Table 1 summarizes the lattice constant of KNNLS–xBA ceramics.
The lattice parameters are determined by XRD results using
GwBasic software. The lattice parameters of the KNNLS–0.002BA
ceramics decreased compared with pure KNNLS ceramics. This
should be attributed to the smaller ionic radii of Bi3+ (1.03A˚ )
and Al3+ (0.535A˚ ) than those of Na+ (1.02A˚ ), K+(1.38A˚ ) and Nb5+
(0.64A˚ ) [18], which gave rise to a small shrinkage of the cell volume.
However, with the further increasing of BA doping, the lattice
parameters of the KNNLS–xBA increased. The cell volume also followed
the same trend. Such an anomalous variation of the lattice
parameters with composition should be attributed to the lattice
distortion that caused by higher level of BA doping.