Direction observation of the grain boundary segregation in molybdenum substituted lanthanum tungstate membranes

Abstract

Molybdenum substituted lanthanum tungstate membranes (LWO-Mo) offer a good alternative for the separation of hydrogen from gas mixtures. During several essential steps of the membrane processing, an intensive employment of...

Structural and Transport Properties of E-Beam Sintered Lanthanide Tungstates and Tungstates-Molybdates

“…Similar to CS samples with the same compositions [24], it is apparently related to faster oxygen diffusion along grain boundaries for the NWMO sample compared with that of other samples (Table 4). This can be explained by the difference in the W-O and Mo-O binding energy as well as the effect of the Mo cation on the extended defect features, such as oxygen vacancy ordering or clustering [37,38], thin secondary phase film segregation along grain boundaries [39,40] and the probable effect on the porous structure [41]. At temperatures above 500 • C, the behavior of the isotope exchange process is almost the same for all three samples (Figure 7).…”

Structural and transport properties of Nd tungstates and their composites with Ni0.5Cu0.5O obtained by mechanical activation

“…6), the diffusion coefficient values along grain boundaries are close for the NWO and NLWO samples with high effective activation energy (Table 4). For the NWMO sample, the effective activation energy for the diffusion coefficient along grain boundaries is lower probably due to the difference in the W-O and Mo-O binding energy and/or the Mo cation effect on the extended defect features such as oxygen vacancy ordering or clustering, 29,30 thin secondary phase film segregation along grain boundaries [31][32][33] and the probable effect on the porous structure. 34 Within the frame of this model, the nonuniformity of the bulk oxygen mobility was revealed.…”