Metal salts as dopants for ZnO ceramics-thermogravimetry coupled with mass spectrometry studies

Abstract

The paper presents results concerning thermal decomposition of copper II salts (acetylacetonate, acetate monohydrate and nitrate trihydrate) in synthetic air and argon flow. Thermogravimetry tests coupled with mass spectrometry were performed in temperature range of 25–1300 °C. The influence of salt addition on the rheological properties and sintering behaviour of ceramic samples was then investigated. The microstructure evolution based on light and scanning electron microscopies coupled with stereological methods was described. The performed investigations revealed not only the differences in thermal decomposition of examined salts but also differences in the phenomena related to the oxidation and reduction processes of copper products. The atmosphere has also influenced the mechanisms of salts decomposition as well as further changes in decomposition products. Moreover, the presence of ZnO powder has changed the thermal decomposition process of copper II acetylacetonate. The investigations showed that acetates and nitrates can be efficient in homogeneous distribution of small amounts of metal additives in the ZnO-based suspensions. Higher concentrations of these type of salts lead to the increase of viscosity due to the fact that acetates and nitrates increase the ionic strength in the slurry. On the other hand, acetylacetonates do not disturb the stability of the slurries. However, they are characterized by low water solubility and thus homogenous distribution of small amount of these dopants is more difficult. The addition of copper increased the grain size of the sintered ZnO samples. The copper was not segregated at grain boundaries in the form of oxide, it diffused into ZnO matrix.

ZTA Pipes with a Gradient Structure-Effect of the Rheological the Behavior of Ceramic Suspensions on the Gradient Structure and Characterized of the Obtained Products

“…Great emphasis is placed primarily on the search for new or improvement of existing methods for forming ceramic products. The main objective is, of course, the widely understood improvement of the ecological aspects of the molding process, such as reduction or elimination of toxic substances, the use of additives which decompose to simple and harmless compounds during the sintering process, the use of water as a solvent or minimization of raw material losses [ 4 , 5 , 6 , 7 , 8 ]. It is also very important to make sure that ceramic materials receive in the forming process a shape that is as close as possible to that of the final product, and that parts with different, even complicated geometries, can be formed.…”