Sintering of Mn-Zn Ferrites with High Density and Predetermined Oxygen Contents

Abstract

Mn-Zn ferrites with predetermined oxygen contents and nearly theoretical density were prepared from mixture of MnO, ZnO and Fe2O3 by sintering in the atmosphere of appropriate partial pressures of oxygen. The sintering process were determined on the basis of mechanisms how the formation of Mn-Zn ferrite from mixture of the oxides and the densification of the preform occur with changing sintering temperature. The process for densification without grain growth was necessary to prepare ferrites without pores. The oxygen content in a Mn-Zn ferrite was controlled by making the oxygen partial pressure in the atmosphere equal to the equilibrium oxygen partial pressure of the Mn-Zn ferrite with a desired oxygen content, mainly, in the densification process.The electrical resistivity of these ferrites was independent of applied frequencies below 20 MHz, and decreased with increasing Fe and/or decreasing oxygen content.