## 3 Results and Discussion
Figure 2: Rietveld refinement of XRD data of **(a)** BNKLBT, and **(b)** BNKMBT ceramics using FULLPROF software to analyze structure. Figure 3a,b shows images of the top surface images of BNKLBT and BNKMBT ceramics respectively. No holes or cracks appear on the ceramic surfaces, confirming that the high temperature sintering process did not affect the ceramics. Highly dense samples were produced under the high pressure (200 MPa), with a density of 5.86 g/cm\({}^{3}\) for BNKLBT and 5.78 g/cm\({}^{3}\) for BNKMBT. The grain sizes for both ceramics were in the range of 1-2.5 \(\upmu\)m. To further analyze the proper uniform distribution of each element in the ceramics, elemental distribution mapping was performed. Ti had the highest degree of dispersion for both ceramic samples because of its high stoichiometric ratio. All other constituent elements in both ceramic compositions were the same except La for BNKLBT and Mg for BNKMBT. Both La and Mg had uniform distributions, but with a lesser degree of distribution because of their low stoichiometric ratios in the ceramics. Morphological analysis clearly confirmed the contribution and presence of all constituent elements. Temperature\(-\)dependent relative dielectric constant (\(\varepsilon_{r}\)) plots for BNKLBT and BNKMBT samples are shown in Figure 4a,e for the temperature range 27-500 \({}^{\circ}\)C, and under a frequency range of 100 Hz to 1 MHz. Strong, long-range dielectric maxima (\(\varepsilon_{m}\)) dispersion appeared at wide transition temperatures (\(T_{m}\)), which indicates that the fabricated ceramics belong to the relaxor ferroelectrics family [20]. In the \(\varepsilon_{r}\)\(-\)\(T\) curves, some temperature shoulders (\(T_{S}\)) were observed for the temperature range 120-170 \({}^{\circ}\)C, which are associated with the generation of the polar nano-regions created due to the presence of different ionic radii and varying electrovalence states of cations at the A-site of the ceramics [21]. These cations not only cause distortion of the lattice structures of the materials but also harvest variable electrovalence states in the sub-nano area, leading towards the creation of domains with diverse polarization activities. [PERSON] et al., proposed such distorted units to be polar units [16]. The shifting of \(\varepsilon_{m}\) towards a higher temperature by varying the frequency relates to the relaxation polarization of the ceramics [22]. For the BNKLBT ceramic, the \(\varepsilon_{m}\) for 1 kHz, 100 kHz and 1 MHz were 1281 at 233 \({}^{\circ}\)C, 1179 at 244 \({}^{\circ}\)C and 1071 at 269 \({}^{\circ}\)C, respectively (Figure 4a). Similar behavior was observed for the BNKMBT ceramic; the \(\varepsilon_{m}\) for 1 kHz, 100 kHz and 1 MHz being 1474 at 249 \({}^{\circ}\)C, 1342 at 260 \({}^{\circ}\)C and 1222 at 270 \({}^{\circ}\)C respectively (Figure 4e). The temperature dependent dielectric loss curves of BNKLBT (Figure 4b) and BNKMBT (Figure 4e) ceramics are presented where the values of  
Figure 3: **(a)** Morphological and colored elemental mapping of elements in the BNKLBT ceramic. **(b)** Morphological and colored elemental mapping of elements in the BNKMBT ceramic. _tan\(\delta\)_ were less than 0.003 and 0.016, respectively, at room temperature. At low frequencies, the sharp increase in the values of _tan\(\delta\)_ occurred after crossing 300 \({}^{\circ}\)C for both ceramic samples, which can be related to space charge polarization [23]. The modified Curie\(-\)[PERSON] law can be used to evaluate the relaxation degree of the fabricated ceramics [24]:  
\[\frac{1}{\varepsilon_{r}}-\frac{1}{\varepsilon_{m}}=\frac{(T-T_{m})^{\gamma}} {C}(1\leq\gamma\leq 2) \tag{2}\]  
where \(C\) refers to the Curie-Weiss constant, \(\gamma\) refers to the diffusion co-efficient, whose value lies between 1 (Ferroelectric) and 2, the ideal relaxor ferroelectric.