Born-Infeld-$f(R)$ gravity with de Sitter solutions

In this study, we consider the Born–Infeld-$f(R)$ gravity in which the $f(R)$ term enters directly into the square root in the Palatini formulation. We shortly analyzed this model for an explicit $f(R)$ function which includes positive and negative powers of the curvature scalar. We also show that both the ordinary Born–Infeld-$f(R)$ and this modification reduce to the same gravitational action form under the conformal approach. Then we consider the existence of a maximally symmetric vacuum solution for the gravitational field equations and find the de Sitter solution for this modified model.