Metal 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. 

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.

Recently, efforts have been devoted to the fabrication and characterization of PbZri- Ti c03 family thin films for their potential applications in nonvolatile memory devices (See Ref. 17, for example). Partly because of the convenient stoichiometry control during processing, it was found that chemical methods, such as sol-gel and metal organic decomposition (MOD), are superior to physical means in many aspects. To appreciate better the science and technology of ferroelectric thin-film fabrication, it is important to give a brief account of the past efforts and the present status and, it is hoped, shed some light on the future. 

BiV04 Metal-organics decomposition Porous BiV04 film with spherical nanoparticles 90-120 nm in size 2.4 175 mW cm (350-500 nm) 0.5 M Na2S04 (2.2) at 1 V (4.0) at 1 V when pretreated with Ag ions 44% at 440 nm (pietreated with Ag ions) [96]... 

B1VO4 film preparation by the metal organic decomposition (MOD) method BiV04 films were prepared by a modified MOD method [9]. Bismuth 2-ethyl-hexanoate in acetylacetone and vanadium (IV) (oxy)acetylacetonate in acetylacetone were mixed in a stoichiometric ratio, PEG 300 was added and the solution was concentrated by evaporation of the solvent. A spin coater was used to coatFTO conducting glass with the solution, and the coated glass was fired at 400-550°C for 30 min. 

Metal—organic decomposition Polymeric precursors/sol-gel method alkoxide precursor, halide precursors, nitrate and acetate precursors Impregnation/infiltration Slurry coating... 

Metal organic decomposition (MOD). These methods use long-chain car-boxylate compoimds. Hydrolysis and condensation do not occur, but simple mixing of the reactants occurs in a solvent medium. 

Reeently, Bis Ndo sTisO thin films were prepared on indium tin oxide/glass substrates using a metal organic decomposition method at temperatures ranging from 500 to 650 °C [30]. A predominantly (lOO)-oriented BNdT thin film can be obtained even at 550 °C. The largest values of the remanent polarization and piezoresponse are observed in the BNdT thin film annealed at 650 °C, which can be ascribed to the grain growth and the release of the inplane residue tension stress. 

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