A polymerized complex technique was utilized to prepare high-purity La2Ti2O7 and Nd2Ti2O7. Heating of mixed solutions of citric acid (CA), ethylene glycol (EG), La (or Nd) and Ti ions with a molar ratio of CA:EG:La(or Nd):Ti = 5:20:1:1 at 130°C produced a yellowish transparent polymeric gel without any precipitation, which was subsequently used as a precursor for the production of La2Ti2O7 and Nd2Ti2O7. We suggest, based on the results of 13C NMR spectroscopy, that mixed-metal chelate complexes, (La,Ti)-CAn or (Nd,Ti)-CAn, formed in starting CA-EG solutions. The formation of pure La2Ti2O7 and Nd2Ti2O7 occurred when the precursor was heat treated in a furnace set at 700°C and 800°C respectively in static air for 4 h.
ASJC Scopus subject areas