Description
We investigate the phase structures of Lorentzian Dyonic Taub-NUT-AdS spacetimes with spherical, flat, and hyperbolic horizon geometries. First, we construct a consistent approach for the thermodynamics of these solution, which is verified through the first law, the Gibbs-Duhem relation, and the generalized Smarr relation. Second, to analyze these phases we consider both canonical and mixed ensembles. Our analysis of the phase structure, in the spherical case, shows some intriguing features. It shows the existence of two distinguished critical points with a region of continuous phase transitions in between, and the possibility of merging the two into one. Furthermore, the flat and hyperbolic cases behave differently, in comparison with Van der Waals fluids. In these cases, the continuous phase transition occurs at low temperatures and pressures i.e., below the critical point and in contrast with the Van der Waals behavior.