PHASE TRANSFORMATIONS IN THREE-COMPONENTAL  SYSTEMS Ln-Mn-O (Ln= RARE EARTH ELEMENTS) ON AIR AND AT VARIABLE PRESSURE OF OXYGEN

V.F.Balakirev, A.M.Yankin, Yu.V.Golikov, L.B.Vedmid, O.M.Fedorova 

Institute of metallurgy of Ural Branch of  the Russian Academy of Science, Ekaterinburg, 
Russia, 620016, elarisa100@mail.ru

Subsolidus phase diagrams for the Ln-Mn-O (Ln=Ce, Sm,…Lu, Y) systems in air were constructed over the temperature range 850-1400єC based on an XRD  analysis of homogeneous and heterogeneous phases, received by ceramic synthesis and their comparative analysis is executed.
Thus, construction of diagrams of this type for all class rare earth element - manganese - oxygen is completed. The comparative analysis of the constructed diagrams, has shown, that the dominating factor determining crystal structure оксидов RMnO3 (R- rare earth  element), is the radius trivalent cation  rare earth element. Dependences of temperature thermal dissociations binary oxides  RMn2O5 on air from a serial number which is included in them rare earth element, number f-электронов cation R (III), numbers not coupled electrons in it and his ionic radius are constructed. The interrelation between temperatures thermal dissociations   RMn2O5 and the top temperatures of thermal stability of cubic updating R2O3 on air is established.
Necessity of an experimental research of areas of homogeneity of these oxides both on oxygen, and on metal components is proved depending on temperature of synthesis.
The static method of research heterogeneous equilibriums in a combination with XRD analysis (ДРОН-2.0, CuKα) investigates process thermal dissociations connections RMnO3 and RMn2O5 (R=Sm, Tb, Dy, Ho - Lu). The thermodynamic analysis phase equilibriums, found out in conditions of carrying out of experiment is lead. On the basis of the received data are constructed P-T-X the diagrams of these systems submitted as projections in various coordinates.
Work is executed at financial support of Advice under grants of the President of the Russian Federation and the state support of scientific schools, grant NSC-408.2008.3, on equipment CKP "Ural - M" GU Institute of metallurgy of Ural Branch of  the Russian Academy of Science .