Low temperature synthesis of Y 3NbO 7 by polymerizable complex method: Utilization of a methanol-citric acid solution of NbCl 5 as a novel niobium precursor

Abstract

A modified polymerizable complex method was used to prepare pure Y 3NbO 7 powders at reduced temperature. To acquire a niobium-containing solution stable enough for the polymerizable complex processing, methanol was chosen to solvate NbCl 5. Dissolution of NbCl 5 in methanol gave a colorless transparent solution, to which citric acid (CA), yttrium carbonate and ethylene glycol (EG) were added successively to produce a transparent solution containing yttrium-CA complexes and niobium-CA complexes. The solution was heated at ∼130°C to remove excess methanol and promote esterification between CA and EG to yield a transparent polymeric resin without precipitation; this material was used subsequently as a precursor for Y 3NbO 7. The formation of Y 3NbO 7 occurred when the resin precursor was heat-treated at 500°C for 2 h in static air.