Temperature zirconia-based

The tape-casting method makes possible the fabrication of films in the region of several hundred micrometers thick. The mechanical strength allows the use of such a solid electrolyte as the structural element for devices such as the high-temperature solid oxide fuel cell in which zirconia-based solid electrolytes are employed both as electrolyte and as mechanical separator of the electrodes. 

Another approach to increase HPLC speed is the use of higher temperatures. The viscosity of a typical mobile phase used in reversed-phase separation decreases as the column temperature is increased. This allows an HPLC system to operate at a higher flow rate without suffering too much from increased back pressure. Zirconia-based packing materials provide excellent physical and chemical stability. They have been used successfully for high-throughput bioanalysis at elevated temperatures.9... 

Activation Energy (Ea) and Conductivity (o) Values at High- and Low-Temperature Range for Some Zirconia-Based Electrolytes [10]... 

Lei and Zhu [63] found that adding 2.0 mol% Mn203 to llScSZ can inhibit the cubic-rhombohedral phase transformation in both oxidation and reduction atmospheres, and the codoped zirconia can reach nearly full density when sintered at temperatures as low as 850°C. The conductivity of 2Mn203-l IScSZ sintered at 900°C is 0.1 Scm-1 at 800°C. Figure 1.11 illustrates the conductivity of some zirconia-based ternary systems [32,42,57,63-67],... 

Although most classical silica-ODS columns are not stable at temperatures much above 60°C (dependent on eluent conditions), columns made from other materials such as polymeric and zirconia-based phases have been used for high temperature work (see earlier text). 

The stability of zirconia and zirconia-based packings also allows the use of these columns at an elevated temperature. The key advantage of this is the reduction in analysis time due to the reduction in the viscosity of the mobile phase. In addition, the much broader temperature range also permits a fine-tuning of the selectivity of a separation compared with silica-based packings. 

C is not recommended and high-temperature LC has not been rigorously explored. With the advent of thermally stable phases such as zir-conia-based stationary phases, temperatures in excess of 150°C can now be utilized. Many zirconia-based phases are available, so the stability of stationary phases is less of an issue. 

Cubic fluorite-structure (Fm3m) zirconia-based solid solution, (Zr,ACT,REE)02 x, exhibi ts significant compositional flexibility to incorporate high concentrations of Pu, neutron absorbers, and impurities contained in Pu-bearing wastes (Gong et al. 1999). The phase has excellent radiation stability. No amorphization was observed under ion irradiation at room temperature to a dose corresponding to 200 dpa, and at 20 K to a dose of 25 dpa. Irradiation with I+ and Sr+ up to 300 dpa produced defect clusters in Y-stabilized zirconia, but did not cause amorphization. Amorphization... 

Column temperature affects the relative retention of different compounds and elevated temperature permits high-speed chromatography to be conducted.25 Figure 25-28 suggests a systematic procedure for method development in which solvent composition and temperature are the two independent variables.1 For elevated temperature operation, pH should be below 6 to retard dissolution of silica. Alternatively, zirconia-based stationary phases work up to at least 200°C. 

Considering the obtained experimental data, it is possible to propose a model of the formation of a porous structure of the films of zirconia-based solid electrolytes. The model assumes the formation of pores and submicropores when vacancies, which are trapped during sputtering of the solid-electrolyte films (the sputtering temperature was Tf < 0.3Tmeit), pass to sinks and then condense [2,3,4,5], The sinks are boundaries between the crystallites forming the film structure. 

We have recently suggested a new approach to the preparation of active sites in sulfated zirconia catalysts [5, 6]. In this case, the catalysts are prepared by deposition of sulfate ions on crystalline zirconium dioxide samples with highly defective structure. According to numerous reports, the monoclinic phase typical for ZrOa is not suitable for this purpose. We have shown that active materials could be obtained by impregnation of zirconia-based oxides with cubic crystalline structure. It should be noted that the cubic structure is not thermodynamically stable for pure zirconia at low temperatures. It can be stabilized by introducing different additives, in particular, alkaline-earth metal cations [7]. Recently, similar results have been obtained for ZrOa stabilized by Y2O3 [8]. 

It is known that supported palladium catalysts are the most active for the total oxidation of methane [3], and there are many studies focusing on the alumina supported ones [4 and references cited therein] However, alumina is not stable at the temperatures commonly used for methane oxidation. To avoid this problem, other authors [5] have suggested the use of zirconia-based supports, which are considered as more thermally stable. In this way, these supports were found to present very different properties, depending on the synthesis method and the presence of additives. 

Kurosawa, H., Yan, Y., Miura, N. and Yamazoe, N. (1995) Stabilized zirconia-based NOx sensor operative at high temperature. Solid State Ionics, 79, 558 5. 

In contrast from the single-phase electrolytes, the two-phase electrolytes are characterized by the deeper aging, and the duration of aging is usually much longer. The absence of equilibrium was reported for the zirconia-based electrolytes held at the temperature of 1100°C for 2000-3000 hours [13], for the Z1O2-SC2O3 electrolyte part of the aging curve has the 5-shape form [34],... 

For the zirconia-based gas sensors, the low level of threshold temperature, when the zirconia electrolytes possess pure ionic conductivity, is approximately 500-550°C for polycrystalline stractures [44 6] and around 380-420 C for single crystals [47, 48]. The conductivity of the YSZ-based electrolyte below these temperatures is compatible with the conductivity of isolators. Moreover, any reduction in operating... 

FIGURE 2.6 Effect of the sintering temperature of the SE matrix on the catalytic activity to the gas-phase decomposition reaction of NOj. (Reprinted from Zhuiykov, S. and Minra, N., Development of zirconia-based potentiometiic NOx sensors for antomotive and energy industries in the early 21st century What are the prospects for sensors Sensors and Actuators B Chem. 121 (2007) 639-651, with permission from Elsevier Science.)... 

---