Phase formation in the Nd2Ti2O7-SrTiO3 system at 1350 degrees C in the presence of V2O5, CuV2O6, or SrCuO2

The system Nd4Ti4O14 (=Nd2Ti2O7)-SrTiO3 has been studied by powder X-ray diffraction and electron microscopy. The samples were prepared by normal ceramic methods and contained one of the additives V2O5, CuV2O6, or SrCuO2. Each of these additives caused the reaction to take place at greatly increased rates compared to that without additives. The major products were Nd4Ti4O14 and SrTiO3, which were formed in 8 hr at 1350 degrees C. The vanadium in the additives formed NdVO4 while the other components were incorporated into the product phases. The Nd4Ti4O14 was generally well ordered but the SrTiO3 showed a complex microdomain microstructure which was associated with a variety of changes in the unit cell observed by X-ray diffraction. Heating for several days caused the SrTiO3 to revert to the normal cubic form, at which point the microdomain structure was lost. (C) 1996 Academic Press, Inc.