Deep inside the ceramic texture: A microscopic–chemical approach to the phase transition via partial-sintering processes in ancient ceramic matrices

• Archeological ceramics are appropriate for the investigation of the pre-sintering microstructure due to their inhomogeneous matrix.
• Atomic force microscopy was employed for detecting the sintering based on viscosity change inside the grain boundaries.
• Partial sintering is a pathway that occurs via the affected mineral grain boundaries.
• Crystallographic structure can be a critical factor for identifying partial sintering.

High-resolution microscopy investigations on ancient ceramics recommend the complex progression of crystalline phases in an antique object via the sintering process. Based on materials-science point of view, sintering is not a routinely reaction in all crystalline phases with the same crystallographic pattern, but also is a transition pathway. Sintering depends on the processing of raw materials via the manufacturing process. Five samples are chosen for this analytical approach from two different periods from Tappeh Zaghe, Iran (5100 millennium bc). A multimicroscopical approach was carried out by means of polarized light microscopy, environmental scanning electron microscopy, and atomic force microscopy. Crystalline phases were determined by X-ray diffraction and refined after Rietveld method. The observation of the behavior of phase–interphase boundaries of a crystalline part in the nano area suggests that the partial sintering is the point at which the mineral began to be decomposed, and the conditions of the occurrences of this phenomenon depend on crystallographic properties.