%0 Journal Article
%T Synthesis Mechanism of Low-Voltage Praseodymium Oxide Doped Zinc Oxide Varistor Ceramics Prepared Through Modified Citrate Gel Coating
%A Wan Rafizah Wan Abdullah
%A Azmi Zakaria
%A Mohd Sabri Mohd Ghazali
%J International Journal of Molecular Sciences
%D 2012
%I MDPI AG
%R 10.3390/ijms13045278
%X High demands on low-voltage electronics have increased the need for zinc oxide (ZnO) varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synthesis mechanism for obtaining praseodymium oxide (Pr 6O 11) based ZnO varistor ceramics having breakdown voltages of 2.8 to 13.3 V/mm through employment of direct modified citrate gel coating technique. Precursor powder and its ceramics were examined by means of TG/DTG, FTIR, XRD and FESEM analyses. The electrical properties as a function of Pr 6O 11 addition were analyzed on the basis of I-V characteristic measurement. The breakdown voltage could be adjusted from 0.01 to 0.06 V per grain boundary by controlling the amount of Pr 6O 11 from 0.2 to 0.8 mol%, without alteration of the grain size. The non-linearity coefficient, ¦Á, varied from 3.0 to 3.5 and the barrier height ranged from 0.56 to 0.64 eV. Breakdown voltage and ¦Á lowering with increasing Pr 6O 11 content were associated to reduction in the barrier height caused by variation in O vacancies at grain boundary.
%K citrate gel
%K praseodymium oxide
%K varistors
%K zinc oxide
%U http://www.mdpi.com/1422-0067/13/4/5278