Shenglin Jiang

Mechanical metamaterials exploit precise control of unit-cell geometry and their macroscopic organization to realize unusual properties. Expanding the capabilities of mechanical metamaterials to incorporate additional functionality remains a challenge. We describe 3D-printed metamaterials embedded with molecular ferroelectrics for use as self-powered pressure sensors. Our gradient lattice design allows for adaptive reconfiguration and controlled deformation-mode transitions, yielding a synergy of low modulus and high load-bearing capacity alongside a monotonic mechanical load–electrical signal response. Furthermore, we implement a modulus gradient in the metamaterials to enhance sensitivity in low-loading regions and extend the detection range across six orders of magnitude. With a combination of high sensitivity and broad detection range, the dual-gradient metamaterials overcome the limitations imposed by the inverse relationships in existing sensors.

The increasing demand for higher operating speeds and greater integration densities in electronic devices has made heat dissipation one of the most critical challenges for next-generation technologies. This challenge has driven extensive efforts aimed at achieving a giant electrocaloric effect in ferroelectrics for high-efficiency cooling. Here, we propose a defect dipole engineering strategy to manipulate the polarization behavior of ferroelectric ceramics, leading to superior electrocaloric effect. By incorporating Sm and Li ions, the (Sm_Bȧ-Li_Baʹ) defect dipoles enhance the polarizability of BaTiO₃. Simultaneously, these dipole defects increase the carrier activation energy, effectively mitigating the inherent trade-off between high breakdown strength and high polarization, thereby allowing the application of a high electric field to fully activate the electrocaloric potential. As a result, defect dipole engineering enables BaTiO₃ to achieve a remarkable electrocaloric effect over a wide temperature range, achieving a high temperature change of 2.7 K at 70 °C— typical for integrated circuits.

Multiferroics have many novel applications such as multifunctional photo-magneto-electric sensors and ultra-low power consumption storage. However, it is still a challenge to couple magnetic order and ferroelectric order for all-in-one materials that are highly piezoelectric multiferroics. In this work, room temperature multiferroicity as well as piezoelectricity were realized in Fe-doped Pb(Ti[ ]Fe[ ]Zr[ ]O₃ ([ ]–[ ]). An increase in the remnant magnetization (from 0 to 44.5[ ]memu/g) is accompanied by an increase in [ ] (from 17 to 65[ ]pC/N) which is achieved with an optimal doping level. In addition, broad UV–Vis–NIR light absorption was achieved (200–2500[ ]nm). The coupling of intrinsic ferroelectric polarization with defect dipoles formed by Fe and oxygen vacancy should be mainly responsible for the magnetization enhancement at appropriate Fe concentration. The defect energy levels induced by defect dipole contribute to a broad UV–Vis–NIR light absorption. This material has the potential for multifunctional photo-magneto-electric sensors and storage technology.

Dielectric capacitors with high energy storage performance are highly desired for advanced power electronic devices and systems. Even though strenuous efforts have been dedicated to closing the gap of energy storage density between the dielectric capacitors and the electrochemical capacitors/batteries, a single-minded pursuit of high energy density without a near-zero energy loss for ultrahigh energy efficiency as the grantee is in vain. Herein, for the purpose of decoupling the inherent conflicts between high polarization and low electric hysteresis (loss), and achieving high energy storage density and efficiency simultaneously in multilayer ceramic capacitors (MLCCs), we propose an interlaminar strain engineering strategy to modulate the domain structure and manipulate the polarization behavior of the dielectric mediums. With a heterogeneous layered structure consisting of different antiferroelectric ceramics [(Pb_0.9Ba_0.04La_0.04)(Zr_0.65Sn_0.3Ti_0.05)O₃/(Pb_0.95Ba_0.02La_0.02)(Zr_0.6Sn_0.4)O₃/(Pb_0.92Ca_0.06La_0.02)(Zr_0.6Sn_0.4)_0.995O₃], our MLCC exhibits a giant recoverable energy density of 22.0 J cm⁻³ with an ultrahigh energy efficiency of 96.1%. Combined with the favorable temperature and frequency stabilities and the high antifatigue property, this work provides a strain engineering paradigm for designing MLCCs for high-power energy storage and conversion systems.

High energy density ( W _rec ) dielectrics with excellent efficiency ( η ) and thermal stability are crucial in high‐power energy storage applications. In this work, we introduce Ba(Zr _0.2 Ti _0.8 )O ₃ (BZT) into Bi _0.5 Na _0.5 TiO ₃ (BNT) to delay saturation polarization and refine grain sizes for enhancing energy storage performance. BZT diffusing into BNT lattice not only increases electronegativity between A‒O/B‒O bond and the relaxor, but also is beneficial for refining grain sizes and suppressing the development of local electric branches. Therefore, high P _max with moderate P _r and improved breakdown strength is achieved in BNT‒ x BZT ceramics with x  = 0.6 mol. Additionally, BNT‒0.60BZT ceramics demonstrate enhanced recoverable energy storage density of 4.1 J cm ⁻³ with high energy storage efficiency of 91%, along with favorable overdamped charge‒discharge properties including a maximum current, discharge energy density, and discharge time of 10 A, 2.4 J cm ⁻³ , and 150 ns, respectively.

As the demand for miniaturization of electronic devices increases, ceramics with an ABO₃ structure require further improvement of the dielectric constant with high permittivity. In the present work, Ba_1−1.5xBi_xTiO₃ (BB100xT, x = 0.0025, 0.005, 0.0075, 0.01) ceramics were prepared via a solid-state reaction process. The effect of Bi doping on dielectric properties of lead-free relaxor ferroelectric BaTiO₃-based ceramics was studied. The results showed that both colossal permittivity (37,174) and a temperature stability of TCC ≤ ±15% (−27–141 °C) were achieved in BB100xT ceramics at x = 0.5%. The A-site donor doping produces A-site vacancies, a larger space for Ti⁴⁺, and fluctuation of the component, which is partially responsible for the high permittivity and responsible for the temperature stability. Meanwhile, the contribution of defect dipoles, and IBLC and SBLC effects to polarization leads to the colossal permittivity. The formation of a liquid phase during sintering promotes mass transfer when the doping content is higher than 0.5%. This work benefits the exploration of novel multilayer ceramic capacitors with colossal permittivity and temperature stability via defect engineering.

Thermal management emerges as a grand challenge of next-generation electronics. Efforts to develop compact, solid-state cooling devices have led to the exploration of the electrocaloric effect of ferroelectric polymers. Despite recent advances, the applications of electrocaloric polymers on electronics operating at elevated temperatures remain essentially unexplored. Here, we report that the ferroelectric polymer composite composed of highly-polarized barium strontium titanate nanofibers and electron-accepting [6,6] phenyl-C61-butyric acid methyl ester retains fast electrocaloric responses and stable cyclability at elevated temperatures. We demonstrate the effectiveness of electrocaloric cooling in a polymer composite for a pyroelectric energy harvesting device. The device utilizes a simulated central processing unit (CPU) as the heat source. Our results show that the device remains operational even when the CPU is overheated. Furthermore, we show that the composite functions simultaneously as a pyroelectric energy converter to harvest thermal energy from an overheated chip into electricity in the electrocaloric process. This work suggests a distinct approach for overheating protection and recycling waste heat of microelectronics.

The integrable substrate for THz modulation directly influences both the quality of films and THz absorption. Currently, the available THz substrate candidate library is still not clear. Here, we have carried out a systematic investigation of commonly used commercial substrates, including Si, quartz SiO₂, MgO, Al₂O₃, GdScO₃ and TbScO₃ in the range of 0.4–1.6[ ]THz. It is found that low resistance Si, TSO and GSO are certainly not appropriate for THz light modulation due to their relatively higher absorption and dielectric constant, while the rest show better THz transmittance, low refractive index and loss. However, the dielectric constant and refractive index of high resistance Si are generally two times larger than quartz SiO₂, Al₂O₃ and MgO. Compared with Al₂O₃ and MgO, quartz SiO₂ shows at least 50% lower dielectric constant, refractive index and absorption, making it the best candidate. Our research is believed to build the rich substrate candidate library for THz range light modulation.

We demonstrate 0–3 type heterogeneous NBT–NN–ST/HfO₂ composites to achieve high E_b and P_max. Some HfO₂ are concentrated in grain boundaries to suppress local electric branches’ development for enhancing E_b while others diffuse into lattice to improve bonds’ polarity for maintaining high P_max.