Acceptor and Donor Dopants in Potassium Sodium Niobate Based Ceramics

Abstract

B-site doping in potassium sodium niobate (KNN) with Mn2+ ((Formula presented.)) and Ti4+ ((Formula presented.)) dopants were soluble but prevented KNN from achieving a high relative density, while Sn4+ ((Formula presented.)) was not soluble in the structure as evidenced by second phase peaks in X-ray diffraction (XRD) traces. However, SnO2 was an effective sintering aid in KNN-50/50. A-site doping with Sr2+ ((Formula presented.)) up to 1 mol% initially improved dielectric properties but higher sintering temperatures were required for compositions with >1 mol% Sr. Samples with 5% and 7% of Sr-doping completely shifted the transition of TO–T to below RT and broadened the TC peaks as the relaxor. All Ti-doped and Sr-doped compositions showed an increase in conductivity, manifested as high values of dielectric loss (tanδ). More than 1% of acceptor and donor dopants showed the ionic-type conduction mechanism, while 1% displayed the electronic mechanism as attributed from the strongly frequency-dependent tanδ. In conclusion, these samples have the potential to open up new applications in the field of electroceramics.