The oxide films formed on etched aluminum foils play an important role as dielectric layers in aluminum electrolytic capacitors. Y2O3-doped ZrO2 (YZ) films were coated on the etched aluminum foils by sol-gel dip coating, and the electrical properties of YZ-coated Al foils were characterized. YZ films annealed at 450 oC were crystallized into a cubic phase, and as the Y2O3 doping content increased, the unit cell of ZrO2 expanded and the grain size decreased. The etch pits of Al foils were filled by YZ sol when it dried at atmospheric pressure after repeating for several times, but this step could essentially be avoided when being dried in a vacuum. YZ-coated foils indicated that the specific capacitance and dissipation factor were 2-2.5 μF/cm2 and 2-4 at 1 kHz, respectively, and the leakage current and withstanding voltage of films approximately 200 nm thick were 5 × 10−4A at 21 V and 22 V, respectively. After being anodized at 500 V, the foils exhibited a specific capacitance and dissipation factor of 0.6-0.7 μF/cm2 and 0.1-0.2, respectively, at 1 kHz, while the leakage current and withstanding voltage were 2 × 10−4 - 3 × 10−5 A at 400 V and 420-450 V, respectively. This suggests that YZ film is a promising dielectric that can be used in high voltage Al electrolytic capacitors.

1. Introduction
 2. Experimental procedure
  2.1 Sample preparation
  2.2 Characterization of samples
 3. Results and discussion
 4. Conclusions
 Acknowledgement
 References

• Fei Chen(School of Nano Materials Engineering, Kyungpook National University, Sangju 742-711, Korea)
• Sang-Shik Park(School of Nano Materials Engineering, Kyungpook National University, Sangju 742-711, Korea) Corresponding author