2026-05-28T08:44:41Zhttps://riuma.uma.es/rest/oai/request

oai:riuma.uma.es:10630/160342026-02-03T12:16:46Zcom_10630_2254col_10630_37959

Influence of Nb-doping on the structural and electrical properties of lanthanum molybdates, La5.4MoO11.1 López Vergara, Adrián Porras-Vázquez, José Manuel Vollestad, Einar Canales-Vázquez, J. Ramírez-Losilla, Enrique Marrero-López, David Lantánidos Nowadays, hydrogen is receiving a great deal of attention as an energy carrier. Commonly, it is obtained by hydrocarbons reforming, such as natural gas, coal and biomass. However, the resulting hydrogen needs to be purified to remove by-products and impurities, increasing the production costs. An alternative for hydrogen production is proton-conducting ceramics, where hydrogen separation takes place via a chemical potential gradient across the membrane.1, 2 In this work, Nb-doped La6MoO12--based compounds have been investigated as part of a new family of materials very competitive as SOFC electrolyte and hydrogen separation membranes.3 These materials, La5.4Mo1-xNbxO11.1-x/2 (x = 0.05, 0.10, 0.15 y 0.20) were synthesized by the freeze-drying precursor method and calcination conditions have been optimized to obtain single phases. A complete characterization has been carried out using X-Ray powder diffraction and scanning and transmission electron microscopy. The total conductivity was determined by complex impedance spectroscopy at different atmospheres. Different polymorphs are obtained as a function of the cooling rate and the dopant amount. The samples cooled by quenching are cubic with a fluorite-type structure (Fm3 ̅m) and the ones cooled at 50 y 0.5 ºC•min-1 are rhombohedral (R1 and R2 polymorphs). For niobium contents higher than x = 0.10 the R1 polymorph is stabilised at cooling rates equal or inferior to 50 ºC•min-1. For all three series, the incorporation of niobium into La5.4MoO11.1 increases the conductivity, reaching the best values for x=0.10 and the sample obtained by quenching. 2018-06-28T06:36:13Z 2018-06-28T06:36:13Z 2018 2018-06-28 conference output https://hdl.handle.net/10630/16034 eng 18 Reunión del Grupo Especializado de Química Inorgánica, 12 Reunión del Grupo Especializado de Química de Estado Sólido San Cristobal de la Laguna,Tenerife 17-20 de junio de 2018 http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional