Organic decomposition

Powder Preparation. The goal in powder preparation is to achieve a ceramic powder which yields a product satisfying specified performance standards. Examples of the most important powder preparation methods for electronic ceramics include mixing/calcination, coprecipitation from solvents, hydrothermal processing, and metal organic decomposition. The trend in powder synthesis is toward powders having particle sizes less than 1 p.m and Httie or no hard agglomerates for enhanced reactivity and uniformity. Examples of the four basic methods are presented in Table 2 for the preparation of BaTiO powder. Reviews of these synthesis techniques can be found in the Hterature (2,5). 

Metal organic decomposition (MOD) is a synthesis technique in which metal-containing organic chemicals react with water in a nonaqueous solvent to produce a metal hydroxide or hydrous oxide, or in special cases, an anhydrous metal oxide (7). MOD techniques can also be used to prepare nonoxide powders (8,9). Powders may require calcination to obtain the desired phase. A major advantage of the MOD method is the control over purity and stoichiometry that can be achieved. Two limitations are atmosphere control (if required) and expense of the chemicals. However, the cost of metal organic chemicals is decreasing with greater use of MOD techniques. 

Greater dimensional control and thinner tapes in multilayer ceramics are the driving forces for techniques to prepare finer particles. Metal organic decomposition and hydrothermal processing are two synthesis methods that have the potential to produce submicrometer powders having low levels of agglomeration to meet the demand for more precise tape fabrication. 

Solution Deposition of Thin Films. Chemical methods of preparation may also be used for the fabrication of ceramic thin films (qv). MetaHo-organic precursors, notably metal alkoxides (see Alkoxides, metal) and metal carboxylates, are most frequently used for film preparation by sol-gel or metallo-organic decomposition (MOD) solution deposition processes (see Sol-GEL technology). These methods involve dissolution of the precursors in a mutual solvent control of solution characteristics such as viscosity and concentration, film deposition by spin-casting or dip-coating, and heat treatment to remove volatile organic species and induce crystaHhation of the as-deposited amorphous film into the desired stmcture. 

Biomethanogenesis plays a major role in the cycling of carbon in nature. It has been reported in a broad variety of environments where organic decomposition... 

Organic decomposition (or mineralization) (organic material O2 inorganic material) Microorganisms, especially fungi and bacteria... 

Using an 8-in. Nichrome wire strip connected with springs to a variac, organic decomposition can be carried out in a very fine line to locate zones. The resulting carbon is small in quantity and will not interfere in subsequent elutions. 

One key in dehning structural evolution, and thus, the resulting characteristics of the hnal him, is the chemical reactions that occur (intended or otherwise) during solution preparation. These reactions have been investigated in great detail for a variety of material systems, and the basic reaction chemistry for the more common processes is well understood. This chemistry lends itself to categorization into three divisions sol-gel, chelate, and metallo-organic decomposition (MOD) processes. These processes and their associated reaction chemistries are discussed below, prior to discussion of the role of solution species nature on structural evolution. 

The third general classification of solution synthesis approaches used for inorganic electronic thin film fabrication is referred to as metallo-organic decomposition, or MOD for short.23-29,37,38,85 Historically long-chain carboxylate compounds, such as lead 2-ethylhexanoate, zirconium neodecanoate, and titanium di-methoxy di-neodecanoate have been used.23-29,85 Both commercially available precursors and in-house synthesized starting reagents have been used. 

Vest, G. Vest, R. 1984. Metallo-organic decomposition (MOD) silver metallization for photovoltaics. JPL Proceedings of the 23rd Project Integration Meeting (NASA Center for AeroSpace Information Pasadena, CA). (Document ID. 19850006969). 

Figure 14.5. Micrograph image of ink-jet-printed silver lines using a metal-organic decomposition precursor. Lines printed on SiNx-coated ribbon silicon. Line width is -40 pm.

A variety of nitrogen oxides (NO ) such as nitric oxide (NO) and nitrogen dioxide (NO2) as well as nitrous oxide (N2O) are present in the atmosphere. The sources of these oxides are biological actions and organic decomposition in the soil and in the ocean... 

The two intermediates depicted above differ fundamentally from each other. The COx-producing intermediate has a direct metal-carbon (M-R) bond whereas the C2-producing intermediate has a metal-oxygen-carbon (M-O-R) bond. From known organic decomposition pathways, the formation of selective oxidation products from the M-O-R intermediate is likely. An a-H elimination produces acetaldehyde and a P-H elimination produces ethylene. 

From a synthetic objective it is unfortunate that attempts to produce the dianion of OFCOT by various reduction procedures have not resulted in a stable dianion. Although the organic decomposition products resulting from reduction by alkali metals or sodium naphthalenide are unknown, fluoride ion is produced (126). However, the nine-7t-electron radical anion has been produced at low temperatures by y irradiation of OFCOT, and electron spin resonance (ESR) spectroscopy indicates that it possesses the anticipated planar delocalized D8b structure 55 (127). The unavailability of the dianion... 

Spent decontamination solution (SDS) consists of caustic or bleach-based aqueous solutions that have been used in the decontamination of personal protective clothing or the operations areas. SDS may also result from rinsing drained TCs or munition cavities. These solutions are captured and stored for treatment and disposal, either on-site or off-site. SDS typically contains less than 1 percent levels of sodium chloride and organic decomposition products from agent hydrolysis. 

Chain Mechanisms. The fact that first-order kinetics are observed for a gas-phase reaction does not prove that the unimolecular mechanism described above must be involved. Indeed very many organic decompositions that experimentally are first order have complicated free-radical chain mechanisms. 

Max. organic decomposition, sulfide production, reductive dissolution of metal oxides, pH=7.0 Accumulation of FeS... 

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