Phase equilibrium in the system Ln-Mn-O II. Ln = Nd at 1100 degrees C

Phase equilibrium is established in a Nd-Mn-O system at 1100 degreesC by ch anging the oxygen partial pressure from 0 to 12.00 in -log(Po-2/atm); a pha se diagram at 1100 degreesC is presented for a Nd2O3-MnO-MnO2 system. Under the experimental conditions, Nd2O3, MnO, Mn3O4, and NdMnO3 phases are pres ent at 1100 degreesC, but Nd2MnO4, Mn2O3, and MnO2 are not stable in the sy stem, Wide ranges of nonstoichiometry were found in the NdMnO3 phase, which coexisted with Nd2O3. X ranges from -0.006 at log Po-2 = -10.85 to 0.104 a t log Po-2 = 0 in the form of NdMnO3+x. The nonstoichiometry is represented by the equation No/N-NdMnO3 = 4.34 x 10(-5)(log Po-2)(3) + 1.99 X 10(-3)(l og Po-2)(2) + 2.65 x 10(-2)(log Po-2) + 0.104; the activities of the compon ents in the solid solution are also calculated with this equation, NdMnO3 h as a composition range to the Nd2O3-rich or Nd2O3-poor side of LaMnO3, Latt ice constants of NdMnO3 made in different oxygen partial pressures were det ermined, (C) 2001 Academic Press.