The effects of Barium Strontium Titanate (BST) on the soft magnetic properties and loss performance of MnZn ferrites. Issue 12 (15th June 2023)

• Record Type: Journal Article
• Authors: Li, Ziyu; Yi, Yaohua; Wang, Hong; Yu, Zhong; Wu, Chuanjian; Dou, Haizhi; Li, Qifan; Sun, Ke; Jiang, Xiaona; Lan, Zhongwen
• Is Part Of: Ceramics international. Volume 49:Issue 12(2023)
• Page Start: 19631
• Page End: 19640
• Publication Date: 2023-06-15
• Subjects: MnZn ferrites -- Barium strontium titanate -- Soft magnetic materials -- Positive temperature coefficient of resistivity -- Power loss; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2023.02.160
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: With the increasing power density of the switched mode power supply (SMPS) developed nowadays, higher efficiency is required from the magnetic core, where the MnZn ferrites are often adopted. However, the relatively high operating temperature of the SMPS often results in reduced resistivity of the MnZn, which increases the eddy current loss. To enhance the resistivity of MnZn ferrite at high temperature range (>100 °C), donor-doped barium strontium titanate (BST) with a positive temperature coefficient of resistivity (PTCR) is prepared and dopped in the MnZn ferrite. The influence of BST addition from 0.000 wt% to 0.020 wt% on the MnZn ferrite is investigated over a wide temperature range from 25 °C to 140 °C. The XRD result suggests ionic exchange between the spinel phase and perovskite phase. The SEM result shows a refined and more uniform microstructure of MnZn ferrite brought about by the BST addition. At the maximum of 0.020 wt%, the BST addition shows almost no influence on density and the saturation magnetic induction. However, the initial permeability is slightly reduced by the BST addition, due to the microstructural change. Moreover, the BST concentrating at the grain boundaries improves the DC-resistivity across the temperature range from 25 °C to 140 °C. Due to the addition of BST, the reduction in eddy current loss at 300kHz/100 mT is around 35% at 25 °C, and ∼20% reduction at 140 °C.