Solid state reaction technique

Study of Magnetic Properties of Mixed Cobalt-Zinc Ferrites Synthesized By Solid State Reaction Technique. 

The spinel ferrites were fabricated by solid state reaction technique. Cobalt and Zinc ferrites CoxZnyFe204,(x=0.7,0.3,0.4,0.2 and y=0.3,0.7,0.6,0.8) were prepared by solid state reaction technique. The crystalline structure of the sample was investigated by X-ray diffraction(XRD). All samples show cubic spinel structure. The lattice parameter decreases with increasing cobalt content. Magnetic properties shows that the prepared sample exhibit ferromagnetic behaviour at room temperature. The saturation magnetization increases with increasing cobalt content. Curie temperature... 

A new family of high conductivity, mixed metal oxides having the pyrochlore crystal structure has been discovered. These compounds display a variable cation stoichiometry, as given by Equation 1. The ability to synthesize these materials is highly dependent upon the low temperature, alkaline solution preparative technique that has been described the relatively low thermal stability of those phases where an appreciable fraction of the B-sites are occupied by post transition element cations precludes their synthesis in pure form by conventional solid state reaction techniques. 

In particular, K-Ni-Ca-Ox/ZSl, prepared by solid state reaction technique, showed great results in terms of methane and carbon dioxide conversion, and its resistance to... 

The filler, ferroelectric ceramic material (Barium Sodium Niobate (BNN)) was prepared by usual ceramic technique using reagent grade sodium carbonate, barium carbonate, and niobium pentoxide. Solid-state reaction technique was adopted for the preparation of BNN. The starting materials were BaCO (Merck Ltd., Mumbai, India), Na2C03 and Nb O (CDH, New Delhi, India). The powders were taken by satisfying the stoichiometric ratios (eqrration 16.1), mixed, milled and calcined at a temperature of 1000 °C for 3 h. Sintering was carried out at a temperatrrre of 1200 °C for 5 hrs. 

Kinetic investigations cover a wide range from various viewpoints. Chemical reactions occur in various phases such as the gas phase, in solution using various solvents, at gas-solid, and other interfaces in the liquid and solid states. Many techniques have been employed for studying the rates of these reaction types, and even for following fast reactions. Generally, chemical kinetics relates to tlie studies of the rates at which chemical processes occur, the factors on which these rates depend, and the molecular acts involved in reaction mechanisms. Table 1 shows the wide scope of chemical kinetics, and its relevance to many branches of sciences. 

Magnetic resonance techniques, EPR (ESR) and NMR, can be used [341,342] to obtain information about atomic, ionic, molecular and crystallographic states before, during and after solid state reactions. Only a very restricted use has been made of the NMR of solids [342—345]. 

However, if we set the furnace temperature just slightly greater than T2, we would obtain a reaction limited to that of A - B, and thus could identily the intermediate reaction product, B. This technique is called isothermal thermogravimetry. Thus, we can follow a solid state reaction by first surveying via d3mamic TGA. If there are any intermediate products, we can isolate each in turn, and after cooling (assmning each is stable at room temperature) cam identify it by x-ray analysis. Note that we can obtain an assay easily ... 

With the exception of single-crystal transmission work, most solids are too opaque to permit the conventional use of ultraviolet/visible (UV/VIS) electronic spectroscopy. As a result, such work must be performed through the use of diffuse reflection techniques [8-10]. Important work has been conducted in which UV/VIS spectroscopy has been used to study the reaction pathways of various solid state reactions. Other applications have been made in the fields of color measurement and color matching, areas which can be of considerable importance when applied to the coloring agents used in formulations. 

It was recognized very early that diffuse reflectance spectroscopy could be used to study the interactions of various compounds in a formulation, and the technique has been particularly useful in the characterization of solid state reactions [24]. Lach concluded that diffuse reflectance spectroscopy could also be used to verify the potency of a drug in its formulation. In addition, studies conducted under stress conditions would be useful in the study of drug-excipient interactions, drug degradation pathways, and alterations in bioavailability owing to chemisorption of the drug onto other components in the formulation [24]. 

Solid state NMR has been used to study polymers of various classes over the past several years. In particular, the technique has been used to study curing reactions in epoxies (12). polyimides (1), and acetylenic terminated sulfones (13). The ability to observe the evolution of the carbons of the reacting species has been clearly shown to provide valuable information which has been difficult or impossible to obtain with other techniques. The use of 13C solid state NMR techniques is essential for the understanding of curing reactions in high temperature polymers in order to be able to correlate the reaction chemistry with the structural and resulting physical properties. 

Nowadays a large number of functional crystals belongs to the TTB family and presents electro-optic, ferro- piezo- pyroelectric properties (e g. the well-known barium sodium niobate Ba2NaNb50i5 (BNN)). In this work iron and manganese based Kx(lvr%(]Vr )i-xF3 fluorides (0.4solid state reaction and characterised by different diffraction techniques in order to investigate their crystalline stmcture. 

Spectroscopic analyses of solid-state reactions must first use solid-state techniques (IR, UV/Vis, Raman, luminescence, NMR, ESR, CD, X-ray powder diffraction, DSC, etc.) in order to secure the solid-state conversion, before the solution techniques (detection of minor side products, specific rotation, etc.) are applied. 

Solid anilines (236) and solid aromatic aldehydes (77) give the benzylidene anilines 54 upon grinding with 100% yield after drying at 80 °C 20 combinations were performed [101-102] (Scheme 51). A semibatch large-scale experiment of236h with 77b yields quantitatively the hydrated imine 54h that can be dried as well [7]. The reaction of aniline (236s) with benzaldehyde (77k) cannot be run as a solid-state reaction. However, it should be mentioned that the stoichiometric liquid-liquid reaction proceeds with 100% yield because it profits from direct crystallization of the product 54s upon reaction. This technique can... 

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