Electrocaloric properties of [110] and [111] oriented 0.73Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃ single crystals were studied in the temperature range of 293–423 K. The Maxwell relations and the Landau–Ginsburg–Devonshire (LGD) phenomenological theory were employed as the indirect method to calculate the electrocaloric properties, while a high-resolution calorimeter was used to measure the adiabatic temperature change of the electrocaloric effect (ECE) directly. The results indicate that the directly measured temperature changes of ΔT > 2.5 K at room temperature were procured when the applied electric field was reversed from 1 MV/m to −1 MV/m, which are larger than those deduced pursuant to the Maxwell relation, and even larger than those calculated using the LGD theory in the temperature range of 293–~380 K.

Piezoelectric composite materials have demonstrated significant potential for developing high-performance wearable sensors. However, optimizing the piezoelectric output performance in polymer-based devices remains challenging due to the suboptimal synergy between the piezoelectric reinforcement phase and substrate materials. Moreover, the instability of response signals further hampers the sensor’s practical utility. In this investigation, wet-spinning technology was applied to fabricate a novel Barium Titanate (BaTiO₃)/Polyvinylidene fluoride (PVDF) composite fiber. Through this approach, we enhanced the piezoelectric properties of the material. Notably, our electron diffraction analysis revealed compelling lattice deformations in the ceramic particle-polymer interface, yielding significant enhancements in the piezoelectric characteristics. Remarkably, incorporating just 1.5 wt% of BaTiO₃ in PVDF led to a piezoelectric output of 0.88 V during dynamic cycle tests at 1 Hz. Encouragingly, the output signal exhibited a robust linear correlation (R² = 0.996) with applied compression force.