Electrical and microstructural evaluation of ZnO varistor ceramics with different CaSiO3 contents

• Published in: Materials chemistry and physics 2022-09, Vol.289, p.126464, Article 126464
• Main Authors: Badruddin, Malia Athirah, Shaifudin, Muhamad Syaizwadi, Suhaimi, Abdul Mu'iz Aniq Aiman Mohd, Kamaruzzaman, Wan Mohamad Ikhmal Wan Mohamad, Mohd Nasir, Nursabrina Amirah, Yusof, Nusaibah, Kien, Chen Soo, Mohd Ghazali, Mohd Sabri
• Format: Article
• Language: English
• Subjects: Calcium silicate; Electrical behaviour; Microstructure; Varistor ceramics; Zinc oxide
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2022.126464

In the present study, the impact of CaSiO3 addition on microstructure and electrical characteristics of a ZnO-based varistor system was investigated. The ceramic materials were prepared by solid-state reaction route by varying the CaSiO3 concentrations (0, 3, 6, 9, 12, and 15 wt%) and sintered at 1300 °C. Characterization of the pelletized samples was carried out by density measurement, scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, and current density-electric field characteristics measurement. The growth of ZnO grain was restrained with the introduction of CaSiO3; the average grain size decreases from 18.09 to 10.85 μm, whereas their relative density increases up to 99.79%. Structural results indicated the existence of the CaSiO3-rich phase without any other secondary phase formation. It is also revealed that different CaSiO3 contents significantly affect the electrical properties, prominently in the sample with 12 wt% CaSiO3 addition. The maximal value of the nonlinear coefficient, breakdown voltage, and barrier height acquired in this work were 4.41, 0.80 V/mm, and 0.691 eV, respectively, along with a sharp decline in leakage current density to 373.93 μA/cm2. Further increase in CaSiO3 content (15 wt%) eventually caused a deterioration in varistor behavior. •Implementing CaSiO3 as the main varistor former in ZnO-based varistor ceramics.•The gradual incorporation of CaSiO3 additive favours the ceramics densification.•The presence of the CaSiO3-rich phase directly affects the electrical properties.