Study of dielectric properties of (Sr1-xPbx)TiO3:: MgO composites for field tunable devices

(Sr1-xPbx)TiO3 (SPT) ceramics have low loss tangents and high dielectric tunabilities under DC bias fields at room temperature, but they have the disadvantage of high dielectric constants. In order to exploit these materials for microwave applications, the reduction of dielectric permittivities is necessary. Thus, the composites of the SPT system by the addition of a non-ferroelectric oxide such as MgO were prepared and electrical properties were measured. Loss tangents of the composite sintered at the same temperature as SPT's sintering were less than 0.3% in paraelectric region just above the transition temperature and the dielectric tunabilities of similar to20% at 20 kV/cm and similar to35% at 40 kV/cm were observed at 10 kHz.