DIELECTRIC PROPERTIES OF SrTiO₃ GLASS-CERAMICS.

Strontium titanate glass-ceramics have been investigated for possible application as low-loss dielectric materials at microwave and millimeter wave frequencies. Under suitable crystallization conditions, these glass-ceramics exhibit temperature compensated dielectric permittivity, a consequence of the balance between the negative temperature coefficient of the SrTiO//3 crystalline phase and the positive temperature coefficient of the residual alumino-silicate glass phase. Temperature coefficients of less than 10 ppm/ degree C with dielectric constants in the range of 16-18 have been achieved over a temperature range of minus 55 to 125 degree C. Dielectric losses at frequencies up to 4 MHz are extremely low (tan delta less than 0. 0005). However, the losses increase as the frequency approaches the millimeter wave region, indicating that these glass-ceramics might not be acceptable as millimeter wave dielectrics.