Reduced degree of phase coexistence in KNN-Based ceramics by competing additives

This work reveals the role of Bi3+ in the controlling ability of (Bi0.5Ag0.5)ZrO3 to the phase structure of potassium sodium niobate based ceramics by introducing Ba2+. The substitution on (Bi0.5Ag0.5)2+ with Ba2+ results in the reduced degree of phase coexistence, accompanying the phase transition from coexisting orthorhombic-tetragonal (O–T) phases to an orthorhombic (O) phase, which is demonstrated by the systematic phase structure analysis and variations of electrical properties. The analysis reveals that the high electronegativity of Bi3+ results in the increased covalent bond character and then increases the stabilization of the T phase, leading to a decrease in orthorhombic-tetragonal phase transition temperature (T O-T). Therefore, this work not only compares the controlling ability of Ba2+ and (Bi0.5Ag0.5)2+ to T O-T but also reveals which and how elements cause the decreased T O-T, promoting the understanding of the effect of additives on the phase structure.