Correlations between Micro- and Nanostructures and Magnetic Transitions in the Ru-Doped Sm0.2Ca0.8MnO3 Manganites
Abstract The electron microscopy study of the Ru-doped manganites Sm 0.2 Ca 0.8 Mn 1− x Ru x O 3 (0≤ x ≤0.10) shows that the magnetic properties of these materials are strongly correlated to their microstructure. Charge ordering induced by Mn-site doping is shown for the first time, in contrast to what is generally observed. It is shown that Ru-doping paradoxically favors the simultaneous development of ferromagnetic orthorhombic domains and charge-ordered antiferromagnetic domains at low temperature, starting from a monophasic orthorhombic paramagnetic sample at room temperature. This structural phase separation phenomenon at low temperature is explained in terms of two antagonist effects introduced by Ru 5+ substitution: ferromagnetic superexchange interactions and Mn valency.
We have obtained sorbents modified by the cationic SAS based on hydromica and kaolinite—layer silicates with a rigid structural cell. We have studied structure—sorption properties of initial and developed materials. It has been shown that modification results in a sharp decrease of hydrophilicity of minerals, enhancement of their affinity to the molecules of anionic and nonionogenic SAS. We have noted a substantial increase of sorption capacity of modified minerals with respect to nonionogenic SAS, which is explained by the formation on the surface of the sorbent of bulk associates from the molecules of cationic and nonionogenic SAS.