Silicon dioxide preparation

Xu X and Goodman D W 1992 New approach to the preparation of ultrathin silicon dioxide films at low temperature Appl. Phys. Lett. 61 774... 

Ceramic materials are typically noncrystalline inorganic oxides prepared by heat-treatment of a powder and have a network structure. They include many silicate minerals, such as quartz (silicon dioxide, which has the empirical formula SiO,), and high-temperature superconductors (Box 5.2). Ceramic materials have great strength and stability, because covalent bonds must be broken to cause any deformation in the crystal. As a result, ceramic materials under physical stress tend to shatter rather than bend. Section 14.22 contains further information on the properties of ceramic materials. 

Therefore, the samples are prepared by mixing fluorescent particles solution and silicon dioxide nano-particles solution as shown in Table 1. 

C04-0145. Silicon tetrachloride is used in the electronics industry to make elemental silicon for computer chips. Silicon tetrachloride is prepared from silicon dioxide, carbon graphite, and chlorine gas. 

A desirable glass melts at a reasonable temperature, is easy to work with, and yet is chemically inert. Such a glass can be prepared by adding a third component that has bonding characteristics intermediate between those of purely ionic sodium oxide and those of purely covalent silicon dioxide. Several different components are used, depending on the properties desired in the glass. 

Figures 6 and 7 show the absorption spectra of colloidal CdS and ZnS at various times of illumination. The two colloids were prepared by adding an NaSH solution to solutions of Cd(C10j2 or Zn(C104)2, respectively, colloidal silicon dioxide (commercially available from Dupont Ludox HS30) being present at 6 x 10 M as stabilizer in both cases. The absorption starts in both cases close to the wavelengths that correspond to the photon energies (515 nm or 2.4 eV for CdS 340 nm or 3.7 eV for ZnS) at which the absorptions begin in the macrocrystalline materials. It is seen that illumination causes not only a decrease in the intensity of the absorption spectrum but also a change in the shape of the spectrum. The onset of light absorption is shifted towards...

The luminescence of macrocrystalline cadmium and zinc sulfides has been studied very thoroughly The colloidal solutions of these compounds also fluoresce, the intensity and wavelengths of emission depending on how the colloids were prepared. We will divide the description of the fluorescence phenomena into two parts. In this section we will discuss the fluorescence of larger colloidal particles, i.e. of CdS particles which are yellow as the macrocrystalline material, and of ZnS particles whose absorption spectrum also resembles that of the macrocrystals. These colloids are obtained by precipitating CdS or ZnS in the presence of the silicon dioxide stabilizer mentioned in Sect. 3.2, or in the presence of 10 M sodium polyphosphate , or surfactants such as sodium dodecyl sulfate and cetyldimethylbenzyl-ammonium... 

Preparation ofNb5Si3 Metallic niobium and silicon dioxide do not react if heated (for instance at 1100°C) under vacuum. In the presence of traces of H2 or I2 the formation of transporting compounds (SiO or Nbl4) is observed, followed by their migration and reaction according to the following schemes ... 

For the dielectric loss measurement by a bridge (Ando Co. TR-10C),metal-PPE-metal sandwich specimens were prepared on the silicon dioxide substrate (Corning 7059). Evaporated aluminum was used as a metal electrode. The PPE film for the use of dielectric measurement was formed with the discharge electrode whose surface area was 26 cm2 and the remainder of the electrode was covered by the Teflon plate. Two kinds of samples were prepared for this experiment. One of them was formed at 5 KHz, 0.5 torr, 20 cm3STP/min and 5 watts. The other was formed at 13.56 MHz, 0.5 torr, 40 cm3STP/min and 25 watts. 

Silicon dioxide plays a critical role in the electronics industry. The silicon used to produce silicon chips is derived from silicon dioxide. Semipure silicon dioxide (to about 99%) is prepared from the reaction of silicon dioxide with coke (a poor grade of graphite) using high temperature and an electronic arc. 

Silicon tetrachloride is prepared by heating silicon dioxide and carbon in a stream of chlorine ... 

The preparation method is similar to that for the cresol-formaldehyde Novolak resin with a molar ratio of cresol/benzaldehyde = 1.1 in acidic conditions. We have prepared varieties of substituted m-cresol-benzaldehyde Novolak resins, and 1-, and 2-naphthol-4-hydroxybenzaldehyde Novolak resins in the same manner. Almost all of these benzaldehyde Novolak resins give excellent resist films when spin-coated onto silicon or silicon dioxide substrates after being dissolved, together with a photoactive compound, in a solvent like 2-... 

The selection of raw materials and the method of preparation of the catalyst base are important in determining the final quality of the catalyst. Impregnating almost any iron oxide with potassium hydroxide and drying it will yield a catalyst of some activity, but care must be exercised both in selecting the raw materials and in the method of preparation, if a superior catalyst is to be obtained. Generally, the purer the components the better the catalyst, but substantial quantities of impurities such as silicon dioxide, aluminum oxide, and carbon can be tolerated. Suitable raw materials are obtainable at low cost, and satisfactory methods of preparation are simple and inexpensive. 

In our investigation, sodium sulfate was selected as the electrolyte. Rare earth sulfates Lj CSO, (LnsY and Gd) were added in order to increase the electrical conductivity. Silicon dioxide was ad ed so as to obtain the network structure which is effective for Na cation conduction and to prevent the electrolyte from becoming too soft. A thinner electrolyte was possible to prepare by mixing in SiC. The suppression of the phase transformation(15, 16) from Na2S0,-I(a high temperature phase) to Na2S0 -IH(a low temperature phase was also achieved by mixing rare earth sulfates(Ln=Y and Gd) and silicon dioxide into sodium sulfate. 

In Activity 4.3 we prepared and applied glazes to clay slabs. The glazes were composed mostly of silicon dioxide, along with aluminum and potassium oxides (to reduce the melting point) and compounds such as copper oxide and iron oxide (colorants). 

Preparation and properties of silicon. Elemental silicon of about 98% purity may be produced by the reduction of silicon dioxide by aluminum. 

Independent of this dispute concerning the crystalline state, the existence of amorphous SiO in the solid state may also be possible. Electron diffraction investigations show specific lines in some preparations. Emons found that only the dark brown product shows these lines. The yellow product shows only the lines of silicon and silicon dioxide. These observations suggest the possibility of the existence of a solid, probably amorphous SiO. 

In the 1940s, it was demonstrated in the pioneering work of Zisman and coworkers [8] that the LB technique is not the only way to create an organized organic monolayer on a solid substrate. It was demonstrated that when a compatible substrate is exposed to a solution of an amphiphilic compound, the dissolved molecules form a self-assembled monolayer on the substrate surface. Such films maintain their structural integrity after they are removed from solution. The most common examples of such films are organosulfur films on gold substrates [9] and alkyltrichlorosilane films on silicon dioxide substrates [10]. Compared with the LB films, the self-assembled films are somewhat less ordered. On the other hand, these films are easier to prepare, since they do not require special instrumentation and can easily be deposited on both planar and non-planar substrates. Also, in many cases the amphiphilic molecules which make the self-assembled film are chemisorbed on the substrate. Such films are more stable when heated or exposed to solvents than are typical LB films, which are held to the substrate by non-covalent interactions. 

Silicon tetrachloride is a raw stock for preparing ethers of orthosilicon acid and is used in the production of silicone polymers used to obtain highly thermostable plastics and synthetic lubricants, as well as high-quality electroinsulation. Silicon tetrachloride is also used to prepare superfine silicon dioxide (Aerosil). A mixture of silicon tetrachloride and... 

T. Maruyama and J. Shionoya, Silicon Dioxide Films Prepared by Chemical Vapour Deposition from Silicon Tetraacetate , Jap. J. Appl. Rhys., 28 [12] L2253-54 (1989). 

Silicon Dioxide and Silicic Acid, (a) Wet a little silicon dioxide (very finely powdered quartz, or better the product of Preparation 41), test with litmus, and note that litmus is not... 

Keywords silicon dioxide, medicinal chemistry, surface chemistry, sorbent, efferent therapy, enteosorption, medicinal preparation, infectious diseases, detoxication, bioactive silica, purulent wound, pyoinflammatory diseases, diarrhea... 

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