Tambunan, WalfredMalik, Usman2014-03-272014-03-272014-03-27wahyu sari yenihttp://repository.unri.ac.id/xmlui/handle/123456789/5965The varistor ZnO has been made by using raw materials: ZnO (E-Merck) and additive 0 %, 2.5 %, 5%, 7.5%, and 10% wt. Bi2O3. The important property of varistor ZnO is coefficient of non linier () and it can give influence correlation between current I and voltage V. The mixing process of raw materials was done by using magnetic stirrer and liquid acetone as media, and then was dried at 60oC, and also grinded until passing 400 meshes. Pellet was made by using pressing 50 MPa, and fired at 1050oC with holding time 2 hours. After firing, all samples are characterized, such as: measurement of coefficient of non linier (), and observation of microstructure by using Scanning Electron Microscope (SEM). The results show that sample without additive has  less than 5 and this sample has not properties as varistor, but the highest value of  is 64 for sample with additive 7.5% Bi2O3. The result of photos SEM shows that the increase of percentage of additive Bi2O3 can influence of formation grain boundary and grain size. Where, value of coefficient of non linier () is depend on existing of grain boundary and thickness of grain boundary.enBismuth OxideCoefficient non linierGrain boundaryNon ohmicVaristor ZnOUR-Scientific Work Lecturer