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<p>The set of ZnO-based varistors from different manufacturers was examined before and after aging with 8/20&#xa0;µs current lightning strokes. Aging resulted in an increase in leakage current of up to 25%. Powder X-ray diffraction (pXRD) analysis allowed identifiation except dominant ZnO oxide also δ-Bi<sub>2</sub>O<sub>3</sub> phases at grain boundaries, as well as additional phases such as pyrochlore (Zn<sub>2</sub>Bi<sub>3</sub>Sb<sub>3</sub>O<sub>14</sub>) and spinel (Zn<sub>7</sub>Sb<sub>2</sub>O<sub>12</sub>), indicating recrystallization of the samples after aging and an increase in microstrains (<i>ε</i>). Scanning electron microscopy (SEM) confirmed recrystallization caused by Joule heating and showed grain sintering inhomogeneities due to improper manufacturing processes. Electron paramagnetic resonance (EPR) studies indicated that aging caused an increase in the concentration of Mn<sup>2+</sup> and Co<sup>2+</sup>, which can be explained by a partial conversion of Mn<sup>3+</sup> and Co<sup>3+</sup> ions to their detectable states (Mn<sup>2+</sup> and Co<sup>2+</sup>). Dielectric spectroscopy demonstrated up to 40% changes in permittivity and distinct relaxation mechanisms between pristine and aged ceramics. The results highlight the necessity of employing comprehensive material studies in the assessment of commercial low voltage varistor quality.</p>

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Morphological, structural and physical characterization of commercially available low voltage ZnO-based varistors

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月6日

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  • Kuba Wójcik,
  • Leszek Litzbarski,
  • Marek Olesz,
  • Michał Winiarski,
  • Waldemar Bednarski,
  • Paweł Ławniczak,
  • Bartłomiej Andrzejewski

摘要

The set of ZnO-based varistors from different manufacturers was examined before and after aging with 8/20 µs current lightning strokes. Aging resulted in an increase in leakage current of up to 25%. Powder X-ray diffraction (pXRD) analysis allowed identifiation except dominant ZnO oxide also δ-Bi2O3 phases at grain boundaries, as well as additional phases such as pyrochlore (Zn2Bi3Sb3O14) and spinel (Zn7Sb2O12), indicating recrystallization of the samples after aging and an increase in microstrains (ε). Scanning electron microscopy (SEM) confirmed recrystallization caused by Joule heating and showed grain sintering inhomogeneities due to improper manufacturing processes. Electron paramagnetic resonance (EPR) studies indicated that aging caused an increase in the concentration of Mn2+ and Co2+, which can be explained by a partial conversion of Mn3+ and Co3+ ions to their detectable states (Mn2+ and Co2+). Dielectric spectroscopy demonstrated up to 40% changes in permittivity and distinct relaxation mechanisms between pristine and aged ceramics. The results highlight the necessity of employing comprehensive material studies in the assessment of commercial low voltage varistor quality.