scholarly journals Synthesis and characterization of nano-LaFeO3 powders by a softchemistry method and corresponding ceramics

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Phase Transition ◽  
Surface Area ◽  
Rhombohedral Phase ◽  
Phase Evolution ◽  
High Specific Surface Area ◽  
Coarse Grained ◽  
Complexing Agent ◽  
Porous Powder ◽  
Enthalpy Changes ◽  
Crystallite Sizes

The preparation of a nano-sized LaFeO3 powder by a soft-chemistry method usingstarch as complexing agent is described herein. Phase evolution and development of thespecific surface area during the decomposition process of (LaFe)-gels were monitored up to1000 °C. A phase-pure nano-sized LaFeO3 powder with a high specific surface area of 25.7m2/g and a crystallite size of 37 nm was obtained after calcining at 570 °C. TEMinvestigations reveal a porous powder with particles in the range of 20 to 60 nm. Calcinationsto 1000 °C result in crystallite sizes up to 166 nm. Dilatometric measurements of the sinteringbehaviour show that the beginning of shrinkage of pellets from the nano-sized powder is downshifted by more than 300 °C compared to coarse-grained mixed-oxide powder. The orthorhombic - rhombohedral phase transition was observed at 980 °C in DTAmeasurements for coarse-grained ceramic bodies. The enthalpy change (dH) during the phasetransition and the thermal expansion coefficient (adil) for ceramics was determined as 410 J/mol and 11.8×10-6 K-1, respectively. Whereas the enthalpy changes during the phase transition of the nano-sized LaFeO3 powders are £ 200 J/mol.

Fabrication of Porous Ni-ZrO2 for SOFC Using NiO-ZrO2 Composite Powders

2006 ◽  
Vol 317-318 ◽  
pp. 705-708 ◽  
Author(s):  
K. Sato ◽  
Sawao Honda ◽  
T. Nishikawa ◽  
Hideo Awaji
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Average Particle Size ◽  
High Specific Surface Area ◽  
Average Particle ◽  
Composite Powders ◽  
Epma Analysis ◽  
Coating Method ◽  
Crystallite Sizes

Porous NiZrO2 has been widely used as anode in SOFC. However, it has been reported that there was reduction in cell performance at high temperature since Ni grains in the porous Ni ZrO2 sintered during cell operation. In this study, NiOZrO2 composite powders in which NiO powder were covered with ZrO2 particles were prepared with controlled microstructure of porous NiZrO2 which can prevent sintering of Ni grains during cell operation. NiOZrO2 composite powders (HNZ) were prepared using NiO powder of high specific surface area and ZrO2 sol of average particle size of 50 nm by ball milling (sol-coating method). SEM and EPMA analysis of prepared NiOZrO2 composite powders showed that NiO particles were covered with ZrO2 particles. The crystallite phases, crystallite sizes, BET specific surface area of NiOZrO2 composite powders and porosities of fabricated porous NiZrO2 were characterized. SEM and EPMA analysis showed that ZrO2 was distributed around Ni of a few μm range in the porous Ni ZrO2 (HNZ) fabricated by the sol-coating method. Mechanical properties of porous NiZrO2 (HNZ) are required to be improved.

scholarly journals A green approach of preparation of fine active alumina with high specific surface area from sodium aluminate solution

RSC Advances ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 5628-5638
Author(s):  
Guoyu Wu ◽  
Guihua Liu ◽  
Xiaobin Li ◽  
Zhihong Peng ◽  
Qiusheng Zhou ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Phase Evolution ◽  
Sodium Aluminate ◽  
High Specific Surface Area ◽  
Aluminate Solution ◽  
Green Approach ◽  
Active Alumina ◽  
Sodium Aluminate Solution

A green preparation of fine active alumina from saturated sodium aluminate solution by phase evolution is presented. High capillary pressure, numerous mesopores, and the inhibition of aggregation produced FAA with an extremely high specific surface area.

Experience with nutrient removal in a fixed-film system at full-scale wastewater treatment plants

1997 ◽  
Vol 36 (1) ◽  
pp. 129-137 ◽  
Author(s):  
Vibeke R. Borregaard
Keyword(s):  
Wastewater Treatment ◽  
Surface Area ◽  
Nutrient Removal ◽  
Wastewater Treatment Plants ◽  
High Specific Surface Area ◽  
Biological Nutrient Removal ◽  
Growth Processes ◽  
Total N ◽  
Attached Growth ◽  
On Line

In the upgrade of wastewater treatment plants to include biological nutrient removal the space available is often a limiting facor. It may be difficult to use conventional suspended growth processes (i.e. activated sludge) owing to the relatively large surface area required for these processes. Recent years have therefore seen a revived interest in treatment technologies using various types of attached growth processes. The “new” attached growth processes, like the Biostyr process, utilise various kinds of manufactured media, e.g. polystyrene granules, which offer a high specific surface area, and are therefore very compact. The Biostyr plants allow a combination of nitrification-denitrification and filtration in one and the same unit. The results obtained are 8 mg total N/l and an SS content normally below 10 mg/l. The plants in Denmark which have been extended with a Biostyr unit have various levels of PLC control and on-line instrumentation.

scholarly journals Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 345 ◽  
Author(s):  
Lianzan Yang ◽  
Yongyan Li ◽  
Zhifeng Wang ◽  
Weimin Zhao ◽  
Chunling Qin
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hierarchical Porous

High-entropy alloys (HEAs) present excellent mechanical properties. However, the exploitation of chemical properties of HEAs is far less than that of mechanical properties, which is mainly limited by the low specific surface area of HEAs synthesized by traditional methods. Thus, it is vital to develop new routes to fabricate HEAs with novel three-dimensional structures and a high specific surface area. Herein, we develop a facile approach to fabricate nanoporous noble metal quasi-HEA microspheres by melt-spinning and dealloying. The as-obtained nanoporous Cu30Au23Pt22Pd25 quasi-HEA microspheres present a hierarchical porous structure with a high specific surface area of 69.5 m2/g and a multiphase approximatively componential solid solution characteristic with a broad single-group face-centered cubic XRD pattern, which is different from the traditional single-phase or two-phase solid solution HEAs. To differentiate, these are named quasi-HEAs. The synthetic strategy proposed in this paper opens the door for the synthesis of porous quasi-HEAs related materials, and is expected to promote further applications of quasi-HEAs in various chemical fields.

Formation and phase evolution of calcium phosphates modulated by ion exchange ionomer Nafion

CrystEngComm ◽  
2020 ◽  
Vol 22 (47) ◽  
pp. 8243-8250
Author(s):  
Shuquan Sun ◽  
Qixuan Chen ◽  
Qijun Song
Keyword(s):  
Phase Transition ◽  
Ion Exchange ◽  
Calcium Phosphates ◽  
Phase Evolution

The phase transition of calcium phosphates regulated by Nafion with the inherent acidity and ion exchange features.

KCl-assisted activation: Moringa oleifera branch-derived porous carbon for high performance supercapacitor

2021 ◽  
Vol 45 (12) ◽  
pp. 5712-5719
Author(s):  
Yongxiang Zhang ◽  
Peifeng Yu ◽  
Mingtao Zheng ◽  
Yong Xiao ◽  
Hang Hu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Porous Carbon ◽  
High Performance ◽  
Moringa Oleifera ◽  
High Specific Surface Area ◽  
Porous Carbons

Porous carbons with a high specific surface area (2314–3470 m2 g−1) are prepared via a novel KCl-assisted activation strategy for high-performance supercapacitor.

Carbon material with high specific surface area and high pseudocapacitance: Possible application in supercapacitors

2021 ◽  
Vol 319 ◽  
pp. 111063
Author(s):  
Yury M. Volfkovich ◽  
Valentin E. Sosenkin ◽  
Alexei Y. Rychagov ◽  
Alexandr V. Melezhik ◽  
Alexei G. Tkachev ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Material ◽  
High Specific Surface Area

Efficient conversion of CO2 to methane using thin-layer SiOx matrix anchored nickel catalysts

2019 ◽  
Vol 43 (33) ◽  
pp. 13217-13224 ◽  
Author(s):  
Xieyi Huang ◽  
Peng Wang ◽  
Zhichao Zhang ◽  
Shaoning Zhang ◽  
Xianlong Du ◽  
...  
Keyword(s):  
Thin Layer ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Geometric Structure ◽  
Nickel Catalysts ◽  
High Specific Surface Area ◽  
Efficient Conversion

Thin-layer SiOx matrix anchored nickel catalysts with high specific surface area and a unique electronic/geometric structure were fabricated for efficient CO2 methanation.

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