.5m, 1m, 2m) as mineralizer. The hydrothermal synthesis has been examined at 140℃, 150℃ and 160℃. Synthesized PZT powders showed a rectangular shape and were agglomerate. At 1m and 2m KOH concentrations PZT powders were synthesized the respective time of 8 hrs and 1hr but at 0.5m KOH concentration phase pure PZT powders were not synthesized for 5days reaction. At the conditions of low temperature and low KOH concentration unreacted Ti/Zr gel remained although synthesized powders were almost PZT. The size of PZT powders increased with KOH concentrations. PbO solid solutions were formed as intermediate phases and these were classified to PbO-10%TiO2 solid solution and PbO-3% TiO-3% TiO2 solid solution.

• Electrical & Electronic Materials
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• v.6 no.5
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• pp.436-445
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• 1993

2단계하소법에 의해 낮은 하소온도에서 미세하고도 균일한 PZT분말을 합성하였다. 우선 Zr $O_{2}$와 Ti $O_{2}$ 혼합분말을 1차하소하여 (Z $r_{0.53}$ $Ti_{0.47}$) $O_{3}$(ZTO) 분말을 합성하고 이 ZTO 고용분말에 PbO와 N $b_{2}$ $O_{5}$을 혼합한 후 650-800.deg.C에서 2시간 하소하여 PZT 분말을 합성하였는데 얻어진 분말은 고상반응법에 비해 미세할 뿐만 아니라 XRD 분석결과 710.deg.C의 낮은 하소온도에서도 PZT 단일상을 나타내었다. 2단계하소법에 의해 하소온도를 낮출 수 있는 주된 이유로는 고상반응법에서는 중간생성물인 PbTi $O_{3}$상의 생성이 수반됨으로 850.deg.C 이상 되어야만 안전한 PZT가 생성될 수 있는 점을 들 수 있다. 또 2단계하소법에 의하면 950.deg.C이하의 낮은 소결온도에서도 치밀화가 미루어지는 소결이 가능함을 알 수 있었는데 이와같이 소결온도를 낮출 수 있는 것은 고상반응법에 비해 미세한 PZT 분말을 사용하였기 때문이라 풀이된다.이된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.1
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• pp.60-69
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• 1992

Fine $TiO_2$ powders were synthesized from ammonium titanium sulphate which produced from $TiCI_4$, and$(NH_4)_2$ SO. solution. Rutile single crystal were grown by the verneuil method with anatase powders and investigated the property of rutile crystal. The optimun growing conditions were as follows $\cdot$The ratio of hydrogen gas and oxygen gas; 3: 1 $\cdot$Growing temperature: $1900^{\circ}C$ $\cdot$The feeding rate of powders: 10g/hr

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.195-200
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• 1997

핵융합로 증식재용 r-LiAlO$_2$, Li$_2$ZrO$_3$, Li$_2$TiO$_3$ 분말을 자발착화 연소반응법으로 합성하였다. LiAlO$_2$와 달리 Li$_2$ZrO$_3$ 와 Li$_2$TiO$_3$는 가열하는 동안 침전물이 생겼지만 카르복실산기만을 지닌 구연산과 아민기만을 지닌 우레아를 화학정량의 조성으로 혼합한 연료로 쉽게 분말을 합성할 수 있었다. LiAlO$_2$나 Li$_2$TiO$_3$분말은 별도의 하소 공정이필요없이 원하는 결정상이 형성되었으며, Li$_2$ZrO$_3$분말은 Li이 과량인 상이 형성되므로 110$0^{\circ}C$에서 하소하여 원하는 상을 얻었다. 합성된 Li계 산화물 분말은 비표면적 10~17 $m^2$/g으로 약 150 nm정도의 입자크기를 갖는 미세한 입자이었다.

• Journal of Powder Materials
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• v.9 no.2
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• pp.110-115
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• 2002

In order to obtain the nano size $10wt%Cu-TiO_2$composite powders by mechanical alloying method for useful composite catalysis, the effects of mechanical alloying time on the formationof $10wt%Cu-TiO_2$ composite powders were analyzed. The phase transformation behaviors were experimented as the heat treating temperature increased. Homogeneous 10wt% Cu-rutile type $TiO_2$composite powders were synthesized in 40 hours by mechanical alloying. After 60 hours mechanical alloying 50 nm size $TiO_2$powders were obtained. Both the phase of mechanically alloyed 10 wt% $Cu-TiO_2$ and pure $TiO_2$ powders were not transformed to anatase after annealing at the temperature range between 350 to 500 $^{\circ}C$. The intermetallic compound of $Cu_2Ti_4$O was formed after 10 hours mechanical alloying, however it could be considered that this intemetallic phase dose not prevent the transformation of rutile $TiO_2$ to the anatase phase after heat treatment at the temperature between 350 and $550^{\circ}C$.

• Journal of Powder Materials
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• v.23 no.1
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• pp.33-37
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• 2016

10 wt.% and 20 wt.%$Li-TiO_2$ composite powders are synthesized by a sol-gel method using titanium isopropoxide and $Li_2CO_3$ as precursors. The as-received amorphous 10 wt.%$Li-TiO_2$ composite powders crystallize into the anatase-type crystal structure upon calcination at $450^{\circ}C$, which then changes to the rutile phase at $750^{\circ}C$. The asreceived 20 wt%$Li-TiO_2$ composite powders, on the other hand, crystallize into the anatase-type structure. As the calcination temperature increases, the anatase $TiO_2$ phase gets transformed to the $LiTiO_2$ phase. The peaks for the samples obtained after calcination at $900^{\circ}C$ mainly exhibit the $LiTiO_2$ and $Li_2TiO_3$ phases. For a comparison of the photocatalytic activity, 10 wt.% and 20 wt.% $Li-TiO_2$ composite powders calcined at $450^{\circ}C$, $600^{\circ}C$, and $750^{\circ}C$ are used. The 20 wt.%$Li-TiO_2$ composite powders calcined at $600^{\circ}C$ show excellent efficiency for the removal of methylorange.

• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.343-353
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• 1999

Microwave(2.45 GHz) was used as energy source in hydrothermal reaction to fabricate ultrafine BaTiO3 powder. Using microwave of 700 W, crytal BaTiO3 began to fom after 5 min in microwave-autoclave sys-tem. The crystallinity was not noticeably increased with increasing longer reaction time than 10 min. On the other hand in microwave-reflux system crytal BaTiO3 began to form after 15min and the crystallinity was not noticeably increased with increasing longer reaction time than 1hr,. In either case particle size dis-tribution was considerably uniform due to the effect of homogeneous heating by microwave. In addition mi-crowave heating gave an extremely small degree of particle agglomeration compared to electric heating. Av-erage sizes of as-synthesized powders were 30-60nm. Ba/Ti ratio in sol played an important role in det-ermining the particle size. It seems that excess barium forms different phases such as Ba(OH)2 which makes thin layer on the surface of BaTiO3 powder. This thin layer would inhibit the agglomeration of Ba-TiO3 powders and keep the small grain size. In microwave-autoclave system tetragonal-BaTiO3 was formed directly by the reaction of only 15 min. In the case of microwave-reflux system tetragonal-BaTiO3 was formed by driyng over 25$0^{\circ}C$.