Synthesis by the polyol process and ionic conductivity of nanostructured La2Mo2O9 powders

Abstract

La 2 Mo 2 O 9 nanostructured powders were synthesized by the polyol process. The effects of the nature of the polyol, the refluxing time, the hydrolysis ratio, the metal concentration and the addition of hydroxyde ions, on the purity and morphology of the powders are determined. Two main morphologies are observed, the particles being in the shape of platelets or spheres, with respectively diethylene glycol or ethylene glycol as solvent. A specific surface area of 24 m².g-1 was reached by varying the metal concentration. The conductivity measurements were recorded on pellets that present in some cases a closed porosity, the relative density reaching 95% without any milling step. According to the synthesis parameters, the grain conductivity can be slightly increased, the total conductivity remaining only slightly lower than that of pellets made of powders synthesized by solid state reaction.

Reduction Kinetics of La2Mo2O9 and Phase Evolution during Reduction and Reoxidation

“…La 2 Mo 2 O 9 powders with higher specific surface areas were also prepared by the polyol process using two glycol solvents, ethylene glycol (EG) and diethylene glycol (DEG), with a final rapid heat treatment of 5 min at 600 °C . The details regarding this synthesis are reported in previous papers by Sellemi et al , …”

“…La 2 Mo 2 O 9 powders with higher specific surface areas were also prepared by the polyol process using two glycol solvents, ethylene glycol (EG) and diethylene glycol (DEG), with a final rapid heat treatment of 5 min at 600 °C. 17 The details regarding this synthesis are reported in previous papers by Sellemi et al 18,19 Hydrogen Reduction and Reoxidation Characterization. Reduction kinetics of La 2 Mo 2 O 9 was studied at 700 and 760 °C using a Setaram TG92 microbalance under a flow rate of 4.8 L•h −1 of 10% H 2 diluted in Ar.…”

“…High values are obtained for the powder samples prepared by the polyol process, for very thin platelet particles synthesized with DEG, and porous spherical grains synthesized with EG. 18,19 Reduction kinetics are presented in Figure 4a. We can notice for EG and DEG samples that reduction has already begun during the heating process.…”

Defining "Giant" Electrostriction

“…Lacorre's team demonstrated La 2 Mo 2 O 9 as a distinct structural group of fast oxide-ion conductors, which is now used in solid oxide fuel cells and oxygen pumping devices 55,56 . La 2 Mo 2 O 9 (with a conductivity of around 0.06S/cm at 800 • C) can achieve comparable ionic conductivity comparable to commercial 10% of yttriastabilized zirconia (YSZ) (∼ 0.1S/cm at 1000…”

Investigation of Polyol Process for the Synthesis of Highly Pure BiFeO3 Ovoid-Like Shape Nanostructured Powders

“…. ) due to its reducing capacity, and then it was enlarged for the synthesis of oxides [20] and perovskites [21] displaying improved physical properties, and most of the time totally new emerging electrical and optical features as a consequence of the changed shape, color, and particle size and structure [22] and the enlarged specific area [23,24]. It is interesting to recognize the large range of the possible sizes, going from the mesoscale down to 4 nm [25], which can be useful if one needs to investigate the overturning of physico-chemical properties of some phases based on the particles size.…”