Entropy-modulated atomic ripple texturing in two-dimensional transition metal carbonitrides.

Abstract

Periodically atomic displacement in two-dimensional (2D) ripple texturing offers a promising route for selective modulation of local potential, crucial for advanced electronic engineering. However, in 2D transition metal carbonitrides (MXenes), the construction and regulation of atomic ripples to control electronic properties meet substantial challenges due to the difficulty in tailoring homogeneous deformation. Here, we propose a competition strategy that leverages configurational entropy and surface termination to controllably modulate the atomic ripple structure within Nb₂CTe_x-based Mxenes. This chemical disorder releases the local in-plane strain induced by termination atoms with large ionic radii, thus enabling the regulation of out-of-plane atomic displacement. The deliberate design of the ripple structure regulates the dielectric relaxation time of the microscopic dipole in the electric field. Consequently, high-entropy MXenes deliver strong intensity of microwave absorption (-41.12 dB) and an absorption bandwidth of nearly 10 GHz, covering the S-, C-, and X-bands. This study establishes the relationship between atomic ripple structure, atomic strain, polarization relaxation, and dielectric properties, providing guidance for designing advanced MXenes materials for various applications.