Sintering conditions of cordierite for microwave/millimeterwave dielectrics.

With the advent of ubiquitous age, the high-quality, dielectric materials have been required for the applications of wireless communications available to millimeterwave as well as microwave frequencies such as ultra-high speed local area network (LAN), electronic toll collection (ETS), and car anticollision systems on the intelligent transport system (ITS), and so on. Cordierite (Mg(2)Al(4)Si(5)O(18)), which is one of the silicates, is a good candidate for microwave/ millimeterwave dielectrics due to low dielectric constant epsilon(r) and low loss. This study is focused on optimization of the sintering condition of cordierite. A single phase of cordierite could be obtained from the powders calcined from 1355 degrees C to 1375 degrees C for 3 hours, and the samples sintered from 1375 degrees C to 1440 degrees C for 2 hours. The highest relative density of 98.7% was obtained for the samples sintered at 1440 degrees C for 2 hours. The dielectric constant and the quality factor of cordierite depend on the sintering temperatures. The density also was improved to 2.51 g/cm(3) by a slower heating and cooling rate of 3 degrees C/minute. The microwave dielectric properties are as follows: epsilon(r) = 6.14, Q . f = 59682 GHz, and tau(f) = -26.1 ppm/ degrees C.