Preparation of Nano-Sized ITO Powder from Waste ITO Target by Spray Pyrolysis Process

폐(廢) ITO 타겟으로부터 분무열분해(噴霧熱分解) 공정(工程)에 의한 ITO 나노 분말(粉末) 제조(製造)

  • Yu, Jae-Keun (Department of Advanced Materials Engineering, Hoseo University) ;
  • Kang, Seong-Gu (Department of Advanced Materials Engineering, Hoseo University) ;
  • Sohn, Jin-Gun (Pohang Research Institute of Industrial Science and Technology)
  • Published : 2007.02.27

Abstract

Nano-sized ITO powders with the average particle size below 50 nm were synthesized from complex acid solution dissolved the ITO target into hydrochloric acid by a spray pyrolysis process, and the influences of reaction factors as reaction temperature and concentration of raw material solution were investigated. As the reaction temperature increases from 800 to $1000^{\circ}C$, the average particle size of the ITO powder increases from 40 nm to 100 nm, the microstructure gradually becomes solid, individual particles independently appear with the shape of polygon, the particle size distribution becomes increasingly irregular, the XRD peak intensity gradually increases and the specific surface area decreases. As the concentration of the raw material solution increases from 50g/l to 400g/l, the average particle size of ITO powder gradually increases, yet the particle size distribution appears more irregular. When the concentration is at 50 g/l, the average particle size of ITO powder is below 30 nm and the particle size distribution appears comparatively uniform. Nevertheless, when the concentration reaches 400 g/l, which is close to e saturated concentration, the particle size distribution appears extremely irregular, and the particles with the size ranging from 20 nm to 100 nm coexist. Along with the concentration rise, the XRD peak intensity gradually increases, yet the specific surface area decreases.

폐 ITO 타겟을 염산에 용해시킨 복합 산용액을 원료로 하여 자체기술에 의해 개발한 분무열분해 반응장치를 통하여 평균입도가 50nm이하인 나노 ITO 분말을 제조하였으며, 반응온도 및 원료용액의 농도 등의 반응인자들의 변화에 따른 ITO 분말의 특성을 파악하였다. 반응온도가 $800^{\circ}C$로부터 $1100^{\circ}C$로 변화함에 따라 생성된 ITO 분말의 평균 입도는 40nm로부터 100nm정도까지 증가하고 있었으며, 조직도 점점 치밀화되면서 각각의 입자들이 독립된 다각형 형태를 나타내었으며, 입도분포는 더욱 불균일하게 나타나고 있었다. 또한 반응온도 증가에 따라 XRD 피크의 강도는 증가하였으며 비표면적은 감소하고 있었다. 원료용액 내의 인듐 성분의 농도가 50g/l로부터 400g/l로 증가됨에 따라 생성된 ITO 분말의 평균입도는 점점 증가하는 반면 입도분포는 더욱 불균일 하였다. 농도가 50g/l인 경우에는 ITO 분말의 평균입도는 30nm 이하이면서 입도분포는 비교적 균일하게 나타나고 있었다. 반면 농도가 포화농도에 가까운 400g/l인 경우에는 분말들의 입도분포는 20nm 정도부터 100nm 이상까지 공존하는 매우 불균일한 형태를 나타내고 있었다. 농도가 증가함에 따라 XRD 피크의 강도는 점점 증가하였으며 비표면적은 점점 감소하였다.

Keywords

References

  1. A. Antony, M. manoj and M.K. jayaraj, 2004 : Influence of Target to Substrate Spacing on the Properties of ITO Thin Films, Appl. Surf. Sci., 225, pp. 294-301 https://doi.org/10.1016/j.apsusc.2003.10.017
  2. L.R. Cruz, C. Legnani, I.G. Matoso, C.L. Ferreira and H.R. Moutinho, 2004 : Influence of Pressure and annealing on the Microstructural and Electro-Optical properties of RF Magnetron Spettered ITO Thin Films, Mat. Res. Bull., 39, pp. 993-1003 https://doi.org/10.1016/j.materresbull.2004.03.008
  3. Y. Hu, X. Diao, C. Wang, W. Hao and T. Wang, 2004 : Effects of Heat Treatment on Properties of ITO Films Prepared by RF Magnetron Sputtering, Vacuum, 75. pp. 183-188 https://doi.org/10.1016/j.vacuum.2004.01.081
  4. K. Maki, N. Komiya and A. Suzuki, 2003 : Fabrication of Thin Films of ITO by Aerosol CVD, Thin Solid Films, 445, pp. 224-248 https://doi.org/10.1016/j.tsf.2003.08.021
  5. S. Tang, J. Yao, J. Chen and J. Luo, 2003 : Preparation of Indium Tin Oxide(ITO) with a Single-Phase Structure, J. Mater. Process. Technol., 137, pp. 82-85 https://doi.org/10.1016/S0924-0136(02)01072-5
  6. K. Utsumi, O. Matsunaga and T. Takahata, 1998 : Low Resistivity ITO Film Prepared Using the Ultra High Density ITO 타겟, Thin Solid Films, 334, pp. 30-34 https://doi.org/10.1016/S0040-6090(98)01111-0
  7. W.F. Wu, B.S. Chiou and S.T. Hsieh, 1994 : Effect of Sputtering Power on the Structural and Optical Properties of RF magnetron Sputtered ITO Films, Semicond. Sci. Technol., 9, pp. 1242-1249 https://doi.org/10.1088/0268-1242/9/6/014
  8. S.G. Chen, C.H. Li, W.H. Xiong, L.M. Liu and H. Wang, 2002 : Preparation of indium-Tin Oxide (ITO) Aciculate by a Novel Concentration-Precipitation and Post-Calcination Method, Mater. Lett., 58, pp. 294-298 https://doi.org/10.1016/S0167-577X(03)00472-5
  9. P.S. Devi, M. Chatterjee and D. Ganguli, 2002 : Indium Tin Oxide Nano Particles through an Emulsion Technique, Mater. Lett., 55, pp. 205-210 https://doi.org/10.1016/S0167-577X(01)00647-4
  10. C.P. Udawatte and K. Yanagisawa, 2001 : Fabrication of Low Porosity Indium Tin Oxide Ceramics in Air from Hydrothermally Prepared Powder, J. Am. Ceram. Soc., 84, pp. 251-253 https://doi.org/10.1111/j.1151-2916.2001.tb00645.x
  11. K. Yanagisawa, C.P. Udawatte and N. Nasu, 2000 : Preparation and Characterization of Fine Indium Tin Oxide (ITO) Powders by a Hydrothermal Treatment and Post Annealing Method, J. Mater. Res., 15, pp. 1404-1408 https://doi.org/10.1557/JMR.2000.0203