Rare earth stannates: A new high-performance wave-transparent material investigated through theoretical and experimental approaches

Abstract

Wave-transparent materials are widely used as integrated structural-functional materials in various aircraft communication systems. However, the lack of high-performance wave-transparent materials has impeded the advancement of hypersonic aircraft. Consequently, the search for novel high-performance wave-transparent materials has become a critical challenge. This study investigates the dielectric, mechanical, and thermal properties of RE₂Sn₂O₇ (RE = La, Nd, Sm, Eu, Gd, Tb, Dy, Er, and Lu) using both theoretical predictions and experimental measurements to evaluate their suitability as wave-transparent materials. Preliminary first-principles calculations predict exceptional mechanical properties for RE₂Sn₂O₇. These predictions are confirmed experimentally, with synthesized RE₂Sn₂O₇ samples exhibiting Young's modulus exceeding 200 GPa and hardness greater than 10 GPa. Additionally, they also present low dielectric constants (∼8) and dielectric loss tangent values below 0.01 with the dielectric constant unaffected by RE species, while the dielectric loss tangent value decreases as the RE³⁺ ionic radius decreases. Their thermal expansion coefficients range between of 8 × 10⁻⁶ K⁻¹ and 10 × 10⁻⁶ K⁻¹, while thermal conductivities can be as low as 2 W m⁻¹ K⁻¹. The relationship between RE³⁺ ionic radius and intrinsic properties is elucidated, revealing that a smaller ionic radius reduces dielectric loss tangent value while enhancing Young's modulus, hardness, and thermal expansion coefficient. These results provide valuable theoretical guidance for design of high-performance wave-transparent materials.