Sepiolite had been reacted with 6 M nitric acid, and samples of amorphous silica
with different surface areas were obtained and used in SBR based composites (ref.
Studied diatomite rocks are light in weight and rich in soft materials as well as in amorphous silica
, which is mainly present in the form of diatom frustules.
Strachan, "Defect level distributions and atomic relaxations induced by charge trapping in amorphous silica
," Applied Physics Letters, vol.
(1) Amorphous silica
is more soluble than quartz, especially at high temperatures.
The broad X-ray diffraction peak at theta equal to 22 degrees confirms the formation of amorphous silica
, in general .
The toner was synthesized by dispersed toner components in the liquid phase and covered mechanically and electrostatically with Ti[O.sub.2] nanoparticles and amorphous silica
nanoparticles as the external additives.
The DeMaster (1981) technique is based on the observation that at high pH (using 1% [Na.sub.2]C[0.sub.3]) and elevated temperature (80-85[degrees]C), most amorphous silica
completely dissolves within the first 2 h of extraction, whereas it is assumed that Si release from silicates is constant over the entire extraction time of usually 5 h.
Synthesis of Na-x hydrate zeolite from fly ash and amorphous silica
from rice husk ash by fusion with caustic soda prior to incubation, in 2011 International Conference on Chemistry and Chemical Process IPCBEE, 2011 May 28-29, Bangkok, Thailand 10: 69-74.
Rice husk is a hard material and is composed of lignin, cellulose, traces metals, and abundant of amorphous silica
[1, 2].Since silica is used in many technological applications; therefore, rice husk is considered a cheap natural source of silica .
A number of studies reported that the use of crystalline silica performed better than amorphous silica
under autoclave curing (Luke 2004; Jupe et al.
Silica forms a tetrahedral structure and there are two common forms of silica-crystalline silica and amorphous silica
. Crystalline silica has a regular tetrahedral structure, while amorphous silica
has an irregular structural arrangement.
The chemical composition results confirm XRD results indicating that limestone is mainly composed of calcite (CaC[O.sub.3]) while silica fume is mainly composed of amorphous silica
as indicated by a broad hump at around 20-25[degrees]2[theta].
The amorphous silica
contained in RHA can react with cementitious binders to perform pozzolanic activity .
The band at 1132-1138 [cm.sup.-1] is due to the formation of amorphous silica
gel by carbonation, indicating the existence of CSH before carbonation in AAS as in OPC.
For the smaller 6.1 pm beads, the minimum diameter occurs at a fluid refractive index of [approximately equal to] 1.43, consistent with the refractive index expected for amorphous silica
beads fabricated by the Stober-Fink-Bohn process .