New type ZnO ceramic linear resistance materials

The effects of MgO, La₂O₃ and ZrO₂ additives on grain growth rate and grain size, and the influences of trace Li₂O on resistivities of ZnO grain and intergranular layer of ZnO ohmic ceramic materials have been investigated. Experimental results have been analysed. It is indicated that all of Mgo, La₂O₃ and ZrO₂ can make voltage-current characteristic of ZnO ceramic linear. MgO additive does not influence ceramic resistivity and growth rate of ZnO grains, however, La₂O₃ and ZrO₂ can be effectively used to control ceramic resistivity, and decrease grain growth rate. It is thought that the additives can change the concentration of interstitial Zinc [Zni], and finally control the growth rate of ZnO grains through changing the concentration of free electrons of ZnO grain during sintering.