Microwave-assisted synthesis and dielectric properties of Al_2O_3-MgAl_2O_4 spinel composites from ironsand

摘要

In this study, we performed the synthesis and sintering of Al_2O_3 and MgAl_2O_4 spinel composites using microwave radiation. Al_2O_3 was used as the ceramic matrix and ironsand with concentrations of 25, 50, and 75 vol% was added to alumina. Specimens were microwave sintered for 30, 60, and 90 min. Heat treatment in an electric furnace was also performed for comparison with the method proposed in this work. The results revealed that the material developed crystalline phases of Al_2O_3 and MgAl_2O_4 spinel-type structure with anorthite and iron oxide as minor phases. The composites exhibited high dielectric constants at low frequency. High density values were found for materials composed of 25% ironsand and 75% alumina. The treatment by microwave radiation was presented as an alternative to conventional heat treatments, with reduced synthesis and sintering times at high processing temperatures. The results showed that the developed material can be useful for microelectronic applications.