Microwave dielectric properties of BaNb(2-x)TaxP2O11 (x=0, 0.5, 1, 1.5 and 2) ceramics

BaNb(2-x)TaxP2O11 (x = 0, 0.5, 1, 1.5 and 2) ceramics were prepared by the conventional solid state ceramic route. The relative permittivity (epsilon(r)) of the ceramics decreased from 25.3 for x = 0 to 12.9 for x = 2. BaTa2P2O11 (x = 2) sintered at 1250A degrees C showed good microwave dielectric properties with Q(u) x f = 28,900 GHz and tau(f) = - 29 ppm/A degrees C. The addition of 5 wt% TiO2 lowered the sintering temperature to 1225A degrees C and improved tau(f) to -6 ppm/A degrees C with epsilon(r) = 13.4 and Q(u) x f = 17,200 GHz.