The sintering behavior and microwave dielectric properties of Bi(Nb,Sb)O4 ceramics

Sb2O5 were selected to substitute Nb2O5 and the effects of substitution on the sintering behavior and the microwave dielectric properties of BiNbO4 ceramics were studied. Solid solutions formed in sintered BiNb(1−x)SbxO4 ceramics with x value being no more than 0.4. The unit cell volume of orthorhombic phase BiNb(1−x)SbxO4 decreased from 331.86 to 324.99 Å3 with x value increasing from 0 to 0.4. The densified temperatures increased from 800 to 940 °C. The microwave dielectric properties of BiNb(1−x)SbxO4 ceramics were found to be affected by the substitution of Sb for Nb and the sintering temperature. The saturated εr values first increased from 44.00 to 44.61 with x increasing from 0 to 0.1 and then decreased to 40.69 with x to 0.4. The saturated Q×f values decreased with increasing of x value. The τf values were correlated to the unit cell volume of BiNb(1−x)SbxO4 and continuously decreased from a positive value of 14.19 ppm/°C for x=0 to a negative value of −30.94 ppm/°C for x=0.4. At a sintering temperature of 820 °C and x value of 0.05, BiNb(1−x)SbxO4 ceramics exhibited the optimum microwave dielectric properties of εr ∼ 44.49, Q×f ∼ 14,278 GHz, and τf ∼ −5.19 ppm/°C.