Fig. 1 shows the XRD patterns of KNNLS–xBA ceramics as a function
of x. The phase structure of all samples was pure perovskite
phase and no secondary impurity was observed, suggesting that
BA has completely diffused into the KNNLS lattice to form a homogeneous
solid solution. The orthorhombic and tetragonal phases
coexist in the ceramics with x = 0 [13]. In addition, there is no obvious
changes in the phase structure for the ceramics with the doping
of BA that can be observed from the XRD patterns. In order to confirm
the phase structure, further discussion was showed in the
following that combined with the temperature dependences of the
dielectric properties.