Influence of Mg_2SiO_4 addition on crystal structure and microwave properties of Mg_2AlSi_5O_(18) ceramic system

摘要

In this work, (1 - x)Mg2Al4Si5O18-xMg(2)SiO(4) (x = 0-80 wt%) composite dielectric ceramics were prepared via traditional solid-state reaction. The results indicate the sinterability of Mg2Al4Si5O18 ceramics is greatly enhanced with the increasing content of Mg2SiO4 by reducing densified temperature from 1460 to 1340 A degrees C. Rietveld refinement analysis shows a great chemical compatibility between two phases. With the increase of Mg2SiO4 content, the densifications of ceramics can be improved. However, excessive amount of Mg2SiO4 induces abnormal grain growth, which deteriorates the microwave dielectric properties. At x = 50 wt%, low-epsilon(r) dielectric ceramics with high Q x f value was obtained when sintered at 1340 A degrees C: epsilon(r) = 5.73, Q x f = 76,374 GHz and tau(f) = - 24 ppm/ A degrees C. Relative cheap raw materials and adjustable permittivity values, which makes it promising for low-permittivity microwave applications.