Role of excess manganese in formation of the structure and transport properties of manganite (Nd$_{0.67}$Sr$_{0.33})_{1-x}$Mn$_{1+x}$О$_{3}$ ($x$ = 0; 0.2) sintered at 1273–1473 K

The Nd$_{0.67}$Sr$_{0.33}$MnО$_{3}$ manganite is a material promising for application as a cathode for medium-temperature solid oxide fuel elements. A high electrical conductivity of such a cathode is the parameter determining the efficiency of the operation of a fuel element. In this report, the effect of influence of excess manganese on the structure and the conductivity of manganite ceramics with compositions (Nd$_{0.67}$Sr$_{0.33})_{1-x}$Mn$_{1+x}$O$_{3\pm\Delta}$ ($x$ = 0, 0.2) sintered at temperatures 1273–1673 K is presented for the first time. The existence of 20% excess manganese in the initial manganite powder after sintering is shown to lead to that the conductivity of the obtained ceramics in the temperature range 823–1073 K is several times higher than the conductivity of the ceramics without excess manganese.