Polarization Field Research Articles

Design of CdZnS/BiOCl heterostructure as a highly-efficient piezo-photocatalyst for removal of antibiotic

Facilitating the surface and bulk photocarrier separation in semiconductors is crucially important for enhancing their photocatalytic activities. In this study, we have immobilized CdxZn1−xS (x = 0.7) nanoparticles on the surface of (001)-facet-exposed BiOCl (BOC) nanosheets to form heterostructured CZS/BOC piezo-photocatalysts. Experiments and theories were performed to unveil the piezo-photocatalytic performances of the CZS/BOC heterostructures and involved mechanisms. It is corroborated that the CZS/BOC heterostructures exhibit efficient transfer/separation of photocarriers, and hence possess excellent photocatalysis for eliminating tetracycline hydrochloride (TC). When irradiated by simulated sunlight, the 20 %CZS/BOC heterostructure manifests a photocatalytic activity with η(40 min)/kapp = 95 %/0.06825 min−1, which is enhanced by 6.9 (or 1.9) times over that of bare BOC (or Cd0.7Zn0.3S). While exerting ultrasonic vibration during the simulated-sunlight illumination, i.e., for the piezo-photocatalysis, a further improvement in the TC degradation rate is observed. The synergistic factor is calculated to be 1.5, quantifying the enhancement degree achieved by piezo-photocatalysis collaboration. The enhanced piezo-photocatalysis can be interpreted by the accelerated separation of the bulk photoelectrons and photoholes in the photocatalysts resulted from ultrasonic-induced polarization field, thus elevating their utilization for redox reactions. This work could advance the application of piezo-photocatalysts in environmental remediation.

Piezoelectric field accelerating charge transfer in Z-scheme heterojunction 2D-KNbO3/1D-CdS for efficient piezo-photocatalytic H2 evolution and TCH degradation

The piezo-phototronic effect utilizes the piezoelectric polarization field to tune the photogenerated carrier separation and transport performance in heterojunctions, which portrays a promising strategy for addressing energy shortage and environmental pollutants. Herein, a novel Z-scheme piezoelectric semiconductor heterojunction, 2D-KNbO3/1D-CdS-x (KNCS-x), was fabricated using hydrothermal and solvothermal methods, resulting in enhanced redox capacity. Under the simultaneous light and strain, KNCS-15 exhibits the highest piezo-photocatalytic activity, with degradation rates of tetracycline hydrochloride degradation rate constant, H2O2 as well as H2 production rates being 1.806 × 10−2s−1, 45.56 mM·h−1·g−1 and 8.87 mmol·h−1·g−1, respectively, which are 1.4, 2.4 and 1.9 times of photocatalysis alone, and 9.8, 9.2 and 9.8 times of piezocatalysis alone. DFT calculations, EPR and PALS indicate that the Z-scheme structure realizes effective separation of electron-hole pairs with strong redox ability and a higher carrier concentration. The enhanced catalytic activity is attributed to the introduction of piezoelectric potential, which facilitates improved spatial separation of electrons with high reduction and holes with high oxidation potential.

An Antiferroelectric‐Coated Metal Foam Infiltrated with Liquid Metal as a Dielectric Capacitor

Nickel metal foams serve as both a substrate and bottom electrode for a dielectric capacitor using atomic‐layer deposition (ALD) and a eutectic gallium–indium (EGaIn) liquid metal (LQM) counter electrode. The conformal dielectric has a composition of 6.25% Al–HfO2 in the antiferroelectric phase, confirmed with polarization versus electric field measurements. Liquid EGaIn is pressure‐infiltrated within the coated foams to form the dielectric capacitor. Capacitances up to 4 μF are realized. Calorimetry of the infiltrated capacitor shows a 60 J g−1 latent heat upon melting a frozen EGaIn electrode, suggesting that the phase change can alleviate thermal deviations from pulsed power capacitor operation. Infiltrated capacitors are also shown to survive bending and freeze–thaw cycles. The metal foam–ALD dielectric–LQM capacitor shows a combined set of thermal and electrical properties not available in other classes of capacitors.

Spontaneous parametric downconversion in a laser-poled lithium niobate nonlinear photonic crystal with nanoscale resolution.

Based on quasi-phase-matching (QPM) theory, nonlinear photonic crystals (NPCs) are capable of realizing efficient spontaneous parametric downconversion (SPDC) for the generation of photonic entangled states. However, the traditional electric field poling techniques employed in NPC fabrication often result in non-negligible processing errors of a few hundred nanometers, thus impeding the production of quantum photon pairs as intended. In this work, we investigate the SPDC photon pairs generated in a laser-poled lithium niobate (LN) NPC. By using the recently developed laser poling technique, the processing error of the NPC is substantially reduced to approximately 15 nm. Consequently, the coincidence counts of the generated photon pairs in the experiment reach 83.6% of the designed value. Our result paves the way for on-demand production of high-quality quantum sources, which has potential applications in quantum communications and quantum computations.

Surface-near domain engineering in multi-domain x-cut lithium niobate tantalate mixed crystals

Lithium niobate and lithium tantalate are among the most widespread materials for nonlinear, integrated photonics. Mixed crystals with arbitrary Nb–Ta ratios provide an additional degree of freedom to not only tune materials properties, such as the birefringence but also leverage the advantages of the singular compounds, for example, by combining the thermal stability of lithium tantalate with the larger nonlinear or piezoelectric constants of lithium niobate. Periodic poling allows to achieve phase-matching independent of waveguide geometry and is, therefore, one of the commonly used methods in integrated nonlinear optics. For mixed crystals, periodic poling has been challenging so far due to the lack of homogeneous, mono-domain crystals, which severely inhibit domain growth and nucleation. In this work, we investigate surface-near (<1μm depth) domain inversion on x-cut lithium niobate tantalate mixed crystals via electric field poling and lithographically structured electrodes. We find that naturally occurring head-to-head or tail-to-tail domain walls in the as-grown crystal inhibit domain inversion at a larger scale. However, periodic poling is possible if the gap size between the poling electrodes is of the same order of magnitude or smaller than the average size of naturally occurring domains. This work provides the basis for the nonlinear optical application of lithium niobate tantalate mixed crystals.

Kinetic theory of vacuum pair production in uniform electric fields revisited

We investigate the phenomenon of electron-positron pair production from vacuum in the presence of a uniform time-dependent electric field of arbitrary polarization. Taking into account the interaction with the external classical background in a nonperturbative manner, we quantize the electron-positron field and derive a system of ten quantum kinetic equations (QKEs) showing that the previously-used QKEs are incorrect once the external field rotates in space. We employ then the Wigner-function formalism of the field quantization and establish a direct connection between the Dirac-Heisenberg-Wigner (DHW) approach to investigating the vacuum pair-production process and the QKEs. We provide a self-contained description of the two theoretical frameworks rigorously proving their equivalence and present an exact one-to-one correspondence between the kinetic functions involved within the two techniques. Special focus is placed on the analysis of the spin effects in the final particle distributions. Published by the American Physical Society 2024

The Role of Meridional Flow in the Generation of Solar/Stellar Magnetic Fields and Cycles

Meridional flow is crucial in generating the solar poloidal magnetic field by facilitating poleward transport of the field from decayed bipolar magnetic regions (BMRs). As the meridional circulation changes with the stellar rotation rate, the properties of stellar magnetic cycles are expected to be influenced by this flow. In this study, we explore the role of meridional flow in generating magnetic fields in the Sun and Sun-like stars using the STABLE (surface flux transport and Babcock–Leighton) dynamo model. We find that a moderate meridional flow increases the polar field by efficiently driving the trailing polarity flux toward the pole, while a strong flow tends to transport both polarities of BMRs poleward, potentially reducing the polar field. Our findings are in perfect agreement with what one can expect from the surface flux transport model. Similarly, the toroidal field initially increases with moderate flow speeds and then decreases beyond a certain value. This trend is due to the competitive effects of shearing and diffusion. Furthermore, our study highlights the impact of meridional flow on the strength and duration of stellar cycles. By including the meridional flow from a mean-field hydrodynamics model in STABLE, we show that the magnetic field strength initially increases with the stellar rotation rate and then declines in rapidly rotating stars, offering an explanation of the observed variation of stellar magnetic field with rotation rate.

Composition and temperature dependent remanent polarization and coercive field in wurtzite AlScN ferroelectric memory materials

Composition and temperature dependent remanent polarization and coercive field in wurtzite AlScN ferroelectric memory materials

Mechanism of Circular Polarization in Giant Pulses and Fast Radio Bursts

Some giant pulses and fast radio bursts (FRBs) exhibit notable circular polarization, which remains unexplained and carries significant implications for their emission mechanisms. In this study, we identify multiple nanoshot pairs uniformly spaced by approximately 21 μs within a giant pulse emitted by the Crab pulsar. Among these pairs, a subset displays left-hand and right-hand circular polarization in two distinct nanoshots. We propose that the occurrence of such nanoshot pairs with dual circular polarizations arises from the fragmentation of a linearly polarized nanoshot along the magnetic field lines under the extreme Faraday effect, leveraging highly asymmetrical pair plasma and the ultra-intense field of nanoshots. The asymmetry in pair plasmas is likely linked to discharge activities in pulsars. Moreover, the intense field of nanoshots induces cyclotron resonance within the magnetosphere, effectively slowing down the propagation velocity of the circularly polarized mode. Our findings suggest that Crab giant pulses composing nanoshots originate in its polar cap region and escape the magnetosphere along the polar magnetic field. This mechanism can also elucidate the origin of circular polarization in some FRBs and thus lends support to their magnetospheric origin.

Enhanced energy storage properties of BaTiO3 ceramics: Effect of doping Bi(Mg0.25Zn0.25Ti0.5)O3 on microstructure, dielectric and ferroelectric properties

(1-x) BaTiO3 – x Bi(Mg0.25Zn0.25Ti0.5)O3 (x = 0.00, 0.06, 0.12, 0.20,molar ratio) ceramics were prepared by solid sintering method. The effects of Bi(Mg0.25Zn0.25Ti0.5)O3 (BMZT) doping on microstructure, dielectric, ferroelectric and energy storage properties of BaTiO3 (BTO) were studied. With BMZT addition, the sintering temperature gradually decreases, the grain size reaches a minimum at x = 0.12 and the phase structure changes from tetragonal to cubic. And dielectric properties changed from temperature-dependent to temperature-insensitive. Additionally, higher cubic phase content induced slim polarization and electric field (P-E) loop and low remnant polarization (Pr). Therefore, 0.88 BaTiO3 - 0.12 Bi(Mg0.25Zn0.25Ti0.5)O3 ceramics achieved recoverable energy storage density (Wrec) of 702.7 mJ/cm3 and high energy efficiency of 87.3 % under electric field of 93 kV/cm. It exhibited optimum properties, including a minimum grain size (0.620 μm), superior dielectric properties (εr = 1811.3, tanδ = 0.0552 at 1150 °C), a high maximum polarization strength (14.3 μC/cm2), and the maximum dielectric breakdown strength (93 kV/cm), as identified in the present study. It simultaneously maintains high energy storage density and efficiency over a wide electric field range and large temperature range (room temperature - 90 °C). Thus (1-x) BaTiO3 – x Bi(Mg0.25Zn0.25Ti0.5)O3 ceramics are a promising material for energy storage applications.

Fabrication of hydrothermal PPKTP and its spontaneous parametric down-conversion characteristics

High-voltage electric field polarization, selective corrosion, current monitoring, and other methods are used to develop hydrothermal PPKTP. It is found that the reversal domain nucleation of hydrothermal-grown KTP crystals has four kinds of microscopic morphology, namely, strip shape, spindle shape, bullet shape and irregular shape, in the process of high voltage electric field polarization. Compared with the leakage current in the process of polarization of flux-grown KTP crystals, the hydrothermal-grown KTP crystals only exist when the applied electric field is much larger than the coercive field. The leakage current can be suppressed by multiple loading of short pulses, and the PPKTP with a poled period of 10 μm and 46 μm were fabricated, respectively. Subsequently, based on the fabricated PPKTP, the SPDC characteristics are studied. To the PPKTP with a poled period of 10 μm, the quantum entanglement source whose brightness exceeds 2.1 kHz @ 810 nm is prepared by the SPDC technique. Otherwise, the PPKTP with a poled period of 46 μm is used for SPDC, and the brightness of entangled photon pairs in channel 1 and channel 2 are 3.21 kHz @ 1560 nm and 5.31 kHz @ 1560 nm, respectively.

The relationship between chlorophyll fluorescence and polarized light field: Polarization-Curve Fluorescence Height

The impact of the un-polarized nature of chlorophyll fluorescence, which causes a dip in the degree of polarization of the underwater light field matching the fluorescence spectrum, led to the development of a theoretical relationship indicating that the resulting fractional reduction in observed polarization is linearly proportional to the magnitude of the fluorescence causing it. To evaluate this relationship, we used a vector radiative transfer code (VRTE) for the coupled atmosphere-ocean system using measured inherent optical properties (IOPs) for a variety of oligotrophic and eutrophic waters as inputs. The VRTE was used to simulate elastic components of the underwater reflectance as well as the degree of linear polarization (DoLP) for these different conditions. These values were compared with the underwater reflectances and the DoLPs measured by a multi-angular hyperspectral polarimeter to determine the magnitude of the fluorescence component in the reflectance spectra at 685 nm, and the decrease of the DoLP due to the fluorescence impact at the same wavelength. Fluorescence magnitudes retrieved from the differences between simulated and measured reflectances were found to match well the magnitudes estimated through the relationship based on the drop of the DoLP. It is noted that retrieval accuracies increase for both larger fluorescence and larger underlying DoLP values. Furthermore, a new method is evolved from the measured polarization analysis, Polarization-Curve Fluorescence Height (PCFH). Measured polarization were used to approximate the elastic signal and derive the inelastic un-polarized signal (fluorescence) from the difference in the fluorescence vicinity. These results open possibilities for estimating the magnitude of natural fluorescence using polarization measurements below or above the water surface, .in-situ, or remotely from aircraft or future satellites. Results of ongoing work on potential sensitivities and retrieval accuracies for these applications will be reported.

Internal quantum efficiency improvement of InGaN-based red LED by using double V-pits layers as strain relief layer

Micro/mini light emitting diodes (LEDs) based on AlInGaN material system have vast potential in display applications. Nevertheless, the low internal quantum efficiency (IQE) of InGaN-based red LED limits its development and application. In the epitaxial structure of our designed red LED, double V-pits layers were used as strain relief layers to reduce compressive strain and improve the IQE of the active layer. First, InGaN/GaN superlattices (SLs) were grown below the active layer to form low-density large V-pits layer. Subsequently, multi-period green and red composite quantum wells were adopted as the active layer. A high-density small V-pits layer was introduced into the active region to release the compressive strain by adjusting the growth parameters of green multiple quantum wells (MQWs). The V-shaped pits divide the continuous large-area of active layer into mutually isolated small pieces, which prevents the transmission of strain and converts the long-range strain into separated local strain. The peak IQEs of LED A2 with single V-pits layer and LED B4 with double V-pits layers were measured to be 10.5% at 613 nm and 21.5% at 612.1 nm, respectively. The IQE is greatly improved by 204.7%. The research results indicate that the double V-pits layers structure can alleviate the compressive strain of InGaN QWs more effectively, reduce the influence of piezoelectric polarization field, and improve the IQE.

Synergistic Interactions of Bulk Polarization and Built-In Electric Field Inducing 2D/2D S-Scheme Homojunction Toward Enhanced Photocatalytic Performance.

The rational design of S-scheme photocatalysts, achieved by serially integrating two different semiconductors, represents a promising strategy for efficient charge separation and amplified photocatalytic performance, yet it remains a challenge. Herein, ZnIn2S4 (ZIS) and oxygen-doped ZnIn2S4 (O-ZIS) nanosheets are chosen to construct a homojunction catalyst architecture. Theoretical simulations alongside comprehensive in situ and ex situ characterizations confirm that ZIS and O-ZIS with noncentrosymmetric layered structures can generate a polarization-induced bulk-internal electric field (IEF) within the crystal. A robust interface-IEF is also created by the strong interfacial interaction between O-ZIS and ZIS with different work functions. Owing to these features, the O-ZIS/ZIS homojunction adopts an S-scheme directional charge transfer route, wherein photoexcited electrons in ZIS and holes in O-ZIS concurrently migrate to their interface and subsequently recombine. This enables spatial charge separation and provides a high driving force for both reduction and oxidation reactions simultaneously. Consequently, such photocatalyst exhibits an H2 evolution rate up to 142.9µmol h-1 without any cocatalysts, which is 4.6- and 3.4-fold higher than that of pristine ZIS and O-ZIS, respectively. Benzaldehyde is also produced as a value-added oxidation product with a rate of 146.9µmol h-1. This work offers a new perspective on the design of S-scheme systems.

Mechanically activated and deactivated ion transport across nanopores with heterogeneous surface charge distributions

To mimic the intricate and adaptive functionalities of biological ion channels, electrohydrodynamic ion transport has been studied extensively, albeit mostly, across uniformly charged nanochannels. Here, we analyze the ion transport under coupled electric field and pressure across heterogeneously charged nanopores with oppositely charged sections on their lateral surface. We only consider such pores with symmetric hourglass-like and cylindrical shapes to focus on the effects of the non-uniform surface charge distribution. Finite-element simulations of a continuum model demonstrate that a pressure applied in either direction of the pore-axis equally suppresses or amplifies the ionic conductance, depending on the electric field polarity, by distorting the quasi-static distribution of ions in the pore. The resulting anomalous mechanical deactivation and activation of ionic current under opposite voltage biases exhibit the functional modularity of our setup, while their intensities are highly tunable, substantially greater than those of analogous behaviors in other nanochannels, and fundamentally correlated to ionic current rectification (ICR) in our pores. A detailed study of ICR subsequently reveals its counterintuitive non-monotonous variations, in the pores, with the magnitude of applied voltage and the pore length, that can help optimize their diode-like behavior. We further illustrate that while the hourglass-shaped nanopores yield the more efficient mechanical suppressors of ion transport, their cylindrical analogs are the superior rectifiers and mechanical amplifiers of ion conduction. Therefore, this article provides a blueprint for the strategic design of nanofluidic circuits to attain a robust, modular, and tunable control of ion transport under external electrical and mechanical stimuli.

Favorable Conditions for Heavy Element Nucleosynthesis in Rotating Protomagnetar Winds

The neutrino-driven wind cooling phase of proto-neutron stars (PNSs) follows successful supernovae. Wind models without magnetic fields or rotation fail to achieve the necessary conditions for production of the third r-process peak, but robustly produce a weak r-process in neutron-rich winds. Using 2D magnetohydrodynamic simulations with magnetar-strength magnetic fields and rotation, we show that the PNS rotation rate significantly affects the thermodynamic conditions of the wind. We show that high-entropy material is quasiperiodically ejected from the closed zone of the PNS magnetosphere with the required thermodynamic conditions to produce heavy elements. We show that maximum entropy S of the material ejected depends systematically on the magnetar spin period P ⋆ and scales as S∝P⋆−5/6 for sufficiently rapid rotation. We present results from simulations at a constant neutrino luminosity representative of ∼1–2 s after the onset of cooling for P ⋆ ranging from 5–200 ms and a few simulations with evolving neutrino luminosity where we follow the evolution of the magnetar wind until 10–14 s after the onset of cooling. We estimate at magnetar polar magnetic field strength B 0 = 3 × 1015 G and 1015 G that neutron-rich magnetar winds can, respectively, produce at least ∼1–5 × 10−5 M ⊙ and ∼1–4 × 10−7 M ⊙ of material with the required parameters for synthesis of the third r-process peak, within 1–2 s and 10 s, respectively, in that order after the onset of cooling. We show that proton-rich magnetar winds can have favorable conditions for production of p-nuclei, even at a modest B 0 = 5 × 1014 G.

Photo-induced BiVO4 to produce P25-like structure for enhancing piezo-photocatalytic activity

Piezo-photocatalysis is considered a promising pollutant treatment strategy. Herein, a simple strategy is proposed to construct lattice distortion in BiVO4 to realize an efficient piezo-photocatalytic degradation process. Specifically, the phase structure of BiVO4 is regulated by introducing different wavelengths of illumination, resulting in the homojunction formation. Compared with BiVO4 prepared under dark conditions (BVO), the VO bonds are shortened and the BiO bonds are elongated in the structure of BiVO4 synthesized under 460 nm illumination (BVO-460). Furthermore, the Tafel curve reveals that electrons flow from the monoclinic phase to the tetragonal phase. By the tetracycline hydrochloride degradation, it is found that the BVO-460 has excellent piezo-photocatalytic efficiency, attributed to the piezoelectric polarization field enhanced charge transfer. In this paper, the piezo-photocatalytic performance of BiVO4 is investigated in the insight of crystal phase structure, which provided a new idea for the application of layered bismuth-based materials in environmental purification.

Dual boosting of the built-in polarization field in the BiFeO3/ZnS heterostructure for water purification: Effects of Z-scheme heterostructure and corona poling

In this study, we have designed a novel 1D-0D lead-free Z-scheme heterostructure of BiFeO3–ZnS (BFO/ZnS) using an isoelectric point-assistant annealing method for piezocatalytic reactions. The open circuit voltage measurements exhibited a greater internal electric field for BFO/ZnS (90/10) than for individual components, causing its excellent piezocatalytic performance for MTZ antibiotics, organic dyes oxidation, and Cr(VI) reduction. BFO/ZnS (90/10) was treated by corona poling to boost its polarization, resulting in the highest remanent polarization and dielectric constant. Piezocatalytic experiments demonstrated that BFO/ZnS (90/10; poled) can degrade 99% of RhB by 9 min ultrasonic vibration with kapp = 0.44 min−1, which is 2.5, 5.5, and 16.3 times greater than those of BFO/ZnS (90/10), BFO, and ZnS, respectively. Also, the efficiency of piezodegradation for MTZ, Cr(VI), MO, and MB over BFO/ZnS (90/10; poled) was found to be 74.5% (90 min), 84.6% (60 min), 95.3% (40 min), and 97.2% (30 min), respectively. This outstanding piezocatalytic performance of BFO/ZnS (90/10; poled) is ascribed to the enhanced built-in polarization field due to the Z-scheme heterostructure and corona poling treatment. As supported by PL and EIS analysis, the stronger built-in electric field can effectively separate and transmit the charge carriers, causing excellent piezocatalytic activity.

On the viscoelastic-electromagnetic-gravitational analogy

The analogy between electromagnetism and gravitation was achieved by linearizing the tensorial gravitational equations of general relativity and converting them into a vector form corresponding to Maxwell’s electromagnetic equations. On this basis, we use the equivalence with viscoelasticity and propose a theory of gravitational waves. We add a damping term to the differential equations, which is equivalent to Ohm’s law in electromagnetism and Maxwell’s viscosity in viscoelasticity, to describe the attenuation of the waves. The differential equations in viscoelasticity are those of cross-plane shear waves, commonly referred to as SH waves. A plane-wave analysis gives the phase velocity, the energy velocity, the quality factor and the attenuation factor of the field as well as the energy balance. To obtain these properties, we use the analogy with viscoelasticity; the properties of electromagnetic and gravitational waves are similar to those of shear waves. The presence of attenuation means that the transient field is generally a composition of inhomogeneous (non-uniform) plane waves, where the propagation and attenuation vectors do not point in the same direction and the phase velocity vector and the energy flux (energy velocity) are not collinear. The polarization of cross-plane field is linear and perpendicular to the propagation-attenuation plane, while the polarization of the field within the plane is elliptical. Transient wave fields in the space–time domain are analyzed with the Green function (in homogeneous media) and with a grid method (in heterogeneous media) based on the Fourier pseudospectral method for calculating the spatial derivatives and a Runge–Kutta scheme of order 4 for the time stepping. In the examples, wave propagation at the Sun–Earth and Earth–Moon distances using quadrupole sources is considered in comparison to viscoelastic waves. The Green and grid solutions are compared to test the latter algorithm. Finally, an example of propagation in heterogeneous media is presented.

Physics of Ferroelectric Wurtzite Al1−xScxN Thin Films

AbstractAl1−xScxN emerges as a revolutionary ferroelectric material within the III‐N family. It combines exceptional switchable polarization (80–165 µC cm−2), highly tunable coercive fields (1.5–6.5 MV cm−¹), and a wide bandgap (4.9–5.6 eV). Unlike conventional ferroelectrics, Al1−xScxN exhibits remarkable compatibility with both CMOS and III‐N technologies. It can be fabricated on plastic substrates at low temperatures, demonstrating excellent flexibility and biocompatibility. Remarkably, Al1−xScxN maintains superior performance in harsh environments due to its outstanding thermal stability (up to 1100 °C). These unique characteristics position Al1−xScxN as a highly promising candidate for a wide range of applications, including high‐performance memory, in‐memory computing, neuromorphic computing, and next‐generation wearable and implantable devices, particularly for operation in complex environments. Despite its potential, Al1−xScxN faces challenges such as high coercive fields, significant leakage currents, and limited polarization reversal cycle life. Addressing these challenges require a deeper understanding of the fundamental physics controlling Al1−xScxN films. This review explores the origins of Al1−xScxN's ferroelectricity and phase stability, delves into the fundamental theory of wurtzite ferroelectricity, investigates mechanisms for controlling spontaneous polarization and coercive fields, examines recent research progress in Al1−xScxN ferroelectric devices, and outlines future development directions for this exciting material.