Phase transition of black holes in Brans--Dicke Born--Infeld gravity through geometrical thermodynamics

Abstract

Using the geometrical thermodynamic approach, we study phase transition of Brans--Dicke Born--Infeld black holes. We apply introduced methods and describe their shortcomings. We also use the recently proposed new method and compare its results with those of canonical ensemble. By considering the new method, we find that its Ricci scalar diverges in the places of phase transition and bound points. We also show that the bound point can be distinguished from the phase transition points through the sign of thermodynamical Ricci scalar around its divergencies.