Pielectric droperties of SrTiO₃ glass-ceramics

Strontium titanate Elass-ceramics, Drenared by the crystallization of strontium titanate-aluminosilicate glasses have been investigated for possible application as low-loss dielectric materials at microwave and millimeter wave frequencies. Under suitable cryst allization conditions, these glass-ceramics exhibit temperature compensated dielectric Dermittivity, a consequence of the balance between the negative temperature coefficient of the SrTi03 crystal line nhase and the positive temperature coefficient of the residual aluminos ilicate glass phase. Temperature coefficients of less than 10 ppm/OC with dielectric constants in the range of 16-18 have been achieved over a temperature range of-55to125°C. Dielectric losses at frequencies UD to 4MHz are extremely low(ten6<0.0005). However, dielectric measurements in the range of 100-1000MHz have shown that the losses increase as the frequency approaches the millimeter wave repion, indicatinp that these glass-ceramics might not be acceotable as millimeter wave dielectrics.