Kalium natrium niobate, K0.5Na0.5NbO3 (KNN) is a ceramic possessing a perovskite ABO3 structure, which has been extensively studied due to its good dielectric and piezoelectric properties, high Curie temperature, and environmental friendliness in the last decade. KNN pose polymorphism orthorhombic at room temperature up to 200 °C before transform to tetragonal, and above 400 °C it changes to a cubic phase.

Studies of doped KNN-based ceramics that explore the relationship between the structure, ionic arrangement and electrical properties still attract attention because they can help to improve the characteristics of the composition or find new compositions. In this work, the B0.8Cr0.2TiO3 (BCT) and B0.8Sr0.2TiO3 (BST) is used as dopant that substituted in the KNN systems. The XRD and XAS were utilized to characterize the structure and the local distortion then be related to the electrical

The orthorhombic structure of KNN

The XRD Pattern of the KNN based materials

The further deeper analysis on the local structure as an effect of substitution Ti4+ into Nb5+ and Ba2+/Ca2+/Sr2+ into K+/Na+ described in the defect reaction equation below (Figure 3),

on A sites,

on B sites,

The linear plot of the oxidation state of Ti vs. edge

The linear plot of the oxidation state of Ti vs. edge

The XANES spectra of normalized Ti K-edge of the sintered sample (1-x) KNN – x BCT/BST

The Currie-Weiss plots log (T-Tm) vs (1/ε-1/εm)

Figure 4 shows Ti K-edge XANES  region In the pre-edge, there are three peaks should be distinguished, peak a and b related to the quadrupole and dipole 1s→3d (t2g) and 1s→3d (ee) transition of Ti, reflects the 3d→4d hybridization of Ti, while peak c is related to the Ti 1s transition to the unoccupied 4p. Meanwhile, Figure 5 shows the relationship of oxidation state and edge energy E0, the energy shifting can be deduced that there are mixture of Ti4+/Ti3+ in the system.