Large Piezoelectric Constant Research Articles

Complete property tensors of some low-symmetry borate NLO crystals

Several low-symmetry borate crystals, such as α-BiB3O6 (BiBO), YCa4O(BO3)3 (YCOB) and La2CaB10O19 (LCB) show not only promising nonlinear optical (NLO) properties but also other favorable physical properties like large electro-optic (EO) coefficients and exceptionally large piezoelectric constants. Those materials may serve as high temperature sensors and electro- or acoustic- modulators beyond their traditional applications in high power laser generations. The knowledge of their full property tensors are indispensable for their efficient and practical usages. Due to the low-symmetry nature, more none-zero matrix elements are present and those elements most likely are combined when measuring them. Therefore, experimental determinations of the full tensor elements are not always easy especially for those high rank tensors. In fact, though being discovered over several decades, some of the property tensor matrices are still missing. Recently it is shown that by applying a modified post-DFT LD (density functional theory + London dispersion) correction based on linear combination of atomic orbitals (LCAO) and B3LYP functional, many important material property tensors of BiBO crystal are calculated in unprecedented precisions. Among them, theoretical calculation of the refractive indices in the terahertz (THz) range was firstly achieved. The calculation also confirms that BiBO has an exceptional large piezoelectric constant d22 = 40 pC/N and largest free EO coefficients on the order of 10 pm/V among borate crystals. The same calculation has been extended to the other low-symmetry borate NLO crystals, including YCOB and LCB. With those calculated material constants, practical devices may be designed with preferable figure of merits over existing materials.

Improved piezoelectric performance in CBN-based ceramic through triple-doping (Li, Bi, Ce) strategy

Bismuth layered structural ferroelectrics (BLSFs) with high Curie temperature (TC) and low aging rate establish the groundwork for the advancement of high-temperature piezoelectric devices. CaBi2Nb2O9 (CBN) is an excellent candidate for possessing the highest TC value (∼940 °C) among BLSFs. However, its poor piezoelectricity impedes practical applications. Generally, the excellent piezoelectric properties of CBN-based ceramics depend on intrinsic and extrinsic contributions. Here, Aurivillius ferroelectrics with triple-doping ions, Ca1–2x(LiBi0.7Ce0.3)xBi2Nb2O9 (CBN-xLBC), were fabricated to achieve large piezoelectric constant (d33∼23.3 pC/N) and high Curie temperature (∼906 °C) simultaneously due to tetragonal distortion and smaller nanodomains. Besides, the DC resistivity of optimal sample is still above 1×105 Ω·cm at 600 °C. At the same time, the ferroelectricity is improved significantly with large Pr (∼18.9 μC/cm2) when x=0.275. The improved comprehensive performance of CBN-based ceramic indicates that proper various ions synergetic effect plays an important role and CBN-0.275LBC ceramic is expected to apply in practical industry.

High‐performance bismuth titanate‐ferrite (Bi5Ti3FeO15) for high‐temperature piezoelectric applications

AbstractAdvancing the development of high‐temperature piezoelectric sensors requires high‐performance piezoelectric materials with high Curie temperatures, wherein the charge signals can be efficiently collected at elevated temperatures. The bismuth layer‐structured ferroelectric (BLSF) bismuth titanate‐ferrite (Bi5Ti3FeO15, BTF) has recently attracted considerable attention because of its high Curie temperature (TC) of ∼761°C. However, the piezoelectric properties of BTF‐based compounds have not been extensively investigated because of their extremely poor piezoelectric performances and low electrical resistivities at elevated temperatures. Herein, tungsten‐substituted BTF (BTF‐100xW) ceramics were synthesized using a solid‐state reaction method. X‐ray diffraction refinement results confirmed the lattice distortion of the BO6 octahedron, while piezoelectric force microscopy images verified an increase in the domain wall density with tungsten modification, both of which contribute to significant enhancement of the piezoelectric properties of BTF‐100xW as intrinsic and extrinsic contributions, respectively. Remarkably, BTF‐3W exhibits a high TC of 793°C and a large piezoelectric constant (d33) of 24.3 pC/N, which is over three times that of BTF (7.1 pC/N). Importantly, the substitution of tungsten decreases the concentration of oxygen vacancies, increases the direct current electrical resistivity, and improves the electrical homogeneity at high temperatures, resulting in extremely stable piezoelectric and electromechanical properties at high temperatures, with a high in‐situ relative d33 of >90% at 400°C and a small variation in the electromechanical coupling factor (kp) of <8% at temperatures up to 450°C. These results suggest that the tungsten‐substituted BTF is a potential candidate for high‐temperature piezoelectric ceramics, and is a promising material for applications in high‐temperature piezoelectric sensors.

High piezoelectric performance in lead-free (K, Na)NbO3 ceramics under a low driving field

In this work, lead-free (K0.485Na0.485Li0.03)Nb0.8Ta0.2O3 composition was designed to control the orthorhombic-tetragonal phases boundary near the room temperature as confirmed by Rietveld analysis, high-angle annular dark field scanning transmission electron microscopy, and temperature dependent dielectric constant. A comparative study of the direct and indirect synthesis methods was carried out and their functional properties were optimized as a function of sintering temperature (Ts) and dwell time. Here, we achieved a large dynamic piezoelectric constant (d33*) of 510 pm/V under a very low electric field of 15–30 kV/cm. Moreover, an enhanced static piezoelectric constant (d33) of 335 pC/N was obtained with a high Curie temperature (TC) of 315 °C. The large d33 and d33* simultaneously with high TC in a single composition are promising results in lead-free polycrystalline ceramics. The strategic design of this work opens a new door for the possible development of novel functional materials for device applications.

Ab initio study of temperature-dependent piezoelectric and electronic properties of thermally stable GaPO4.

Gallium-phosphate (GaPO4) is one of the ultra-high thermally stable piezoelectric materials with a high critical temperature of 1206 K. Here, first principles calculations with quasi-harmonic approximation are performed to study thermal and other physical properties of α-GaPO4. For the electronic structure, we focus on the electron-phonon interaction and lattice expansion effects on the temperature-dependent band gap, which plays a significant role in zero-point renormalization. Significantly, the large piezoelectric constants e11 primarily comes from intrinsic sensitivity of Ga and O sites to axial strain, while P atoms contribute little, which remains true in other quartz-like type APO4 (A = B, Al, In). Our work provides an insight into the temperature-dependent electronic and piezoelectric properties of α-GaPO4 and motivates its applications in a high temperature environment.

Oxygen vacancies and electrical properties of different valence ions (W6+, Nb5+, Zr4+, Cr3+) doped Bi4Ti3O12 ceramics

Numerous literatures have attested that donor doping in BiT ceramics will inhibit the generation of oxygen vacancies to improve electrical properties, but our study detects an originality that acceptor doped into BiT ceramics can also reduce the concentrate of oxygen vacancies and raise the values of Curie temperature and piezoelectric constant. A serious BiT-based ceramics with different valence transition metal dopants of W6+, Nb5+, Zr4+, Cr3+ were prepared via traditional solid phase method, achieving a high Curie temperature of 680–699 °C and a large piezoelectric constant of 7–17 pC/N. To improve the structural and electrical properties of BiT-based ceramics, this paper researched the concentration of oxygen vacancies with charge compensation effect of ions substitution by investigating the phase composition, microstructure, dielectricity, and conductivity systematically. The results show that all transition metal dopants enter the B-site of BiT ceramics to different extent and Cr partially replace the A-site of BiT ceramics, while the relaxation behavior and conduction mechanism of these ceramics are mainly contributed by the migration of oxygen vacancies. Due to the increase in the number of free electrons formed by donor doping W6+ and Nb5+ into BiT ceramics, the reduction in the number of trapped electrons proffered by equivalent doping Zr4+ that occupied the Ti3+ position and the consumption in the vacancies of Bi and O provided by Cr3+ that occupied the A-site after Bi volatilization, the oxygen vacancies defects of the BiT-based ceramics were decreased after ions doped.

Tetragonal BF-xPT-0.1BZT ceramics with high Curie temperature and large piezoelectric constant

Obtaining both high Curie temperature and large piezoelectric constant simultaneously is of great significance for the application of actuators and sensors. In this research, the piezoelectric ceramics of (0.9-x)BiFeO3-xPbTiO3-0.1Ba(Zr0.5Ti0.5)O3 (BF-xPT-0.1BZT, x = 0.29, 0.30, 0.31 and 0.32) were fabricated by the traditional solid-state reaction method. BF-xPT-0.1BZT ceramics exhibit the tetragonal perovskite structure without detectable second phases, and the tetragonality c/a ratio and the tolerance factor of ceramics are about 1.03 and 0.98, respectively. SEM images reveal that ceramics are well densified with the average grain size of 5–12 μm. The Curie temperature TC of BF-xPT-0.1BZT ceramics is about 490–509 °C, slightly changing with the variation of PT content. The excellent comprehensive dielectric and piezoelectric properties are achieved for BF-0.31PT-0.1BZT ceramics with dielectric constant εr (1 kHz), tanδ, piezoelectric constant d33 and TC of 1001, 0.008, 230 pC/N and 509 °C, respectively. The significant enhancement of piezoelectric constant in the x = 0.31 sample is attributed to the enlargement of grain size. Moreover, the d33 and the planar coupling coefficient kp remain stable in the elevated temperature range of 200–400 °C, and the fluctuations are only 2% /℃ and 0.007% /℃, respectively, both of which are superior to that of BS-PT based piezoelectric ceramics. Our results indicate that BF-0.31PT-0.1BZT ceramics with high TC, large d33 and good thermal stability possess great potential for high temperature piezoelectric applications.

Effect of the slurry composition on the piezoelectric properties of PZT ceramics fabricated via materials extrusion 3D printing

Herein, the effect of the binder content in lead zirconate titanate (PZT) slurry has been systematically studied to improve the piezoelectric properties of PZT ceramics prepared via material extrusion 3D printing. For smooth printing, a slurry with a binder concentration ranging from 6 to 12 wt% was proposed. The porosity of the green body first decreased and then increased with an increase in the binder concentration, and the minimum porosity was obtained when the binder concentration reached 10 wt%. Samples with increased density were obtained after debinding and lead-rich atmosphere sintering. PZT piezoceramics fabricated using a binder content of 10 wt% exhibit the maximum relative density (96.9%), largest piezoelectric constant (342.6 pC/N) and dielectric constant (1621). Based on the above process, the wood pile structure and helical twentytetrahedral structural components were successfully fabricated using the material extrusion process. This research lays the foundation for the engineering application of 3D printing to fabricate high-performance piezoceramics with complex shapes.

Demonstration of Thin Film Bulk Acoustic Resonator Based on AlN/AlScN Composite Film with a Feasible Keff2.

Film bulk acoustic resonators (FBARs) with a desired effective electromechanical coupling coefficient (Keff2) are essential for designing filter devices. Using AlN/AlScN composite film with the adjustable thickness ratio can be a feasible approach to obtain the required Keff2. In this work, we research the resonant characteristics of FBARs based on AlN/AlScN composite films with different thickness ratios by finite element method and fabricate FBAR devices in a micro-electromechanical systems process. Benefiting from the large piezoelectric constants, with a 1 μm-thick Al0.8Sc0.2N film, Keff2 can be twice compared with that of FBAR based on pure AlN films. For the composite films with different thickness ratios, Keff2 can be adjusted in a relatively wide range. In this case, a filter with the specific N77 sub-band is demonstrated using AlN/Al0.8Sc0.2N composite film, which verifies the enormous potential for AlN/AlScN composite film in design filters.

ε-Ga2 O3 : An Emerging Wide Bandgap Piezoelectric Semiconductor for Application in Radio Frequency Resonators.

The explosion of mobile data from the internet of things (IoT) is leading to the emergence of 5G technology with dramatic frequency band expansion and efficient band allocations. Along with this, the demand for high-performance filters for 5G radio frequency (RF) front-ends keeps growing. The most popular 5G filters are constructed by piezoelectric resonators based on AlN semiconductor. However, AlN possesses a piezoelectric constant d33 lower than 5pm V-1 and it becomes necessary to develop novel semiconductors with larger piezoelectric constant. In this work, it is shown that strong piezoelectricity exists in ε-Ga2 O3 . High-quality phase-pure ε-Ga2 O3 thin films with a relatively low residual stress are prepared. A switching spectroscopy piezoelectric force microscope (SS-PFM) measurement is carried out and the piezoelectric constant d33 of ε-Ga2 O3 is determined to be ≈10.8-11.2pm V-1 , which is twice as large as that of AlN. For the first time, surface acoustic wave (SAW) resonators are demonstrated on the ε-Ga2 O3 thin films and different vibration modes resonating in the GHz range are observed. The results suggest that ε-Ga2 O3 is a great material candidate for application in piezoelectric devices, thanks to its wide bandgap, strong piezoelectric property, small acoustic impedance, and low residual stress.

Machine learning combined with feature engineering to search for BaTiO3 based ceramics with large piezoelectric constant

Machine learning based strategies have been increasingly applied in materials science to accelerate the discovery process. Regression algorithm learns the mapping from compositions/features to targeted property and makes prediction for unknown compositions. The quality of features, in some degree, determines the upper limit of the surrogate model performance and the associated search efficiency for desired candidates. We herein propose a data-driven framework combining feature engineering, machine learning, experimental design and synthesis, to optimize the piezoelectric constant of BaTiO3 based ceramics, with the emphasis on feature engineering realized by four strategies. The search for improved piezoelectric constant in the initial data set behaves differently compared to that in the whole unknown space, indicating that the initial data set might be biased to a local scheme. The best composition with a piezoelectric constant of ~ 430 pC/N is synthesized in the second iteration, better than the majority in the initial data set. Insight for the change of piezoelectric constant for the newly synthesized 12 compositions is provided by examining the corresponding evolution of dielectric permittivity within the thermodynamic theory.

High and temperature-insensitive piezoelectric performance in the lead-free Sm-doped BiFeO3–BaTiO3 ceramics with high Curie temperature

Large sensor piezoelectric constant (d33 = 334 pC/N) and superior actuator piezoelectric constant (d33* = 552 pm/V) as well as a high Curie temperature (TC = 454 °C) were obtained simultaneously in the lead-free 0.67Bi1.03FeO3-0.33Ba1-xSmxTiO3 ceramics. Such an excellent and temperature-insensitive piezoelectric performance with only 10% temperature variation of piezoelectric strain at the range of 25–125 °C is highly desirable for real applications. The structural origin of the enhanced piezoelectric performance is mainly attributed to the morphotropic phase boundary and the highest known tetragonality (cT/aT = 1.02) in such materials. Transmission electron microscopy and electro-mechanical phenomenological theory demonstrate that the superior d33 and d33* are associated with the hybrids nanodomains (60–90 nm) and flattened thermodynamic energy profile owing to the local structure heterogeneity. These results are superior as the piezoelectric properties are temperature-independent and the material has large d33*, and high TC compared to other lead-free piezoelectric ceramics.

Anisotropic growth kinetics and electric properties of PZT‐5H single crystal by solid‐state crystal growth method

AbstractThe PZT‐5H single crystal growth on [111]c‐, [110]c‐, and [001]c‐oriented seed crystal by solid‐state crystal growth (SSCG) method was investigated. The growth rate of PZT‐5H single crystal strongly depends on seed crystal orientation and annealing time. The mean growth distance is 682, 620, and 93 μm for [111]c‐, [110]c‐, and [001]c‐oriented PZT‐5H single crystal grown at 1150°C for 8 h, respectively. The growth kinetics of SSCG‐grown PZT‐5H single crystal was discussed. It is found that the growth of single crystal is driven by the solubility difference between the matrix grains and single crystal growth front interface, arising from the local curvature and the crystallographic directions dependent solubility. The growth of [001]c‐oriented PZT‐5H single crystal was mainly contributed from the difference solubility arising from the local curvature of growth front interface, while the growth of [111]c‐ and [110]c‐oriented PZT‐5H single crystal was mainly contributed from the difference solubility between {111} and {110} plane of single crystal and matrix grains. The piezoelectric coefficient d33 of up to 1028pC/N (about 50% larger than that of the same component ceramic) was obtained in a [110]c‐oriented PZT‐5H single crystal with a Curie temperature of about 230°C. The large field piezoelectric constants d33* of up to 1160 pm/V (about 50% larger than that of the same component ceramic) at 15 kV/cm was also obtained in [110]c‐oriented PZT‐5H single crystal with a large strain of 0.18%. This work deepens our understanding on the growth kinetics of SSCG and pushes the way of growth of soft PZT single crystal by SSCG.

Position and electric field dependent local lattice strain detected by nanobeam x-ray diffraction on a relaxor ferroelectric single crystal

Under a static electric field, we present the scanning nanobeam x-ray diffraction of a relaxor ferroelectric single crystal. The x-ray intensity distributions of a Bragg peak in reciprocal space diffracted from local volumes on the surface of a $0.7\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}\ensuremath{-}0.3\mathrm{PbTi}{\mathrm{O}}_{3}$ (PMN-30PT) single crystal show position and electric field dependence. While the spatially averaged intensity distribution has a single peak corresponding to the average crystal structure, intensity distributions from each local volume have several strong sharp peaks and a weak broad peak, and show strong position dependence as the translation symmetry is broken in nano- to microscale. A static local lattice strain with spatially valuable lattice constants and nanodomains is responsible for peak splitting and heterogeneous crystal structure. The locally strained lattice exhibits a significant tensile lattice strain caused by an electric field, which is compatible with its large piezoelectric constant of approximately $2\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{0.16em}{0ex}}\mathrm{pC}/\mathrm{N}$. When the electric field surpasses the coercive field of 3 kV/cm, polarization switching causes a substantial shear lattice strain with intensity redistribution. Position dependence can also be seen in the piezoelectric constants and coercive fields calculated from x-ray diffraction data for each local location. The standard deviation of the local lattice strain distribution is $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ regardless of the electric field, which is greater than the piezoelectric lattice strain of $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ caused by an electric field of 8 kV/cm. The enormous electric field induced lattice strain and fatigue-free polarization switching are enabled and facilitated by the nano- to microscale heterogeneous crystal structure with widely and continuously distributed local lattice strain.

High piezoelectric properties in 0.7BiFeO3–0.3BaTiO3 ceramics with MnO and MnO2 addition

BiFeO3–BaTiO3–based solid solutions are promising candidates for high–temperature piezoelectric devices because of their high Curie temperature (TC) and considerable electrical properties. Here, we reported an optimum composition of 0.7Bi(Fe0.999Mn0.001)O3–0.3BaTiO3 ceramic with a large piezoelectric constant (d33) of 230 pC/N and a high TC of 505 °C, which was attributed to the intentional introducing of the ceramic with MnO and MnO2 mixture. Furthermore, an in situ d33 measurement was carried out, demonstrating excellent thermal stability for the 0.7Bi(Fe0.999Mn0.001)O3–0.3BaTiO3 specimen. The d33 remained above 200 pC/N in the temperature range of 25 °C–400 °C and its fluctuation was less than ± 15 %. It was determined that the high d33 in the 0.7BiFe0.999Mn0.001)O3–0.3BaTiO3 ceramic originated from a synergistic effect of rhombohedral distortion, intrinsic response, and ferroelectric order. The findings establish a solid correlation between electrical properties and phase/domain structure, and provide a novel approach to improve the piezoelectric properties for BiFeO3–BaTiO3–based ceramics.

Structural and piezoelectric properties of textured NLKNS‐CZ thick films and their application in planar piezoactuator

Abstract0.97(Na0.5‐xLixK0.5)(Nb0.89Sb0.11)O3‐0.03CaZrO3 [(N0.5‐xLxK)(NS)‐CZ] piezoceramic (x = 0.325) has a pseudocubic‐tetragonal‐orthorhombic (PC‐T‐O) multi‐structure. The PC structure formed in this piezoceramic was identified as the R3m rhombohedral structure. This piezoceramic showed the large piezoelectric charge constant (d33) of 515 pC/N due to the PC‐T‐O multi‐structure. The NaNbO3 (NN) templates were used to texture the (N0.5‐xLxK)(NS)‐CZ thick films along the (001) direction, and the textured thick film (x = 0.0375) had a large Lotgering factor of 95.6%. The PC‐T‐O multi‐structure was observed in this thick film (x = 0.0375), but the thick film (x = 0.0325) showed a PC‐O structure owing to the diffusion of the NN templates into the thick film. The textured thick film (x = 0.0375) exhibited an increased d33 of 625 pC/N because of the PC‐T‐O multi‐structure and the lineup of grains along the [001] direction. A textured thick film (x = 0.0375) was used to fabricate a planar‐type actuator to confirm its applicability to electrical devices. This actuator exhibits large acceleration (580.3 G) and displacement (150 μm) at a low electric field of 0.2 kV/mm with a short response time of 3.0 ms. Therefore, the (N0.5‐xLxK)(NS)‐CZ thick films are excellent lead‐free piezoceramics.

A review on zinc oxide composites for energy storage applications: solar cells, batteries, and supercapacitors

Zinc oxide (ZnO) is used for various purposes because of its special physico-chemical properties, including large band gap, high binding energy of exciton, nontoxicity, high chemical and thermal stability, large piezoelectric constants, and wurtzite crystal structure with various and widespread applications in electronics, optoelectronics, biochemical sensing, biomedical, and energy-saving systems. This review mainly aimed to present the recent improvement in ZnO-based composite materials with utilization in energy storage systems with a specific focus on lithium-ion batteries, dye-sensitized solar cells, and supercapacitors. The first part of this paper looks at the structure and properties of ZnO and then describes some of the most common synthesizing methods of ZnO composites, including electrochemical, chemical, solvo/hydrothermal, and physical deposition methods. Finally, the recent advancement of ZnO-based composite materials applied in energy storage systems was discussed.

Potential High-Temperature Piezoelectric Ceramics with Remarkable Performances Enhanced by the Second-Order Jahn-Teller Effect.

Herein, the second-order Jahn-Teller effect was applied to the design of the bismuth ferrite-based ceramics. A large distortion of an electron structure arranged along the z axis and an asymmetric distribution of charge density were calculated in 0.80(0.725BiFeO3-0.275BaTiO3)-0.20PT (0.20 PT) based on the density functional theory, indicating good ferro/piezoelectric properties. The top experimental polarization of 36.89 μC/cm2, optimal d33 value of 258 pC/N measured at room temperature, and ultrahigh d33 value of 303 pC/N measured at 370 °C were obtained at 0.20 PT, thereby further confirming the calculations. Furthermore, a high Curie point of 488 °C, as well as outstanding temperature stability ranging from room temperature to 430 °C of the 0.20 PT ceramic was observed. The domain of the 0.20 PT exhibited greater order and smaller size, resulting in easy switching when applying voltage. The distorted electron structure, plumb grains, ordered and easily switchable domains, and coexistences of tetragonal (T) and rhombohedral (R) phases contributed to the large piezoelectric constant of the 0.2 PT ceramic. BFBT-xPT ceramics are potentially promising for high-temperature piezoelectric field applications.

Phase Switching as the Origin of Large Piezoelectric Response in Organic-Inorganic Perovskites: A First-Principles Study.

Piezoelectrics are critical functional components of many practical applications such as sensors, ultrasonic transducers, actuators, medical imaging, and telecommunications. So far, the best performing piezoelectrics are ferroelectric ceramics, many of which are toxic, heavy, hard, and cost-ineffective. Recently, a groundbreaking discovery of extraordinarily large piezoelectric coefficients in the family of organic-inorganic perovskites gave a hope for a cheaper, environmentally friendly, inexpensive, lightweight, and flexible alternative. However, the origin of such a response in organic-inorganic ferroelectrics whose spontaneous polarization is an order of magnitude smaller than for inorganic counterparts remains unclear. In our study, we employ first-principles simulations to predict that the mechanism associated with large piezoelectric constants is of extrinsic origin and associated with switching between the stable phase and a previously overlooked energetically competitive metastable phase that can be stabilized by the external stress. The phase switching changes the polarization direction and therefore produces a large piezoelectric response similar to PbZr_{1-x}Ti_{x}O_{3} near the morphotropic phase boundary. The existence of such metastable phases is likely to manifest as the dynamical molecular disorder above the Curie temperature and therefore could be intrinsic to the entire family of organic-inorganic ferroelectrics with such disorder.

Prediction of an Extended Ferroelectric Clathrate.

Using first-principles calculations, we predict a lightweight room-temperature ferroelectric carbon-boron framework in a host-guest clathrate structure. This ferroelectric clathrate, with composition ScB_{3}C_{3}, exhibits high polarization density and low mass density compared with widely used commercial ferroelectrics. Molecular dynamics simulations show spontaneous polarization with a moderate above-room-temperature T_{c} of ∼370 K, which implies large susceptibility and possibly large electrocaloric and piezoelectric constants at room temperature. Our findings open the possibility for a new class of ferroelectric materials with potential across a broad range of applications.