Temperature Tunable Anderson Localization and Metal-Insulator Transition of Acoustic Waves in High-Entropy Phononic Crystal

Inspired by the electrical insulators made by high-entropy alloys, this work studies the feasibility of using a 2D high-entropy phononic crystal (PnC) to achieve Anderson localization within its first transmission band. The entropy of sound increases proportionally with the increase of additional eigenmodes at a certain frequency which decreases the transmitted energy through the structure. 2D disorder in sizes (or) and materials of the scatterers is introduced to achieve that on a perfect periodic PnC designed with metallic scatterers in an ambient water-based lattice medium. Around the band edge of the first transmission band, Anderson's localization of sound is discovered. At a resonant frequency within a perfect periodic crystal, the introduction of a disorder in the PnC results in an exponential decay of sound wave transmission along the propagation direction due to the entropy generation from acoustic energy. Furthermore, the temperature tunability of the proposed crystal is proposed. A variation of the room temperature to 0 degrees C leads to the phase transition of water to ice and results in a strong transition of the acoustic localization at resonant frequencies with a 25 dB+ difference.