ELECTRICAL AND CRYSTALLOGRAPHIC STUDIES OF SYSTEM CUXNI1-XMN2O4

Electrical and crystallographic properties of the system CuxNi1-xMn2O4 have been studied. The negative deviation of lattice parameters from Vegard's linearity rule indicates that CuMn2O4 is a normal cubic spinel. The electrical resistivity temperature-behaviour obeys the relation ρ=ρ0exp.[formula omitted], and the value of activation energy (ΔE) for conduction in NiMn2O4 remains constant even after addition of 50 mole percent CuMn2O4. The thermoelectric power of NiMn2O4 changes sign from negative to positive by an addition of 20 mole percent CuMn2O4. It is concluded that in CuMn2O4 the Cu is present predominantly in Cu2+ valence state along with a small number of Cu1+ ions at tetrahedral sites. The electrical conduction in this system seems to take place through hopping of charge carriers between Mn3+ and Mn4+ ions at octahedral sites. A contribution to electrical conduction from tetrahedral]y located Cu2+ and Cu1+ ions has also been considered. © 1969, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.