Yaodong Yang

The morphotropic phase boundary (MPB) with multiphase coexistence serves as a critical region for piezoelectric materials, but the individual contributions of various microscopic mechanisms to the overall electromechanical response remains a challenge for further subdivision. Here, we systematically investigate the microscopic origins of outstanding piezoelectricity in -oriented Pb(Mg_1/3Nb_2/3)O₃-30PbTiO₃ (PMN-30PT) single crystals and quantitatively identify the dominant factors for giant electrostrain and ultrahigh piezoelectric coefficient. Large electrostrain arises predominantly from polarization rotation within the easily distorted monoclinic phase and the high-energy-barrier monoclinic-to-tetragonal phase transition, enabled by a synergistic interplay of broad electric field adaptability and high strain sensitivity. In contrast, the peak piezoelectric coefficient (d₃₃ > 2100 pC/N) is attributed to the low-energy-barrier rhombohedral-to-monoclinic phase transition, which facilitates polarization rotation. Furthermore, the critical yet distinct roles of monoclinic phase compared to piezoelectric and electrostrain have been confirmed. By the quantitative segmentation of various microscopic factors, this work provides fundamental insights into the design of high-performance piezoelectrics.

Digital light processing is a recently developed solution to fabricate complex structured piezoelectric devices. To obtain a high-performance device, the slurry configuration, model slicing, and heat treatment methods during the printing should be carefully determined. In this article, 200 nm particle size barium titanate powders with an optimized solid content of 80% (mass fraction) were used to configure the slurry with higher printing efficiency. The slicing method with the printing direction perpendicular to the poling direction demonstrated higher piezoelectric performance. In addition, piezoelectric parts have a higher piezoelectric response and less deformation after sintering at 1450°C. After finding the above three important optimization parameters, a piezoelectric structure with high porosity was fabricated as an example to show that printed parts of 70% porosity still can keep a high piezoelectric response.

Traditional fabrication methods for creating flexible magnetoelectric sensors are often laborious and challenging when it comes to personalization. This article employs fused deposition modeling 3D printing technology to produce flexible multifunctional sensors. (0-3) type composite filaments were prepared using polyvinylidene fluoride and cobalt ferrite (CoFe ₂ O ₄ , abbreviated as CFO). These filaments can be printed into various shapes, exhibiting good mechanical and electrical properties. Crucial parameters, such as different component ratios and CFO particle sizes, were analyzed. This study can serve as a valuable reference for the future development of personalized wearable sensors.

The versatile electrocaloric (EC) behaviors of the (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPT (PMN-100xPT) single crystal are closely related to the multiple phase transitions under the multiple fields of electric field and temperature. In this work, the EC effect of -oriented PMN-30PT single crystals with chemical composition at morphotropic phase boundary has been studied during the phase transformation process from the ferroelectric rhombohedral (R) phase to the tetragonal (T) phase. Two consecutive negative EC peaks have been achieved for the first time. Based on the projection of the EC effect in the electric field-temperature phase diagram, the relationship between the EC behaviors and the phase transitions is further established. It was found that the monoclinic (M) phase actually existed during the transformation from the R phase to the T phase, and the related R-M phase transition and M-T phase transition could both induce negative EC peaks. Under the electric field of E = 10 kV/cm, the first negative EC peaks induced by the R-M phase transition is at 57 °C with ΔT_max = −0.11 K. And the M-T phase transition can produce a higher negative EC peak, and its value can reach −0.22 K at 68 °C. Based on thermodynamic calculations, the relationship between the entropy change in different phase transitions and the EC behaviors has been further elucidated. The negative EC effect originates from the structural entropy increase in the electric field-induced phase transition process. This work not only advances the research on the electrical properties of relaxor ferroelectric single crystals but also provides a new insight into high-performance ferroelectric materials design.

Background: With the rapid development of artificial intelligence, prediction of warfarin dose via machine learning has received more and more attention. Since the dose prediction involve both linear and nonlinear problems, traditional machine learning algorithms are ineffective to solve such problems at one time.Objective: Based on the characteristics of clinical data of Chinese warfarin patients, an improved stacking ensemble learning can achieve higher prediction accuracy.Methods: Information of 641 patients from southern China who had reached a steady state on warfarin was collected, including demographic information, medical history, genotype, and co-medication status. The dataset was randomly divided into a training set (90%) and a test set (10%). The predictive capability is evaluated on a new test set generated by stacking ensemble learning. Additional factors associated with warfarin dose were discovered by feature selection methods.Results: A newly proposed heuristic-stacking ensemble learning performs better than traditional-stacking ensemble learning in key metrics such as accuracy of ideal dose (73.44%, 71.88%), mean absolute errors (0.11 mg/day, 0.13 mg/day), root mean square errors (0.18 mg/day, 0.20 mg/day) and R² (0.87, 0.82).Conclusions: The developed heuristic-stacking ensemble learning can satisfactorily predict warfarin dose with high accuracy. A relationship between hypertension, a history of severe preoperative embolism, and warfarin dose is found, which provides a useful reference for the warfarin dose administration in the future.

Digital light processing (DLP) technology has emerged as a promising 3D printing technology with the potential for the efficient manufacturing of complex ceramic devices. However, the quality of printed products is highly dependent on various process parameters, including slurry formulation, heat treatment process, and poling process. This paper optimizes the printing process with respect to these key parameters, such as using a ceramic slurry with 75 wt% powder content. The employed degreasing heating rate is 4 °C/min, the carbon-removing heating rate is 4 °C/min, and the sintering heating rate is 2 °C/min for heat treatment of the printed green body. The resulting parts are polarized using a poling field of 10 kV/cm, a poling time of 50 min, and a poling temperature of 60 °C, which yields a piezoelectric device with a high piezoelectric constant of 211 pC/N. To demonstrate the practical application of the device, its use as a force sensor and magnetic sensor is validated.

This study investigates the impact of Sr doping on the tribocatalytic performance of BaTiO₃ in degrading organic pollutants. Ba_1-xSr_xTiO₃ (x = 0–0.3) nanopowders are synthesized and their tribocatalytic performance evaluated. By doping Sr into BaTiO₃, the tribocatalytic performance was enhanced, resulting in an approximately 35% improvement in the degradation efficiency of Rhodamine B using Ba_0.8Sr_0.2TiO₃. Factors such as the friction contact area, stirring speed, and materials of the friction pairs also influenced the dye degradation. Electrochemical impedance spectroscopy revealed that Sr doping improved BaTiO₃’s charge transfer efficiency, thereby boosting its tribocatalytic performance. These findings indicate potential applications for Ba_1-xSr_xTiO₃ in dye degradation processes.