Effect of Specific Surface Area of In-Process Calcined Powder on Electrical and Magnetic Properties of Finished Mn-Zn Ferrites

Abstract

The technology of ferrites or magnetic ceramics has assumed a new importance during the last several decades and especially in the last few years. In addition to the advent of new developments such as radars, satellite communications, memory and computer applications, there has been a corresponding growth in consumer electronics markets in radio, television, power inverters etc. In this thesis work, Mn-Zn ferrite core of the basic composition of 51.96 mole% ferric oxide , 37.88 mole% manganese oxide and remaining 10.16 mole% zinc Oxide and other composition is 50.78 mole% ferric oxide, 27.18 mole% manganese oxide and remaining 22.04 mole% zinc Oxide have been synthesized by conventional route. These ferrites have been investigated for their specific surface area (SSA), electrical and magnetic properties such as initial permeability, resistance and power loss. The specific surface area plays an important role for the electrical and magnetic properties of Mn-Zn Ferrite. This has great influence on green and sintered strength. According for the required properties can be achieved with optimum ball milling time and attritor time. Specific surface area increases and particle size decreases with increases of milling time of ball milling and attritor. For low power loss materials, specific surface area affects electrical and magnetic property as at 5159 cm2/gm SSA exhibits low power loss (69kw/m3) and low resistance while at 5468 cm2/gm power loss increases (74kw/m3) and resistance also increase. For high permeability (μi) material, at 10 KHz frequency and SSA 5359 cm2/gm initial permeability exhibits higher (8960nH) and while at 5562cm2/gm initial permeability decreases (7906 nH). At 100 kHz frequency and SSA 5359 cm2/gm initial permeability exhibits higher (7739nH), while at 5562cm2/gm initial permeability decrease (6917nH).