Synthesis of La2NiO4+δ oxides by sol–gel process: Structural and microstructural evolution from amorphous to nanocrystallized powders

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID : 2601 AbstractIn this paper, the structural and microstructural transition from amorphous to La 2 NiO 4+d nanocrystallized oxides synthesized by a polymeric route based on Pechini's work has been studied by several experimental techniques including infrared spectroscopy and wide angle X-ray scattering. The synthesis parameters which govern this transition have been identified in order to synthesize La 2 NiO 4+d oxides with various mean crystallite sizes and non stoichiometry levels. Therefore, it has been demonstrated that the control of the nature and the content of organic compounds in the polymeric sols allows the preparation of La 2 NiO 4+d metastable phases with a mean crystallite size ranging from 100 to 220 nm and a non stoichiometry level ranging from 0.15 to 0.22 at 25 8C. As the cathodic performance strongly depends on the physical characteristics of the oxides, this study shows that our versatile process may be suitable to elaborate electrodes with different electrochemical behaviours.

In situ variable temperature X-ray diffraction studies on the transformations of nano-precursors to La–Ni–O phases

“…The synthesis of La 2 NiO 4 in air is well known to yield a hyperstoichiometric compound, with a general formula La 2 NiO 4 þ d (d40) [7][8][9][45][46][47][48][49][50]; hence, a stoichiometric compound may only be obtained in an inert atmosphere (e.g. argon).…”

Prediction of thermal radiative properties (300–1000 K) of La2NiO4+δ ceramics

“…7 The chemical composition was checked by Inductively Coupled Plasma spectrometry for cationic composition, and thermogravimetric analysis-differential scanning calorimetry ͑TGA-DSC͒ and iodometric titration for oxygen content. The feed rod was sintered in air at 1300°C for 12 h and prepared from La 2 NiO 4.18 powders according to the Pecchini method.…”

Influence of the Index Metallic Salts - Complexing Agent in a Sol-Gel Process to Obtain Nanoscaled Zirconium Substituted Yttrium (Ysz) to Electrolyte Application in Solid Oxide Fuel Cell (Sofc)

“…In these images the YSZ powder morphology is spherical. In addition their YSZ powder size presents their nano character as reported [8]. The YSZ grain dimension was calculated with a mean 50 nm and standard deviation close at 9 nm, other research work as reference 8 report for a calcination near to 1000 °C, with sol-gel technique a size between 30 and 40 nm, but they do not say their heating speed, neither their time inside the four, the reference 10 reported for YSZ thin film with laser technique a grain size 21.4± 1.4 nm.…”

“…Between 300 and 470 ºC it is principal mass loss with near 80%, it is attributed at organic material calcination, and justified by the strong exothermic reaction. The research team [8], who used the same sol-gel protocol but to get the La 2 NiO 4+δ material report the structural steps to thermic sol decomposition are three and they were determinate by infrared spectroscopy; the first one, it be down of 300 °C, they are exhibit five wide band between 1900 and 900 cm -1 . It is attributed a stable polymeric precursor formation and the nitrate species do not decomposed below 300 °C; second step is characterized, by the extinction of the bands previous, when the temperature Table 1.…”