Structural self-organization, domain structure, and magnetic characteristics of manganites of the La-Sr-Mn-Ti-Ni-O system

Effect of ageing on magnetic and electrical properties of Ti–substituted La-Sr manganites

“…At the same time, the decrease of magnetic moment of the manganese ions and the dilution of octahedral sublattice by cation vacancies are competing factors. Difference of radii and charges of the ions, Coulomb interaction cause the formation of microinhomogeneities and microstresses [8,9,12], broadening X-ray diffraction reflexes. At room temperature the contribution of entropy to free energy (-TS term) is less than at thermal processing, and separation of inhomogeneities becomes more evident, which can be promoted by the presence of Ti impurity.…”

“…Generally, in considered materials the drift of their characteristics during prolonged storage in the absence of thermodynamic equilibrium under specified conditions may be due to various processes: interaction with the oxygen in surrounding atmosphere leading to the changes in the states of variable valency ions and concentration of nonstoichiometry defects; ordering or redistribution of cations and vacancies on the sublattices and in the volume of the crystals; relaxation of elastic stresses or grain boundaries, etc. The introduction of micro-components in the complex non-stoichiometric crystals may have different effects on the solid-state reactions and on exchange of oxygen with the ambient atmosphere depending on the nature of impurities [1,[8][9][10].…”

Properties of La1 − x Sr x Mn0.925Zn0.075O3 (x = 0.075, 0.095, 0.115) ceramics

“…At the same time, the application of known models of particular physical processes to mul ticomponent compositions of manganites is debatable. In many cases, the experimental data are rather incomplete and contradictory, which is due to the absence of phase diagrams for manganites with partial replacement of manganese and also the existence in them of clusters and heterogeneities with competing exchange interactions and structural distortions, as well as various types of magnetic and electron ordering [1][2][3][4][5][6]. The most important factors determining the properties of manganites are the Zener double exchange between the Mn 3+ and Mn 4+ ions and the Jahn-Teller effect at the Mn 3+ ions [1,7].…”