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It is urgent to develop a polyamide (PA) thin-film composite (TFC) membrane with a new method in this study by designing and constructing a new nanomaterial support layer instead of the conventional support layer. Polydopamine-wrapped single-walled carbon nanotubes (PDA@MWCNTs) as the place of the polymerization reaction can optimize the PA film structure and performance. The resulting composite membrane presents a higher water flux of 15.8 L·m−2·h−1·bar−1 and a rejection rate of 97% to Na2SO4, simultaneously maintaining this high separation performance in 300 min. It is a new ideal to construct novel support layer by using inorganic nanoparticles and organic polymer nanofiber membranes. [ABSTRACT FROM AUTHOR]

With the proposal of the concept that lucid waters and lush mountains are invaluable assets, ecological issues have become increasingly important issues of concern to people. The process of urbanization is accelerating, and the importance of urban waterfront space in improving the environmental quality of the city and people's quality of life, enhancing the vitality of the city, the overall appearance of the city, and the competitiveness of the city, is receiving increasing attention. And how to properly handle the construction and development of urban waterfront space has become increasingly prominent in urban planning. Under the the concept of "ecological conservation", it is thought that the construction of urban waterfront space should follow the principle of harmony between nature and man, and strengthen the multifaceted connection of the city. Through field research on Swan Lake, a comprehensive evaluation of the problems in the plank road and land ecology is conducted. It is proposed to improve the current situation of Swan Lake by grasping the two keywords of "waterfront" and "city", and starting from the improvement of water body and the enhancement of urban cultural construction in the lake area. [ABSTRACT FROM AUTHOR]

Photoelectric devices based on the photothermoelectric (PTE) effect show promising prospects for broadband detection without an external power supply. However, effective strategies are still required to regulate the conversion efficiency of light to heat and electricity. Herein, significantly enhanced photoresponse properties of PbI2 generated from a PTE mechanism via a high‐pressure strategy are reported. PbI2 exhibits a stable, fast, self‐driven, and broadband photoresponse at ≈980 nm. Intriguingly, the synergy of the photoconductivity and PTE mechanism is conducive to enhancing the photoelectric properties, and extending the detection bandwidth to the optical communication waveband (1650 nm) with an external bias. The dramatically enhanced photoresponse characteristics are attributed to narrowing of the band gap and a significantly decreased resistance, which originate from the enhancement of atomic orbital overlap owing to pressure‐induced Pb‐I bond contraction. These findings open up a new avenue toward designing self‐driven and broadband photoelectric devices. [ABSTRACT FROM AUTHOR]

The bandgap and type of optical transition are key factors in determining the functionalities and applications of photoelectric materials. However, it is extremely difficult to modulate the bandgap and indirect‐direct bandgap transition for most materials. This study reports significant enhancements in photocurrents and an extended detection bandwidth resulting from pressure‐regulated indirect–direct bandgap transition in hypervalent CsI3. Furthermore, this study achieves an increase in the photocurrent by almost five orders of magnitude under visible‐light illumination. Impressively, the detection band‐edge shows a successive redshift from visible light to 1650 nm (optical communication waveband) upon compression. And high pressure is conducive to CsI3 operating at an ultralow bias input. Extensive high‐pressure spectroscopy analyses and theoretical calculations suggest that changes in the photoelectric properties of CsI3 are associated with enhanced I–I interactions along the quasi‐endless linear chain directions under compression. These findings offer an effective band engineering strategy for achieving broadband spectral response and high gains with an ultralow bias in photoelectric detectors. [ABSTRACT FROM AUTHOR]

The bandgap and type of optical transition are key factors in determining the functionalities and applications of photoelectric materials. However, it is extremely difficult to modulate the bandgap and indirect‐direct bandgap transition for most materials. This study reports significant enhancements in photocurrents and an extended detection bandwidth resulting from pressure‐regulated indirect–direct bandgap transition in hypervalent CsI3. Furthermore, this study achieves an increase in the photocurrent by almost five orders of magnitude under visible‐light illumination. Impressively, the detection band‐edge shows a successive redshift from visible light to 1650 nm (optical communication waveband) upon compression. And high pressure is conducive to CsI3 operating at an ultralow bias input. Extensive high‐pressure spectroscopy analyses and theoretical calculations suggest that changes in the photoelectric properties of CsI3 are associated with enhanced I–I interactions along the quasi‐endless linear chain directions under compression. These findings offer an effective band engineering strategy for achieving broadband spectral response and high gains with an ultralow bias in photoelectric detectors. [ABSTRACT FROM AUTHOR]

Wetlands are widely distributed all over the world, and have many wildlife resources, which are the main pieces of the puzzle for natural resource conservation and sustainable development on earth and have important irreplaceability. In this paper, through questionnaire survey, field research, literature review, etc., importance weight analysis was conducted by using principal component analysis, and field survey and questionnaire were carried out to collect data on ecological environment function, environmental protection function, landscape beautification function, disaster prevention and mitigation function of urban wetlands. The problems in wetland parks of Nanjing were discussed, such as lack of awareness of landscape planning, deficient late management of wetland parks, weak ability of sustainable development, and unreasonable landscape layout and function. Finally, corresponding solutions were proposed, such as adhering to the planning and design of urban wetland parks with green as the base and health as the basis, persisting in the construction of a wetland system with high biodiversity and near-natural characteristics, adhering to the principle of sustainable development, adopting the construction idea of symbiosis and circulation of urban wetland parks, strengthening education and publicity work, and paying attention to the organic combination of system protection and coordinated construction. The research can build a new development direction for the model of urban wetland parks and green healthy cities, and provide theoretical support for urban sustainable construction. [ABSTRACT FROM AUTHOR]

We present pressure-induced phase transitions and metallization in VO 2 nanoparticles characterized by synchrotron x-ray diffraction, Raman spectroscopy, and infrared reflectivity measurements. The M1-M1 ′ -Mx phase transitions were found in VO 2 nanoparticles upon compression. The results of IR reflectivity shown that pressure-induced metallization occurs in the M1 ′ phase with increasing pressure and the sample becomes fully metallic at the transition of M1 ′ to Mx . The metallic Mx phase transforms to metastable mixed phases displaying insulating properties upon decompression. We attribute the pressure-induced metallization of the M1 ′ phase to the strong electron correlations, while the metal-insulator transition (MIT) from the Mx to the mixed phases is found to be associated with the structural phase transitions. Both the electron-correlation-driven Mott transition and the structure-driven MIT can be achieved in VO 2 by applying pressure. Compared with bulk samples, the VO 2 nanoparticles exhibit larger bulk moduli and increased transition pressure due to their nanosize effects. High pressure provides an effective method to study the MIT in strongly correlated materials and paves the way for modifying electronic properties of VO 2 . [ABSTRACT FROM AUTHOR]

Layered transition-metal dichalcogenides (TMDs) have recently attracted intense scientific and engineering interest because of their unique semiconducting and opto-electronic properties. We investigated the pressure-induced structural phase transition of layered semiconductor molybdenum disulfide (MoS2) using Raman spectroscopy and studied its metallization using infrared (IR) spectroscopy under both non-hydrostatic and quasi-hydrostatic conditions. Under quasi-hydrostatic and non-hydrostatic conditions, we found that the structural phase transition from 2 Hc stacking to 2 Ha stacking starts at approximately 16 and 21 GPa, respectively, and finishes at ∼35 and ∼41 GPa, respectively. Furthermore, the structural phase transition was followed by a semiconductor-to-metal (S-M) electronic transition. The pressure point of metallization under quasi-hydrostatic conditions is ∼5 GPa lower than that under non-hydrostatic conditions. [ABSTRACT FROM AUTHOR]

Single crystal γ-MnOOH nanorods were successfully prepared by employing a hydrothermal process based on the direct reaction between potassium permanganate (KMnO 4 ) and ethylene glycol (EG). It was found that the reaction time and temperature play important roles in the structural and morphological modifications. Our results show that the γ-MnOOH nanorods are formed through a lamellar growth, assembly and ripening process. Moreover, MnO 2 , Mn 2 O 3 , and Mn 3 O 4 nanorods were obtained by the subsequent calcination of γ-MnOOH precursors under different temperatures and atmospheres. These one-dimensional manganese oxide and oxyhydroxide nanorods are expected to have possible novel properties and wide applications. [ABSTRACT FROM AUTHOR]

Organic–inorganic halide perovskites (HOIPs) are promising light-electric conversion materials for optoelectronic devices. Improving the light responsiveness properties of HOIPs is of great significance for the development of the optoelectronics industry. In this study, we have investigated the effect of pressure on the optoelectronics properties of the archetypical representative HOIPs methylammonium lead iodide nanoplates. An enhancement of the photocurrent accompanied by 4 times-prolonged carrier lifetime, enhanced photoluminescence (PL) intensity, and narrowed bandgap were observed via applying pressure to about 0.36 GPa, while these physical properties got worse with further compression. Strikingly, when released to ambient conditions, the photocurrent is further increased to 4.5 times and the carrier lifetime is prolonged to 1.5 times of the corresponding values for an initial sample, while the bandgap slightly blueshifted and the PL intensity slightly reduced. These results suggest that the increased photocurrent may be related to the increased carrier lifetime of the quenched sample, which gives more time for the separation of photoelectrons from vacancies before recombination. This study demonstrated that pressure engineering can be a real possibility for improving the light responsiveness of the HOIPs material in practical applications. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the effects of synthetic parameters on the morphologies during hydrothermal process and the crystal structural transitions from intermediate titanate to final TiO2 products by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It reveals that hydrothermal duration, temperature and reactant amount play important roles in controlling the morphologies and crystal structures of titanate products. Anatase nanotubes, anatase nanorafts, TiO2–B nanoribbons, and anatse/TiO2–B nanoribbons were synthesized by modifying these synthetic parameters. We found that the crystal structures of intermediate titanate products influence on the transitions from titanate to TiO2. Our results show that anatase and TiO2–B derive from the orthorhombic and monoclinic titanate, respectively. We suggest that the crystallographic relationships between the intermediate products (hydrogen titanate) and the final TiO2 products play important roles in heat treatment. [Copyright &y& Elsevier]

Pressure-induced amorphization (PIA) has drawn great attention since it was first observed in ice. This process depends closely on the crystal structure, the size, the morphology and the correlated pressurization environments, among which the morphology-tuned PIA remains an open question on the widely concerned mesoscale. In this work, we report the synthesis and high-pressure research of VO2(B) nanobelts. XRD and TEM were performed to investigate the amorphization process. The amorphization pressure in VO2(B) nanobelts(~30 GPa) is much higher than that in previous reported 2D VO2(B) nanosheets(~21 GPa), the mechanism is the disruption of connectivity at particular relatively weaker bonds in the (010) plane. These results suggest a morphology-tuned pressure-induced amorphization, which could promote the fundamental understanding of PIA. [ABSTRACT FROM AUTHOR]

The emerging phase change materials (PCMs) have attracted much attention due to their unique properties and applications. However, the optical properties of PCM at high pressures have not been well explored. In this work, the microstructure and optical properties of GeTe and Sn-substituted GeTe at high pressures up to 30 GPa have been systematically investigated. We find that the substitution of small amounts of Sn for Ge combined with the introduction of high pressure can induce an optical contrast of 117% in crystalline GeTe, which is even higher than the highest optical contrast reported so far (90%) caused by amorphous GeTe to crystalline GeTe. The pressure-induced contrast does not originate from any phase transition as previously, but from the combined effect of Peierls distortion elimination and Ge vacancy formation, which leads to an increase in carrier concentration. The relationship between pressure/atomic composition, Peierls distortion/vacancy formation, and optical contrast can be well explained by a combination of experiments and theoretical calculations. Therefore, this study reveals the effect of high pressure on the optical properties of PCMs and provides new ideas for the design of high-optical-contrast PCMs. [ABSTRACT FROM AUTHOR]

As one of the most likely alternatives to traditional vapor compression refrigeration technology, solid refrigeration technology based on the barocaloric effect (BCE) has attracted extensive attention in recent years. Spin-crossover (SCO) compounds are considered suitable for working at low driving pressures due to high-pressure sensitivity and small hysteresis width. However, the entropy change (ΔSSCO) of the SCO compound is smaller than that of other excellent barocaloric materials (plastic crystals and two-dimensional perovskites). Here, we report the BCE of the SCO compound {Fe(pz)2(BH3CN)2} (pz = pyrazine) with a smaller molar mass and a third source of entropy change besides electron and vibrational entropy changes. Compound {Fe(pz)2(BH3CN)2} exhibits high pressure sensitivity ( d T 1 / 2 d P = 20.2 K kbar−1) as well as entropy change (Δ S SCO = 202 J kg−1 K−1). The maximum values of reversible isothermal entropy change (ΔSit,rev,max) and adiabatic temperature change (ΔTad,rev,max) at 1 kbar are only 103 J kg−1 K−1 and ∼0 K, respectively, due to the hysteresis behavior. However, at sufficiently high driving pressures, ΔSit,rev,max exceeds 200 J kg−1 K−1, and ΔTad,rev,max can reach ∼47 K, which exceeds all SCO compounds reported in BCE studies and is comparable to some plastic-crystalline and two-dimensional perovskite barocaloric materials. The excellent BCE of the SCO compound {Fe(pz)2(BH3CN)2} is mainly due to its small molar mass, which makes the unit mass compound exhibit higher ΔSSCO, while the introduction of the third source of entropy change—the reorientation entropy change (ΔSreo), only plays a small role. This is expected to promote the practical application of SCO compounds as barocaloric refrigerants. [ABSTRACT FROM AUTHOR]

Two-dimensional layered metal dichalcogenides have given rise to considerable interest in electronics and optoelectronics fields because of their excellent physical and chemical properties and promising applications. Tin disulfide (SnS2) is an important member of them due to its environment-friendly and resource-rich characteristics. Here, a series of in situ electrical transport experiments and photocurrent measurements under high pressure have been performed to investigate the electrical and opto-electrical properties of 4H-SnS2. With increasing pressure, the electrical resistivity of 4H-SnS2 decrease significantly, leading to a transition from semiconducting to metallic state above 58.6 GPa. The increase in pressure results in a substantial enhancement in photoelectric activity, indicating the extensive potential of utilizing pressure as a trigger for in situ optoelectronic applications. Combined with our previous results of x-ray diffraction and optical absorption at high pressure, pressure-induced structural distortion, bandgap narrowing, metallization, and enhancement of photoelectric activity of 4H-SnS2 are tunable and reversible, which are of great significance for both fundamental research and device design. [ABSTRACT FROM AUTHOR]

In view of the need to limit harmful emissions of chlorofluorocarbons into the atmosphere and sharp increase in life support areas that require cooling, the search for new magnetocaloric materials is very urgent at the present time. In this work, we suggest the ways for improving the magnetocaloric properties of the promising La 0.8- x K 0.2 Mn 1+ x O 3 (0 ≤ x ≤ 0.2) perovskites and compare the functional properties of nanocrystalline samples of about 40 nm with polycrystalline samples of about 1 μ m. The structure, morphology, magnetic properties and magnetocaloric effect of these compounds were studied as a function of manganese doping level. The main crystalline phase of all samples is a rhombohedral R 3 ‾ c perovskite structure. The maximum doping level of excess manganese for preserving single-phase structure of the nanocrystalline La 0.8- x K 0.2 Mn 1+ x O 3 compounds is x = 0.10. As x increases the Curie temperature T C is increased slightly. The best composition with the highest entropy change Δ S M max = −3.629 J/(kg⋅K) under 3 T at T C = 332 K is the La 0.8- x K 0.2 Mn 1+ x O 3 with x = 0.05. On the other hand, the La 0.8- x K 0.2 Mn 1+ x O 3 polycrystalline manganite with x = 0.10 exhibits the highest Δ S M max = −4.176 J/(kg⋅K) under 3 T at T C = 274 K. Additionally, the effect of hydrostatic pressure P up to 1.4 GPa has been investigated for the La 0.7 K 0.2 Mn 1.1 O 3 polycrystalline sample that leads to increasing T C to 287 K and reducing Δ S M max to −3.145 J/(kg⋅K) under 3 T. The obtained results demonstrate the ways for controlling magnetocaloric properties of the La 0.8- x K 0.2 Mn 1+ x O 3 compounds under internal and external conditions. [ABSTRACT FROM AUTHOR]

• Real molar formulas for BiFeO 3−δ and Bi 0.9 La 0.1 FeO 3−δ multiferroics were determined. • Real structure contains Bi3+, La3+, Fe2+, Fe3+, O2− ions and V(a), V(c) vacancies. • Dielectric constant ε ′ reduces in 5000 times at 1 Hz with rising P from 200 to 400 MPa. • Bi 0.9 La 0.1 FeO 3−δ multiferroics show a large value of H C ≥ 10 kOe at room temperature. • "Composition, Structure, Non-stoichiometry, Properties" correlation was established. The structure, microstructure, valence states, non-stoichiometry, dielectric and magnetic properties of lanthanum-modified multiferroics have been studied by X-ray diffraction, thermogravimetric, iodometric titration, SEM, XPS, dielectric spectroscopy and magnetic methods. Multiferroics of bismuth ferrite have been obtained by a rapid liquid phase sintering method under different pressures, P , for compacting stoichiometric mixture of precursors. On the basis of the experimental data, the molar formulas of real BiFeO 3−δ and Bi 0.9 La 0.1 FeO 3−δ structures have been determined. The real structure contains Bi3+, La3+, Fe3+, Fe2+ and O2− ions as well as cation V(c) and anion V(a) vacancies. The optimal temperature regimes of the rapid liquid phase sintering method for obtaining the single-phase Bi 0.9 La 0.1 FeO 3−δ , whose composition corresponds to the concentration region of destruction of a spin cycloid, have been defined. It has been established that oxygen non-stoichiometry δ and concentration of Fe2+ strongly depend on the pressure P. The initial dielectric permittivity of the Bi 0.9 La 0.1 FeO 3−δ multiferroics can be controlled and changed by the pressure P more than 5000 times. The correlations between the composition, structure, non-stoichiometry, dielectric and magnetic properties in the BiFeO 3−δ and Bi 0.9 La 0.1 FeO 3−δ have been established. In the pure BiFeO 3−δ at room temperature, rhombohedral distortions of a hexagonal structure with indications of a ferromagnetic double exchange have been detected. The magnetic structure of the single-phase Bi 0.9 La 0.1 FeO 3−δ is homogeneous with a large value of coercivity, H C ≥ 10 kOe, at room temperature. An analysis of the magnetic properties indicates the appearance of a weak ferromagnetism due to the destruction of the spin cycloid by lanthanum ions. [ABSTRACT FROM AUTHOR]

City park undertakes the function of urban core green island. Hefei Xiaoyaojin Park provides a leisure and entertainment place for Hefei citizens. Although it has been continuously transformed and upgraded, there are still many places to be improved. Through behavior observation and questionnaire, the usage and satisfaction evaluation of tourists in Xiaoyaojin Park were obtained, and the transformation design of Xiaoyaojin Park was analyzed from the perspective of behavior psychology by analyzing the behavior of tourists in different zones of Xiaoyaojin. Based on the premise of exploring the behavior of tourists in different spaces, a city park environment that meets the needs of tourists can be created by promoting the cultural context of the Three Kingdoms, improving the plant landscape and infrastructure of the site, optimizing the spatial function, and exploring the park design and transformation strategy that is more in line with the needs of people, in order to provide new ideas for the future landscape transformation of Xiaoyaojin park, and offer reference suggestions for the future transformation design of old city parks. [ABSTRACT FROM AUTHOR]

In the campus greening design, the shrub height is generally consistent with people's horizontal line of sight, which plays a significant role in people's visual focus. From the perspective of ornamental characteristics of plants, the application of shrub landscape is explored in a campus environment. Based on the analysis of the selection, arrangement and maintenance of shrub plants in campus gardens, the application of shrub landscape on campus was evaluated comprehensively from the theoretical analysis of plant ornamental characteristics and campus shrub landscape. Based on the research background of the problems existing in the application of shrub landscape on campus, this paper first collected and sorted out the relevant theories extensively, and then conducted in-depth research on the relevant theories by using analysis methods such as literature data, field investigation and questionnaire survey. The results will provide a theoretical guidance and practical advocacy for campus garden planning and design, and help to create a livable and comfortable campus environment. It is hoped that the results will have some references for future campus shrub landscape and play a certain promoting role. [ABSTRACT FROM AUTHOR]

As a member of the emerging MXenes family, Nb2CS2 offers distinctive superconductivity, excellent electrical properties, and outstanding chemical stability, making it potentially useful for energy storage, medical imaging, and quantum computing. Herein, we systematically investigate how ultrahigh pressure affects the electrical properties of Nb2CS2. The results indicate that Nb2CS2 retains robust superconductivity with T c > 8 K up to the maximum applied pressure of 146.8 GPa. Moreover, the upper critical magnetic field H c 2 (0) of Nb2CS2 increases with pressure, and the Pauli limit is violated at pressures greater than 120 GPa. Meanwhile, H c 2 (0) increases to 19.3 T at 146.8 GPa, which is 4.8 times greater than at the initial pressure. Further analysis suggests that the significant enhancement of H c 2 (0) below 30 GPa comes from the sharp pressure-induced rise of carrier concentration as the interlayer distance decreases, and the significant increase in H c 2 (0) above 86 GPa may come from enhanced spin–orbit coupling or the possible unconventional superconducting pairing mechanisms. These results provide insights into the superconducting properties of MXene materials and offer guidelines for further research on electronic transport in Mxenes under ultrahigh pressure. [ABSTRACT FROM AUTHOR]

The designed Cr 2 O 3 -ZnO hierarchical heterostructures have been successfully synthesized by a facile two-step route. The SEM, TEM, XRD and EDS mapping characterizations demonstrate that Cr 2 O 3 nanoparticles are well decorated on surfaces of nanosheet-assembled flowerlike ZnO, constructing three dimensional Cr 2 O 3 -ZnO hierarchical heterostructures. Such hierarchical architectures are developed and applied in formaldehyde (HCHO) gas detection. The gas sensing results indicate that Cr 2 O 3 -ZnO heterostructures based sensors exhibit superior HCHO gas sensing properties with rapid response/recovery behavior (1 s/5 s) toward 100 ppm formaldehyde (HCHO) gas, and favorable stability and repeatability with the on/off phenomenon when switching between HCHO and air at a optimal working temperature of 220 °C. The superior formaldehyde gas sensing performances are predominantly attributed to the appropriate sensitization effect induced by Cr 2 O 3 nanoparticles and the special three dimensional hierarchical architectures. [ABSTRACT FROM AUTHOR]

Effective modification of the structure and properties of halide perovskites via the pressure engineering strategy has attracted enormous interest in the past decade. However, sufficient effort and insights regarding the potential properties and applications of the high‐pressure amorphous phase are still lacking. Here, the superior and tunable photoelectric properties that occur in the pressure‐induced amorphization process of the halide perovskite Cs3Bi2I9 are demonstrated. With increasing pressure, the photocurrent with xenon lamp illumination exhibits a rapid increase and achieves an almost five orders of magnitude increment compared to its initial value. Impressively, a broadband photoresponse from 520 to 1650 nm with an optimal responsivity of 6.81 mA W−1 and fast response times of 95/96 ms at 1650 nm is achieved upon successive compression. The high‐gain, fast, broadband, and dramatically enhanced photoresponse properties of Cs3Bi2I9 are the result of comprehensive photoconductive and photothermoelectric mechanisms, which are associated with enhanced orbital coupling caused by an increase in BiI interactions in the [BiI6]3− cluster, even in the amorphous state. These findings provide new insights for further exploring the potential properties and applications of amorphous perovskites. [ABSTRACT FROM AUTHOR]

MoS 2 /RGO hybrids was successfully synthesized via hydrothermal method. The MoS 2 nanoflakes grown on the surface of the graphene were uniform and compact from the TEM images. Through the HRTEM images, we conclude the layer number of MoS 2 nanoflakes is in the range of 2–6. Photocatalytic experiments have been performed to verify the excellent photocatic performance of MoS 2 /RGO hybrids. The methylene blue (MB) was completely decomposition by MoS 2 /RGO hybrids within 55 and 75 min under the UV and VIS irradiation, respectively. It is much better than the photocatalytic performance of P25 (nano TiO 2 powder, the current commercial photocatalyst), especially under the VIS irradiation. Good photocatalytic stability of MoS 2 /RGO hybrids was proved through the secondary loop test, which further indicates its promising practical applications. We suggest that the excellent photocatalytic capability of MoS 2 /RGO hybrids can be attributed to their enhanced adsorptivity and conductivity because of the synergistic effect between the few layer MoS 2 and the graphene. [ABSTRACT FROM AUTHOR]

In this work, a novel multiferroic‐like nanocomposite is designed and obtained using the high‐pressure torsion (HPT) method. The crystal structure, phase composition, morphology, ferromagnetic (FM), and ferroelectric (FE) properties of the initial powders and ferroelectric/ferromagnetic nanocomposites are studied comprehensively. The initial powders and their composite show the perovskite and spinel crystalline phases for the FE and FM fractions, respectively. After HPT, the particle sizes of the initial powders are decreased significantly. It is shown that the novel nanocomposite consists of exchange‐interacting FE and FM phases and demonstrates improved magnetic and electrical properties in low fields at room temperature. A giant increase in residual polarization with an increase in external high‐pressure is found in new composite. The obtained results make it possible to consider the novel nanocomposite as a new functional material for its use both in electronic devices for monitoring ultra‐high‐pressure and in integrated circuits of high‐speed computing nanosystems with low switching energy. The HPT method is a promising method for obtaining new heterophase nanosystems. [ABSTRACT FROM AUTHOR]

Silicon is a long-standing photosensitive material because of its unique photoelectronic properties and mature manufacturing technology. However, silicon photodetectors are generally limited by weak photoresponse in the near-infrared region. In this work, pressure is used as an effective means of tuning the photoresponse of silicon, specifically in the near-infrared region. Silicon has two different types of photoresponse under pressure. In the pressure range from 1 atm to 10 GPa, huge pressure-enhanced photocurrent is observed under illumination by a xenon lamp and near-infrared light (1064 nm). At 10 GPa, the photocurrent density (Jph), responsivity (R), and external quantum efficiency are increased 40-fold from those at 1.2 GPa. Interestingly, above 10 GPa, a unique pressure-induced positive–negative photoresponse switch is found along with the phase transformation from the semiconductive phase (Si I) to the metallic phase (β-tin). Further experiments show that the photothermal effect is the main factor for negative photoresponse. All these pressure-induced properties give silicon more possibilities in the further design of visible and infrared photodetectors. [ABSTRACT FROM AUTHOR]

Exploring the behavior of nanocrystals with varying shapes and sizes under high pressure is crucial to understanding the relationship between the morphology and properties of nanomaterials. In this study, we investigated the compression behaviors of WS2 nanotubes (NT-WS2) and fullerene-like nanoparticles (IF-WS2) by in situ high-pressure X-ray diffraction (XRD) and Raman spectroscopy. It was found that the bulk modulus of NT-WS2 is 81.7 GPa, which is approximately twice as large as that of IF-WS2 (46.3 GPa). This might be attributed to the fact that IF-WS2 with larger d-spacing along the c-axis and higher defect density are more compressible under isotropic pressure than NT-WS2. Thus, the slender NT-WS2 possess a more stable crystal structure than the IF-WS2. Our findings reveal that the effects of morphology and size play crucial roles in determining the high-pressure properties of WS2 nanoparticles, and provide significant insight into the relationship between structure and properties. [ABSTRACT FROM AUTHOR]

Constantly exploring and improving the photoelectric properties of functional materials is of paramount importance for the development of the optoelectronics industry. Herein, a new strategy to extend the spectral response range and enhance the photoelectric properties of functional materials using high pressure is presented. In addition, the successful application of this strategy to the regulation of the photoelectric properties of 2D layered semiconductor iodine is reported. The maximum photocurrent is four orders of magnitude higher than that measured under initial pressure, with visible‐light illumination. Impressively, the light‐response range of iodine is successfully extended to the near‐infrared (1064 nm) with the application of pressure, and the photoresponse properties are also significantly enhanced with compression. These dramatically enhanced photoelectric activities are attributed to charge delocalization as well as an increased charge density in the regions between parallel molecules, which occur as a result of pressure‐induced charge transfer in the iodine molecules. These findings can be extended to guide the modification of the spectral response range and photoelectric properties of other functional materials. [ABSTRACT FROM AUTHOR]

Metal halide perovskite quantum dots (QDs) have garnered tremendous attention in optoelectronic devices owing to their excellent optical and electrical properties. However, these perovskite QDs are plagued by pressure‐induced photoluminescence (PL) quenching, which greatly restricts their potential applications. Herein, the unique optical and electrical properties of Eu3+‐doped CsPbCl3 QDs under high pressure are reported. Intriguingly, the PL of Eu3+ ions displays an enhancement with pressure up to 10.1 GPa and still preserves a relatively high intensity at 22 GPa. The optical and structural analysis indicates that the sample experiences an isostructural phase transition at approximately 1.53 GPa, followed by an amorphous state evolution, which is simulated and confirmed through density functional theory calculations. The pressure‐induced PL enhancement of Eu3+ ions can be associated with the enhanced energy transfer rate from excitonic state to Eu3+ ions. The photoelectric performance is enhanced by compression and can be preserved upon the release of pressure, which is attributed to the decreased defect density and increased carrier mobility induced by the high pressure. This work enriches the understanding of the high‐pressure behavior of rare‐earth‐doped luminescent materials and proves that high pressure technique is a promising way to design and realize superior optoelectronic materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • At high pressure, V 2 ZnC is thermodynamically and dynamically stable and no phase transition occurs. • Compared to V-C bonds, V-Zn and Zn-C bonds break more easily under stress, making it possible to obtain derived MXene materials (V 2 C). • High pressure increases the stability and hardness of V 2 ZnC, but decreases its conductivity. • At high pressure, V 2 ZnC has a high Debye temperature and melting point, making it suitable for high temperature applications. Based on the first principles of density functional theory, the effects of pressure on the crystal structure, elastic, electronic, thermodynamic stability and thermodynamic properties of the novel MAX phase V 2 ZnC were investigated. The elastic constants and phonon dispersion calculations indicated that V 2 ZnC is mechanically and dynamically stable in the pressure range 0–40 GPa. The enthalpy of formation calculation shows that V 2 ZnC is thermodynamically stable at a given pressure range, and pressure can improve the thermodynamic stability of V 2 ZnC. The calculated elastic constants and elastic modulus of V 2 ZnC increase with increasing pressure. In addition, pressure can improve the stiffness and elastic anisotropy of V 2 ZnC. Calculation of Poisson's ratio and B/G revealed a significant transition in the mechanical behavior of V 2 ZnC from brittleness to ductility at a pressure of 20 GPa. The analysis of the band structure and density of states confirms the metallic nature of V 2 ZnC. Under increasing pressure, a notable decrease in the electron state density at the Fermi level is observed, leading to an enhanced stability of V 2 ZnC. Furthermore, a systematic investigation of the thermophysical properties of V 2 ZnC under high pressure (0–40 GPa) has been conducted. It was found that the Debye temperature and melting point increase with the increase of pressure, indicating that the effective role of pressure in modulating the thermophysical characteristics of V 2 ZnC. [ABSTRACT FROM AUTHOR]

The development of the optoelectronics industry relies on the constant exploration and improvement of the photoelectric properties of functional materials. Responsivity and response speed are two key performance indicators of photodetectors. However, these parameters are often mutually suppressed, and ensuring both simultaneously is challenging. Herein, we developed a viable strategy to enhance the overall photodetection performance by applying pressure to improve both the photoresponsivity and the response speed of BiOBr simultaneously. The results showed that the responsivity of BiOBr at a pressure of 3.8 GPa was more than an order of magnitude higher than that measured at the initial pressure (0.2 GPa) under Xenon-light illumination. More importantly, the response speed of BiOBr was improved by almost an order of magnitude under 3.7 GPa and 405 nm laser illumination. The considerably enhanced photoresponsivity and photoresponse speed suggest that pressure effectively reduces the effective mass of carriers and promotes charge transfer between Bi-O atoms. Our findings reveal that comprehensive enhancement of optoelectronic properties in layered compounds can be achieved through pressure modulation of the electronic structure, providing a promising approach for materials design toward extraordinary properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Single-phase lanthanum-modified bismuth ferrite multiferroic ceramics have been synthesized by the rapid liquid-phase sintering (RLS) method. Phase composition, crystal structure, microstructure and dielectric properties of the Bi 0·9 La 0·1 FeO 3 multiferroic have been studied using TG/DTA, XRD, SEM, capacitive and composite dielectric resonator methods. It has been established that the optimal conditions for formation of a perovskite Bi 0·9 La 0·1 FeO 3 structure are 850 °C after 5 min in air. It has been found that the compacting pressure of the initial mixture of precursors from 90 to 1090 MPa can change the dielectric constant by ~25% in the low-frequency range and by ~80% in the microwave range up to complete elimination of the elastic polarization mechanism. The use of the RLS method under various compacting pressures opens additional possibilities for creating multifunctional multiferroics with controlled magnetoelectric coupling. Image 1 • Single-phase BLFO ceramics were synthesized by RLS method under different pressures. • Optimal conditions for formation of BLFO perovskite are 850 °C after 5 min in air. • Compacting pressure can change ε ′ of BLFO by ~25% in LF and by ~80% in MW ranges. [ABSTRACT FROM AUTHOR]

The AlInN film with a band gap of 2.96 eV is prepared on glass by radio frequency magnetron sputtering. Photoluminescence spectra reveals that the emission band is originated from both the band-edge and some defect-related radiation. The interdigital AlInN photodetector based on metal−semiconductor−metal (MSM) structure exhibits photoresponse characteristics from ultraviolet to visible light. The defect energy level is responsible for the multi-wavelength response of the low-energy incident irradiation light. The photodetector exhibits the best performance under 660 nm illumination, with a responsivity of 102 A/W, an external quantum efficiency of 190% and a specific detectivity of 2.8 × 109 Jones. These three factors improve by 4–6 orders of magnitude compared to point electrodes. The AlInN MSM interdigital electrode structure provides a relatively promising candidate structure for achieving high-performance multi-wavelength photodetectors. [ABSTRACT FROM AUTHOR]

Enhancement of the luminescence efficiency of up-conversion nanocrystals is essential for the development of near-infrared (NIR)-responsive photocatalysts. In this study, δ-doped hexagonal NaYF4:Yb,Tm@TiO2 (β-NaYF4:Yb,Tm@TiO2) nanocrystals, with the dopant ions Tm3+ and Yb3+ in two-dimensional planes, integrated with reduced graphene oxide (RGO) nanosheets were synthesized by a simple solvothermal process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), luminescence and ultraviolet absorption spectroscopy. The core, inner shell and outter shell of the δ-doped β-NaYF4:Yb,Tm are in the most efficient host structure phase, with a diameter of 29 nm and thicknesses of 6.4 and 1.2 nm, respectively. The δ-doped β-NaYF4:Yb,Tm exhibits about a 13 times increase in the luminescence intensity than the bare β-NaYF4:Yb,Tm due to the effective reduction of both the surface and inner defects around Yb3+. Moreover, the δ-doped β-NaYF4:Yb,Tm@TiO2/RGO exhibits significantly enhanced photocatalytic activity in the degradation of rhodamine B (RhB) under both NIR and UV irradiation. Our results highlight that the δ-doping construction of the most efficient host structure is promising for developing NIR-responsive photocatalysts. [ABSTRACT FROM AUTHOR]

(InGa) 2 O 3 films are grown on quartz substrates by radio frequency magnetron sputtering using In/Ga 2 O 3 target. The crystal structure, morphology, chemical states and optical properties of (InGa) 2 O 3 films after annealing are investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscope, X-ray photoelectron spectroscopy, optical transmission spectroscopy and photoluminescence spectroscopy. The crystallinity of (InGa) 2 O 3 film improves and phase segregation occurs as the annealing temperature is raised to 800 °C. A mass of cavities are formed on the surface of annealed (InGa) 2 O 3 films. The nanocrystal particles are found in the (InGa) 2 O 3 film annealed at 800 °C. The optical bandgap values of (InGa) 2 O 3 films change from 4.68 to 4.89 eV with increasing annealing temperature from room temperature to 800 °C, which is associated with the decrease of oxygen vacancies and loss of In component of (InGa) 2 O 3 films. The variation of emission band in (InGa) 2 O 3 films is influenced by the tunable bandgap, increasing grain boundary and phase segregation. This work investigates the effect of annealing on the optical properties of (InGa) 2 O 3 films and promotes the application of (InGa) 2 O 3 films in the optical field. • Amorphous (InGa) 2 O 3 films are deposited using well-designed In/Ga 2 O 3 target. • The bandgap tunability of (InGa) 2 O 3 films from 4.68 to 4.89 eV is ascribed to the decrease of oxygen vacancies and loss of In atoms after annealing. • The variation of emission bands in (InGa) 2 O 3 films with annealing temperature is associated with the tunable bandgap, increasing grain boundary and phase segregation. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) porous CoMnO thin films on nickel foam substrates were successfully prepared via electrostatic spray deposition (ESD) technique and then an annealing process for lithium-ion battery anodes. The CoMnO thin films exhibited high initial coulombic efficiency of 90% and excellent cycling performance with a reversible capacity of over 1366 mAh g after 100 cycles at a current density of 400 mA g. The improved electrochemical performances are attributed to the synergistic advantages of 3D porous CoMnO film and the Ni foam collector, which can provide effective void space to the large volume change during cycling, enhance reaction sites, and improve the electron transport. The ESD technique is facile and cost-effective and can be used as a promising method to synthesize 3D porous mixed transition-metal oxides materials. [ABSTRACT FROM AUTHOR]

Experimental synthesis of new sp 3 hybridized carbon/boron nitride structures remains challenging despite that numerous sp 3 structures have been proposed in theory. Here, we showed that compressed multi-walled boron nitride nanotubes (MWBNNTs) and boron nitride peapods (C 60 @BNNTs) with small diameters could transform into a new sp 3 hybridized boron nitride allotrope (Z -BN). This strategy is considered from the topological transition point of view in boron nitride nanotubes upon compression. Due to the increased curvature in compressed small-diameter MWBNNTs, the uncommon 4- and 8-membered rings in Z -BN could be more favorably formed. And the irreversible tube collapse is proved to be a critical factor for the capture of the formed Z -BN, because of the competition between the resilience of tube before collapse and the stress limitation for the lattice stabilization of Z-BN upon decompression. In this case, Z-BN starts to form above 19.0 GPa, which is fully reversible below 45 GPa and finally becomes quenchable at 93.5 GPa. This collapse-induced capture of the high-pressure phase could also be extended to other tubular materials for quenching novel sp 3 structures. [Display omitted] • A new sp 3 hybridized boron nitride allotrope (Z -BN) was captured by compressing MWBNNTs. • The increased curvature in small-diameter MWBNNTs was advantageous for forming uncommon 4- and 8-membered BN rings. • The competition between the resilience of tube and the stress limitation for the stabilization of Z-BN was proposed. • The strategies on synthesizing and capturing new structures are expected to be applicable to other nanotubes materials. [ABSTRACT FROM AUTHOR]

Themetal-organic framework (MOF) materials could exhibit advanced applications in many fields and their mechanical stability upon external stimuli is extremely important for the applications. Here, we discovered a Cd(II)-based metal-organic framework (Cd-MOF) exhibits a very high structural stability and the Cd-MOF structure remains stable and reversible upon compression up to at least 28 GPa, a pressure that has never been reported before. Moreover, this Cd-MOF material shows an obvious change in the photoluminescence (PL) emission upon compression, which has blue-green luminance at ambient conditions, while the blue emission is preserved but the green emission is quenched at above 5 GPa. This transition in PL emission is due to a pressure-induced framework transition, which is caused by an anisotropic compression of Cd-MOF framework under pressure, as revealed by our theoretical simulations. Our results show that such highly stable MOF framework could exhibit a potential for applications under extreme conditions as a novel optical material. An anisotropic and reversible compression was found in the Cd-MOF framework, which induced a novel photoluminescence change. [Display omitted] • Cd-MOF have a high structural stability and reversible upon compression up to 28 GPa. • Anisotropic compression of Cd-MOF framework was found at pressures lower than 5 GPa. • A PL change from blue-green to blue was obtained at 5 GPa upon compression. • The relationship between structural and optical properties of Cd-MOF was revealed. [ABSTRACT FROM AUTHOR]

We present an experimental study of a new hybrid material where nitrogen is encapsulated in the channels of porous zeolite AlPO4-5 (AFI) single crystals by a high-pressure method. The high-pressure behavior of nitrogen confined inside the AFI nano-channels is then investigated by Raman spectroscopy up to 44 GPa. Under pressure, the Raman modes of confined nitrogen show behaviors different from those of the bulk nitrogen. After the return to atmospheric pressure, it is demonstrated that non-gaseous nitrogen can be effectively stabilized by being confined inside the intact AFI sample. This result provides new insight into nitrogen capture and storage technologies. [ABSTRACT FROM AUTHOR]

Raman spectra of iodine species confined in one-dimensional elliptical channels of AlPO4-11 (AEL) crystals have been studied from room temperature down to −196 °C. As temperature decreases, thermal fluctuations of individual iodine molecules confined in AEL channels are slowed down and they prefer to rotate to channel axis direction, which increases the population of iodine molecules along channel axis (i.e., lying molecules and chains). Such temperature-driven orientation transformation of iodine molecules is found to be reversible upon heating up to room temperature. The experimental observations are in good agreement with our theoretical simulations by molecular dynamics on low density iodine-filled AEL crystals. We thus provide a new way to modulate the orientation of iodine molecules in nanochannels, which may have implications in low-temperature-sensitive nanoscale devices. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• The high pressure phase transitions of HfSe 2 were studied. • Pressure-induced semiconductor-metal transition appeared in the original P-3m1 phase. • The metallization was due to the overlap of valance and conduction bands with the contribution of Hf d and Se p orbitals. • A new metallic I 4 /mmm structure in HfSe 2 was found under high pressure. [Display omitted] In this study, we report the phase transitions and semiconductor-to-metal (S-M) transition of hafnium selenide (HfSe 2) under high pressure through experiments and theoretical calculations. The starting hexagonal structure transforms to an intermediate phase and I 4 /mmm structure above 10 GPa, and then converts into the I 4 /mmm structure completely above 47.2 GPa. Pressure-induced S-M transition at ~10 GPa was revealed by infrared (IR) reflectivity and resistance measurements. Theoretical calculations indicate that the pressure-induced metallization occurs in the initial hexagonal phase, which arises from the overlap of the valance and conduction bands with the contribution of the Hf d and Se p orbitals under high pressure. Upon pressure releases, the I 4 /mmm phase transforms into the initial hexagonal structure. This work provides new insights into the structures and electronic states of HfSe 2. [ABSTRACT FROM AUTHOR]

Design and enhancing the luminescence of rare earth materials under pressure have been important topics in the past few years. Here we report a new strategy for realizing pressure induced emission enhancement of rare earth element thulium (Tm) by confining the dopant luminescentions in a two-dimensional hexagonal NaYF 4 planes, NaYF 4 @β-NaYF 4 :Yb 0.2 ,Tm 0.005 @NaYF 4 delta-doped structure. Upon compression, NaYF 4 @β-NaYF 4 :Yb 0.2 ,Tm 0.005 @NaYF 4 exhibits a 2 fold increase in emissions, obviously higher than that of corresponding homogeneous doped samples. When Tm3+ was overdoped, this pressure induced emissions enhancement would absent in the whole pressure region due to concentration quenching. Moreover, both NaYF 4 @β-NaYF 4 :Yb 0.2 ,Tm 0.005 @NaYF 4 and corresponding homogeneous doped samples undergo structure transition under pressure. Raman study and calculations show that the delta-doping induced phonon peak red shift and reduced defects density increasing rate could play major roles for the pressure-induced emission enhancement of NaYF 4 @β-NaYF 4 :Yb 0.2 ,Tm 0.005 @NaYF 4 , and the deformation of the Y-F 9 polyhedrons at vertices leading to the structure transitions of both delta and homogeneous doped samples. These findings suggest that the pressure induced emission enhancement of rare earth materials can be realized by passivating inner and surface defects using a delta-doped structure. Image 1 • Realizing pressure induced emission enhancement of Tm by using δ-doped structure. • Reduced defect density increasing rate contribute emission enhancement under pressure. • The doping content of Tm plays a key role in their emissions under pressure. • Homogeneous and δ-doped β-NaYF 4 :Yb,Tm undergo structure transitions under pressure. [ABSTRACT FROM AUTHOR]

Understanding helium (He) incorporation into materials is essential to estimate the material performance in a nuclear environment for the fabrication of nuclear devices. The effect of helium irradiation on Zr 3 Al 3 C 5 was studied by using the first-principles method. It is found that the He interstitial atoms tend to situate in the Al-C layers in Zr 3 Al 3 C 5. The calculation of defect formation energy shows that the defects at the Zr sites are the most difficult to form, while vacancies at the Al and C sites are more ready to form in Zr 3 Al 3 C 5. The numbers of He atoms that can be trapped by an Al(2) and a C(3) vacancy are seven and three, respectively, which show that Al vacancies have a stronger ability to trap He atom than C vacancies. The migration of He in Zr 3 Al 3 C 5 is also investigated. The results indicate that He impurity atoms migrate more easily along the c-axis than in the a-b basal plane in the Al-C layer. The diffusion barrier of He atom from the Al-C into the Zr-C layer is determined to be 3.13 eV. The results imply that the Al-C layers tend to be disordered while the Zr-C layers exhibit good tolerance of damage under He irradiation. Additionally, we also studied the stress-strain relationships of Zr 3 Al 3 C 5 under tensile and shear loading, with the ideal tensile strength and shear strength of Zr 3 Al 3 C 5 predicted. [ABSTRACT FROM AUTHOR]

Cr 2 Ge 2 Te 6 is a rare layered ferromagnetic semiconductor that represents a promising material for novel thermoelectric and spintronic devices. High pressure is an effective way to change the electronic structure, and profoundly affects the physical and chemical properties of two-dimensional (2D) layered materials. Here we combined experimental results and theoretical calculations to investigate the structural evolution and properties of Cr 2 Ge 2 Te 6 under high pressure. It is found that Cr 2 Ge 2 Te 6 undergoes an isostructural phase transition from layered to non-layered structure at ~14 GPa, accompanied with a semiconductor to metal transition, which is distinct from the previous reports. The pressure-induced metallization is verified by the overlap of the valence and conduction bands, and the layered-to-non-layered isostructural transition is attributed to the enhanced interlayer Te–Te interaction by First-principles calculations. Our results provide a potential pathway to control the structure and property of layered materials and possibility for conceptually new devices via pressure engineering. • Cr 2 Ge 2 Te 6 undergoes an isostructural phase transition at ~14 GPa, and accompanied with a semiconductor to metal transition. • The semiconductor-to-metal transition was verified by IR and electrical experiments. • The metallization mechanism was interpreted by theoretical calculations. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles of the La 0. 6 Ag 0. 2 Mn 1. 2 O 3 manganite with superstoichiometric manganese have been obtained using nitrate pyrolysis method. Structure, phase composition, morphology, and size of the nanoparticles have been determined. Magnetic properties of the La 0. 6 Ag 0. 2 Mn 1. 2 O 3 nanoparticles have been studied near the temperature of their magnetic ordering. It has been shown that magnetization near critical temperature is equilibrium and superparamagnetic. It has been found that magnetization and a change in entropy have critical behavior with a large value of the magnetocaloric effect. Interrelation between the critical indices of magnetization and the magnetocaloric effect has been established. In strong magnetic field, these properties of the nanoparticles have behaviour comparable with bulk samples. In weak magnetic field, the effect of superparamagnetism on the entropy has been found. The magnitude of the contribution from superparamagnetism to the magnetocaloric effect has anomalous temperature dependence. The obtained results of the influence of superparamagnetism on the thermomagnetic properties of the nanoparticles near critical temperature are important to understand and can be used for applied applications. • Magnetically homogeneous La 0 · 6 Ag 0 · 2 Mn 1 · 2 O 3 nanopowder has been prepared. • It has been found that the soft magnetic nanoparticles are in SPM state near T C. • Critical indices obtained experimentally are in good agreement with each other. • In small H , an entropy change Δ S M associated with SPM near T C has anomalous maximum. • High values of Δ S M in the nanopowder under small magnetic field have been obtained. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskites with well-defined morphology have attracted much attention due to their unique photophysical properties. However, controlling the morphology of nanocrystalline perovskite to improve its photoelectric application remains a challenge. In this article, using a modified solution deposition method, we successfully synthesized uniform methylammonium lead iodide (MAPbI3) nanoplates, nanocubes, and nanorods and investigated the effect of morphology on the photoelectric properties of these materials. We found that the morphology can be controlled by regulating the amounts of reactant methylammonium iodide (MAI) and the rate at which MAPbI3 precursor is added into toluene solution, and that the corresponding size distributions can be optimized by tuning the final vacuum-drying temperature. The morphology has an obvious effect on the bandgap optimization and fluorescence enhancement of MAPbI3, and the nanoplates exhibit stronger photoluminescence intensity and have a longer carrier lifetime than nanocubes and nanorods. The results show that the morphologies of MAPbI3 perovskite nanocrystals can be controlled by tuning the synthesizing conditions, and the MAPbI3 perovskite nanocrystals with special morphology can be used in special nanosize optoelectronic devices. [ABSTRACT FROM AUTHOR]

We have studied the structural transformation of Sm@C88 under pressure up to 18 GPa by infrared spectroscopy combined with theoretical simulations. The infrared-active vibrational modes of Sm@C88 at ambient conditions have been assigned for the first time. Pressure-induced blue and red shifts of the corresponding vibrational modes indicate an anisotropic deformation of the carbon cage upon compression. We propose that the carbon cage changes from ellipsoidal to approximately spherical around 7 GPa. A smaller deformation of the carbon bonds in the area close to the Sm atom in the cage suggests that the trapped Sm atom plays a role in minimizing the compression of the adjacent bonds. Pressure induced a significant reduction of the band gap of the crystal. The HOMO-LUMO gap of the Sm@C88 molecule decreases remarkably at 7 GPa as the carbon cage is deformed. Also, compression enhances intermolecular interactions and causes a widening of the energy bands. Both effects decrease the band gap of the sample. The carbon cage deforms significantly above 7 GPa, from spherical to a peanut-like shape and collapses at 18 GPa. [ABSTRACT FROM AUTHOR]