Structural and thermal study of highly porous nanocomposite SiO2-based aerogels

2010 ◽  
Vol 356 (18-19) ◽  
pp. 879-883 ◽  
Author(s):  
Hexin Zhang ◽  
Yingjie Qiao ◽  
Xiaohong Zhang ◽  
Shuangquan Fang
Keyword(s):  
Thermal Study ◽  
Porous Nanocomposite ◽  
Highly Porous

Role of Urea in the Preparation of Highly Porous Nanocomposite Aerogels

Langmuir ◽  
2007 ◽  
Vol 23 (7) ◽  
pp. 3509-3512 ◽  
Author(s):  
Maria F. Casula ◽  
Danilo Loche ◽  
Sergio Marras ◽  
Giorgio Paschina ◽  
Anna Corrias
Keyword(s):  
Porous Nanocomposite ◽  
Highly Porous

Structural study of highly porous nanocomposite aerogels

2007 ◽  
Vol 353 (18-21) ◽  
pp. 1785-1788 ◽  
Author(s):  
Daniela Carta ◽  
Anna Corrias ◽  
Gavin Mountjoy ◽  
Gabriele Navarra
Keyword(s):  
Structural Study ◽  
Porous Nanocomposite ◽  
Highly Porous

A highly porous nanocomposite (Fe3O4@BFR) for the removal of toxic Cd(II) ions from aqueous environment: Adsorption modelling and regeneration study

2019 ◽  
Vol 172 ◽  
pp. 179-185 ◽  
Author(s):  
Mu. Naushad ◽  
Tansir Ahamad ◽  
Khalid A. Al-Ghanim ◽  
Ala'a H. Al-Muhtaseb ◽  
Gaber E. Eldesoky ◽  
...  
Keyword(s):  
Aqueous Environment ◽  
Porous Nanocomposite ◽  
Regeneration Study ◽  
Highly Porous ◽  
Adsorption Modelling

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

Microstructural observations of the “Wustite-Spinel” coexistence following quenching of cation-excess spinels, Ni2(1+x)Ti1-xO4

1990 ◽  
Vol 48 (4) ◽  
pp. 1058-1059
Author(s):  
Ian M. Anderson ◽  
Arnulf Muan ◽  
C. Barry Carter
Keyword(s):  
Film Growth ◽  
Spinel Phase ◽  
Model Systems ◽  
Ion Milling ◽  
Coexistence Of Phases ◽  
Nonequilibrium Conditions ◽  
Diffraction Patterns ◽  
Spinel Structures ◽  
Highly Porous ◽  
Standard Techniques

Oxide mixtures which feature a coexistence of phases with the wüstite and spinel structures are considered model systems for the study of solid-state reaction kinetics, phase boundaries, and thin-film growth, and such systems are especially suited to TEM studies. (In this paper, the terms “wüstite” and “spinel” will refer to phases of those structure types.) The study of wüstite-spinel coexistence has been limited mostly to systems near their equilibrium condition, where the assumptions of local thermodynamic equilibrium are valid. The cation-excess spinels of the type Ni2(1+x)Ti1-xO4, which reportedly exist only above 1375°C4, provide an excellent system for the study of wüstite-spinel coexistence under highly nonequilibrium conditions. The nature of these compounds has been debated in the literature. X-ray and neutron powder diffraction patterns have been used to advocate the existence of a single-phase, non- stoichiometric spinel. TEM studies of the microstructure have been used to suggest equilibrium coexistence of a stoichiometric spinel, Ni2TiO4, and a wüstite phase; this latter study has shown a coexistence of wüstite and spinel phases in specimens thought to have been composed of a single, non- stoichiometric spinel phase. The microstructure and nature of this phase coexistence is the focus of this study. Specimens were prepared by ball-milling a mixture of NiO and TiO2 powders with 10 wt.% TiO2. The mixture was fired in air at 1483°C for 5 days, and then quenched to room temperature. The aggregate thus produced was highly porous, and needed to be infiltrated prior to TEM sample preparation, which was performed using the standard techniques of lapping, dimpling, and ion milling.

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