Synthesis and characterization of Y2Ti2O7 nanoparticles from Y–Ti hydride nanocomposite at a low sintering temperature

Abstract

The Y–Ti hydrides nanoparticles were prepared by hydrogen plasma-metal reaction (HPMR) method. Transmission electron microscopy (TEM) observation revealed that they were spherical in shape and ranged from 5 to 75 nm with a mean diameter of 31 nm. Each nanoparticle contained different hydride phases (YH2, YH3 and TiH1.924), and there existed dislocations to relax lattice misfit strain and minimize the interfacial energy. The hydride nanocomposite started to oxidize at 218 °C during annealing in air, and the pyrochlore-type Y2Ti2O7 nanoparticles of single crystalline were fabricated successfully at a low sintering temperature of 900 °C for 1 h. The Y2Ti2O7 nanoparticles of axiolitic shape had an average size of 70 nm, much smaller than the conventional Y2Ti2O7 prepared by sintering Y and Ti oxides above 1300 °C. The formation of Y2Ti2O7 nanoparticles from the hydride nanocomposite at a low temperature and short reaction time can be attributed to the very short diffusion distance of Y and Ti at nanoscale, and the accelerated diffusion rate due to the strained interface of different hydride phases. The novel strategy opens a new way to prepare the nanosized pyrochlore-type oxides at a low temperature.