Cerium gadolinium oxide

In the preparation of the electrolyte/anode dual-layer hollow fibers for this woik, two ceramic suspensions were prepared separately. Suspension of the anode inner layer was composed of 60 wt% of nickel oxide (NiO) and 40 wt% of cerium gadolinium oxide (CGO), whereas the one for the electrolyte outer layer contained 100% CGO powder. Hie suspension compositions for the fabrication of four different dual-layer hollow fibers are listed in Table 11.2. Caamic powdas wctc first mixed with DMSO and Arlacel P135 as the solvent and dispasant, respectively, and stirred for 48 h. After this time, PESf pellets as the polymer binder were slowly added into the mixtures with stirring at 300 rpm. The mixing continued for an extra 48 h to obtain homogeneous spinning suspension. 

Lanthanide (III) Oxides. The lanthanide(III) oxides will be used to illustrate the present breadth of our most extensive knowledge of the chemical thermodynamics of lanthanide compounds. Cryogenic heat capacities of hexagonal (III) lanthanum, neodymium, and samarium oxides, together with those of cubic (III) oxides of gadolinium, dysprosium, holmium, erbium, and ytterbium, have been reported (90, 91, 195). In addition, those of thulium, lutetium, and a composition approaching that of cerium (III) oxide have also been determined, and five well-characterized compositions between PrOi.714 and PrOi.833 are currently under study (J93). 

Chemicae Eormulas Common compounds o Cerium oxide CeiOs o Gadolinium oxide Gd203 o Lanthanum oxide LaiOs o Yttrium oxide Y2O3 o Cerium nitrate Ce(N03)3 o Cerium chloride CeCls... 

Gadolinium is produced from both its ores, monazite and bastnasite. After the initial steps of crushing and beneficiation, rare earths in the form of oxides are attacked by sulfuric or hydrochloric acid. Insoluble rare earth oxides are converted into soluble sulfates or chlorides. When produced from monazite sand, the mixture of sand and sulfuric acid is initially heated at 150°C in cast iron vessels. Exothermic reaction sustains the temperature at about 200 to 250°C. The reaction mixture is cooled and treated with cold water to dissolve rare earth sulfates. The solution is then treated with sodium pyrophosphate to precipitate thorium. Cerium is removed next. Treatment with caustic soda solution fohowed by air drying converts the metal to cerium(lV) hydroxide. Treatment with hydrochloric or nitric acid sol-... 

The lutetium hahdes (except the fluoride), together with the nitrates, perchlorates, and acetates, are soluble in water. The hydroxide oxide, carbonate, oxalate, and phosphate compotmds are insoluble. Lutetium compounds are all colorless in the solid state and in solution. Due to its closed electronic configuration (4f " ), lutetium has no absorption bands and does not emit radiation. For these reasons it does not have any magnetic or optical importance, see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Neodymium Praseodymium Promethium Samarium Terbium Ytterbium. 

For a higher conductivity, cerium dioxide can be doped either with gadolinium Cei cGd (02 or with samarium Cex jSmj02 doped cerias are quite stable chemicdly. In solid oxide fuel cells they lack the effect of interactions between the electrolyte and the cathode materials that would lead to the formation of poorly conducting compounds. However, doped cerias have an important defect in that at low oxygen partial pressures (such as those existing close to the anode) they develop a marked electronic conduction. This is entirely inadmissible for the electrolyte, as it leads to internal self-discharge currents and even to a complete internal short circuit. The electronic conduction comes about when Ce" ions in the lattice are partly reduced to Ce " ions, which creates the possibility for electrons to hop between ions of different valency. 

Face-centered cubic ( fee) phase cerium, 278-280 gadolinium, 296-297 lanthanum, 277 praseodymium, 281 promethium, 287 ytterbium, 313-314 First-order phase transition, 19-20 Fluorescent lamp wastes recycling, 189/, 191/ Flux/slag process, magnets separation glass slag method, 181—182 by molten fluorides, 181/ plant waste (sludge), 182 rare-earth oxides, 181... 

The oxidation state of IV demonstrated by thorium is then analogous to the IV oxidation state of cerium. From the behavior of uranium, neptunium and plutonium it must be deduced that as many as three of the assumed 3f electrons are readily given up, so that the failure of thorium to demonstrate an oxidation state of III is accounted for. On the basis of this hypothesis, elements 95 and 96 should exhibit very stable III states in fact, element 96 should exhibit the III state almost exclusively because, with its seven 3f electrons, it should have an electron structure analogous to that of gadolinium, with its seven 4f electrons. 

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