Phase Equilibrium in the System Ln-Mn-O II. Ln=Nd at 1100 C

Phase equilibrium is established in a Nd-Mn-O system at 1100 C by changing the oxygen partial pressure from 0 to 12.00 in -log(Po(sub 2)/atm); a phase diagram at 1100 C is presented for a Nd(sub 2)O(sub 3)-MnO-MnO(sub 2) system. Under the experimental conditions, Nd(sub 2)O(sub 3), MnO, Mn(sub 3)O(sub 4), and NdMnO(sub 3) phases are present at 1100 C, but Nd(sub 2)MnO(sub 4), Mn(sub 2)O(sub 3), and MnO(sub 2) are not stable in the system. Wide ranges of nonstoichiometry were found in the NdMnO(sub 3) phase, which coexisted with Nd(sub 2)O(sub 3). X ranges from -0.006 at log Po(sub 2)=-10.85 to 0.104 at log Po(sub 2)=0 in the form of NdMnO(sub 3+X). The nonstoichiometry is represented by the equation No/N(sub NdMnO(sub 3))=4.34x10(sup -5)(log Po(sub 2))(sup 3)+1.99x10(sup -3)(log Po(sub 2))(sup 2)+2.65x10(sup -2)(log Po(sub 2))+0.104; the activities of the components in the solid solution are also calculated with this equation. NdMnO(sub 3) has a composition range to the Nd(sub 2)O(sub 3)-rich or Nd(sub 2)O(sub 3)-poor side of LaMnO(sub 3). Lattice constants of NdMnO(sub 3) made in different oxygen partial pressures were determined