Using electron microscopy techniques studies in microstructure of NdFeCoAl-(B,C) based alloys

Abstract

Poster SessionsLAMOX, the new family of oxide conductors, obtained on the basis of La2Mo2O9 compound with the use of different substitutions is the object for intensive studies. In 2005 year single crystals of the anionic conductor La2Mo2O9 were grown by crystallization from the nonstoichiometric flux [1]. Their polymorphism, domain structure and temperature dependences of conductivity and permittivity were studied [1]. Conductivity of these crystals at 750-600 C reaches 10 -1 -10 -2 Om -1 sm -1 . It was established that in dependence of the cooling rate and of the admixture content, these crystals can exist at the room temperature as stable monoclinic A-phase or metastable cubic B1-phase or as their mixture. Obtaining of the most complete and precise structural data about the crystals of cubic metastable B1phase from X-ray experiment was the purpose of the present study. It is important that these studies were done for the first time for single crystals. Cubic cell with a=7.158(1)Å, which was found for the studied single crystal, allowed to index about 84% of measured reflections. While solving the structure (in sp.gr. P213) it was established that La and Mo atoms are shifted from the threefold axes. Occupation of three positions of La and Mo atoms was found to be equal to 100%. Two of the three independent oxygen positions in this crystal are not fully occupied, have quite large thermal parameters and are located at the short distances from each other.