Synthesis and sintering of Ce_1-xGd_xO_2-x/2 nanopowders via chemical routes.

Abstract

Gd-doped ceria (Ce0.80Gd0.20O1.90) obtained by several nanopowder synthesis processes are compared structurally, morphologically and electrochemically. The powders have been sintered into pellets and investigated by ac-impedance measurements. The electrochemical properties of the electrolytes have been correlated to the structural morphology of the sintered pellets. When the intergrain region exhibits an elevated interdiffusion, the observation of the grain boundaries becomes difficult while the electrochemical properties are improved. Acrylamide polymerization and oxalic co-precipitation techniques showed the best properties.

In Situ HT‐ESEM Observation of CeO2 Grain Growth During Sintering

“…Such discrepancies could be explained by the numerous factors influencing significantly the sintering of CeO 2 , including temperature range, initial powder granulometry, and oxide stoichiometry. Indeed, important differences were also noted when comparing the densification of nanopowders with that of conventional material . Also, it is well known that the surrounding atmosphere, and particularly the value of P O2 , is one of the main parameters controlling thermodynamics and kinetics of CeO 2 sintering, due to the partial reduction of Ce(IV) into Ce(III) .…”

Temperature-dependent Raman study of Ce0.75Nd0.25O2−δ nanocrystals

“…3,4 Nanosized CeO 2 doped with rare earth elements is a promising solid electrolyte with excellent ionic conductivity at low temperature because of the high oxygen vacancy concentration. 5, 6 Although in recent years numerous investigations have been performed on the structural 7-9 and transport properties of doped ceria, 5,6 we are not aware of any other Raman work aimed to the examination of temperature-induced changes on the vibrational properties in these materials. In the present study, we investigated the temperature dependence of the Raman spectra of Ce 0.75 Nd 0.25 O 2−␦ nanocrystals.…”

Iron–Air Battery Operating at High Temperature

“…Reduction of Ce 4+ ions may occur by effect of a chemical reduction with hydrogen or by effect of a low applied electrochemical potential, for example, by flowing electrons into the negative electrode during a battery charging process. The reduction process propagates in the ceria‐based electrolyte …”

“…Ceria is doped with gadolinia not only to increase the ionic conductivity but also to depress the reduction mechanism from Ce 4+ to Ce 3+ by shifting to the left side of Equation (1) . As a consequence, the formation of free electrons responsible for the internal short circuit in the electrolyte is mitigated.…”