PREPARATION AND CHARACTERIZATION OF LOW-DIELECTRIC GLASS COMPOSITE WITH ALUMINUM BORATE

The effect of aluminum berate (Al18B4O33) on crystallization and therm al expansion of Pyrex borosilicate glass has been studied. X-ray diffr action (XRD) results show that with 40 vol% aluminum berate, the preci pitation of cristobalite in the Pyrex borosilicate glass is completely inhibited. This result is further evidenced by the linear thermal exp ansion measurement in which, in cont.rast to the system without alumin um berate, the thermal expansion coefficient remains unchanged with si ntering time and is close to that of silicon, 3 x 10(-6) K-1. Moreover , the composite with 10 vol% aluminum berate has a dielectric constant of 5.2 and a dielectric loss of 0.8% at 1 MHz.