Korean Journal of Materials Research ISSN:1225-0562(Print) 2287-7258(Online) 한국재료학회지

This study describes the doping effect of Yb₂O₃ on microstructure, electrical and dielectric properties of ZnO-V₂O₅-MnO₂-Nb₂O₅ (ZVMN) ceramic semiconductors sintered at a temperature as low as 900°C. As the doping content of Yb₂O₃ increases, the ceramic density slightly increases from 5.50 to 5.54 g/cm³; also, the average ZnO grain size is in the range of 5.3-5.6 μm. The switching voltage increases from 4,874 to 5,494 V/cm when the doping content of Yb₂O₃ is less than 0.1 mol%, whereas further doping decreases this value. The ZVMN ceramic semiconductors doped with 0.1 mol% Yb₂O₃ reveal an excellent nonohmic coefficient as high as 70. The donor density of ZnO gain increases in the range of 2.46-7.41×10¹⁷ cm⁻³ with increasing doping content of Yb₂O₃ and the potential barrier height and surface state density at the grain boundaries exhibits a maximum value (1.25 eV) at 0.1 mol%. The dielectric constant (at 1 kHz) decreases from 592.7 to 501.4 until the doping content of Yb₂O₃ reaches 0.1 mol%, whereas further doping increases it. The value of tanδ increases from 0.209 to 0.268 with the doping content of Yb₂O₃.