Crystal Growth Orientation Research Articles

Aminoacid-Assisted Synthesis of Hollow Hierarchical FER Zeolite with Improved Catalytic Performance.

Hierarchical zeolites are highly-desired catalysts in the petrochemical industry due to their shorter diffusion length, faster diffusion rate, and better accessibility to active acid sites compared with conventional zeolites. Herein, we report a simple aminoacid-assisted method to synthesize urchin-like hollow hierarchical FER zeolite with abundant mesopores and macroporous inner cavities. An aminoacid (i.e. L-lysine) is used to facilitate the agglomeration of primary nanoparticles, and the agglomerates with staged crystallization in the internal and surface. The preferential nucleation and crystal growth at the external surfaces together with the lagged crystallization of the inner core of the agglomerates results in the formation of hollow inner cavities after the exhaustion of interior materials. Thanks to the unique hierarchical structure and more accessible acid sites, the hollow hierarchical FER zeolite exhibits improved catalytic performance over the conventional one in the skeletal isomerization of 1-butene to isobutene.

Silanol-Engineered Nonclassical Growth of Zeolite Nanosheets from Oriented Attachment of Amorphous Protozeolite Nanoparticles.

Zeolite nonclassical growth via particle attachment has been proposed for two decades, yet the attachment mechanism and kinetic regulation remain elusive. Here, nonclassical growth of an MFI-type zeolite has been achieved by using amorphous protozeolite (PZ) nanoparticles containing encapsulated TPA+ templates and abundant silanols (Si-OH) as sole precursors under hydrothermal conditions. The silanol characteristics of the precursor were studied by two-dimensional (2D) solid-state nuclear magnetic resonance (NMR) correlation spectroscopy, which were proven to play critical roles in determining precursor attachment behavior and crystal growth orientation. Under mechanical ball-milling or tablet-pressing process, pressure drove the fusion of spherical PZ into platelet-like integrated PZ (IPZ) coupled with transformations of external silanols from evenly distributed to curvature-dependent distributed and internal silanols from isolated to spatially proximate. Compared to isolated silanols, the spatially proximate silanols possessed a stronger correlation with TPA+, benefiting the formation of Si-O-Si bonds via silanol condensation. Subsequently, driven by minimization of surface energy, particle attachment of the platelet-like IPZ precursor preferentially occurred at high-curvature surfaces with high-density silanols, leading to anisotropic rates of nonclassical growth and thus the formation of high-aspect-ratio MFI-type zeolite nanosheets. Advanced electron microscopy provided direct evidence of attachment of amorphous IPZ precursors to crystalline intermediate surfaces along the c-axis direction with the formation of amorphous-crystalline interfaces, followed by interface elimination and structural evolution to a single-crystalline phase. Our findings not only unravel the zeolite nonclassical growth mechanism but also reveal the critical role of silanol chemistry in kinetic regulation, which is of great importance for pursuing a tailored zeolite synthesis.

Optical floating zone growth and thermionic emission properties of La0.9Sr0.1B6 single crystal

This paper has studied the crystal structure, growth orientation, crystal quality and thermionic emission properties of the La0.9Sr0.1B6 single crystal prepared by the optical floating zone method. By the means of XRD, single crystal X-ray diffraction, X-ray Laue diffraction, X-ray rocking curve and TEM, the La0.9Sr0.1B6 single crystal grown along [100] orientation is determined to be a single-phase solid solution of Sr-doped LaB6 with the typical cubic structure and have a good crystal quality and integrity. The higher J1kV (42.55 A/cm2), Jo (31.19 A/cm2) and lower Φeff (2.492 eV) than LaB6 under the cathode operating temperature of 1500 °C as well as the good thermionic emission stability strongly suggest that the grown La0.9Sr0.1B6 single crystal has a good potential to be a promising hot cathode material.

Buried-Interface Engineering of Conformal 2d/3d Perovskite Heterojunction for Efficient Perovskite/Silicon Tandem Solar Cells on Industrially Textured Silicon.

Exploring strategies to control the crystallization and modulate interfacial properties for high-quality perovskite film on industry-relevant textured crystalline silicon solar cells is highly valued in the perovskite/silicon tandem photovoltaics community. The formation of a two-dimensional/three-dimensional (2D/3D) perovskite heterojunction has been widely employed to passivate defects and suppress ion migration in the film surface of perovskite solar cells. However, realizing solution-processed heterostructures at the buried interface face solvent incompatibilities with the challenge of underlying-layer disruption and texture incompatibilities with the challenge of uneven coverage. Here, we use a hybrid two-step deposition method to prepare robust 2D perovskites with cross-linkable ligands underneath the 3D perovskite. This structurally coherent interlayer benefits the preferred crystal growth of strain-free and uniform upper perovskite, inhibits interfacial defect-induced instability and recombination, and promotes charge-carrier extraction with ideal energy-level alignment. We demonstrate the broad applicability of the bottom-contact heterostructure for different textured substrates with conformal coverage and various precursor solutions with intact properties free of erosion. With this buried interface engineering strategy, the resulting perovskite/silicon tandem cells based on industrially textured Czochralski (CZ) silicon achieve a certified efficiency of 28.4% (1.0 cm2 ), while retaining 89% of the initial PCE after over 1,000-hour operation. This article is protected by copyright. All rights reserved.

Characterising Hydroxyapatite Deposited from Solution onto Novel Substrates: Growth Mechanism and Physical Properties.

Whilst titanium, stainless steel, and cobalt-chrome alloys are the most common materials for use in orthopaedic implant devices, there are significant advantages in moving to alternative non-metallic substrates. Substrates such as polymers may have advantageous mechanical biological properties whilst other substrates may bring unique capability. A key challenge in the use of non-metal products is producing substrates which can be modified to allow the formation of well-adhered hydroxyapatite films which promote osteointegration and have other beneficial properties. In this work, we aim to develop methodology for the growth of hydroxyapatite films on surfaces other than bulk metallic parts using a wet chemical coating process, and we provide a detailed characterisation of the coatings. In this study, hydroxyapatite is grown from saturated solutions onto thin titanium films and silicon substrates and compared to results from titanium alloy substrates. The coating process efficacy is shown to be dependent on substrate roughness, hydrophilicity, and activation. The mechanism of the hydroxyapatite growth is investigated in terms of initial attachment and morphological development using SEM and XPS analysis. XPS analysis reveals the exact chemical state of the hydroxyapatite compositional elements of Ca, P, and O. The characterisation of grown hydroxyapatite layers by XRD reveals that the hydroxyapatite forms from amorphous phases, displaying preferential crystal growth along the [002] direction, with TEM imagery confirming polycrystalline pockets amid an amorphous matrix. SEM-EDX and FTIR confirmed the presence of hydroxyapatite phases through elemental atomic weight percentages and bond assignment. All data are collated and reviewed for the different substrates. The results demonstrate that once hydroxyapatite seeds, it crystallises in the same manner as bulk titanium whether that be on a titanium or silicon substrate. These data suggest that a range of substrates may be coated using this facile hydroxyapatite deposition technique, just broadening the choice of substrate for a particular function.

Investigation of the acicular aragonite growth behavior in AOD stainless steel slag during slurry-phase carbonation

This study presents a novel method for producing acicular aragonite using argon oxygen decarburization (AOD) slag while controlling the reaction temperature, reaction time, stirring speed, and the magnesium-to‑calcium stoichiometric ratio. This approach provides steel plants with an opportunity to decrease their CO2 emissions and promote efficient resource utilization and CO2 storage through the production of high-quality value-added products. The experimental results showed that reaction temperature was the most significant factor affecting the carbonation efficiency of AOD slag, followed by reaction time, stirring speed, CO2 partial pressure, and the liquid-to-solid ratio (L/S). The study also found that elevated temperature and prolonged reaction duration favored the preferential precipitation of aragonite. Additionally, raising the temperature and the magnesium-to‑calcium stoichiometric ratio was shown to enhance the formation of aragonite, affecting its crystal growth orientation and dimensions. The optimal combination of reaction parameters for the preparation of acicular aragonite was found to be the reaction time of 8 h, the magnesium-to‑calcium stoichiometric ratio of 0.8, the reaction temperature of 120 °C, and the stirring speed of 200 r·min−1. Under these conditions, the resulting acicular aragonite exhibited excellent overall uniformity, a large aspect ratio, and a smooth crystal surface, with a content of 91.49 %, a single crystal length ranging from 9.86 to 32.6 μm, and a diameter ranging from 0.63 to 2.15 μm. This study provides valuable insights into the efficient production of acicular aragonite from steel slag while reducing CO2 emissions and promoting the sustainable use of resources.

Microstructure Evolution of CET-Free Epitaxial Growth NiCoCrAlYTa Coating by Electron Beam Cladding

Some unavoidable factors in the operating environment could damage single-crystal components of nickel-based single-crystal superalloys. This work prepared an epitaxial growth NiCoCrAlYTa repaired coating without the columnar-to-equiaxed transition (CET) phenomenon on a nickel-based single-crystal superalloy by electron beam cladding. The microstructure of two cross-sections and two surfaces at different depths were characterized. Moreover, the formation mechanism of coating dendrite was revealed by studying the relationship between coating dendrite size, growth direction, and solidification rate. The microstructure evolution and crystal growth orientation of the coating were investigated. The microstructural investigation of the sample revealed that the dendrites’ orientations on the coating’s horizontal section were different, and its characteristics were highly visible on the surface of the coating. The crystal growth orientations of the coating on the vertical cross-section parallel/perpendicular to the scanning direction of the electron beam were also different. Moreover, the average primary dendrite arm spacing (PDAS) of the columnar dendrite in the different areas of the coating was different and increased from 2 μm to 4 μm. The oxidation resistance of the coating at 1000 °C was about three times higher than that of the substrate.

A control strategy for microwave absorption performance on a two-dimensional scale

Two-dimensional (2D) zeolitic imidazolate frameworks (ZIFs) are promising materials for microwave absorption for their desirable features. However, there has been a lack of a corresponding relationship between the growth pattern of 2D ZIF materials at the micro-scale and the macroscopic microwave absorption performance. This work synthesized 2D ZIF-L and its derivatives via a precise structural regulation strategy. By changing the axial orientation of crystal growth, the synthesis of two-dimensional bladed and rod-shaped precursors with controllable thickness and varying shapes at the macro scale was controlled. The leaf-like structure of ZIF-L derivates with large surface area is beneficial for the exposure of reactive oxygen vacancies, increasing the relaxation loss. While the ultra-thin rod-shaped structure which can shorten the electron migration and jump paths to reduce the energy barrier is advantageous to conductive loss. As a result, the prepared L-7 exhibits superior electromagnetic wave absorption ability with the widest effective absorption bandwidth (EAB) of 5.53 GHz at a thickness of 1.80 mm. When the total thickness is 1.90 mm, R-7 can exhibit the minimum reflection loss (RLmin) value of about −60.40 dB. This study emphasizes the 2D scale regulation for obtaining new generation and environmentally friendly microwave absorbers. Metal-based materials derived from ZIF-L with extremely thin thicknesses and a large surface area have shown great potential in microwave absorbers.

Effects of 300 keV N+ Ion Irradiation on Radio-Frequency Sputtered Al-ZnO Thin Films for a Low Energy Regime

The experimentally observed effects induced by ion irradiation in AZO thin films are discussed in limited articles. Here, in the present study, we report the results of ion irradiation by 300 keV Nitrogen ions. To study the structural, morphological, and optical properties of thin film, XRD, FE-SEM, and UV visible spectroscopy were used and it was confirmed by the structural investigation that the ion irradiation resulted in changes in different calculated structural parameters. Furthermore, different dopant concentrations are examined in relation to the effects of irradiation. The polar crystal growth orientation mechanism is initiated over nonpolar crystal growth orientation, as the 2%AZO thin films are presented to ion beam irradiation. The transition in the stress of thin film after N ion irradiation is also discussed. The phenomena responsible for the morphological changes is discussed. The observed morphological changes are correlated with structural changes. The change in the colour of the thin films after irradiation is explained. The other alterations in the thin films’ optical properties are also discussed. The systematics study of the irradiated thin films may be helpful for device fabrication.

Directing Highly a-Axis-Oriented ZSM-5 Nanosheets with Pre-estimated Bifunctional Imidazole Cations.

An MFI-topology nanosheet zeolite with a highly a-axis-oriented structure has rarely been reported but with a great potential for industrial applications. Theoretical calculations on the interaction energies between the MFI skeleton and ionic liquid molecules indicated the possibility of preferential crystal growth along a specific direction, according to which highly a-oriented ZSM-5 nanosheets were synthesized from commercially available 1-(2-hydroxyethyl)-3-methylimidazolium and layered silicate sources. The imidazolium molecules directed the structure formation and meanwhile acted as zeolite growth modifiers to restrict the crystal growth perpendicular to the MFI bc plane, which induced unique a-axis-orientated thin sheets with ∼12 nm thickness. The a-oriented ZSM-5 exhibited more competitive propylene selectivity and longer lifetime than bulky crystals in methanol-to-propylene (MTP) reaction. This research would provide a versatile protocol for the rational design and synthesis of shape-selective zeolite catalysts with promising applications.

Recent Progress in Long‐Wavelength InGaN Light‐Emitting Diodes from the Perspective of Epitaxial Structure

Over the last decades, continuous technological advancements have been made in III‐nitride light‐emitting diodes (LEDs), so that they are considered as a promising replacement of traditional light sources. With the emission wavelength covering the entire visible spectrum, InGaN LEDs find various applications such as solid‐state lightings, full‐color displays, and visible light communication. However, the quantum efficiency of InGaN LEDs suffers from a dramatic decline as the emission wavelength extends from blue to green–red region. This issue restrains the lighting and display applications based on the color‐mixing monolithic lighting source system. In this review, the recent breakthroughs in long‐wavelength InGaN LEDs, together with the challenges and approaches to realize high‐indium‐composition InGaN epilayers, are introduced. These cover the different epitaxial substrates, nucleation layers, and epitaxial structures, especially multiple quantum wells active region. The related studies are also discussed to improve the long‐wavelength LEDs performance from the aspect of crystal quality, growth orientation, carrier‐injection, and 3D nanostructures. Finally, current status and perspectives for future long‐wavelength LEDs development are proposed briefly.

Synthesis and characterization of pure and Cu-doped WO3 thin films for high performance of toxic gas sensing applications

Oxygen vacancies and the high surface area of nanostructured materials offers stronger gas adsorption active sites for improved gas sensing performance. In the present work, we have deposited WO3-based thin films using a chemical spray pyrolysis technique at a substrate temperature of 400 °C with other optimized preparation parameters. Besides, this study reports the influence of Cu doping at various weight percentages on the structural, morphological, optical and toxic gas sensing properties of WO3 films in detail. The crystalline structure of the material was investigated using the X-ray diffraction technique. Each X-ray diffraction analysis of the films demonstrated a polycrystalline nature, matching the hexagonal phase of WO3 with the (200) plane of preferential orientation of crystal growth. The optical characteristics of the thin film's material were analyzed by UV–Vis absorption spectroscopy. The optical energy bandgap (Eg) of the deposited thin films was estimated using the Tauc relation, and the value was decreased along with the increase in the Cu-doping concentration. The surface roughness of the films has been investigated using atomic force microscopy. The TEM patterns of sprayed Cu-doped WO3 thin films exhibit nanocrystalline features. Detecting toxic gasses is of great importance across the globe due to an alarming enhancement in respiratory, ocular, skin, and lung diseases. Hence, cost-effective and room temperature-operated Cu-doped WO3 thin film sensors to trace low concentrations of toxic gasses have been investigated and systematically reported. It is observed that the sensor response is to be increased with the increase in Cu-doping concentration, particularly the 4 wt.% Cu-doped sensor exhibited a response value of 7.2 and fast response and recovery times in the presence of 50 ppm ammonia vapor.

Multi-Physical Field Simulation of Cracking during Crystal Growth by Bridgman Method.

Crystal materials are prone to cracking during growth, which is a key problem leading to slow growth and difficulty in forming large-size crystals. In this study, based on the commercial finite element software COMSOL Multiphysics, the transient finite element simulation of the multi-physical field, including fluid heat transfer-phase transition-solid equilibrium-damage coupling behaviors, is performed. The phase-transition material properties and maximum tensile strain damage variables are customized. Using the re-meshing technique, the crystal growth and damage are captured. The results show the following: The convection channel at the bottom of the Bridgman furnace greatly influences the temperature field inside the furnace, and the temperature gradient field significantly influences the solidification and cracking behaviors during crystal growth. The crystal solidifies faster when it enters the higher-temperature gradient region and is prone to cracking. The temperature field inside the furnace needs to be properly adjusted so that the crystal temperature decreases relatively uniformly and slowly during the growth process to avoid crack formation. In addition, the crystal growth orientation also significantly affects the nucleation and growth direction of cracks. Crystals grown along the a-axis tend to form long cracks starting from the bottom and growing vertically, while crystals grown along the c-axis induce the laminar cracks from the bottom in a horizontal direction. The numerical simulation framework of the damage during crystal growth, which can accurately simulate the process of crystal growth and crack evolution and can be used to optimize the temperature field and crystal growth orientation in the Bridgman furnace cavity, is a reliable method to solve the crystal cracking problem.

A structured CoWO4 synthesized by microwave-assisted hydrothermal process as electrode for hybrid supercapacitor

A structured carambola-like CoWO4 was fast prepared by a microwave-assisted hydrothermal method with the help of urea and NH4F. Physical characterization indicated that the as-obtained CoWO4 displayed a large specific surface area, high dispersion and self-selected orientation of crystal growth. Further electrochemical tests presented a high specific capacity of 492.0 C[Formula: see text]⋅[Formula: see text]g[Formula: see text] at 1 A[Formula: see text]⋅[Formula: see text]g[Formula: see text], low internal resistance and excellent cycle stability as 137.3% capacity maintenance after 8000 cycles at 20 A[Formula: see text]⋅[Formula: see text]g[Formula: see text]. These excellent electrochemical properties for the as-obtained material indicate that CoWO4 has great potential as hybrid supercapacitor electrode materials. This work also provides a new and effective solution for regulating the morphology of CoWO4-based hybrid supercapacitor materials to further improve the electrochemical performance.

An Ultrasensitive Sandwiched Heterostructure Planar Photodetector with Gradient Quasi‐2D Perovskite

Abstract2D Ruddlesden–Popper perovskites have attracted increasing attention for their outstanding optoelectronic properties and improved stability compared to the 3D counterparts. The unique nature of the crystal growth orientations and the uneven distribution in the 2D perovskites provide a great opportunity to construct a promising lateral photodetector device that has not been fully uncovered. Here, by improving the random orientation to the vertical orientation of the film in the lateral device structure, the dark current is expected to be significantly suppressed in the photodetector. Accompanied by the gradient phase distribution, a p‐type conductive channel at the bottom and another electron collection layer on the top are applied to achieve a high on/off ratio. Overall, the resultant photodetector realizes a low dark current of 10−10 A and exhibits impressive photodetection performance, including a high responsivity of 10.10 A W−1, a notable detectivity of 6.83 × 1012 Jones, and fast response speeds (14 ms/31 ms).

Influence of Ca/P ratio on the catalytic performance of hydroxyapatite for decarboxylation of itaconic acid to methacrylic acid

Methacrylic acid, an important organic chemical, is commercially manufactured starting from fossil feedstock. The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid. In view of the problems existing in the researches on this route such as use of noble metal catalyst, harsh reaction conditions and low desired-product yield, we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance. The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity. The highest yield of MAA up to 61.2% was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH, 2 MPa of N2, 250 ℃, and 2 h. On this basis, a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established. With the aid of catalyst characterization using X-ray powder diffraction, NH3/CO2 temperature-programmed desorption, N2 physisorption, inductively coupled plasma optical emission spectrometry, and scanning electron microscopy, we found that the distribution of surface acid sites and basic sites, crystal growth orientation, texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio. Furthermore, the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.

Ion Implantation in the Form of Layers: A Novel Method to Surface Properties

In this study, a novel method was adopted to tailor the surface properties of iron. We attempted to increase the degradation rate of iron by H-induced damaging. Equal number of H ions were implanted in four samples using a 2MV Pelletron accelerator. But the ion distribution was varied in the iron matrix by adding H ion layers in successively increasing depths. Interesting outcomes, contrary to our assumption were observed. The open-circuit potential was observed to shift toward a stable side. The Tefal plot also revealed improved corrosion potential and decreased corrosion current by adding H layers. Crystallographic studies revealed improved crystallinity and a small shift in preferred orientation of crystal growth.

Chlorine-Assisted Growth of Epitaxial InGaN and AlGaN Crystals at Low Temperatures Using Plasma-Enhanced Chemical Vapor Deposition

The chlorine-assisted growth of epitaxial indium gallium nitride (InGaN) and aluminum gallium nitride (AlGaN) crystals was achieved with high reproducibility at the low temperature of 600 °C in the plasma-enhanced chemical vapor deposition (PECVD) reactor via the reaction between the metal trichlorides with high vapor pressures and nitrogen plasma. After adding hydrogen gas to the growth processes of InGaN and AlGaN, the problems for the etching of chlorine plasma on the as-grown InGaN crystals and the appearance of crystal planes different from (002), derived from the worse and the better bonding abilities of materials, respectively, were solved effectively. Inside AlGaN crystals, the phase separation of gallium nitride (GaN) and aluminum nitride (AlN) can be avoided by controlling the amount of precursor aluminum. The epitaxial InGaN and AlGaN crystals have the same (002) crystal plane as the GaN(002) bottom layers and exhibit the same ⟨0001⟩ crystallographic growth direction along the axial direction of GaN microrods, representing the consistent growth orientation of the epitaxial crystals. The process temperatures of InGaN and AlGaN can be greatly decreased using chlorine gas and plasma so that the related applications of low-temperature growth may be expanded drastically in the future.

Relationship between morphological and physical properties in nanostructured CuMnO2

In this study, crednerite CuMnO 2 nanostructures were prepared using a hydrothermal method at 100 °C with various amounts of NaOH mineralizator. Obtained nanostructured crednerite CuMnO 2 with monoclinic structure (space group C 2/ m ) exhibits two morphologies: nanobelts with lengths of 1–1.5 nm and thickness of 15–25 nm, and nanoplates with diameters of 50–70 nm. Comparative analyses of the prepared samples reveal a close relationship between morphological and physical properties of nanostructured CuMnO 2 . A low NaOH concentration promotes elongated crystal growth along the c-axis, resulting in nanobelt-shaped morphology. A strong base solution, on the other hand, promotes the formation of nanoplates. The different morphologies of nanostructured CuMnO 2 have different spectroscopic and magnetic properties. The Raman active A 1g mode at 637 cm −1 and a modified Curie-Weiss behavior characterize the nanobelt-shaped sample. This phase has two magnetic phase transitions: ferromagnetic at 9.2 K and antiferromagnetic at 42 K. The nanoplate-shaped sample, on the other hand, exhibits typical behavior as reported in the literature, namely the Raman active A 1g mode at 688 cm −1 and low-dimensional magnetism with antiferromagnetic ordering below 62 K. The variation in magnetic properties is presumably due to partial oxidation of Cu 1+ /Cu 2+ and Mn 3+ /Mn 4+ , as well as a change in Mn 3+ spin states from low-spin in nanobelt-shaped samples to high-spin in nanoplate-shaped samples. Both morphological and preferred crystal growth of nanostructured CuMnO2 can be tuned utilizing suitable amounts of NaOH mineralizator in the growth solution. A pure CuMnO2 phase of monoclinic structure has been prepared in the form of nanobelts with lengths up to 1.5 mm or nanoplates possessing 50–70 nm in diameter. The physical properties measurements imply distinct behaviour amongst these samples.The CuMnO2 nano-belts exhibit a Raman peak at a lower Raman number compared to that of the nanoplates. The nanobelt sample has been shown to be undergone two successive magnetic phase transitions: antiferromagnetically at 42 K and ferromagnetically at 9.2 K. The nanoplate samples have exhibited low-dimensional magnetic behaviour. The variation in the magnetic properties can be ascribed to the partial oxidation of Cu1+/Cu2+ and Mn3+/Mn4+. The variation of spin states of the Mn ions can be correlated with the change in the morphologies, i.e., from a low-spin state in the belt-shaped sample to a high-spin state in the plate-shaped samples. • Both morphological and preferred crystal growth of nanostructured CuMnO2 and then their physical properties can be tuned utilizing suitable amounts of NaOH mineralizator in the growth solution. Remarkably, a nanobelt CuMnO2 has been obtained for the first time. • Our experiments divulge that a pure CuMnO2 phase of monoclinic structure can been prepared in the form of nano-belts with lengths up to 1.5 mm or nanoplates possessing 50–70 nm in diameter. • The physical properties measurements imply distinct behaviour amongst these samples. The CuMnO2 nano-belts exhibits Raman peak at a lower Raman number compared to that of the nanoplates. • Regarding to the magnetic characteristics, the nanobelt samples have shown to be undergone into two successive magnetic phase transitions: antiferromagnetically at 42 K and ferromagnetically at 9.2 K. • The variation in the magnetic properties can be ascribed to the partial oxidation of Cu 1+ /Cu2+ and Mn 3+ /Mn4+. Remarkably, the variation of spin states of the Mn ions can be correlated with the change in the morphologies, i.e., from low-spin state in the belt-shaped sample to high-spin state in the plate-shaped samples.

Design and Synthesis of Carbazole‐Cyclopentathiophene Alternating Copolymers for Inhibiting Phase Separation of Cs0.15FA0.85PbI3

AbstractTo inhibit phase separation of CsxFA1−xPbI3 perovskite into optically inactive δ‐CsPbI3 and δ‐FAPbI3 under high humidity and light conditions, herein two polymers, poly[3‐methyl‐6‐(2‐methylspiro[cyclopenta[1,2‐b:5,4‐b′]dithiophene‐4,2′‐[1,3]dithiolan]‐6‐yl)‐9‐octyl‐9H‐carbazole] (TM3) and poly[3‐methyl‐6‐(2‐methylspiro[cyclopenta[1,2‐b:5,4‐b′]dithiophene‐4,2′‐[1,3]dioxolan]‐6‐yl)‐9‐octyl‐9H‐carbazole] (TM4), are designed and synthesized to dope the Cs0.15FA0.85PbI3 perovskite film for perovskite solar cells (PSCs). The results of X‐ray photoelectron spectroscopy and nuclear magnetic resonance confirm the existence of coordination and hydrogen bonds between the polymer and Cs0.15FA0.85PbI3 perovskite. Ion migration in the perovskite film is thus markedly suppressed by the TM doping, as verified by the electrical poling measurement. Benefiting from these interactions, the TM doping is able to inhibit phase separation of Cs0.15FA0.85PbI3 markedly at a relative humidity of 55–65% and under light. Furthermore, the TM doping has other positive effects such as enhancing perovskite crystallinity, improving crystal growth orientation, reducing trap density, increasing hole extraction, and suppressing charge recombination. Consequently, the TM3‐ and TM4‐doped PSCs achieve a power conversion efficiency of 21.96% and 20.01%, respectively, against 17.82% for the undoped PSC. The humidity, environmental, illumination, and thermal stabilities of unencapsulated devices are also improved significantly by the TM3‐ and TM4‐doping, respectively. By comparison, TM3 with the S substitution shows abetter effect than TM4 with the O substation on photovoltaic performance and device stability.