ZnO-based varistor samples with a relatively high Sb_2O_3 to Bi_2O_3 ratio of 5 were fired at 1200 deg C and found to have a high threshold voltage (V_T) of 280 V/mm and a low energy-absorption capacity of 50 J/cm~3. The introduction of rare-earth oxides (REO) increased the energy-absorption capacity of Pr_6O_(11)- and Nd_2O_3-doped samples to 110 J/cm~3 while their threshold voltage (V_T) remained slightly above 300 V/mm. Doping with Pr_6O_(11) and Nd_2O_3 altered the formation of the spinel phase and significantly changed its particle size and distribution which, as a result, had a positive effect on the energy-absorption capacity of the REO-doped samples. Doping with small amounts of Pr_6O_(11) and Nd_2O_3 appears to be promising for the preparation of ZnO-based varistors with a high breakdown voltage and a high energy absorption capacity.
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