title: Synthesis of nanoparticles of barium lanthanum hafnium oxide by a modified combustion process.
abstract: Barium lanthanum hafnium oxide, a complex perovskite ceramic, has been synthesized as nanoparticles by a modified combustion process for the first time. The Ba, La, and Hf ions required for the formation of Ba2LaHfO5.5 were obtained in solution by dissolving in boiling nitric acid a stoichiometric mixture of BaCO3, La2O3, and HfO2 that had been heated at 1200 degrees C for 4 h. By complexing the ions with citric acid and using ammonia as fuel, it was possible to get Ba2LaHfO5.5 as nanoparticles in a single-step combustion process. The powder obtained by the present combustion process was characterized by X-ray diffraction, BET surface area analysis, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, and scanning and high-resolution transmission electron microscopy. According to the results of X-ray and electron diffraction, the powder synthesized through the combustion process showed single-phase barium lanthanum hafnium oxide. The transmission electron microscopic investigations showed a grain size of 42 nm, with a standard deviation of 8 nm. The nanoparticles of Ba2LaHfO5.5 synthesized by the present combustion technique could be sintered to > 97% of the theoretical density at a relatively low temperature of 1425 degrees C. Scanning electron microscopic studies on the sintered Ba2LaHfO5.5 samples showed that the final grain size of the sintered specimen was < 500 nm.
authors.affiliation: Regional Research Laboratory, Council of Scientific and Industrial Research, Trivandrum 695 019, India.
authors.forename: Asha M
authors.initials: AM
authors.lastname: John
authors.forename: R
authors.initials: R
authors.lastname: Jose
authors.forename: R
authors.initials: R
authors.lastname: Divakar
authors.forename: J
authors.initials: J
authors.lastname: Koshy
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry; D002516:Ceramics / Q000138:chemical synthesis* / Q000737:chemistry; D003460:Crystallization / Q000379:methods*; D006358:Hot Temperature; D008422:Materials Testing / Q000379:methods*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D010087:Oxides / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D011208:Powders / Q000138:chemical synthesis / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014025:Titanium / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D011208:Powders; C477258:barium lanthanum hafnium oxide; C059910:perovskite; D014025:Titanium