Sains Malaysiana 49(4)(2020): 871-876

http://dx.doi.org/10.17576/jsm-2020-4904-16

Enhancement of Non-Ohmic Properties of CoO DopeD ZnO Varistor Ceramics using Soda Lime Silica (SLS) Glass

(Peningkatan Sifat Bukan Ohmik Seramik Varistor CoO DopeD ZnO menggunakan Kaca Soda Kapur Silika (SLS))

NUR QURATUL AINI ISMAIL, NOR KAMILAH SA'AT* & MOHD HAFIZ MOHD ZAID

 Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia

  Received: 9 October 2019/Accepted: 2 January 2020  

ABSTRACT

ZnO-SLS-CoO (ZSC) based varistor ceramics were prepared at a high sintering temperature of 1100 ºC via the conventional solid-state method. The effect of SLS glass on the electrical properties was studied at the different concentration of SLS glass ranging from 0.5 mol% to 2 mol%. Scanning electron microscopy (SEM) and X-ray diffractometer (XRD) were used to examine microstructure and crystal structure of the glass phase based ZSC varistor. For the electrical characteristics, the source measuring unit was used. The result shows that SiO₂ as the major chemical compound found in the SLS glass that responsible for controlling the ZnO grain growth. When the concentration of SLS glass higher than 1 mol%, the dominant peak of ZnO was found in XRD pattern, which is the primary phase whereas the additional peak belongs to Zn₂SiO₄ as the secondary phase. ZSC varistor ceramics with 2 mol% of SLS glass possessed the best electrical properties with the highest nonlinear coefficient α at 4.38 and the lowest leakage current. The increasing value of α could be due to the increase in oxygen vacancies that eventually contributes to the increase of Schottky barrier formation.

  Keywords: Nonlinear coefficient; Schottky barrier; solid-state method; varistors; zinc oxide

ABSTRAK

Seramik varistor berasaskan ZnO-SLS-CoO (ZSC) disediakan pada suhu pensinteran tinggi 1100 ºC melalui kaedah keadaan pepejal konvensional. Kesan kaca SLS terhadap sifat elektrik dikaji pada kepekatan berbeza kaca SLS antara 0.5 mol% hingga 2 mol%. Mikroskopi elektron imbasan (SEM) dan difraktometer sinar-X (XRD) digunakan untuk memeriksa mikrostruktur dan struktur kristal fasa kaca berdasarkan varistor ZSC. Untuk ciri elektrik, unit pengukur sumber telah digunakan. Hasilnya menunjukkan bahawa SiO₂adalah sebatian kimia utama yang terdapat di dalam kaca SLS yang bertanggungjawab mengawal pertumbuhan bijirin ZnO. Apabila kepekatan kaca SLS lebih tinggi daripada 1 mol%, puncak ZnO yang dominan didapati dalam corak XRD, yang merupakan fasa utama manakala puncak tambahan milik Zn₂SiO₄ sebagai fasa sekunder. Seramik varistor ZSC dengan 2 mol% kaca SLS memiliki sifat elektrik terbaik dengan pekali tak linear α tertinggi pada 4.38 dan arus kebocoran terendah. Peningkatan nilai α mungkin disebabkan oleh peningkatan kekosongan oksigen yang akhirnya menyumbang kepada peningkatan pembentukan halangan Schottky.

Kata kunci: Halangan Schottky; kaedah keadaan pepejal; pekali tak linear; varistor; zink oksida

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*Corresponding author; email: kamilah@upm.edu.my