Synthesis and structure of pure SiO2 chabazite: the SiO2 polymorph with the lowest framework density

1998 ◽  
pp. 1881-1882 ◽  
Author(s):  
María-José Díaz-Cabañas ◽  
Philip A. Barrett
Keyword(s):  
Pure Sio2 ◽  
Framework Density

ChemInform Abstract: Synthesis and Structure of Pure SiO2 Chabazite: The SiO2 Polymorph with the Lowest Framework Density.

ChemInform ◽  
2010 ◽  
Vol 29 (46) ◽  
pp. no-no
Author(s):  
M.-J. DIAZ-CABANAS ◽  
P. A. BARRETT ◽  
M. A. CAMBLOR
Keyword(s):  
Pure Sio2 ◽  
Framework Density

Anion packing density: a universal quantity for both dense and porous crystalline inorganic phases

2002 ◽  
Vol 58 (3) ◽  
pp. 457-462 ◽  
Author(s):  
F. Liebau ◽  
H. Küppers
Keyword(s):  
High Pressure ◽  
Packing Density ◽  
Three Dimensional ◽  
Ionic Radii ◽  
Generalized Framework ◽  
Molal Volumes ◽  
Definition Of ◽  
Anion Packing ◽  
Very High ◽  
Framework Density

To compare densities of inorganic high-pressure phases their molal volumes or specific gravities are usually employed, whereas for zeolites and other microporous materials the so-called framework density, FD, is applied. The definition of FD, which refers only to phases with three-dimensional tetrahedron frameworks, is extended to a `generalized framework density' d f, which is independent of the dimensionality of the framework and the coordination number(s) of the framework cations. In this paper the anion packing density, d ap, is introduced as a new quantity which is not only applicable to any inorganic phase but, in contrast to FD and d f, also allows quantitative comparisons to be made for crystalline inorganic phases of any kind. The anion packing density can readily be calculated if the volume and content of the unit cell and the radii of the anions of a phase are known. From d ap values calculated for high-pressure silica polymorphs studied under very high pressure, it is concluded that Shannon–Prewitt effective ionic radii do not sufficiently take into account the compressibility of the anions.

Impurity Free Vacancy Disordering Using Phosphorus Doped SiO2 and Pure SiO2 Caps

1996 ◽  
Vol 450 ◽  
Author(s):  
P. Cusumano ◽  
A. Saher Helmy ◽  
B. S. Ooi ◽  
R. M. De La Rue ◽  
A. C. Bryce ◽  
...  
Keyword(s):  
Quantum Well ◽  
Resonance Method ◽  
Lasing Wavelength ◽  
Quantum Well Laser ◽  
Fabry Perot ◽  
Extended Cavity ◽  
Low Threshold ◽  
Ridge Lasers ◽  
Phosphorus Doped ◽  
Pure Sio2

ABSTRACTA spatially selective quantum well intermixing process, using phosphorus-doped silica (SiO2:P) containing 5 wt% P to inhibit intermixing and pure SiO2 to enhance intermixing, is presented. The SiO2:P cap has been found to suppress bandgap shifts in both p-i-n and n-i-p GaAs/AlGaAs quantum well laser structures, with bandgap shift differences as large as 100 meV observed from samples capped with SiO2 and with SiO2:P after rapid thermal processing at temperatures as high as 950 °C for 60 s. Extended cavity ridge lasers exhibited low threshold currents with TE losses of 3.2 cm−1 measured in the passive waveguide sections at the lasing wavelength using the Fabry-Perot resonance method. This value is among the lowest reported so far using an impurity-free disordering technique.

Rapid and facile synthesis of hierarchical nanocrystalline SSZ-13 via the interzeolite transformation of ZSM-5

2020 ◽  
Vol 44 (14) ◽  
pp. 5501-5507
Author(s):  
Qiang Li ◽  
Liancheng Bing ◽  
Fangni Li ◽  
Jiajia Liu ◽  
Dezhi Han ◽  
...  
Keyword(s):  
Facile Synthesis ◽  
Hydrothermal Conditions ◽  
Framework Density

Hierarchical SSZ-13 was successfully synthesized via the interzeolite conversion of ZSM-5 with high framework density (FD = 18.4 T/1000 Å3) in the presence of N,N,N-trimethyl-1-adamantanamine hydroxide (TMAdaOH) under hydrothermal conditions.

Preparation and Luminescent Properties of Zn2SiO4:Mn2+

2008 ◽  
Vol 368-372 ◽  
pp. 375-377 ◽  
Author(s):  
Li Mei Cao ◽  
Wen Bo Bu ◽  
Chuan Ai Ren ◽  
Xiao Xu ◽  
Qiang Li
Keyword(s):  
Solid State ◽  
Active Carbon ◽  
Solid State Reaction ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Zinc Nitrate ◽  
Manganese Nitrate ◽  
Reducing Atmosphere ◽  
Pure Sio2

Zn2SiO4:Mn2+ was synthesized via a dipping method. Stoichiometric high pure SiO2 was put into the solution of zinc nitrate and manganese nitrate. The mixture was milled while being heated until the water was vaporized completely. The as-received mixture was added into the ethanol, and dispersed well, then the mixture was milled and heated to remove the ethanol thoroughly by evaporation. The precursor were dried for several hours at 60°C, and annealed in a reducing atmosphere of active carbon at 1000°C for 4 h. As-prepared powders of Zn2SiO4:Mn2+ was tested by XRD and SEM. Its luminescent properties were characterized by excitation and emission spectra. The results are compared with those of Zn2SiO4:Mn2+ prepared by a general solid state reaction.

Synthesis of Rod-Like α-SiAlON by Carbothermal Reduction-Nitridation

2008 ◽  
Vol 368-372 ◽  
pp. 888-890
Author(s):  
Xian Feng Leng ◽  
Yan Gai Liu ◽  
Ming Hao Fang ◽  
Zhao Hui Huang
Keyword(s):  
Carbon Black ◽  
Reaction Temperature ◽  
Carbothermal Reduction ◽  
Addition Agent ◽  
Pure Sio2

Rod-like α-sialon was synthesized successfully using pure SiO2 and AlN as the starting materials, carbon black as reductant, CaF2 and Y2O3 as addition agent by carbothermal reduction-nitridation. The effects of reaction temperature (1450°C, 1500°C, 1600°C and 1700°C) and additive (Li2CO3, CaF2, Y2O3 and Y2O3+CaF2) on phases and microstructure of the final products were studied by XRD and SEM. The results showed that α-sialon was synthesized by carbothermal reduction-nitridation at 1700°C for 3 hours. The morphology of the synthesized α-sialon was rod-like.

A Process for Sintering of Diopside Prepared from Dolomite

2005 ◽  
Vol 492-493 ◽  
pp. 235-240 ◽  
Author(s):  
S. Zouai ◽  
F.Z. Mezahi ◽  
S. Achour ◽  
Abdelhamid Harabi
Keyword(s):  
Sintering Temperature ◽  
Raw Materials ◽  
Egg White ◽  
Different Temperatures ◽  
Pure Sio2

Diopside CaMgSi2O6 is an attractive material because of its multi applications. It was prepared by sintering the mixture at different temperatures (900°C-1300°C). Starting materials were pure SiO2 and dolomite raw materials. In order to improve the properties of sintered samples, such as the density egg white (ovalbemin) has been added into diopside. Furthermore, the effect of P2O5 addition on the sintering of the prepared diopside in the range of 0.5 to 5.0 wt% was studied as a function of the sintering temperature. A density of 96.5% of theoretical has been achieved when 5.0 wt% P2O5 was added, at a sintering temperature of 1225°C, whereas the density of diopside samples, without P2O5 addition was lower than 83.0% of theoretical.

Issues in the Synthesis of Crystalline Molecular Sieves: Towards the Crystallization of Low Framework-Density Structures

ChemInform ◽  
2004 ◽  
Vol 35 (49) ◽  
Author(s):  
Avelino Corma ◽  
Mark E. Davis
Keyword(s):  
Molecular Sieves ◽  
Framework Density

scholarly journals Thermophysical Properties of Hybrid Nano Fluids

2019 ◽  
Vol 9 (1) ◽  
pp. 5038-5040
Keyword(s):  
Thermophysical Properties ◽  
Acid Treatment ◽  
Nano Particles ◽  
Agriculture Waste ◽  
Nano Fluid ◽  
Bamboo Leaves ◽  
Pure Sio2 ◽  
Nano Fluids

In this study, the ash from agriculture waste of bamboo leaves was used in the synthesis of silica nano particles followed by leaching and acid treatment. The required ash from agriculture waste (bamboo leaves) is subjected to sintered at 700 degree centigrade for 5 hours to eliminate residues from ash. The obtained powder was treated with 1M NaOH for leaching and then acid- treatment with 0.5 M H2SO4 to precipitate pure SiO2 nano particles powder. The synthesized silica were characterized by XRD, FTIR, SEM, PSA, ZETA POTENSIAL. And the synthesis of CuO-SiO2 hybrid nano fluid from the agriculture waste of silica.

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