On Thermodynamics of AdS Black Holes in Arbitrary Dimensions
  Considering the cosmological constant $\Lambda$ as a thermodynamic pressure and its conjugate quantity as a thermodynamic volume as proposed in Kubiznak and Mann (2012), we discuss the critical behavior of charged AdS black hole in arbitrary dimensions $d$. In particular, we present a comparative study in terms of the spacetime dimension $d$ and the displacement of critical points controlling the transition between the small and the large black holes. Such behaviors vary nicely in terms of $d$. Among our result in this context consists in showing that the equation of state for a charged RN-AdS black hole predicts an universal number given by $\frac{2d-5}{4d-8}$. The three dimensional solution is also discussed. 
A. Belhaj, M. Chabab, H. El Moumni, M. B. Sedra
hep-th gr-qc