Conductivity and magnetic properties of new LnMnO(3) derivatives

The new phases of composition Ln(1.33)Na(x)Mn(x)Ti(2-x)O(6) (Ln = Pr, x = 0 .66; Ln = Nd, x = 0.66 and 0.55), derived from LnMnO(3) by partial substitu tion of Mn3+ by Ti4+ and Na+, are reported. Powder neutron diffraction data were used to refine the crystal structures and to analyze the ferromagneti c interactions. These phases can be described as orthorhombic perovskites, space group Pbnm, in which A(Ln, Na) and B(Mn, Ti) cations are disordered a t random. Conductivity results are attributed to an electronic contribution and the activation energies are relatively low, about 0.3 eV. (C) 2001 Aca demic Press.