Interfacial thermal transport plays a prominent role in the thermal management of nanoscale objects and is of fundamental importance for basic research and nanodevices. At metal/insulator interfaces, a configuration commonly found in electronic devices, heat transport strongly depends upon the effective energy transfer from thermalized electrons in the metal to the phonons in the insulator. However, the mechanism of interfacial electron–phonon coupling and thermal transport at metal/insulator interfaces is not well understood. Here, the observation of a substantial enhancement of the interfacial thermal resistance and the important role of surface charges at the metal/ferroelectric interface in an Al/BiFeO3 membrane are reported. By applying uniaxial strain, the interfacial thermal resistance can be varied substantially (up to an order of magnitude), which is attributed to the renormalized interfacial electron–phonon coupling caused by the charge redistribution at the interface due to the polarization rotation. These results imply that surface charges at a metal/insulator interface can substantially enhance the interfacial electron–phonon‐mediated thermal coupling, providing a new route to optimize the thermal transport performance in next‐generation nanodevices, power electronics, and thermal logic devices.

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Sr 2? /Ba 2? modified potassium sodium niobate transparent ceramics [(K 0.5 Na 0.5 ) 1-2x (Sr 0.75 Ba 0.25 ) x ] 0.93 Li 0.07 Nb 0.93 Bi 0.07 O 3 (KNNLB:Sr 2? /Ba 2? ) were fabricated via hot-pressing, using Li and Bi as sintering aids. The crystal structure, microstructure, optical, piezoelectric and dielectric properties of KNNLB with varied Sr 2? /Ba 2? content were investigated. The optical transparency of such ceramics is up to 60 % in the UV-visible region and close to 100 % in the infrared region. Moreover, the optimum dielectric and piezoelectric performances of e r = 1679, d 33 = 151 pC/N and tand = 0.026 were obtained for KNNLB:Sr 2? /Ba 2? ceramics with x = 0.025. Consequently, the doping of Sr 2? /Ba 2? is considered as an effective way to improve electrical properties and maintain excellent optical properties of the fine-grain transparent ceramics.

Lead-free thermoelectric material, copper chalcogenides, have been attracting much interest from many research and industrial applications owing to their high capability of harvesting energy from heat. The state-of-the-art copper chalcogenides are commonly fabricated by the spark plasma sintering (SPS) and hot pressing (HP) techniques. Those methods are still costly and complicated particularly when compared to the conventional solid-state sintering method. Here, we report an easy-to-fabricate lead-free copper(I)-selenium (Cu 2 Se) that was fabricated using the conventional sintering method. The fabrication conditions, including sintering temperature and dwelling time, have been systematically studied to optimize the thermoelectric performance of Cu 2 Se. The optimized zT value for the pure Cu 2 Se was found to be 1.2 for the sample sintered at 1173 K for 2 h. The study shows that Cu 2 Se developed using the simple and low-cost techniques could exhibit comparable thermoelectric performance when compared with those fabricated by the SPS method, which provides an alternative potential technique to synthesize high-performance thermoelectric materials in a cost-effective way for industrialization.