Effects of Mn3+ ions on the electrical and magnetic properties of Ca(Mn1−xZrx)O3−δ (0⩽x⩽0.07)

Perovskite-type Ca(Mn1−xZrx)O3−δ (0⩽x⩽0.07) has an orthorhombic GdFeO3-type structure with space group Pnma. According to the Rietveld method, the (Mn, Zr)-O distance is independent of x and the (Mn, Zr)-O-(Mn, Zr) angles decrease very slightly with x. The electrical measurement indicates that Ca(Mn1−xZrx)O3−δ is an n-type semiconductor and exhibits hopping conductivity in a small-polaron model. The magnetic measurement indicates that Ca(Mn1−xZrx)O3−δ is antiferromagnetic and that the spin state of the Mn3+ ion is low. The activation energy for hopping (Eh) has a minimum value (≈0.043 eV) at x=0.03 due to acceleration of the electron transfer through the Mn(III)-O-Mn(IV) path and the inhibition of the electron transfer by Zr4+ ions.