Study of Synthesizing Zinc Oxide For Varistors Application By Sol-Gel Method

• Main Author: Yohansyah, Rudy
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/33656
• Institution: Institut Teknologi Bandung

Varistors are component that protect electronic circuits from voltage surge, both low voltage and high voltage which have the potential to damage other components in the circuit. Therefore, the main characteristic of a varistor is its nonlinear electrical properties which is the alternative to the generally used of the ohm law. The properties needed in a varistor are nonohmic properties where the resistance of the varistor material will decrease as the voltage increases. Varistors generally use zinc oxide material because zinc oxide has a higher nonlinearity than other materials that are often used for varistors. The initial developing ofvaristors started in 1930 and the development with ZnO started since 1960s. Further developments are done to enhance the performance, microstructure homogenity and resistance to degradation. However, the varistors production process is still on an industrial scale. Therefore, further studies are needed to study the production process of varistors on a laboratory scale. The ZnO synthesis process uses the sol-gel method. Zinc oxide crystalline powder with a size of 0.5-2 micrometers were obtained. After the powder is obtained, it is compacted with the specified load variable and then sintered. Then the material was characterized using XRD to obtain elemental content, SEM to determine morphology, and I-V meter to determine the degree of linearity of the current and voltage passing through it. From XRD was found zinc oxide as much as 83,97% and other phases are 16,03%. The density of the specimens that were obtained are 48,3%, 50,4% and 52,8% relatively to the reference. The structure of the powder that was obtained from SEM is hexagonal wurtzite. For the 5 tons load has porous morphology, 7 tons load has dense morphology and has smaller crystals that fill the gap among the grains and then the 10 tons load has similar morphology to the 7 tons load but has bigger crystals that fill the gap among the grains. The results of each load given has nonlinear electric property, but the 7 tons load results the highest breakdown voltage that is shown with the gradient of the graph in the reverse bias region is about 0,1o compared to the 5 tons load with 1o gradient and 10 tons load has 10o gradient.