Ceramic compositional interpretation

A Ceramic Compositional Interpretation of Incense-Burner Trade in the Palenque Area, Mexico... 

Bishop R, Rands RL, Harbottle G (1982) A Ceramic Compositional Interpretation of Incense-Burner Trade in the Palenqw Area, Mexfco, in Nuclear and Chemkal Eating Technique (ed. Currie LA) p. 411, Washington, D.C., Amer. Chem. Soc. 

Assigning oxidation states of —2 to oxygen, + 3 to yttrium and + 2 to barium, one would obtain an oxidation state 7/3 for copper when jc = 0. The non-integer oxidation state of copper is interpreted as if 2/3 of the ions are present as Cu2+ and 1/3 as Cu3 +. This mixed-valent composition seems to be determinant for the occurrence of superconductivity. In fact, as noted in Table 1, all the superconducting ceramic oxides contain Cu in a non-stoichiometric composition. 

Acoustic microscopy has a special place in this powerful armoury. It depends on the elastic response of the material to acoustic waves, and therefore provides information on local changes in elastic properties thus, for example, it is particularly sensitive to fine cracks (which might not be observable by other techniques). It has already been applied to a wide range of materials, including biological specimens, minerals, semiconductor devices, composites, ceramics, etc. As is the case for all other techniques, it is essential to have a clear understanding of the contrast mechanisms, so that the observations can be interpreted with confidence. This book provides potential users, such as materials scientists and biologists, with a comprehensive account of the basic techniques, of the contrast mechanisms, and of the way the techniques can be applied to obtain information on microstructure in different types of specimen. 

In the past, most solids were prepared on a large scale by standard ceramic techniques, in which accurate control of the composition, as well as uniform homogeneity of the product, were not readily achieved. Unfortunately, this has sometimes led to uncertainty in the interpretation of the physical measurements. In recent years more novel methods have been developed to facilitate the reaction between solids. This is particularly true for the preparation of polycrystalline samples, on which the most measurements have been made. It is of utmost importance to prepare pure single-phase compounds, and this may be very difficult to attain. Even for a well-established reaction, careful control of the exact conditions is essential to ensure reproducible results. For any particular experiment, it is essential to devise a set of analytical criteria to which each specimen must be subjected. It will be seen from the solid-state syntheses included in this volume that one or more of the following common tests of purity are used to characterize a product. 

With electro-osmosis data, on the other hand, interpretation is not subject to the complexities of the electrophoretic measurement. Analysis of zeta potential is straightforward, and a wide range of pH can be employed. In this light it would be promising to characterize ceramic and mineral materials of a wide variety of compositions and forms, e.g., powders and processed plates. 

Unlike chemical provenience studies of geological materials, the compositions of which normally remain unchanged by human choices, the composition of ceramics are the result of human choice, making the interpretation of such chemical data much more problematic. Potters at a given location can and do choose different recipes for different pots with different functions or styles. For example, water jars from Veracruz can give a different mix of clays and tempers for the base of the jar, for the filter, and for the funnel at the top, giving three different compositions for the same vessel. 

Quantitative interpretation of the toughening effects of elastomers in blends and in composites, particularly the polymer-modifled ceramics. 

---