## 2 Materials and Methods  
To obtain the La\({}_{0.9}\)A\({}_{0.1}\)Mn\({}_{0.9}\)Co\({}_{0.1}\)O\({}_{3}\) (where A is Li, K, Na) compounds, the combustion method was applied [25]. Firstly, lanthanum (REaton(r), 99.999%, Karlsruhe, Germany), manganese (Puratronic(r), 99.995%, Karlsruhe, Germany) and cobalt (ACS, 98.0-102.0%, Washington, DC, USA) nitrates, and A-precursors (LiNO\({}_{3}\)-ACS, 99.0% min, NaNO\({}_{3}\)-ACS, 99.0% min or KNO\({}_{3}\) ACS, 99.0% min, Washington, DC, USA) with the molar ratio of La/A and Mn/Co = 0.9/0.1 were dissolved in distilled water. Then 10% of molten stearic acid (Calbiochem, San Diego, CA, USA) was added to the solution in a porcelain reactor. The resulting mixture was continuously stirred and kept at a temperature of 140 \({}^{\circ}\)C. After 2 h La-Mn-stearic acid formed a gel. Then, the porcelain crucible reactor was placed in a furnace and heated up to 500 \({}^{\circ}\)C. The gel volatilized and auto ignited; with the evolution of a large volume of gases it produced loose grey powder. The obtained powders were ground in the agate mortar and additionally calcined at 700 \({}^{\circ}\)C for 1 h to remove all organic residues. After calcination, all powderswere grinded and taken for further experiments. Half of the powders were used for ceramics sintering, using the high pressure sintering technique [26]. For a short duration powders were pressed (200 MPa) at room temperature to \"green body\" (GB). The GB was placed into a CaCO\({}_{3}\) container with a graphite heater and the inside was isolated by hexagonal boron nitride. The shape of the container allowed to keep isostatic pressure during axial pressing. After the application of 8 GPa pressure, the pellets were sintered at 500 \({}^{\circ}\)C for 1 min into ceramics. After sintering, the as obtained ceramics were polished and taken for further studies. The structure of the powders and ceramics were characterized and analyzed by powder X-ray diffraction (XRD) using a PANalytical X'Pert diffractometer (Malvern Panalytical, Almelo, The Netherlands) with Ni-filtered CuK\({}_{\lambda}\) radiation, \(\lambda\) = 1.5418 A with the step of 0.02626 20 for 1 h. The powders and ceramics were measured in the reflection mode. In the case of the powder, it was ground and placed directly in the sample holder, while the ceramics were placed in plasticine so that the surface of the ceramics would be parallel to the surface of the holder. For SEM imaging, the powders were ground in an agate mortar and glued to the carbon tape. The excess powder was removed using compressed air and the prepared material was taken for measurements. In the case of ceramics, the sample was simply glued to the carbon tape on the holder. Scanning electron microscopy (SEM) characterization was conducted using a commercial Tescan Vega3 SB microscope (SEM, Brno, Czech Republic) at 5 kV (acceleration voltage) with 3.5 spot (size of electron beam) and 3.2-3.7 mm working distance in order to analyze grain size and morphology. The chemical homogeneity of the powders and ceramics was measured using a scanning electron microscope FESEM FEI Nova NanoSEM 230 equipped with an energy dispersive spectroscopy (EDS) spectrometer (EDAX Genesis) at 18 kV (acceleration voltage) with 4.0 spot (size of electron beam) and 4.0 mm working distance. The XPS analysis was carried out with a Kratos Axis Supra spectrometer using monochromatic Al K(alpha) source (25 mA, 15 kV). The instrument work function was calibrated to give the binding energy (BE) of 83.96 eV for the Au 4f7/2 line for metallic gold, and the spectrometer dispersion was adjusted to give a BE of 932.62 eV for the Cu 2p3/2 line of metallic copper. The Kratos charge neutralizer system was used on all specimens. Survey scan analyses were carried out with an analysis area of 300 \(\times\) 700 microns and a pass energy of 160 eV. High resolution analyses were carried out with an analysis area of 300 \(\times\) 700 microns and a pass energy of 20 eV.