MgO-CeO

Figure 4 FTIR spectra for MgO, CeO Figure 5 FTIR spectra for pure ceria, pure CaO, and and solids with composition Mg Ce O, 12Ca96Ce oxide precipitated by co-precipitation (cp)...

Yuan Z, Ni C, Zhang C, Gao D, Wang S, Xie Y, Okada A (2009) Rh/MgO/Ceo.sZro.sOj supported catalyst for autothermal reforming of methane the effects of ceria-zirconia doping. Catal Today 146 124-131... 

Abimanyu etal. studied the synthesis of DMC by ethylene carbonate transesterification with methanol (step 2) with various MgO-CeOs mixed oxide catalysts at 150°C. They showed that a high ethylene carbonate conversion of 64% (DMC selectivity of 95%) could be obtained by a catalyst with a cerium content around 25 mo %P... 

Pure and mixed metal oxides have been widely investigated as Lewis acid and/or Lewis base for the reaction epoxides with CO to form the corresponding cyclic carbonates. Bhanage et al. [31] investigated several kinds of basic metal oxides (MgO, CaO, ZnO, ZrO, La Oj, CeO, Al Oj and K CO ) for the reactions of EO and PO with CO to the corresponding cyclic carbonates and for the transesterification reactions of the cyclic carbonates with methanol to DMC and the corresponding glycols. The catalytic performance of the various metal oxides for the synthesis of PC (express in Yp ) was (54.1%) >MgO (32.1%) > ZrO (10.9%) > K CO (8.7%) =... 

Thermodynamic stability of the interface with silicon is also important for correct selection of sensor material. According to Hubbard and Schlom (1996), for MgO and ZrO, thermodynamic stability of their interfaces with silicon was predicted. For HfO, AI2O3, CaO, and Y2O3, experimental evidence showed that these oxides also form stable interfaces with silicon. The CeO /Si interface is thermodynamically unstable, in accordance with experimental observations of formation of a Ce203 interlayer at the CeO /Si interface. Present analysis shows that, for the majority of metal oxides used, the interface with Si is stable. However, ZrO or YSZ thin films are permeable for oxygen at elevated temperatures, so that oxygen diffuses to the silicon substrate and a SiO layer is formed at the interface (Jia et al. 1995). It should be noted that this problem exists for all metal oxides used for gas sensor design. 

The intial densification kinetics in the sintering of powder compacts have been examined for five oxides ZrOz-CaO, MgO, CaO, CeO, and SiOz. Study of the initial sintering, the densification which occurs as the temperature of the specimen is increased, permits the observation of densification kinetics which may not be diffusion controlled. The densification kinetics demonstrate several features which are not compatible with a diffusion-controlled process. For example, there is a disproportionately large increase in the densification rate when the temperature is increased compared to that expected from a volume diffusion process. Other tests indicate that isostatic pressing of partially sintered powder compacts causes densification on subsequent heat treatment. An explanation of these effects by a diffusion sintering process, either volume or grain boundary diffusion, is not evident however, a qualitative explanation based on dislocation transport of material can be proposed. This explanation rests on the premise that as the temperature is increased, the stress required for motion and generation of dislocations decreases. 

Fig. 5. The electronic and hole conductivity of Zro.85Yo.15O1 925 (Park and Blumental, 1989), Lao.gSro iGao -Mgo.2O2.85 (LSGM9182), (Yamaji et al., 1997 Kim and Yoo, 2001) and Ceo sGdo oOi 9 (GDC), (Xiong et al., 2004) measured by the ion blocking method at 1273 K.

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