Dielectric and piezoelectric properties of alkaline-earth titanate doped (K0.5Na0.5)NbO3 ceramics

Abstract (K 0.5 Na 0.5 )NbO 3 (KNN) and 0.995(K 0.5 Na 0.5 )NbO 3 –0.005AETiO 3 (AE = Mg, Ca, Sr, Ba) were successfully prepared by conventional ceramic processing and without the cold-isostatic-pressing (CIP) process. The effects of low AETiO 3 (AET) concentration on crystal structure, density, dielectric and piezoelectric properties of the KNN based ceramics were evaluated. The results show that adding MgTiO 3 (MT) and BaTiO 3 (BT) to KNN can lead to the appearance of a trace amount of second phase(s), reduced density and deteriorated electrical properties. Adding CaTiO 3 (CT) and SrTiO 3 (ST) to KNN can promote densification and optimize electrical properties. Two phase transitions at T t–o ( the temperature at which the phase transition from orthorhombic to tetragonal occurs) and T c (the Curie temperature) were observed in KNN and all KNN–AET ceramics, by using differential scanning calorimetry (DSC) analysis and dielectric characterization. Adding AET to KNN caused the variations of T t–o and T c .