Acoustic lenses are crucial for focused ultrasound, enhancing imaging resolution and achieving high-intensity focus. Conventional lenses face challenges in curved surface processing and low transmission efficiency. In this study, the focus was on developing a high-transmission high-temperature vulcanized silicone rubber (HTV) composite and its application in fabricating phase-reversal Fresnel zone plate (PR-FZP). Various HTV composites with solid contents ranging from 10 wt% to 35 wt% were prepared by incorporating SiO2 and Yb2O3, and their acoustic properties such as density, ultrasonic velocity, acoustic impedance, and attenuation coefficient were characterized. The HTV composites doped with 35 wt% Yb2O3 showed relatively good acoustic performance with better acoustic impedance matching, high acoustic transmittance (psi similar to 96.8 %) and low acoustic attenuation coefficient (alpha similar to 0.56 dB/(mm*MHz)). Besides, a comparative analysis was conducted on the acoustic properties of PR-FZP fabricated from pure HTV, HTV doped with 35 wt% SiO2, and HTV doped with 35 wt% Yb2O3. The focused acoustic field, signal amplitude, and acoustic pressure of the PR-FZP prepared from these different materials were evaluated and subsequently applied in photoacoustic imaging. The results illustrated that PR-FZP composed of Yb2O3-doped HTV composite demonstrates promising potential in enhancing acoustic field focusing and ultrasound imaging applications, offering a new avenue to enhance the effectiveness of acoustic lenses.

Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals possess excellent piezoelectric properties but exhibit high brittleness, posing challenges for ultrafast laser micromachining. To elucidate the interaction mechanism between ultrafast lasers and PMN-PT single crystals, this study developed a two-temperature model (TTM) based on the finite element method, which was coupled with thermoelastic mechanical equations, to numerically simulate ultrafast laser ablation. The results indicate that the electron temperature exhibits nonlinear growth with single-pulse energy, while the electron-lattice coupling time is primarily modulated by pulse width. Ablation depth increases with single-pulse energy but exhibits a trend of first increasing and then decreasing with pulse width. Under multi-pulse irradiation, the heat accumulation effect becomes significant, progressively deepening the ablation depth. Thermal stress analysis indicates that tensile stress concentration at the laser spot edge is the primary driver for microcrack initiation. The experimental results are in good agreement with the numerical simulation results, with errors in ablation depth and width both less than 11%, validating the effectiveness and accuracy of the TTM model. This study provides a theoretical basis for optimizing ultrafast laser processing parameters of PMN-PT single crystals, facilitating their application in high-precision microdevices.

Accurate prediction of the output acoustic power of an ultrasonic therapy system is critical to treatment safety and efficacy. Here, we systematically verify the accuracy of a system-level Krimholtz–Leedom–Matthaei power model that fully integrates the driving source, cable and tuning network, power ultrasonic transducer, and acoustic load using the transmission matrix method. Validated in three representative power transducers made of PZT-4 ceramic, PZT-4 composite, and PZT-5H ceramic up to an intensity-on-transducer-surface (ITS) of 21.5 W/cm2, the model achieves relative errors of only −6% to −10% without requiring nonlinear material parameters, a value limited by the current measurement setup rather than by the model's inherent capability. Moreover, a counterintuitive threshold effect was discovered: for thickness mode power transducers, once the mechanical quality factor Qm exceeds ∼90, further increase yields negligible gain in output efficiency. This finding provides new design guidelines for the selection of piezoelectric materials in high-power applications, showing that chasing ultrahigh Qm is unnecessary beyond this saturation point.

PZT-8 ceramics exhibit outstanding performance in sensor applications owing to their superior piezoelectric properties. Nevertheless, conventional dense PZT-8 ceramics are subject to certain limitations, including high acoustic impedance and relatively low energy conversion efficiency, which restrict their broader application potential. Porous architectures offer a viable solution by enabling controlled porosity, thereby improving acoustic matching and enhancing energy harvesting efficiency. Although 3D printing presents a cost-effective method for fabricating complex ceramic geometries, ultraviolet (UV) light-based photopolymerization techniques have encountered challenges in processing PZT-8 ceramics due to their strong UV absorption characteristics. To address this limitation, this study introduces a novel strategy by incorporating non-absorbent polymethyl methacrylate (PMMA) into the formulation of high-performance porous PZT-8 piezoelectric ceramics tailored for digital light processing (DLP)-based 3D printing. Systematic investigations demonstrate that increasing PMMA content (5 wt% to 25 wt%) positively influences curing depth while simultaneously affecting microstructure and electrical properties. The experimental results show d33 values ranging from 176 to 272 pC/ N, kt values from 35.84 % to 46.55 %, Z values from 18.13 to 22.22 MRayls, FOM values from 8.92 to 10.55 & times; 10-12 m2/N, and HFOM values from 3.47 to 4.40 & times; 10-12 m2/N.

The photopolymerization-based three-dimensional (3D) printing technique overcomes the limitations associated with complex geometries and significantly reduces manufacturing time, making it increasingly suitable for fabricating micro-scale materials. This study evaluates the influence of printing parameters on the microstructure and electrical properties of piezoelectric ceramics by fabricating BaTiO3 (BT) ceramics with varying solid contents (34-47 vol%) and printing layer thicknesses (5-40 mu m) using photopolymerization. The printed BT ceramic exhibits favorable electrical properties (d(33)similar to 255 pC/N, epsilon(r)similar to 1681, tan delta similar to 0.013) when the solid content is 40 vol% and the layer thickness is 10 mu m. In addition, micro-columns with a width of 150 mu m are successfully printed and integrated into a high-performance 1-3 composite ultrasonic transducer, achieving a center frequency of 13.5 MHz and a -6 dB bandwidth of 52%. These results indicated that optimizing the solid content and printing layer thickness is essential for producing ceramics with superior performance. Photopolymerization-based 3D printing presents strong potential for fabricating complex structures and highly precise piezoelectric composites.

Transparent-photochromic materials have garnered significant attention for their applications in optical information storage and anti-counterfeiting, which necessitate excellent transparency and high optical contrast. Herein, x mol% Sr2+ and 1 mol% Ho3+-codoped (K0.5Na0.5)NbO3 (xSr-1Ho-KNN) ceramics were synthesized by a conventional solid-state reaction and pressureless sintering. Notably, the 7Sr-1Ho-KNN ceramic displays exceptional transmittance (60.7% at 780 nm), attributed to its fine grains and highly symmetric crystal structure. The photochromic (PC) contrast based on the change in photoluminescence (PL) intensity of 7Sr-1Ho-KNN under excitation with a 980 nm laser reaches as high as 91.5%. After thermal treatment under appropriate conditions, the transmittance and PL intensity of the ceramic can revert to their respective original values, demonstrating superior optical stability in response to alternating light and thermal stimuli. The combination of high transparency and PC contrast suggests that the xSr-1Ho-KNN ceramics have promising potential for optical information storage and optical anti-counterfeiting applications, which can guide the development of other KNN-based materials or even multifunctional luminescent ferroelectrics.

For applications in environmental protection, industrial production, and personal health monitoring by breath exhalation, the sensitive and selective detection of n-butanol is of extreme importance. An n-butanol gas sensor has been developed utilizing LaFeO3 nanofibers doped with Er3+ by an electrospinning technique. Compared to the pure sample, the gas sensor shows an improved response of 58.97 to 30 ppm n-butanol, which was boosted by 5.99-fold due to the smaller average grain sizes (21.2 nm), porosity of the nanofiber, and abundant chemicalabsorbed oxygen species (38.5 %) at an Er doping level of 3 at%. It has excellent selectivity to n-butanol, a fast response/recovery time (17 s/27 s), superior stability during 30 days, and a low detection limit (100 ppb), which indicates that Er-doped LaFeO3 nanofibers have excellent sensing capabilities for real-time n-butanol detection.

Sr/Ho-codoped (K 0.5 Na 0.5 )NbO 3 ceramics exhibit high optical transparency, remarkable photochromic contrast and outstanding cycling stability, which can be applied in high-security anti-counterfeiting labels and rewritable information storage.

The backing layer is the core component of an ultrasonic transducer, which can absorb the acoustic energy and suppresses excess vibration to obtain a broad bandwidth pulse-echo signal. Ultrasound-assisted 3D printing can control the orientation/alignment and local composition of particles in liquid resin and fabricate materials with periodic complex structures. In this paper, three types of tungsten/photosensitive resin composites (1-3, 2-2, and 3-3) were prepared using ultrasound-assisted stereolithography technique. The acoustic properties of these composites were investigated in relation to the particle arrangement patterns under ultrasonic stimulation at two different frequencies (0.92 MHz and 1.12 MHz). Among the three types, the 3-3 type composite exhibits relatively good acoustic properties with high attenuation coefficients and low acoustic impedance, which is more suitable for backing layer applications. Besides, the composites printed under higher frequency stimulation (1.12MHz) have higher acoustic velocity and lower acoustic impedance. Finally, the 3-3 type composite stimulated by a frequency of 1.12MHz was selected as the backing layer for evaluating the transducer performance. Transducers based on PZT ceramics were designed and fabricated with center frequencies of 5MHz and 20MHz, respectively. After attaching backing layer, the -6dB relative bandwidth of 5MHz transducer increased from 14.76% to 30.48%, and that of the 20MHz transducer increased from 10.78% to 22.33%. Besides, the trailing of the pulse echo is significantly improved. The results suggest that the ultrasound-assisted 3D printing have good potential applications in backing layers with periodic complex structures.

Owing to the difficulty in replication and high security, delayed anti-counterfeiting is an emerging technology for its applicability in encrypting high-precision devices. Materials with photochromic (PC) effects and self-recovery behavior are appropriate candidates for realizing delayed anti-counterfeiting. Herein, Dy3+-doped (K0.5Na0.5) NbO3-based ceramics were designed and prepared via tape-casting method. Down-conversion photoluminescence with white emission, conspicuous PC reaction and dynamic PC self-bleaching process were observed in the ceramics. The concentrations and positions of different defect traps, along with the oxygen vacancies of the ceramics, contributed to PC self-recovery. Taking advantage of the difference in PC self-recovery rates between yellow and blue emissions with time and the difference in color temperatures (C.T.), we propose a method of encrypting, calibrating, and performing C.T. detection on the nodes and paths of a single ceramic for optical signal input. This study will guide the construction of visual-invisible double-encryption anti- counterfeiting systems based on other novel materials.

Photoacoustic tomography (PAT) provides both structural and functional information, making it a powerful tool for guiding interventional procedures. However, conventional ultrasound transducers are generally optically opaque, complicating PAT system design and hindering seamless integration with other optical imaging modalities. A novel transparent ultrasound transducer (TUT) linear array has been developed specifically for real-time interventional guidance. The TUT array-based PAT system demonstrates high performance with 378.2[Formula: see text] [Formula: see text]m lateral resolution, 599.1[Formula: see text] [Formula: see text]m axial resolution, and a fast imaging rate of 0.05[Formula: see text]s/frame. The system’s interventional imaging capability was demonstrated through real-time visualization of needle morphology and dye diffusion during injections in chicken breast tissue. In summary, the TUT array enables potential applications in real-time multimodal imaging, combining photoacoustic, ultrasound, and optical modalities for comprehensive tissue characterization.

Currently, in the design and manufacturing of piezoelectric ceramic composites and sensors using 3D printing, there is a lack of complete set parameters that are essential for critical design stages like structural optimization and performance evaluation. This absence of accurate quantitative data hinders the full potential of 3D printing technology in materials science and device manufacturing. This study utilizes 3D printing technology to fabricate PMN-PT piezoelectric ceramics with special structures, which serve as the piezoelectric phase within the composites. The impact of slurry solid content and printing layer thickness on the crystal structure, microstructure, and electrical properties of the ceramics was systematically investigated, ultimately leading to the achievement of high-performance PMN-PT ceramics accompanied by a complete set of performance parameters. Furthermore, both 1-3 and 3-3 composites with good performance were designed and fabricated, and the structure and properties were analyzed through theoretical models. The results indicate that the optimal performances of 1-3 composites are achieved at a volume fraction of 50 %, resulting in a d33 value of 380 pC/N, a kt value of 0.65. For the 3-3 composite, within the volume fraction ranging from 43 % to 71 %, the d33 exhibits values ranging from 265 to 362 pC/N, and the hydrostatic figure of merit varies from 1.85 to 0.78 ( x 10-12 m2/N). The findings suggest that appropriate solid content and optimal printing layer thickness are essential for producing highperformance ceramics. 3D printing presents numerous benefits in creating intricate and accurate piezoelectric composites.

Ultrasound has been extensively utilized to evaluate the bonding quality of coatings. However, current ultrasonic methods based on single temporal or spectral feature cannot accurately characterize the bonding quality within industrial coatings, especially for potential debonding at different layers. This paper proposed an ultrasonic method with multiple temporal and spectral features to evaluate the bonding condition of dual-layer coatings. Ultrasonic features were automatically extracted based on stacked sparse autoencoder (SSAE) to compare with the conventional selected features. Firstly, numerical simulations were carried out to analyze the variation of ultrasonic signals with different stiffnesses at topcoat and primer interfaces. Two temporal and three spectral features were manually extracted and show high sensitivity to different bonding conditions of the two interfaces. Meanwhile, a SSAE network was designed to automatically extract ultrasonic features. The high correlation between the manually and automatically extracted features demonstrates its effectiveness of automatic feature extraction via SSAE. Then, a 50 MHz ultrasonic pulse-echo system was applied to collect signals from 115 coating samples of laptop shell. Four sets of ultrasonic features were extracted via manual method and SSAE networks. Principal components analysis was then employed to reduce the feature space and support vector machine was applied to distinguish topcoat debonding and primer debonding from the intact coatings. The results show that the feature set including 64 temporal and spectral features extracted by SSAE exhibit the best classification with an accuracy of 95.652 %. This proposed multi-feature ultrasonic method can accurately assess the bonding quality of different interfaces in the multi-layer coatings.

Considering the large demand for electricity in the era of artificial intelligence and big data, there is an urgent need to explore novel energy storage media with higher energy density and intelligent temperature self-check functions. High-entropy (HE) ceramic capacitors are of great significance because of their excellent energy storage efficiency and high power density (PD). However, the contradiction between configurational entropy and polarization in traditional HE systems greatly restrains the increase in energy storage density. Herein, the contradiction is effectively solved by regulating the octahedral tilt and cationic displacement in ABO3-type perovskite HE ceramics, i.e., (1-x)[0.6(Bi0.47Na0.47Yb0.03Tm0.01)TiO3-0.4(Ba0.5Sr0.5)TiO3]-xSr(Zr0.5Hf0.5)O3 (BNYTT-BST-xSZH). Combining the tape-casting process and cold isostatic pressing, the optimal BNYTT-BST-0.06SZH ceramic displays a large recoverable energy storage density (10.46 J cm-3) at 685 kV cm-1 and a high PD (332.88 MW cm-3). More importantly, due to Tm/Yb codoping, abnormal fluorescent negative thermal expansion and excellent real-time temperature sensing are developed, thus the application of fault detection and warning in high-voltage transmission line systems is conceptualized. This study provides an effective strategy for enhancing the polarization of energy-storing HE ceramics and offers a promising material for overcoming the problems of insufficient capacitor density and thermal runaway in terminal communication.

Bismuth layer-structured CaBi4Ti3.925(Nb2/3Mn1/3)(0.075)O-15 (CBTNM) piezoelectric ceramics have been prepared using stereolithography (SL) technology. The effects of various solid contents (76-82 wt%) of CBTNM ceramics on the slurry viscosity, phase structure, microstructure, and electric performance were studied in detail. At a solid content of 82 wt%, the ceramic exhibits good piezoelectric properties. The piezoelectric constant d(33), thickness-mode electromechanical coupling coefficient k(t), and Curie temperature Tc were 21 pC/N, 47%, and 790 degrees C, respectively. The piezoelectric constant of the ceramic has a good stability up to 500 degrees C. Furthermore, a high-temperature ultrasound transducer was designed and fabricated based on the CBTNM ceramic, and its pulse-echo performance was characterized from room temperature to 250 degrees C. The pulse-echo performance indicates that the -6 dB bandwidth and echo amplitude of the transducer decrease slightly, but still work normally up to 250 degrees C. These results indicate that the transducer fabricated based on CBTNM ceramics has potential in high-temperature testing applications.

Piezo-catalysis is a green and effective method for degrading rich and obstinate molecules in wastewater. Yet, the piezo-catalytic performance of frequently-used barium titanate (BTO) is still limited for practical applications, thus it is crucial to construct high-efficiency BTO-based catalysts. Herein, BiOBr/BTO heterojunction-based piezo-photocatalysts were successfully prepared using the chemical precipitation method, and an internal electric field was established via ultrasound to promote the separation of photogenerated electron-hole pairs through the synergistic effect of piezocatalysis and photocatalysis. Transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy were utilized to characterize the heterojunction. The degradation performance of Rhodamine B (RhB) by BiOBr/BTO is the best among various pollutants, giving a reaction rate constant up to 20.839 x 10 -2 min -1 , exceeding numerous previously reported catalysts. In addition, the piezo-photocatalytic reaction rate of BiOBr/BTO for Methyl Orange was 9.298 x 10 -2 min -1 , approximate to 3.3 times than those of pure BTO (2.806 x 10 -2 min -1 ), and also approximate to 15.9 times and 3.3 times than those of single photocatalysis (0.585 x 10 -2 min -1 ) or piezocatalysis (2.848 x 10 -2 min - 1 ). Importantly, the BiOBr/BTO heterojunction demonstrates excellent catalytic degradation performance for a broad range of pollutants (e.g., dyes and antibiotics) and their mixtures, as well as favorable cycling stability and repeatability with changed environmental conditions, displaying applicability in actual wastewater treatment. The possible degradation pathways of RhB were analyzed by liquid chromatography-mass spectrometry. The present work supplies a feasible strategy for the preparation of high-efficiency piezo-photocatalytic BTO-based heterojunctions, which can guide other composites for environmental remediation.

Transparent dielectric ceramics are splendid candidates for transparent pulse capacitors (TPCs) due to splendid cycle stability and large power density. However, the performance and service life of TPCs at present are threatened by overheating damage caused by dielectric loss. Here, a cooperative optimization strategy of microstructure control and superparaelectric regional regulation is proposed to simultaneously achieve excellent energy storage performance and real-time temperature monitoring function in NaNbO3-based ceramics. By introducing aliovalent ions and oxides with large bandgap energy, the size of polar nanoregions is continuously reduced. Due to the combined effect of increased relaxor behavior and fine grains, excellent comprehensive performances are obtained through doping appropriate amounts of Bi, Yb, Tm, and Zr, Ta, Hf in A- and B-sites of the NaNbO3 matrix, including recoverable energy storage density (5.39 J cm(-3)), extremely high energy storage efficiency (91.97%), ultra-fast discharge time (29 ns), and superior optical transmittance (approximate to 47.5% at 736 nm). Additionally, the phenomenon of abnormal fluorescent negative thermal expansion is realized due to activation mechanism of surface phonon at high temperatures that can promote the formation of [YbO]-Tm3+ pairs, showing great potential in real-time temperature monitoring of TPCs. This research provides ideas for developing electronic devices with multiple functionalities.

The transparent [Li0.04(K0.5Na0.5)0.96]NbO3+0.5mol% Er2O3 (KNNLN-Er) lead-free piezoelectric ceramics were prepared by stereolithography technique. The influence of different sintering holding time (4h∼8h) on the micromorphology, relative density, shrinkage, electric properties, and photoluminescence properties were systematically investigated. The KNNLN-Er ceramics show the coexistence of orthorhombic and tetragonal structures. The grain size increases obviously and then decreases slightly with the holding time increasing. The KNNLN-Er ceramics exhibit good piezoelectric performance (piezoelectric constant d33∼97 pC/N, electromechanical couple coefficient kt∼0.36) and the moderate transparency of 34% when the holding time is 6h during sintering at 1120°C. Besides, the intensity of the photoluminescence emission spectra increases with the holding time increasing. Furthermore, in order to estimate the properties of the KNNLN-Er transparent ceramics, an ultrasonic transducer with a center frequency of 10.5 MHz was fabricated, which can be used for photoacoustic and fluorescence imaging. The results indicate that the KNNLN-Er ceramics have potential for multimode imaging applications.