Low-temperature sonochemical synthesis of high dielectric Lanthanum doped Cerium oxide nanopowder

Abstract

Lanthanum (La) doped Cerium Oxide (CeO<inf>2</inf>) nanopowder was synthesized at a relatively lower temperature (70°C), without calcination in a simple, faster, and efficient way through sonochemical method. X-ray diffraction (XRD) results confirmed the formation of a cubic fluorite structure of nanocrystalline CeO<inf>2</inf> and lattice deformation due to La-doping in CeO<inf>2</inf>. TEM analysis revealed that the size of La-doped CeO<inf>2</inf> particles is in the range of 20?50 nm. In addition, selective area electron diffraction (SAED) and high-resolution TEM (HRTEM) analyses portrayed the nano-crystallinity, lattice fringe pattern, and d-spacing details of La-doped CeO<inf>2</inf> powder. Lanthanum doping in CeO<inf>2</inf> was further confirmed by a shift in Raman band towards the lower frequency (from 464 cm?1 to 457cm?1) along with peak intensity increase. Photoluminescence (PL) emission spectra showed that emission intensity of the La-doped CeO<inf>2</inf> at 510 nm is increased due to oxygen vacancy mediated charge transfer. All these results confirm the successful doping of La in CeO<inf>2</inf>. The La-doped CeO<inf>2</inf> powder possesses a high dielectric constant (?<inf>r</inf>) of 106 and a low dielectric loss (tan ?) of < 0.4 % at 1 kHz. The La-doped CeO<inf>2</inf> finds potential applications on developing devices in the field of a thin film capacitor, transistors, and solid oxide fuel cells. © 2018 Elsevier B.V.