Papers by Keyword: Nonlinear Coefficient

Abstract: A stability loss of varistor is subjected to any of variety extreme conditions such different stresses AC or DC, temperature, pulse, pressure, humidity, etc. This causes degradation phenomenon and leads to thermal runaway or failure of varistor. The investigation of degradation phenomena is an important subject for prolonging their lives. In this study, we investigate the degradation process of ZnO_1-x-CoO_2.0-SLS_x varistor ceramics where x= 0.5, 1.0, 1.5, and 2.0 mol % by using conventional solid state method at sintering temperature of 1100 °C for 2 hour. The stability of their nonlinear properties was investigated under prolonged application of DC electric field at different SLS glass concentration. The degradation process was speeded up by applying direct current (DC) 85 % of electric field for 12 hours at temperature of 85 °C. A concentration of 2 mol % SLS glass doped ZnO varistor shows the best degradation properties as its nonlinear coefficient has increased by 3.56 %, the breakdown field has increased by 3.85 %, and the leakage current density (J_L ) increased by 2.40 % in comparison to its initial value.

Abstract: The zinc oxide based varistor are widely used as circuit protective devices by literally absorbs these dangerous surges and spikes or grounding this unwanted magnitudes. In this research, zinc oxide is added with 0.5 mol % CaMnO₃ as an additive and 0.2 mol % of rare earth doped of lanthanum oxide. Citrate-gel method is used as fabrication method. Complex compound undergoes sintering process which varied at 900 °C, 950 °C and 1000 °C, while, the sintering time are setting at 1 hour and 2 hours. Thermo gravimetric analysis (TGA) shows the forming of CaMnO₃ at 334-1000 °C. Fourier Transform Infrared (FTIR) spectra proved that the functional group present are.-O-H, C-H and C-O. The surface morphology with the grains size below 1μm was observed by Scanning Electron Microscopy (SEM). The α varistor ceramics was calculated from data analysis of I-V characteristics obtained through a Source Measure Unit (Keithley 236). The calculation of α is done by using Origin Pro8.0 software. I-V characteristic shows the value of α in the range of 1.00 to 4.05.