to study critical phenomena of higher dimensional black holes and black rings [@Arcioni:2004ww] and to determine the conditions of stability for equilibrium configurations of charged black holes surrounded by quintessence [@AzregAinou:2012hy]. In section \[stab\] we present an overview of this method.

By considering the Rényi model in the black hole problem, we also investigated the thermodynamic stability question of Schwarzschild black holes [@Czinner:2015eyk]. First we considered the question of pure, isolated black holes in the microcanonical approach, and showed that these configurations are stable against spherically symmetric perturbations, just like in the Boltzmann picture. However, in considering the case when the black holes are surrounded by a heat bath in the canonical treatment, we found that – in contrast to the Boltzmann approach – Schwarzschild black holes can be in stable equilibrium with thermal radiation at a fixed temperature. This results a stability change at a certain value of the mass-energy parameter of the black hole which belongs to the minimum temperature solution. Black holes with smaller masses are unstable in this model, however larger black holes become stable. These findings are essentially identical to the ones obtained by Hawking and Page in AdS space within the standard Boltzmann entropy 