###### Abstract  
The aim of the work was to check how the introduction of alkali and cobalt ions into a manganese structure can affect the structural disorder and, in consequence, lead to the changes (improvements) of magnetic properties. The high-pressure sintering technique was applied to check if the external factor can modify the magnetization of manganites. Nanocrystalline La\({}_{0.9}\)A\({}_{0.1}\)Mn\({}_{0.9}\)Co\({}_{0.1}\)O\({}_{3}\) (where A is Li, K, Na) powders were synthesized by the combustion technique. The respective powders were used for nanoceramics preparation by the high-pressure sintering technique. The structure and morphology of the compounds were studied by X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Magnetization studies for all compounds were performed in order to check the changes induced by either codoping or the sintering pressure. It was found that the type of the dopant ion and sintering pressure produced significant changes to the magnetic properties of the studied compounds. Alkali ions lead to the stabilization of Co ions in the +2 oxidation state and the formation of positive exchange interactions Mn\({}^{3+}\)-Mn\({}^{4+}\) and Co\({}^{2+}\)-Mn\({}^{4+}\) and the subsequent increase in remanent magnetization. High sintering pressure leads to a decrease in grain size and reduction of long-range ferromagnetic order and lower magnetization. multiferroic; manganites; alkaline ions; transition metal ions; nanoceramics; magnetization 122020204 December 202020  
mainly used for magnetoelectric materials. Such materials have both magnetic and ferroelectric properties simultaneously. To obtain magnetic materials where magnetic moments are not cancelled out by each other, it is necessary to exclude all ions where outer orbitals are completely filled. This limits the potential multiferroic materials to systems containing either transition metals with partially filled 3d shells or lanthanides with partially filled 4f shells. In the case of ferroelectricity, the Jahn-Teller effect has to be taken into account [2], where oppositely charged ions form a local dipole with a spatially degenerate electronic ground state. For the purpose of removing this degeneracy in the structure, a geometrical distortion appears to lead to the lowering of the overall energy of the system. The mentioned effect and the character of the chemical bonds favor ferroelectricity in such systems. The research conducted in the last two decades showed that the nature of colossal magnetoresistance effect (CMR) [3; 4; 5; 6; 7; 8; 9] in lanthanum manganates cannot be explained without invoking the mechanism of the Jahn-Teller distortion of MnO\({}_{6}\) octahedra. The effect of distortions on magnetic interactions and electron transfer can be induced by structural stresses which are lessened by MnO\({}_{6}\) array oxidation and by the doping the structure by ions with different ionic radii [10; 11; 12]. The combination and control of simultaneous ferroic orderings is still a challenge for scientists all around the world. The studies are conducted mainly towards the development of new materials in which, by changing their chemical composition, morphology or form, it will be possible to intentionally introduce the desired properties. The possibility of designing unique magnetic properties and coexistence of Mn\({}^{3+}\) and Mn\({}^{4+}\) ions allows for the widening of the range of applications for lanthanum manganates and lanthanum manganates doped with transition metal ions in Li-O\({}_{2}\) batteries [6], solid oxide fuel cells [13; 14; 15], alkaline fuel cells [16], magnetic refrigeration [17], and catalysts in oxidation reaction [8; 18; 19]. Cobalt doped lanthanum manganite attracts a great deal of attention as catalytic material. The bifunctional catalytic activity of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) can be tailored by the substitution of manganese ions by cobalt ions and control the Mn\({}^{3+}\)/Mn\({}^{4+}\) ratio [8; 9].