Properties of the ceramic manganite (La$_{0.65}$Ca$_{0.35}$)$_{1-x}$Mn$_{1+x}$O$_{3\pm\Delta}$ ($x$ = 0.2) sintered at temperatures of 1000–1450$^\circ$C

It has been shown that the ceramics (La$_{0.65}$Ca$_{0.35}$)$_{1-x}$Mn$_{1+x}$O$_{3\pm\Delta}$ ($x$ = 0.2) sintered at temperatures up to 1450$^\circ$C is formed as a composite material consisting of manganite and manganese oxide grains. It has been found that, at a sintering temperature of 1450$^\circ$C, the manganite grain size abruptly increases, which is accompanied by the formation of a nanometer-sized layered structure. It has been revealed for the first time that the temperature dependence of the magnetoresistance of the ceramic manganite with this structure is characteristic of single crystals.