Tianlong Zhao

In this study, a series of (1 – x)(Ba_0.95Ca_0.05)(Ti_0.95Zr_0.05)O₃-x(Bi_0.5Li_0.5TiO₃) ceramics (x = 0–0.007) codoped with Bi and Li elements were prepared by solid-phase sintering. Bi/Li codoping induces lattice distortion, reduces domain size, and increases tetragonal phase content, thereby enhancing the comprehensive performance of the BCTZ ceramics. The 0.994BCTZ-0.006BLT ceramic exhibits optimal performance: piezoelectric coefficient d₃₃ = 270 pC/N, remnant polarization P_r = 7.3 μC/cm², Curie temperature T_c = 112 °C, electromechanical coupling factors k_p = 0.19 and k_t = 0.45, sound velocity c = 5200 m/s, and dielectric loss tan δ = 0.0222. A 10 MHz planar ultrasonic transducer fabricated from this ceramic shows a pulse-echo peak-to-peak voltage V_pp of 206.74 mV, center frequency f_c of 11.01 MHz, −6 dB bandwidth of 57.9%, and lateral resolution R_lateral of 0.95 mm. After acoustic focusing, the transducer’s performance is further improved: V_pp = 233.53 mV, f_c = 10.25 MHz, −6 dB bandwidth = 72.48%, and the lateral resolution R_lateral = 0.64 mm. Imaging tests on coins and porcine eyeballs demonstrate clear surface details/patterns of coins and excellent visualization of the conjunctiva, cornea, lens, and iris. This demonstrates its potential in the nondestructive testing and biological imaging fields.

A high-temperature piezoelectric accelerometer, employing a pair of radially polarized BiScO₃-PbTiO₃ (BS-PT) ceramic rings, operating in symmetric shear-bending coupling vibration mode is proposed. This coupling mode enhances effective electromechanical coupling through a charge amplification factor, yielding a high sensitivity (22.8 pC/g), approximately three times that of conventional shear-type accelerometers at room temperature. The device exhibits stable performance, maintaining a sensitivity of 14 pC/g after repeated thermal cycling between room temperature and 260 °C and during forced vibration tests, while exhibiting a linear response across a wide frequency range. Operation at even higher temperatures is feasible by employing piezoelectric materials with higher Curie temperatures. The demonstrated combination of high sensitivity, thermal reliability, and structural robustness underscores the potential of this accelerometer for applications in aerospace, energy, and nuclear engineering.

BiScO₃-PbTiO₃ (BS-PT) ceramics combine high piezoelectricity and a high Curie temperature but are limited in power applications by high dielectric loss (tan δ ≈ 4%) and low mechanical quality factor (Q_m ≈ 28). Here, we introduce relaxor ferroelectric Bi(Mn_2/3Nb_1/3)O₃ (BMN) to construct a T-rich morphotropic phase boundary (MPB), achieving simultaneous reduction of tan δ and enhancement of Q_m without significant degradation of piezoelectric properties. The optimized 0.02BMN-BS-0.635PT composition delivers tan δ = 0.57%, d₃₃ = 365 pC/N, Q_m = 124, k_p = 0.53, k_t = 0.54, and T_c = 435 °C. Mn-substitution at the B-site generates oxygen vacancies that couple with receptor centers to form defective dipoles, and their strong interaction with the T-rich phase suppresses polarization rotation and domain-wall motion, yielding reduced dielectric loss and enhanced Q_m, while relaxor-induced polar nanodomains help maintain a high d₃₃ value. In situ electrical and structural characterizations demonstrate excellent thermal stability: k_p and k_t remain 0.5 at 300 °C with d₃₃ increases continuously up to 300 °C, indicating a depolarization temperature above this threshold. High-temperature XRD further shows that the rhombohedral-to-tetragonal phase ratio is stable below 300 °C, consistent with the T-rich MPB design at room temperature, accounting for the observed robustness. This study demonstrates the potential of BMN-BS-PT ceramics for high-temperature, high-power piezoelectric applications and establishes a generalizable phase structure regulation strategy for designing advanced piezoelectric ceramics.

The energy deposition process for the main components of SIC Schottky diodes is simulated based on Geant4. Particle bombardment results were simulated under different angles, target materials and doping concentrations on the same target material for different light particles and heavy ions, and then the Linear Energy Transfer of SiC materials and external conditions that affect LET are obtained. The results show that the LET value of protons exhibits significant oscillations at low energy incidence, gradually decreasing exponentially after 10⁻¹ MeV. Alpha particles have a LET peak near 1 MeV, while beta particles show an exponential decrease. The LET values at low energy levels increase exponentially, while at high energy levels, the LET values show a similar linear relationship with energy. For different incident angles, the average LET value of protons in the low-level region gradually increases as the incident angle increases. The average LET value of protons in the remaining energy ranges is less affected by angle; the incident angle has no significant effect on the LET distribution of alpha particles within the full spectrum range. The results provide important references for understanding the energy deposition process and LET distribution of silicon carbide devices under single-particle interaction.

This study combines density functional theory (DFT) calculations with systematic analysis to reveal the unique properties of a novel 2D Janus MoSTe/MoTe₂ heterostructure. The most stable configuration is identified as an AD-stacked heterojunction with an interlayer spacing of 6.73 Å, supported by minimal binding energy (−2.24 meV Å⁻¹) and validated through phonon dispersion spectra and molecular dynamics simulations. The heterojunction exhibits a type-II band alignment with a 0.39 eV direct bandgap, where electrons are transferred from the MoSTe side to the MoTe₂ side at the interlayer position, creating a built-in electric field. That enhances electron–hole separation efficiency—a critical feature for optoelectronic applications. Optical calculations demonstrate strong ultraviolet absorption with a peak coefficient of 12.8 μm⁻¹ at 5.4 eV, it has excellent performance and is expected to become a promising candidate for ultraviolet photodetectors. Notably, the system displays exceptional strain sensitivity: compressive strain (−2%) induces a reversible type-II to type-I transition, while 2% tensile strain triggers a semiconductor-to-metal transition, evolving into a Dirac-cone-like band structure at 4% tensile strain. Mechanically, the heterojunction shows anisotropic flexibility, coupled with a Poisson’s ratio of 0.36 that decreases sharply under strain, indicating tunable mechanical response. Combined with its robust UV absorption (12.8 μm⁻¹ at 5.4 eV), moderate visible-light transmittance, and strain-mediated electronic transitions, these properties establish the Janus MoSTe/MoTe₂ heterostructure as a highly adaptable material for next-generation flexible optoelectronics.

Si/SiO₂ interfaces, an important functional part of silicon-based devices, are the structures most likely to cause failure. Under external load in the service state, Si/SiO₂ interfaces can degrade in different forms, and they can change from an ideal symmetrical structure to an asymmetric structure with defects. To systematically analyze the Si/SiO₂ interface, the research methods of microstructure, including characterization and modeling, are first introduced. Then, the effects of irradiation, high field stress, mechanical stress, and high temperature on Si/SiO₂ interfaces are studied. Chemical bonds, conductive band structure, and interface roughness can be changed under high field and mechanical stress loads. In addition, defect initiation and impurity migration may occur due to irradiation and temperature loads, which can lead to the failure of devices. Under multiple types of loads, the degradation mechanisms are complex, and the interfaces become more sensitive, which makes investigations into interface degradation laws difficult. For improving the reliability of devices, a systematic analysis of the influence on Si/SiO₂ interfaces under complex loads is summarized.

In this paper, a physics-based ANN assisting method for extracting transient properties of extrinsically triggering photoconductive semiconductor switches (ET-PCSSs) is proposed. It exploits the nonlinear mapping of ANN between transient current (input) and doping concentration (output). According to the basic laws of photoelectric device operating, two types of ANN models are constructed by gaussian and polynomial fitting. The mean absolute error (MAE) of forecasting transient photocurrent can be less than 10 A under low triggering optical powers, which verifies the feasibility of ANN assisting TCAD applied to PCSSs. The results are comparable to computation by Mixed-Mode simulation, yet even thousands of seconds of CPU runtime cost are saved in every period. To improve the robustness of the Poly-ANN predictor, Bayesian optimization (BO) is implemented for minimizing the curl deviation of photocurrent-time curves.

The development of high-temperature nondestructive testing (NDT) requires ultrasonic transducers with good temperature resistance and high sensitivity for improved detection efficiency. Piezoelectric composite can improve the performance of transducers because of its high electromechanical coupling coefficient and adjustable acoustic impedance. In this study, 1-3-2 composites and 1-3-2 high-temperature composite ultrasonic transducers (HTCUTs) based on 0.36BiScO ₃ -0.64PbTiO ₃ (BSPT), which are preferred piezoelectric materials at 200°C-300°C, and high-temperature epoxy with a center frequency of 6 MHz were designed and fabricated. From 25°C to 250°C, 1-3-2 composites show a higher electromechanical coupling coefficient k_t especially at high temperatures (~0.53 at 25°C, and ~0.64 at 250°C) than monolithic BSPT (~0.5). The signal of the pulse-echo response of 1-3-2 HTCUTs is distinguishable up to 250 °C and remains stable ( V_pp ~500 mV) below 150°C, exhibiting higher sensitivity (improved by 7 dB) than that of monolithic BSPT high-temperature ultrasonic transducers (HTUTs). Bandwidth has been greatly enhanced especially at high temperatures (~103250°C) compared with that of monolithic BSPT HTUTs(~30250°C). To verify the excellent performance, B-mode scanning imaging measurement of a stepped steel block and defect location detection of a steel block were performed, showing the potential for high-temperature NDT applications.