Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8045664 | Applied Clay Science | 2018 | 9 Pages |
Abstract
In this study, thermal behavior of the Hellenistic ceramics from Laodicea Temple (Seleucid period), Iran, was investigated through spectroscopic, thermogravimetric, mineralogical and chemical analyses. The results indicate the same calcareous raw material was used for the ceramic production. On the basis of X-ray diffraction (XRD), four firing temperature ranges can be established: Tâ¯<â¯750â¯Â°C, 850-900â¯Â°C, 950-1000â¯Â°C and 1000-1050â¯Â°C. These ceramics were differentiated based on different mineralogical phases resulting from the different firing temperatures. For low temperature fired ceramics, the main crystalline phases were calcite and quartz. Gehlenite is the predominant new mineral at 850â¯Â°C. CaO reacts with gehlenite and forms anorthite at around 950â¯Â°C. Diopside grows with increasing firing temperature up to 1050â¯Â°C in the Ca and Mg-rich clayey compositions and an oxidizing atmosphere, corroborated by trace hematite. The contemporaneous presence of secondary calcite and newly formed crystalline phases (diopside, gehlenite) at high temperatures indicates fast heating rate and/or short soaking time as well as coarse-grained primary calcite. Fourier Transform-Infrared (FT-IR) spectrometry indicates a considerable change in phase structures and a progressive decrease and broadening in calcite bands as a function of firing temperature.
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Authors
Maria Daghmehchi, Christina Rathossi, Hadi Omrani, Mohammadamin Emami, Mehdi Rahbar,