The effect of Nb 2O 5 dopant on the structural and magnetic properties of MnZn-ferrites

• Published in: Journal of magnetism and magnetic materials Vol. 250; pp. 98 - 109
• Main Authors: Zaspalis, V.T, Antoniadis, E, Papazoglou, E, Tsakaloudi, V, Nalbandian, L, Sikalidis, C.A
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2002
• Subjects: MnZn-ferrites; Nb 2O 5; Power losses; Nb 2O 5; Power losses; MnZn-ferrites
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(02)00367-0

In the present work, the role of Nb 2O 5 additions on the structural and electromagnetic properties of MnZn-ferrites has been investigated. Nb 2O 5 additions at a concentration of about 200 ppm are found to lower the losses by almost 17%. At higher concentrations Nb 2O 5 segregates at the grain boundaries, promotes grain growth and affects negatively the microstructure development. At concentrations up to 200 ppm, where a gradual improvement of the magnetic properties is observed, Nb 2O 5 is found to precipitate together with CaO homogeneously along the grain boundaries and participates in the formation of glassy phases. Those phases act as buffers between the grains, smoothening the transition from one grain to the other. Moreover they also reduce Zn-evaporation at the grain boundary area. Both effects are in favour of low electromagnetic power losses and of high relative magnetic permeabilities.