## 3 Results and Discussions  
The phase characterization of the obtained sample BaLa\({}_{2}\)In\({}_{2}\)O\({}_{7}\) was made using XRD analysis. It was shown that all observed diffraction peaks can be related to the single phase belonging to the tetragonal symmetry (space group \(P4_{2}/mmm\)) (Figure 2). The lattice parameters (a = 5.914(9) A, c = 20.846(5) A) were in good agreement with those previously reported by [PERSON] et al. and [PERSON] et al. (a = 5.915(2) A, c = 20.86(1) A [46]; a = 5.9141(3) A, c = 20.8231(2) [47]). The structural parameters are presented in the Table 1.  
The 3D visualization of the crystal structure of the obtained phase is presented in the Figure 1c using VESTA software [48]. As can be seen (Figure 1), for the mono-layered structure (Figure 1b), the ordering in the A and A\({}^{\prime}\) cations does not happen, and Ba and La atoms occupy the same positions in the crystal lattice of BaLaInO\({}_{4}\), and they have the same coordination number (c.n. = 9). Opposite, the ordered arrangement of A and A\({}^{\prime}\) cations is observed for the two-layered complex oxide BaLa\({}_{2}\)In\({}_{2}\)O\({}_{7}\), as it was shown by [PERSON] et al. [47] with using high resolution electron microscopy (Figure 1c). It was \begin{table}
\begin{tabular}{c c c c c} \hline
**Atom** & **Site** & **x** & **y** & **z** \\ \hline Ba & 4f & 0.2483(1) & 0.2483(1) & 0 \\ La & 8j & 0.2687(4) & 0.2687(4) & 0.1851(3) \\ In & 8j & 0.2590(0) & 0.2590(0) & 0.4002(2) \\ O(1) & 4g & 0.806(1) & 0.193(3) & 0 \\ O(2) & 8j & 0.183(4) & 0.183(4) & 0.291(1) \\ O(3) & 8h & 0 & 0.5 & 0.095(2) \\ O(4) & 4e & 0 & 0 & 0.126(1) \\ O(5) & 4e & 0 & 0 & 0.382(1) \\ \hline \end{tabular} \(R_{p}\) = 4.31, \(R_{wp}\) = 3.48, \(\chi^{2}\) = 1.73.  
\end{table} 
Table 1: Refined structural parameters from XRD-data. Figure 2: The XRD-data for the composition BaLa\({}_{2}\)In\({}_{2}\)O\({}_{7}\). confirmed that barium atoms locate in the perovskite blocks, and the lanthanum atoms are placed in the rock-salt layers [47]. In the case of the two-layered structure, the cation with the largest ionic radii (barium in this case) has the c.n. = 12 and forms polyhedra [BaO\({}_{12}\)]; the cation with lower ionic radii (lanthanum) forms the polyhedra (LaO\({}_{9}\)) with c.n. = 9. However, it was shown that both perovskite blocks and rock-salt layers are distorted, and the real coordination numbers are ten and seven for barium and lanthanum, respectively [47]. The electrical conductivity was measured by the impedance spectroscopy method. The Nyquist-plots for the investigated composition BaLa\({}_{2}\)In\({}_{2}\)O\({}_{7}\) obtained under dry air are presented in Figure 3a-c. The fitting of the spectra was made using ZView software, and the obtained results are presented in Table 2. According to the fitting of the spectra (red line) with using the equivalent circuit presented in Figure 3d, three different electrochemical processes can be defined. For the calculation of electrical conductivity, the bulk resistance values R1 were used and are discussed below. It can be noted that, due to the small depression of the semicircles, the constant phase element (CPE) was used during the analysis of Nyquist plots. Figure 3: The Nyquist-plots obtained at the different temperatures under dry air for the composition BaLa\({}_{2}\)In\({}_{2}\)O\({}_{7}\): (**a**) 700 \({}^{\circ}\)C, (**b**) 600 \({}^{\circ}\)C, (**c**) 500 \({}^{\circ}\)C, and (**d**) the equivalent circuit of fitting (red line). The temperature dependencies of bulk conductivities obtained under dry air and dry Ar are presented in Figure 4. As can be seen, the conductivity values for the compound BaLa\({}_{2}\)In\({}_{2}\)O\({}_{7}\) are higher than for BaLaInO\({}_{4}\)[29] by around 0.6-0.7 order of magnitude. This confirms the previously stated assumption that the increase in the ratio of perovskite blocks in the layered structures can lead to the increase in the electrical conductivity values.