Low pressure reversibly driving colossal barocaloric effect in two-dimensional vdW alkylammonium halides.

Plastic crystals as barocaloric materials exhibit the large entropy change rivalling freon, however, the limited pressure-sensitivity and large hysteresis of phase transition hinder the colossal barocaloric effect accomplished reversibly at low pressure. Here we report reversible colossal barocaloric effect at low pressure in two-dimensional van-der-Waals alkylammonium halides. Via introducing long carbon chains in ammonium halide plastic crystals, two-dimensional structure forms in (CH-(CH))NHX (X: halogen element) with weak interlayer van-der-Waals force, which dictates interlayer expansion as large as 13% and consequently volume change as much as 12% during phase transition.

Compressive-Strain-Facilitated Fast Oxygen Migration with Reversible Topotactic Transformation in LaSrCoO via All-Solid-State Electrolyte Gating.

Modifying the crystal structure and corresponding functional properties of complex oxides by regulating their oxygen content has promising applications in energy conversion and chemical looping, where controlling oxygen migration plays an important role. Therefore, finding an efficacious and feasible method to facilitate oxygen migration has become a critical requirement for practical applications. Here, we report a compressive-strain-facilitated oxygen migration with reversible topotactic phase transformation (RTPT) in LaSrCoO films based on all-solid-state electrolyte gating modulation.

Enhanced Performance of Δ upon Frequent Alternating Magnetic Fields in FeRh Alloys by Introducing Second Phases.

The cyclability and frequency dependence of the adiabatic temperature change (Δ) under an alternating magnetic field (AMF) are significantly important from the viewpoint of refrigeration application. Our studies demonstrated, by direct measurements, that the cyclability and low-magnetic-field performance of Δ in FeRh alloys can be largely enhanced by introducing second phases. The Δ under a 1.

A Distinct Spin Structure and Giant Baromagnetic Effect in MnNiGe Compounds with Fe-Doping.

Spin structure of a magnetic system results from the competition of various exchange couplings. Pressure-driven spin structure evolution, through altering interatomic distance, and hence, electronic structure produces baromagnetic effect (BME), which has potential applications in sensor/actuator field. Here, we report a new spin structure(CyS-AFM) with antiferromagnetic(AFM) nature in Fe-doped MnFeNiGe.