TY  - JOUR
T1  - Microstructural and Characteristics Study of Low Voltage ZnO-Bi<SUB>2</SUB>O<SUB>3</SUB>-Based Varistor Doped with Cr<SUB>2</SUB>O<SUB>3</SUB>, SiO<SUB>2 </SUB>and Varying Amounts of Al<SUB>2</SUB>O<SUB>3</SUB>
AU - , A. Djelloul AU - , A. Boumaza AU - , N. Bouzid AU - , A. Mahdjoub AU - , L. Hadjeris 
JO  - Asian Journal of Information Technology
VL  - 5
IS  - 11
SP  - 1248
EP  - 1255
PY  - 2006
DA  - 2001/08/19
SN  - 1682-3915
DO  - ajit.2006.1248.1255
UR  - https://makhillpublications.co/view-article.php?doi=ajit.2006.1248.1255
KW  - Varistor
KW  -microstructure
KW  -ZnO
KW  -ZnAl2O4
AB  - ZnO-Bi<SUB>2</SUB>O<SUB>3</SUB>-based varistor samples doped with 2.0 mol% of (Cr<SUB>2</SUB>O<SUB>3</SUB>+SiO<SUB>2</SUB>) and varying amounts of Al<SUB>2</SUB>O<SUB>3</SUB> in the range from 7.0 to 1.0 mol% were fired at 1200°C for 2h. Anew process is described for achieving the current-voltage characteristics ofa low voltage ZnO varistor. Second phases, segregated and precipitated in ZnO-based varistors, encountered in triple junctions and grain boundaries regions were identified using XRD, SEM and energy dispersive spectrometry. Using IR spectroscopy we have observed OH and H<SUB>2</SUB>O molecular  stretch  modes  at 3444.24 cm<SUP>-1</SUP> with a width of 273.53 cm<SUP>-1</SUP> and near 1637.27 cm<SUP>-1</SUP> with a width of 42.64 cm<SUP>-1</SUP> respectively. The hydrogen in Al doped ZnO-Bi<SUB>2</SUB>O<SUB>3</SUB>-based varistor may have a one site preference, resulting in a wider OH peak. The band at 662 cm<SUP>-1</SUP> should be due to the presence of the ZnAl<SUB>2</SUB>O<SUB>4</SUB> spinel, undoubtedly identified in the XRD patterns of sintered ceramics. Addition of hydrogen to aluminium doped varistors slow down the grain growth effect.
ER  -