High-entropy ilmenite titanate (Mg,Co,Ni,Zn)TiO3: Synthesis, crystal and band structure, and enhanced properties

Abstract

For continuing to explore new high-entropy materials, the first high-entropy ilmenite-phase titanate, (Mg,Co,Ni,Zn)TiO₃, is synthesized in this work, further introducing a new crystal structure type for high-entropy ceramics. The uniform chemical composition and typical ilmenite-phase structure of high-entropy (Mg,Co,Ni,Zn)TiO₃ are verified by XRD, SEM, TEM, EDS, and XPS. Homogeneous element distribution and magnetically-coupled atomic arrangement are further performed using Rietveld refinement, Raman spectral fitting, and high-resolution STEM. On this basis, complementary density functional theory simulation with Hubbard correction (DFT + U) is conducted to reveal the band structure and a 2.529 eV bandgap of high-entropy (Mg,Co,Ni,Zn)TiO₃, thereby enhancing the potential for high emissivity and electronic applications. Excellent thermal stability at 1000–1200 °C, a low thermal conductivity of 2.365 W·m⁻¹·K⁻¹ at room temperature, a high hemispherical emissivity of 0.93 within the 3–14 μm wavelength range, and a low dielectric constant of 22.23 are also demonstrated.