Low temperature stabilization of zirconia by Mn through Co-precipitated hydroxide gel route

1994 ◽  
Vol 9 (4) ◽  
pp. 837-840 ◽  
Author(s):  
A. Keshavaraja ◽  
A. V. Ramaswamy
Keyword(s):  
Low Temperature ◽  
Surface Area ◽  
Linear Correlation ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Gel Formation ◽  
Temperature Stabilization ◽  
Subsequent Calcination ◽  
Mn Content

Stabilization of zirconia into cubic phase is achieved by partly substituting Zr4+ with Mn4+ ions (5–30 mole %) via hydroxide gel formation and subsequent calcination at 773 K and is supported by XRD and IR data. A linear correlation between the lattice parameter and the Mn content confirms the incorporation of Mn into ZrO2. The XPS and TPR results provide some evidence for the presence of Mn4+ ions in these samples which have a surface area of about 100 m2 g-1 and are stable in the cubic phase up to 973 K. On reduction above 973 K, the cubic phase is stabilized probably by Mn2+ ions.

Synthesis of ZrO2–Y6WO12 solid solution powders by a polymerized complex method

1998 ◽  
Vol 13 (4) ◽  
pp. 939-943 ◽  
Author(s):  
Junfeng Ma ◽  
Masahiro Yoshimura ◽  
Masato Kakihana ◽  
Masatomo Yashima
Keyword(s):  
Solid Solution ◽  
Crystallite Size ◽  
Surface Area ◽  
Solid Solutions ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Complex Method ◽  
Amorphous Precursor ◽  
Fine Powders ◽  
Polymerized Complex Method

A series of solid solutions (1 − x) ZrO2 · xY0.857 W0.143 O1.714 (1/7Y6WO12) of metastable cubic phase were synthesized at 800 °C through a polymerized complex method. Lattice parameter a0 of solid solutions varies linearly with Y0.857 W0.143 O1.714 content (x). Crystallization began to occur above 400 °C from amorphous precursor to yield at 800 °C fine powders of 6–10 nm and 19–40 m2/g for crystallite size and surface area, respectively.

Synthesis of Metal Carbides Using Biological Templates

2005 ◽  
Vol 879 ◽  
Author(s):  
Yongsoon Shin ◽  
Xiaohong S. Li ◽  
William D. Samuels ◽  
Yong Wang ◽  
Larry R. Pederson ◽  
...  
Keyword(s):  
High Temperature ◽  
Surface Area ◽  
Carbothermal Reduction ◽  
Lattice Parameter ◽  
Bet Surface Area ◽  
Cubic Phase ◽  
Particle Sizes ◽  
Metal Carbides ◽  
Low Oxygen ◽  
Silica And Titania

AbstractNanocrystalline metal carbides (MC: M=Si, Ti) have been prepared using cellulose network mineralized with silica and titania by carbothermal reduction at high temperature in Ar. Hierarchical biological structures indigenous to the cellulose precursor were completely replicated after the reaction. Cubic phase MC composites show relative low oxygen content 0.24 wt% and a high lattice parameter of 4.327Å in TiC. The particle sizes of the MC composites are 200-700nm for SiC and 10-50nm for TiC, and high BET surface area, up to 150m2/g.

scholarly journals Structural and Magnetic Property of Cr3+ Substituted Cobalt Ferrite Nanomaterials Prepared by the Sol-Gel Method

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2095 ◽  
Author(s):  
Jinpei Lin ◽  
Jiaqi Zhang ◽  
Hao Sun ◽  
Qing Lin ◽  
Zeping Guo ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Sol Gel ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Cobalt Chromium ◽  
X Ray Diffraction ◽  
Chromium Doping ◽  
Auto Combustion ◽  
Cr Concentration

Cobalt-chromium ferrite, CoCrxFe2−xO4 (x = 0–1.2), has been synthesized by the sol-gel auto-combustion method. X-ray diffraction (XRD) indicates that samples calcined at 800 °C for 3 h were a single-cubic phase. The lattice parameter decreased with increasing Cr concentration. Scanning electron microscopy (SEM) confirmed that the sample powders were nanoparticles. It was confirmed from the room temperature Mössbauer spectra that transition from the ferrimagnetic state to the superparamagnetic state occurred with the doping of chromium. Both the saturation magnetization and the coercivity decreased with the chromium doping. With a higher annealing temperature, the saturation magnetization increased and the coercivity increased initially and then decreased for CoCr0.2Fe1.8O4.

PERMEABILITY STUDIES: III. SURFACE AREA MEASUREMENTS OF CARBON BLACKS

1948 ◽  
Vol 26a (2) ◽  
pp. 29-38 ◽  
Author(s):  
J. C. Arnell ◽  
G. O. Henneberry
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Carbon Black ◽  
Surface Area ◽  
Satisfactory Agreement ◽  
Nitrogen Adsorption ◽  
Average Particle ◽  
Carbon Blacks ◽  
Permeability Studies ◽  
Nitrogen Adsorption Isotherms

The modified Kozeny equation has been found to be satisfactory for the measurement of the specific surfaces of carbon blacks having average particle diameters ranging from 0.01 to 0.1 μ to within ±10%. Comparative data were obtained from electron microscope counting and from low temperature nitrogen adsorption isotherms. The three methods examined gave results that were in satisfactory agreement, except when the carbon black was porous, and then the adsorption value was extremely large.

Titanium nitride nanopowders produced via sodium reductionin liquid ammonia

2009 ◽  
Vol 24 (2) ◽  
pp. 448-451 ◽  
Author(s):  
Boyan Yuan ◽  
Mei Yang ◽  
Hongmin Zhu
Keyword(s):  
Titanium Nitride ◽  
Surface Area ◽  
Liquid Ammonia ◽  
Heating Temperature ◽  
Chemical Reduction ◽  
Atomic Ratio ◽  
Area Measurement ◽  
Bet Surface Area ◽  
Cubic Phase ◽  
Tem Analysis

Titanium nitride nanopowders were synthesized through a chemical reduction of titanium tetrachloride by sodium in liquid ammonia. The products of the reaction were the mixture of sodium chloride and titanium nitride nanopowders. The mixture was then separated by ammonia extraction. The nanopowders were heated under vacuum up to 1200 °C and were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET) surface area measurement, and chemical analysis. The results show that the product is nanocrystalline cubic phase TiN with Ti/N atomic ratio performed 1:1, and the surface area is from 20 to 50 m2 ·g−1 depending on the heating temperature. The particle sizes estimated by the TEM analysis correspond well with the results of the surface area measurements. The XRD pattern indicates that the crystal size grows with an increase in heating temperature.

scholarly journals Flower-like boehmite nanopowders obtained at low temperature from Bayer liquor

2020 ◽  
Vol 14 (2) ◽  
pp. 168-172
Author(s):  
Marija Milanovic ◽  
Zoran Obrenovic ◽  
Ivan Stijepovic ◽  
Ljubica Nikolic
Keyword(s):  
Low Temperature ◽  
Specific Surface ◽  
Surface Area ◽  
Industrial Production ◽  
Single Phase ◽  
Low Cost ◽  
High Specific Surface Area ◽  
Nanocrystalline Powders ◽  
Transition Alumina ◽  
Bayer Liquor

Boehmite nanocrystalline powders were obtained by neutralization of Bayer liquor at 70?C with addition of glucose. Temperature of the neutralization induced formation of the flower-like morphology of the nanopowders. XRD and FTIR results confirmed that the single phase boehmite is formed without any other impurities. Calcination at 500?C led to the formation of transition -alumina with the retention of the flower-like morphology. Both as-synthesised and calcined powders possessed high specific surface area with mesopores between 3-6 nm in diameter. Relatively low temperature of neutralization as well as the use of low cost and ecologically friendly glucose as a surfactant are very promising for the possible application in the industrial production of alumina nanopowders.

Defect Reactions in Low Temperature Electron Irradiated AlAs Investigated by Measurements of the Lattice Parameter

1997 ◽  
Vol 258-263 ◽  
pp. 1253-1258
Author(s):  
A. Gaber ◽  
Holger Zillgen ◽  
Peter Ehrhart ◽  
P. Partyka ◽  
Robert S. Averback
Keyword(s):  
Low Temperature ◽  
Lattice Parameter ◽  
Temperature Electron ◽  
Defect Reactions

Synthesis and Characterization of Calcium Zeolite-Cowlesite.

2021 ◽  
Vol 23 (05) ◽  
pp. 787-790
Author(s):  
Abhijit M ◽  
◽  
Suresh Kumar. B. V ◽  
Keyword(s):  
Low Temperature ◽  
Elemental Concentration ◽  
Stoichiometric Composition ◽  
Lattice Parameter ◽  
Raw Material ◽  
Synthesis And Characterization ◽  
Aluminum Silicate ◽  
Hydrothermal Conditions ◽  
Orthorhombic System

Cowlesite is a Calcium Aluminum silicate CaAl2Si3O106H2O which formed under the hydrothermal conditions of low temperature (1800C) and pressure (1.013250bar). Cowlesite minerals are known for their peculiar occurrence. Synthesis of Cowlesite mineral was carried by suitable stoichiometric composition. Hydrothermal synthesized Cowlesite mineral was characterized by XRD, SEM, and EDAX. It crystallized in the orthorhombic system and a lattice parameter a=23.22Å, b=30.58Å, c=25.01Å, Volume of Unit cell=17758.79Å3, α=β=γ=900. EDAX results show the elemental concentration of raw material which was used.

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