J. Aust. Ceram. Soc. 44 [1] (2008) 57-62 In-Situ Synthesis of Magnetic Mn-Zn Ferrite Ceramic Object by Solid State Reaction Emad M. M. Ewais *1 , Mahmoud M. Hessien 2 and Abdel-Hady A. El-Geassy 3 1 Refarctory & Ceramic materials Lab (RCML), Advanced Materials Dept., Central Metallurgical Research and development Institute (CMRDI), P. O. Box 87 Helwan, 11421 Cairo, Egypt 2 Electronic & Magnetic Lab, Advanced Materials Dept., Central Metallurgical Research and development Institute (CMRDI), P. O. Box 87 Helwan, 11421 Cairo, Egypt 3 Ironmaking Lab, Central Metallurgical Research and development Institute (CMRDI), P. O. Box 87 Helwan, 11421 Cairo, Egypt Abstract In-situ MnZn ferrite (Mn 0.8 Zn 0.2 Fe 2 O 4 ) was synthesized by solid state reaction process. Stoichiometric amounts of high purity MnO 2 , ZnO and Fe 2 O 3 were applied. The influence of temperature and reaction time on the rate of ferrite formation was studied. The thermal analysis tests of mixed oxides indicated that the reaction started up at 900-1000 o C and completed at 1150 o C which was followed up by X-ray phase analysis and confirmed by SEM and optical microscopic examination. The reaction products were characterized by measuring the bulk density, cold crushing strength and magnetic properties. It was observed that the reaction rate increased with temperature up to 1150 o C then decreased with further rise in temperature up to 1200 o C. The obtained results were rationalized based on the microstructure feature, porosity measurements and pore size analysis. Successful fabrication of dense MnZn ferrite which has high crushing strength and magnetic properties at 1150 o C was processed. Keywords: MnZn ferrite, thermal analysis, microstructure, Densification, magnetic properties Introduction MnZn-ferrites are considered as one of the great importance of polycrystalline soft ferrite ceramic materials. This type of ceramics find extensive applications in electronic and telecommunication industry such as fabrication of transformers, frequency filters, magnetic recording heads, voice coil motors of computer hard disc drives, …etc., 1-2) . This is due to their excellent properties such as high saturation magnetization, high initial permeability, high resistively and low losses. The essential feature of these materials is the coexistence of high magnetization and high electric resistively. Therefore the replacement of these materials in near future will be questionable 3) . Since the composition, reactants, forming techniques and conditions of sintering of MnZn- ferrites have strong effect on their properties so the question is what the best route can be developed to overcome on the shortcomings arises from gathering of all these factors 4-5) . Various processing techniques included conventional and non- conventional have been developed for synthesis of ferrites. However, each one of these techniques has specific limitations. Non-conventional techniques such as co-precipitation 6) , thermal decomposition 7- 8) , sol-gel 9) and hydrothermal 10-13) , self-propagating high temperature synthesis (SHS) 14-15) and other wet chemical techniques 16-18) were widely used. Despite of these techniques that gives promising results, they have disadvantage from the economic and environmental point of view. On the other hand, the conventional ceramic techniques that involve preferring of raw material mixture in temperature range of 800-1000 o C then milling, compaction to desired shape and sintering at elevated temperatures under appropriate oxygen partial pressure conditions are usually used for fabrication of such ceramics. However, uncontrollable in homogeneities, densities, and sizes of the particles associated with this technique is considered one of its disadvantages. Therefore, the manufacturing of near fully dense MnZn ferrites through minimum steps with high magnetic properties will be benefit from the economic point of view. In this work, in-situ MnZn-ferrite ceramic (Mn 0.8 Zn 0.2 Fe 2 O 4 ) was fabricated by the compaction of pure oxides of Mn, Zn and Fe. The properties in terms of densification pore size distribution, microstructure, cold crushing strength and magnetic measurements of Mn Zn-ferrite compact associated with firing temperature were examined. On the other hand, the results of the formation and magnetic properties of the Mn 0.8 Zn 0.2 Fe 2 O 4 prepared through compacts were compared with the