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Cardiac troponins are highly sensitive and specific biomarkers for cardiac injury. Previous studies evaluating the effect of positive airway pressure (PAP) on cardiac troponins in patients with sleep-disordered breathing (SDB) have yielded conflicting results. The meta-analysis was performed to examine the effect of PAP on cardiac troponins in SDB patients.PubMed, Web of Science, and EMBASE before September 2021 on original English language studies were searched. The data on cardiac troponins in both baseline and post-PAP treatment were extracted from all studies. The data on the change of cardiac troponins in both PAP and control group were extracted from randomized controlled trials. Standardized mean difference (SMD) was used to synthesize quantitative results.A total of 11 studies were included. PAP treatment was not associated with a significant change in cardiac troponin T between the baseline and post-PAP treatment (SMD = -0.163, 95% confidence interval [CI] = -0.652 to 0.326, z = 0.65, p = .514). The pooled estimate of SMD of cardiac troponin I between the pre- and post-PAP treatment was 0.287, and the 95% CI was -0.586 to 1.160 (z = 0.64, p = .519). The pooled SMD of change of cardiac troponin T between the PAP group and control group was -0.473 (95% CI = -1.198 to 0.252, z = 1.28, p = .201).This meta-analysis revealed that PAP treatment was not associated with any change of cardiac troponin in SDB patients.

Joint replacement surgery is one of the orthopedic surgeries with high successful rates; however, wear debris generated from prostheses can ultimately lead to periprosthetic osteolysis and failure of the implant. The implant-derived particulate debris such as ultrahigh molecular weight polyethylene (UHMWPE) can initiate the local immune response and recruit monocytic cells to phagocytose particles for generating reactive oxygen species (ROS). ROS induces osteoclastogenesis and macrophages to secrete cytokines which ultimately promote the development of osteolysis. In this work, we develop the few-layered Nb2C (FNC) as an antioxidant which possesses the feature of decreasing the production of cytokines and inhibiting osteoclastogenesis by its ROS adsorption. Moreover, local injection of FNC attenuates the UHMWPE-induced osteolysis in a mouse calvarial model. In sum, our results suggest that FNC can be used for treating osteolytic bone disease caused by excessive osteoclastogenesis., Graphical abstract Image 1, Highlights • Few-layered Nb2C (FNC) was synthesized by chemical exfoliation from bulk Nb2C (BNC) and showed an outstanding elimination of ROS on the basis of density functional theory (DFT) and inhibition effect of oxidative stress in vitro. • Osteoxlastogenesis was driven by reactive oxygen species (ROS), controlling osteoclasts differentiation in the early stage. • FNC inhibited osteoclastogenesis via scavenging ROS and dampening related signal pathway. • UHMWPE-induced osteolysis was attenuated by FNC therapy.

The λ-shape dielectric anomaly follows the Curie–Weiss law with a 105.8-fold change at a frequency of 500 Hz. The spontaneous polarization of TATC can reach 1.4 μC cm−2. The TATC crystal has a 4.03 eV indirect bandgap.

Two metal–organic frameworks, [Me(n-Bu)3P][Mn(dca)3] (1) and (Et4P)[Mn(dca)3] (2) (dca: N(CN)2–, dicyanamide), exhibit perovskite-like (ABX3) three-dimensional structures. Two phosphonium cations o...

Organic–inorganic hybrid perovskite materials have attracted great attention due to their great application potential in photovoltaics and optoelectronics. Among them, some 2D and 1D lead-iodide-based perovskites were found to exhibit ferroelectricity at room temperature. Yet, no 0D lead-iodide-based perovskites were reported to be room temperature ferroelectric. Here, we report a new lead-iodide-based perovskite material, (DMA)4PbI6, which is ferroelectric at room temperature. The spontaneous polarization of (DMA)4PbI6 is about 0.3 μC cm−2. (DMA)4PbI6 undergoes a ferroelectric–ferroelectric phase transition around 252 K in the heating process. The ferroelectric–ferroelectric phase transition is a first order phase transition with a hysteresis of 18 K between the heating process and the cooling process. The absorption spectra show that (DMA)4PbI6 is a direct band material with a band gap of 2.80 eV. A broadband blue photoluminescence centered at 2.7 eV was observed, which may be attributed to the self-trapped excitons.

In general, it is hard to grow large single crystals with a one-dimensional chain structure due to the preferred growth direction and chain breakage. Most reported one-dimensional lead iodine chain single crystals can grow long, but they are difficult to grow thick. Here, we demonstrate for the first time the growth of 2 mm × 4 mm × 8 mm sized single crystal one dimensional organic lead iodine perovskite – DMAPbI3 ((CH3)2NH2PbI3). Benzylamine addition to the solution may help to dissolve crystals with high defect concentrations so that the crystal can grow larger. Through the measurement on the large single crystal, we found that DMAPbI3 is ferroelectric below 260 K, and the dielectric constant of DMAPbI3 at various frequencies at room temperature is as high as more than 100. Blue photoluminescence centered at 2.6 eV was reported. The ferroelectricity of DMAPbI3 may be used to design more stable and efficient organometal halide perovskite solar cells and photoelectric devices.

Ferroelectrics are widely applied in modern industrial production due to their fascinating physical properties. New findings on organic ferroelectric materials have gained the attention of researchers because they have flexible designs and are easy to produce. Here, we report on an overlooked compound, trimethylammonium bromide ((CH3)3NHBr), that demonstrates ferroelectricity just below room temperature. The compound undergoes a first-order paraelectric–ferroelectric phase transition at the Curie temperature (Tc) around 286 K, accompanied by significant changes in the structural, thermal and electrical properties. The space group of the compound transforms from P21 to P21/m at the Curie temperature Tc. The remnant polarization Pr is about 0.4 μC cm−2 at 230 K and 0.25 μC cm−2 at 243 K. This finding reveals a new pathway to design and synthesize molecular ferroelectrics.

Monolayer molybdenum disulfide (MoS

Organic-inorganic hybrid ferroelectrics (OIHFs) have fueled enormous interest benefiting from their less environmental pollution, performance-tailored functionality, low product costs as well as tunability of structures. However, the lack of material synthesis approaches and diverse targeted molecular design is a stumbling block for designing novel OIHFs rationally. Here, we report a unique organic-inorganic hybrid ferroelectric (3,3-difluoropyrrolidine)2CdCl4 1 and another novel nonferroelectric crystal (3,3-difluoropyrrolidine)2Cd2Cl6 2 by changing various crystallization solvents. Significantly, 1 presents a ferroelectric phase transition behavior at ∼367 K, and the distinct symmetry breaking, i.e., mmmFm, sets up a biaxial ferroelectric with four equivalent directions of polarization, which has a Pr ∼ 0.77 μC/cm2. Systematic studies prove that ferroelectricity can be ascribed to the synergistic effects of the distortion of the inorganic anion skeleton and the ordering of organic cations. This work reveals the potential of constructing novel ferroelectrics based on the solvent selective effect and pyrrolidinium as organic cations.

The double-wave method is widely used in ferroelectric measurements to eliminate the effects of conductance and capacitance components while preserving the ferroelectric domain contribution. However, in polycrystalline ferroelectric material, the assumption of the evolution of domains by the double-wave method no longer applies due to the domain back switch of de-field, and the domain contribution calculated by the current subtraction method is also problematic. Therefore, we proposed a new method to calculate the charge contribution of conductance and eliminate the conductance interference in the hysteresis loop. Finally, the feasibility of this new method is verified in many typical polycrystalline ferroelectric materials. This work provides a path for the study of ferroelectric properties of some high conductivity materials.

Graphitic carbon nitride (g-C3N4) is a two-dimensional (2D) photocatalyst, but it appears a mediocre catalytic property due to the recombination of charge carriers. Constructing heterojunctions can boost the separation and suppress the recombination of photo-generated electron–hole pairs. For the conventional Type-II heterojunction, the oxidation ability is significantly reduced due to the decreasing of band gap. We try to maintain its oxidation capacity and promote the artificial bandgap by tailoring a Z-scheme heterojunction through interface engineering. Herein, we grafted different proportions of YMnO3 3D-nanoparticles onto g-C3N4 2D-nanosheets. This special 2D/3D mixed-dimensional nanocomposite exhibits efficient charge carrier transport performance according to the electrochemistry and photocurrent measurement. The outstanding photocatalytic oxidation ability can be verified by the rate of Rhodamine B degradation, which is 3.8 and 2.3 times of YMnO3 and g-C3N4, respectively. Theoretical calculation, active group capture experiments and electron spin resonance indicate the energy band position and the reactive groups (superoxide radicals and holes). The optimized g-C3N4/YMnO3 heterojunction utilizes the interfacial synergistic effect to achieve a composition of vigorous oxidizing ability and outstanding visible light harvesting. This work will pave a promising access for mechanism and interface engineering of other g-C3N4-based Z-scheme heterojunctions.

The ceramics of Sr3-xBaxSn2O7 (0 ≤ x ≤ 0.6) were synthesized by solid-state reaction method. The lattice constants of Sr3-xBaxSn2O7 increase with increasing of Ba doping. With increasing of the Ba2+ concentration from x = 0 to x = 0.2, the phase transition temperature reduces by 73 K. The vibration modes related to the phase transitions are strongly related to the tilting and rotation of SnO6 octahedra. The doping of Ba significantly aggravates the anharmonic effect and increases the Raman activity of the vibration mode A 2 ( 5 ) , and reduces the phonon lifetime and the Raman activity of the vibration mode A 1 17 .

Large reversible lattice strain that manipulates coupled degrees of freedom can be induced by optics in SrRuO3, suggesting it has great potential in optomechanical and optoelectronic devices. Photo...

A typical multiferroic manganese oxide of HoMnO3 was partially substituted by Fe at Mn site. Orthogonal crystalline phase of HoMn1−xFexO3 was synthesized at normal pressure. This finding has changed the conventional method of synthesizing orthogonal crystalline phase of rare-earth manganese oxides under high-temperature and high-pressure. The doping of iron ions suppresses the formation of hexagonal phase as revealed from X-ray diffraction, Morphology analysis, Raman spectrum and X-ray photoelectron spectroscopy. The doping of Fe3+ into HoMnO3 causes changes in the space group of the sample and ferroelectricity at room temperature. There are two phases with a ferroelectric space group of $${P6}_{3}cm$$ and a paraelectric one of Pnma coexisted in Ho $${\text{Mn}}_{1-x}{Fe}_{x}{O}_{3}$$ polycrystalline with x 0.15, the phase with $${P6}_{3}cm$$ space group disappears, and samples have only one crystalline phase Pnma. We found that the sample remained ferroelectricity at room temperature in the process of changing the doping concentration. The ferroelectric property disappears until it completely changed to the orthogonal phase. The synthesis of orthogonal HoMnO3 at normal pressure has not been previously reported and potentially open up abroad research and application prospects.

Molecule-based ferroelectrics are a class of highly desirable intelligent materials for their highly variable physical properties, easy and environmentally friendly processing, especial light weight and mechanical flexibility. 4-Aminopyridinium Perchlorate (APP), used to be known as a pyroelectric below 243 K, is first discovered to be a new molecular ferroelectric in this work, which has a perfect electric hysteresis loops with a large spontaneous polarization of 1.0 μC/cm2 and a small coercive field of 0.67 kV/cm below 246 K. Owing to the dramatic changes of the protonated cations and order–disorder of anions, the crystal symmetry of APP transforms from P21/c to P21 in this first-order phase transition, which is revealed by other measurements, such as differential scanning calorimetry, heat capacity, dielectric anomalies and Raman spectrum.

Molecular ferroelectrics are a kind of functional materials that have large application prospects. Comparing with the traditional inorganic ferroelectrics, they have some advantages, such as easy design, environment-friendliness, nontoxicity, and flexibility. In this study, a new molecular ferroelectric pyridin-2-ylmethanaminium perchlorate was discovered, which undergoes a ferroelectric phase transition at around 264.8 K. The spontaneous polarization reaches 0.22 μC cm−2, and the coercive fields are as small as 1.1 kV cm−1 at 202 K. The single-crystal X-ray diffraction analysis reveals that the space group transforms from a polar space group of P21 at 173 K to a centrosymmetric space group of P21/c at 293 K. By analyzing the crystal structure changes below and above the phase transition temperature, it can be concluded that the phase transition is induced by the disorder of perchlorate. Its ferroelectricity was confirmed by the measurements of differential scanning calorimetry, dielectric and hysteresis loop.

2D MXene, Ti

Organic-inorganic hybrid perovskites are currently an active research topic in the field of energy and next-generation electronics. Their selectable organic and inorganic components provide infinite possibilities for designing functional materials with multiple applications. Herein, we present a new one-dimensional BaNiO3-like organic-inorganic hybrid perovskite (thiazolidinium)CdBr3 (1), which displays a phase transition at 263 K and a switchable second harmonic generation (SHG) response. Intriguingly, 1 shows a pyroelectric coefficient pe of ∼0.6 μC·cm-2·K-1 and a piezoelectric output voltage of ∼2.0 V for our fabricated piezoelectric generation device, indicating its great potential for pyroelectric sensors, self-powered low-voltage electronic devices, and energy harvesters. Moreover, the presence of a specific thioether donor enables 1 to appropriately adsorb Pd(II) ions, which can be monitored by the corresponding change in phase transition behavior, SHG signal, and pyroelectric response. This work provides a new insight to develop new multifunctional materials, demonstrating the feasibility of utilizing organic-inorganic hybrid perovskites to realize future self-powered low-voltage devices and energy harvesters.

The organic-inorganic hybrid halide compounds have emerged as one of the most promising photoelectric material for their superior optoelectronic properties and hold great prospects for renewable energy substitutes and environmental protection as photocatalysis. Here, we report the optical properties of the Sb-based organic-inorganic hybrid ferroelectric materials: pyridine-4-aminium tetrachloroantimonate ((C5H7N2)SbCl4, sample 1), piperidin-1-aminium tetrachloroantimonate ((C5H13N2)SbCl4, sample 2) and tris(trimethylammonium) nonachlorodiantimonate (((CH3)3NH)3Sb2Cl9, sample 3), which are a kind of exploited efficient photocatalysts. Samples 2 and 3 exhibit distinct photoelectric respond, which are mainly ascribed to their minor narrow band-gap compared with sample 1. For the ferroelectrics, the intrinsic of spontaneous polarization of sample 3 at room temperature is favourable for the separation of photogenerated electrons and holes within the photorespond process. Moreover, sample 3 shows the highest efficiency of photo-decomposed Rhodamine B (90.2% within 80 min) and Methyl Orange (MO) (97.4% within 50 min), thanks to the photo-excited electrons and holes promoting the formation of oxidative radical species during the photo-redox progress. These findings prove that the development of a novel Sb-based organic-inorganic hybrid halide compounds with good stability in the degradation of organic dyes paves a way to designing new photocatalyst.

Transition metal oxide nanomaterials (TMOs) have been adopted to produce reactive oxygen species (ROS) and adjust tumor microenvironment (TME) in cancer therapy. However, mono-modal treatment and the incompatibility of biological enzyme both hampered the therapeutic effect. Herein, we developed a multimodal TMO-based nanoplatform that the ultrathin Ti3C2 nanosheets were attached onto the MnFe2O4 nanoparticles self-assembled by applying chitosan as a chemical crosslinker to construct an interfacial Schottky junction, Ti3C2@Chitosan-MnFe2O4 (TC@Ch-MFO), achieving improved ROS generation as well as optimized biocompatibility. This heterojunction can controllably catalyze hydrogen peroxide (H2O2) to generate O2 and deplete the overexpressed glutathione (GSH) levels in hypoxic TME, which realizes the chemodynamic therapy (CDT) by cyclized Fenton reaction under NIR excitation. TC@Ch-MFO also constructs a multimodal treatment nanoplatform by introducing available high-efficiency photothermal agent (PTA), Ti3C2, for phtotheraml therapy (PTT). In addition, it simultaneously integrates the visualization with T1- and T2-weighting magnetic resonance imaging (MRI). The toxicity of TC@Ch-MFO to normal tissue cells is negligible. This platform could provide new insights into the development of multimoded synergistic nanoplatform for biological applications, especially breaking the shackles of MXenes merely used as a photo-thermal agent, adopting it to bioimaging sensor and drug loading.

The use of 2-naphthalenesulfonate (NAS) ligand in lanthanide chemistry afforded a family of isostructural mononuclear lanthanide complexes with the formula [Ln(NAS)2(H2O)6](NAS)·3H2O [Ln = Tb (1), Dy (2), Er (3), Yb (4)]. Crystallographic studies determined a square antiprismatic geometry (D4d) for the Ln centre and crystallization in an unprecedented chiral space group. The latter was further confirmed by the observation of Cotton effects in single crystal circular dichroism (CD) spectra. Static and dynamic magnetic measurements identified weak intermolecular dipolar interactions in 2, and such effects can be waived by dilution, which was noted by the detection of zero-field single molecule magnet (SMM) behaviour and hysteresis loop in a magnetically diluted sample (5). Compounds 2-4 exhibit SMM behaviours with energy barriers of 53, 32, and 45 K, respectively. To the best of our knowledge, these complexes are the first examples of pure 4f sulfonate-based SMMs.

Methane (CH4) has superior economic value and application prospect compared with CO, and is an ideal product for photoreduction of CO2. However, low CO2 conversion efficiency and poor selectivity on production are both obstacles to its practical application. Herein, we develop a “M-scheme” photocatalyst CeO2/Ti3C2/TiO2 (CTT) for superior CO2 reduction and selective CH4 generation. This dual heterojunction is constructed by annealing precursor CeO2/Ti3C2 to form anatase TiO2 in situ. CTT composed by CeO2/Ti3C2 and TiO2/Ti3C2 significantly promotes the charge carrier transfer, improving its photoelectric performance. Ti3C2 exhibits a metallicity in the composite, which not only plays the role of a platform to receive transferred electrons, but also resembles the behavior of precious metals to assist in the decomposition of H2 molecules to H+. The reaction between H+ and CO on Ti3C2 contributes to the decreased by-products and decent CH4 selectivity. This work provides a facile and up-and-coming model to construct “M-scheme” heterojunction, realizing the megamerger between optimized photoelectric performance and selective CO2 photoreduction.

2D MXene, Ti3 C2 (TC), has displayed enormous potential in applications in photothermal therapy (PTT), attributing to its biocompatibility and outstanding photothermal conversion capability. However, some tumor ablations are difficult to be realized completely by monotherapy due to the essential defects of monotherapy and intricate tumor microenvironment (TME). In this work, the appropriate doped Fe2+ ions are anchored into the layers of 2D ultrathin TC nanosheets (TC NSs) to synthesize a novel multifunctional nanoshell of Fe(II)-Ti3 C2 (FTC) through interlayer electrostatic adsorption. FTC possesses superior photothermal conversion efficiency (PTCE) than TC NSs, attributing to the enhanced conductivity promoted by interlaminar ferrous ion-channels. Moreover, Fenton reaction based on ferrous ions endows FTC the abilities of reactive oxide species (ROS) releasing and glutathione (GSH) suppression triggered by near-infrared (NIR) laser, featuring splendid biocompatibility and curative effect in hypoxic TME. Meanwhile, magnetic resonance imaging (MRI) responding in FTC reveals the potential as an integrated diagnosis and treatment nanoplatform. FTC could provide new insights into the development of multimoded synergistic nanoplatform for biological applications, especially breaking the shackles of MXenes merely used as a photo-thermal agent (PTA), adopting it to bioimaging sensor and drug loading.

A new molecular ferroelectric is discovered in an organic–inorganic hybrid compound, (C6H5NH3)2CdCl4, which undergoes a reversible order–disorder ferroelectric phase transition at 369 K and has a spontaneous polarization of about 0.5 μC cm−2, larger than the Rochelle salt. Large dielectric anomaly, pyroelectricity and P–E hysteresis loop were observed to represent the ferroelectricity of the compound. Especially, the dielectric constant at the transition temperature increases more than 40 times than that at room temperature, which indicates potential applications on switches and sensors for its high-temperature response and excellently reversible characterization.

We obtained one new molecular ferroelectric material tris(2-hydroxyethyl) ammonium bromide (TAB) that crystallizes in aqueous solution at room temperature with a space group of R3m which belongs to ten polar space groups. There is a paraelectric-to-ferroelectric phase transition at 424 K (from hexagonal R3m to hexagonal R3m phase). Such a high transition temperature is close to that of diisopropylamine bromide (426 K) and higher than that of many other molecular ferroelectrics, such as triethylmethylammonium tetrabromoferrate(III) (360 K); some of the organic-inorganic perovskite ferroelectrics, such as (cyclohexylammonium)2PbBr4 (363 K); and some inorganic ferroelectrics, including BaTiO3 (393 K). The saturated polarization and the coercive field of TAB measured from the ferroelectric hysteresis loop are about 0.54 μC·cm-2 and 0.62 kV/cm, respectively. Given its superior performance, including high phase transition temperature, room-temperature ferroelectricity, small coercive electric field, and adjustable ladder-shaped dielectric constant, TAB will have many potential applications.

Hybrid organic-inorganic halide perovskites (HOIPs) MAPbBr

Extraction or injection of charges through the interface in hybrid catalysts is a fascinating strategy for steering charge carrier transfer in solar energy conversion applications. Instead of interfacial charges regulation, we adopt intrinsic spontaneous polarization-modulated internal electric field to drive photo-generated carriers separation and transfer in both the bulk and surface for photocatalysis. Herein, we first report a series of nano-composites made of perovskite ferroelectric BiFe0.9Mn0.1O3 and orthorhombic phase α-MoO3 semiconductor (BFMO-xM, x = 0, 5%, 10%, 15%) via two-step thermal synthesis method. With × = 10%, the heterostructure exhibits significantly enhancement of optical response and photo-decomposion tetracycline capacity under sunlight compared with pure BFMO and M. The improved photocatalysis is attributed to the superimposed actions of the Z-scheme charge transfer through interface and the polarization field in BFMO for the anti-recombination of photo-excited electron-hole pairs. This work indeed offers a strategic design over multicomponent catalyst by consider the synergy of polarization charges and interfacial charge transmission for solar energy conversion.

Cation-assisted method typifies a common means of improving photocatalysis efficiency. However, it is difficult to create a superior breakthrough in hydrogen evolution recently. In this work, we exhibit dramatically enhanced lighting harvest in a Zn2+ and K+ synergetic modulating g-C3N4 crystal, due to that its absorption edge is tuned from 460 nm for g-C3N4 to visible-light region (582 nm), as well as the bandgap is reduced to 2.13 eV. The density functional theory (DFT) calculations reveal that K+ ions construct the “ion-bridge” between perpendicular interlayers, and Zn2+ ions prefer to occupy the vacancy of π-π conjugate planes of the tri-s-triazine, creating the “bonding” between hybridized sp2 orbitals. “Bridging and Bonding” jointly endow this as-prepared material a gorgeous lattice fringe, a stable structure and a superior photocatalytic activity. The efficient hydrogen evolution of the modified g-C3N4 co-doped with Zn2+ and K+ reveals is about 45.5 times of that of pristine g-C3N4, and the apparent quantum yield (AQY) is about of 0.52% at 540 nm, which is 8.7 times higher than that of g-C3N4. It is anticipated that this work will break the deadlock in hydrogen evolution photocatalysis and broaden novel horizons on the g-C3N4-based application.

The ceramics of Sr3-xCaxSn2O7 (x = 0,0.1,0.2,0.3,0.6,0.8,1) were synthesized by solid-state reaction method. The lattice constants of Sr3-xCaxSn2O7 decrease, and the rotation of oxygen octahedron around c axis increases with the increasing of Ca doping. The phase transition temperature of Sr3-xCaxSn2O7 increases 183.3 K with the increase of Ca doping concentration from × = 0 to × = 0.3. The space group of Sr3Sn2O7 changed from A21am to I4/mmm at 407.9 K. Near the phase transition temperature, the Raman shift of phonon mode A 1 ( 2 ) of Sr3-xCaxSn2O7 changes abruptly, and the phonon mode A 2 ( 2 ) disappears gradually.

A pure organic single crystal, [H2dabco]·[2CB]2 ([H2dabco](2+) = diprotonated 1,4-diazabicyclo[2.2.2]octane, 2CB(-) = 2-chlorobenzoate), which undergoes a ferroelectric-to-paraelectric phase transition above room temperature (∼323 K upon heating), was prepared and characterized. This ferroelectric crystal possesses a distinctive supramolecular architecture composed of discrete H-bonded trimeric units (two 2CB(-) anions bridged by one [H2dabco](2+) cation through N-H···O hydrogen bond interactions). In the paraelectric phase, the [H2dabco](2+) cation is rotationally disordered and lies at the symmetric center of the trimer. Upon cooling, it is frozen in an ordered state and deviates toward a 2CB(-) anion at one end along the H-bond. The collective displacement of the cations leads to a polarization of the single crystal along the crystallographic c axis, which is confirmed by the temperature dependence of the second harmonic generation and spontaneous polarization. A significant increase in the phase transition temperature of the deuterated analogue suggests that the proton plays an important role in the ferroelectric phase transition.

Molecule-based ferroelectrics are a class of highly desirable intelligent materials for their rich switchable physical properties, easy and environmentally friendly processing, especial lightweight and mechanical flexibility. In the current work, a new molecule-based ferroelectrics pyridin-4-ylmethanaminium perchlorate was discovered undergoing paraelectric–ferroelectric phase transition at Tc = 258.40(8) K and ferroelectric–ferroelectric phase transition at T1 = 255.93(2) K. It crystallizes in monoclinic crystal system with a centrosymmetric space group of C2/c at 293 K and also crystallizes in monoclinic crystal system but with a polar space group of Cc at 223 K. The spontaneous polarization can reach 1.25 μC/cm2 and the coercive field is about 2.6 kV/cm below 254 K. The paraelectric–ferroelectric phase transition belongs to displacive phase transition and the nearby ferroelectric–ferroelectric phase transition contains order–disorder features, which consistent with the dynamic process including deforma...

Diisopropylammonium bromide (DIPAB) has attracted great attention as a molecular ferroelectric with large spontaneous polarization and high Curie temperature. It is hard to grow the ferroelectric phase DIPAB because of the appearance of the non-ferroelectric phase DIPAB at room temperature. Here, a ferroelectric thin film of DIPAB was successfully fabricated on a Si substrate using a spin coating method from aqueous solution via 12-crown-4 addition at room temperature. The ferroelectric DIPAB film with a thickness of hundreds of nanometers is distributed discontinuously on the substrate in narrow strips. The direction of polarization is along the narrow strip. Piezoresponse force microscopy (PFM) shows that the ferroelectric films have two kinds of domain structures: noncharged antiparallel stripe domains and charged head-to-head (H-H)/tail-to-tail (T-T) type domains. 12-crown-4 has been proved to play important roles in forming the H-H/T-T type domains. The Chynoweth method shows that the DIPAB films synthesized in this way show a better pyroelectric effect than DIPAB crystals.

A series of chlorine doped diisopropylammonium bromide (DIPAB-C) single crystals were grown successfully. The DIPAB-C crystals have two phase transitions (from P212121 to P21 at T1, and from P21 to P21/m at T2) in the warming process but only one (P21/m to P21) in the cooling process. The ferroelectric-to-paraelectric transition temperature can be modulated from 423 K to 429 K by chlorine concentration. The spontaneous polarization decreased from 23 μC cm−2 for undoped DIPAB crystals to 13 μC cm−2 for a chlorine concentration of x = 0.08, then it had a stable value of 14 μC cm−2 for x > 0.1. This indicates that the ferroelectric properties, including spontaneous polarization, the phase transition temperatures, the lattice parameters, etc., can be modulated by doping with congeners.

Organic-inorganic hybrid perovskite MAPbI3 films with large grain size and excellent photoelectric properties are obtained by annealing the precursors at Ar atmosphere with pressure up to 10 MPa. In comparing to the film annealing at Ar with 0.1 MPa, 4 times lager grains are observed with the film annealing at the Ar atmosphere with the pressure of 6 MPa. The structural stability in respect to temperature is confirmed by the temperature dependence of x-ray diffraction. The band gap of MAPbI3 films may be adjusted by varying the annealing pressure. There is one order of magnitude in intensity of photoluminescence (PL) due to annealing at the Ar atmosphere with high pressure, even the intensity of PL increases with increasing the temperature up to 35 °C. Post annealing with high atmosphere pressure may be a new method in fabricating high performance MAPbI3 films.

The rapid development of organic-inorganic metal halides in optoelectronic devices has been considered a promising approach for light-emitting diodes. Mn-based halogen hybrids represent a class of fascinating luminescence functional materials. Up to date, studies on Mn-based metal halides remain blurry and suffer from instability and low photoluminescence quantum yield (PL QY). Here, the single crystalline of MEA(MnBr4-xClx)2 (MEA=((CH3)4N)((C2H5)4N)2·NH4, x = 0, 2, 3) were designed and constructed by a one-pot solution method for the first time, featuring brilliant green emissions under ultraviolet light and revealing PL QY up to 99 ± 1% with x = 3 at room temperature. The excellent luminescence is ascribed to the Mn2+ d5 configuration with the 4T1–6A1 transition. Moreover, the thermostability and anomalous photoluminescence (PL) behavior triggered by heat are modulated via varying halogen ratio Cl/Br. Particularly, MEA(MnBr4)2 has an ultrahigh melting up to 600 K, which is, as we know, the highest one among the Mn-based organic-inorganic hybrid compounds. Our findings not only present the outstanding performance of three crystals, but also highlight the potential of these compounds in optoelectronics.

Graphitic Carbon Nitride (g-C3N4) has extensive application prospect of photodynamic therapy (PDT), which can be attributed to the biocompatibility and photosensitivity. However, it suffers from the near-ultraviolet absorption edge and low reactive oxygen species (ROS) release rate. This work exhibits an atomic-thickness water-soluble g-C3N4 with alkali Zn2+ and K+ modification (MCN), whose absorption edge is tuned from 460 nm for GCN to the entire visible-light region (663 nm), and bandgap is reduced to 1.94 eV. Both K+- bridging intercalation and the in-plane Zn-N significantly enhance the photocatalytic performance, as well as inhibit the overexpression of glutathione (GSH) significantly. The synergistic effect make that the release rate of ROS is about 45.16 % (7.95 % for pristine g-C3N4), accomplishing a considerable inactivation efficiency of malignant melanoma A375. This work fundamentally releases the limitation of g-C3N4 as a PDT photosensitizer, revealing its multifunctional promise to cancer therapy.

The emerging two-dimensional (2D) materials such as graphene have opened the door to industrial applications. Here, we consider the oxide perovskite monolayer of SrTiO3 (STO), LaAlO3 (LAO) and their heterostructures as the 2D transitional metal system. Results show that a band-gap transition from indirect to direct occurs when the separated monolayer STO (indirect band gap of 3.210 eV), and LAO (indirect band gap of 4.024 eV), form the heterostructures (direct band gap of 2.976 eV). The obtained bandgap for the stable bilayers may effectively be modulated by biaxial strains from -12% to 8%. With 12% compressive biaxial strain, the band gap reduces to be 0.23 eV. The optical properties for the stable bilayers are also tuned by the biaxial strain. When the strain increases from compressive strain to tensile strain, the strongest peak of the imaginary part of dielectric function red shifts to lower energy. In comparing with the monolayer STO and LAO, the elastic property enhances obviously for the stable heterostructure, suggesting the heterostructure can be more stable freestanding or may be applied in device fabrications.