Analyzing of segregation in mixtures of 3-methylpyridine and heavy water by dynamic neutron radiography

The closed-loop phase diagram of 3-methylpyridine—heavy water mixture was studied, to our best knowledge, for the first time with dynamic neutron radiography (DNR) at the 10 MW VVR-SM Research Reactor in Budapest (Hungary). Visualized were the (i) lower temperature non-segregated states (below 38°C), (ii) transition (40–43°C), (iii) segregated states (46–128°C), (iv) higher temperature transition (110–128°C) and (v) higher temperature non-segregated states. The non-segregated state belonging to 141°C, was found to be definitely dissimilar from the lower temperature state. Existence of a solid-like structure at the liquid–liquid interface was indicated.