STRUCTURE CHARACTERISTICS AND PROPERTIES OF YCuxMn1−xO3 AFTER MECHANOACTIVATION

Solid solutions of the YCuxMn1−xO3 system have been synthesized at x = 0.00, 0.05, 0.10, 0.15 with the use of preliminary mechanical activation. Studies of the structure and microstructure of the obtained samples have been carried out. The temperature changes in the conductivity of the manufactured objects have been partially studied. Based on X-ray diffraction analysis, it was found that mechanical activation practically completely excludes the formation of a hexagonal phase upon the addition of Cu. In this case, the perovskite phase is formed. In the composition without copper, a hexagonal phase is formed, but its amount is comparable to the orthorhombic non-perovskite phase. The presence of the latter is noted throughout the study interval. The study of the microstructure showed the presence of nanocrystalline fouling of grains. Unlike pure YMnO3, in compositions doped with copper, grains with and without fouling have approximately the same size scatter. It is noted that, as in the case of using the method of conventional ceramic technology, synthesis with preliminary mechanical activation occurs with the presence of liquid phases. The microstructure photographs of all samples with x > 0 clearly show local intergranular adhesions. A study of the electrical resistivity ρ at T = 300–700 K revealed an anomaly that shifts to the low-temperature region with an increase in the copper concentration. Presumably, this anomaly is associated with structural rearrangements preceding the high-temperature phase transition. In the hexagonal state of YMnO3, it consists in the inclination and rotation of oxygen bipyramids, and in the orthorhombic state, in the orbital ordering and rotation of oxygen octahedra. The research results will be useful in the study of solid solutions made with the use of mechanical activation.

yttrium manganese, multiferroics, solid solutions, conductivity, microstructure, liquid phase