The interaction of ion beams and solids is a rich and growing field in materials physics. By delving deeper into some of its traits and peculiarities, we can contribute to the current understanding of a material’s behavior under irradiation. Moreover, ion beams are also a versatile tool for materials modification and nanostructuring. Ion beam parameters like ion species, ion charge states, beam energy (velocity), fluence, and angle of irradiation can be controlled, consequently opening the possibility of defects engineering. Using high-energy ion beams in the ~MeV-GeV range, often called swift heavy ions (SHI), offers additional opportunities for materials nanostructuring. With its linear trajectories and long ranges, SHI can create permanent cylindrical damage around the trajectory, called an ion track. Besides the possibility of damage creation in the bulk of the material, SHI can also create unique structures on the materials’ surfaces and in 2D materials. To predict and control the production of nanostructures this way, it is necessary to thoroughly understand the processes of defect creation during ion beam irradiation. For this purpose, in this thesis, we explore the interactions of various ion beams with two materials: graphene and gallium nitride. The first part of our research focuses on the interaction of a 2D material, graphene (suspended and supported) with ion beams in the energy ranges from 1-23 MeV. We describe the morphology of defects and connect it to the beam parameters. We explain the origin of defects by deconvoluting the contribution of the ion beam's two main energy deposition channels to the material and discuss the role of the substrate. The other part of our research presented here pertains to gallium nitride, a bulk material characterized by its radiation hardness, represented by the high energy threshold for the ion track formation. We describe the conditions for the introduction of defects despite this threshold, irradiating this material by ion beams in the energy range of 2-900 MeV. In the second step, we turn to sequential irradiation using two beams, finally reaching two contrary effects: an increase and a decrease in the number of previously introduced defects. We describe the conditions where these effects are reachable, and for all the above cases, we quantify the number of defects that are permanently present in the material after the irradiations.