The use of mixed cation absorber composition was considered as an efficient strategy to mitigate the degradation effects in halide perovskite solar cells. Despite the reports about partial stabilization at elevated temperatures, unfavorable phase transition after thermocycling and electric field-driven corrosion remains critical bottlenecks of perovskite thin-films semiconductors. In this work, we developed stabilized heterostructures based on CsFAPbI3, modified with mechanically synthesized quasi-2D perovskite incorporating the 5-ammonium valeric acid cation (AVA2FAPb2I7). We found that integration of AVA2FAPb2I7 into grain boundaries boosts phase resilience under harsh thermocycling from -10 up to 100 C and suppresses transitions, as well as decomposition to PbI2. The rapid oxidation of metal contacts in the multi-layer stacks with non-passivated CsFAPbI3 was effectively suppressed in the fabricated heterostructure. A comprehensive interface study of the copper electrode contact revealed that the incorporation of AVA2FAPb2I7 stabilized the lead and iodine states and suppressed contamination of FA cation in ambient conditions. Meanwhile, the metal-perovskite interface remained predominantly in the Cu(0)-Cu(I) state. The observed stabilization in perovskite heterostructure was attributed to an increased activation energy for delta-phase accumulation at the grain boundaries combined with reduced ionic diffusion. The obtained results opened important highlights for the mechanisms of the improved phase stability after thermal cycling and mitigation of the interface corrosion and under an applied electric field.

The formation of liquid crystalline (LC) phases in aqueous suspensions of cellulose nanocrystals (CNCs) largely depends on the geometric dimensions of the CNC particles, their concentration, polydispersity, and surface charge. Obtaining reproducible LC structures requires meticulous control over the particle production conditions that determine these properties. The objective of this work is to investigate the possibility of formation of LC phases in dilute aqueous suspensions of CNCs and the preservation of nematic and chiral nematic order in dried films. CNCs were prepared via sulfuric acid hydrolysis of filter paper. Their properties were characterized using transmission electron microscopy, polarized optical microscopy, FTIR spectroscopy, dynamic light scattering, X-ray diffraction and elemental analysis. The rheological properties of dilute CNC suspensions and the morphology of films formed from these suspensions were examined. Additionally, the effect of ultrasonic treatment on the properties of CNC suspensions was evaluated. It was found that LC phase formation begins at a CNC suspension concentration of approximately 1 wt

The problem of assessing the quality of non-toxic, environmentally safe pure KNN-based ceramics is of vital importance for potential applications in various fields including actuators, piezoelectric gages, and ferroelectric memory (FeRAM). In this work, we carried out a combined study of the chemical composition (XPS), structure (XRD), and ferroelectric properties (PFM) aiming at understanding the effect of doping with 1 mol.% Ba and solid-state synthesis conditions on the quality of KNN-based ceramics. The microstructural images and element maps have been obtained using SEM and EDX. The dielectric permittivity of the material has been studied as a function of temperature. The composition of the secondary P4/mbm K6Nb10.8O30 phase has been identified. We show that Ba doping during two-stage solid-state synthesis reduces the secondary phase content from 15 % to 8 % and improves the ferroelectric properties of the material. However, it was found that the synthesis method has a predominant effect on the secondary phase content. The use of two-stage synthesis instead of one-stage synthesis reduces the secondary phase content from 30 % to 8 %.

The absence of a universal method for isolating cellulose nanocrystals (CNCs) has prompted researchers to explore alternative approaches to traditional sulfuric acid hydrolysis. In this study, the authors continue their previous research by investigating CNC synthesis through cellulose solvolysis in an alcoholic environment. The CNCs were successfully obtained utilizing controlled sulfuric acid solvolysis of sulfate cellulose in a butanol-1/benzene mixture. The highest CNC yield (over 60 %) was achieved at strictly controlled acid-to-benzene ratios in a butanol-1/benzene/sulfuric acid reaction mixture, with a significant reduction in the optimal acid concentration. The study also analyzes the physicochemical properties of the isolated CNCs. No surface alkylation of the synthesized CNCs was observed during the cellulose solvolysis in the butanol-1/benzene mixture. Besides, the properties of these CNCs closely resembled those obtained through traditional sulfuric acid hydrolysis. The paper also discusses the potential mechanism of cellulose solvolysis in the process of CNC production.

The lack of a universal method for isolating cellulose nanocrystals (CNCs) has encouraged researchers to look for new methods and approaches as alternatives to traditional sulfuric acid hydrolysis. Acid alcoholysis has long been actively used in cellulose depolymerization processes to obtain a variety of alkyl glycosides and further alcoholysis products. In the present article, the authors continue their earlier research on the synthesis of CNCs in the presence of a sulfuric acid catalyst in an alcoholic environment. In this work, CNCs were obtained from sulfate- bleached pulp in a medium of primary monohydric alcohols (& Scy; n H 2 n +1 OH, n = 5-8). A maximum CNC yield of 60 % was achieved with pentanol-1 at a sulfuric acid concentration of 50 %. The work revealed that the alcohols studied can be ranked in descending order based on both the acid concentration corresponding to the maximum CNC yield and the yield itself, as follows: pentanol-1, hexanol-1, heptanol-1, and octanol-1. For octanol-1 the maximum CNC yield was 20 % at an acid concentration of 40 %. The physicochemical properties of the isolated CNCs were studied. No surface alkylation of the synthesized CNCs was found to occur during cellulose treatment in the media of the alcohols studied, as the properties of the CNCs, in general, were similar to those of CNCs obtained by standard sulfuric acid hydrolysis. This study broadens the scope of alternative methods to traditional sulfuric acid hydrolysis, and is likely to appeal to researchers engaged in developing novel approaches for CNC extraction.

The lack of a universal method for isolating cellulose nanocrystals (CNCs) has encouraged researchers to look for new methods and approaches as alternatives to traditional sulfuric acid hydrolysis. Moreover, acid alcoholysis has long been actively used in cellulose depolymerization processes to obtain a variety of alkyl glycosides and further alcoholysis products. In the present article, the authors continue their earlier research on the synthesis of CNCs by cellulose alcoholysis in an alcoholic environment. In this work, CNCs were obtained by controlled sulfuric acid alcoholysis of sulfate cellulose in a medium of primary monohydric alcohols (СnH2n+1OH, n = 5–8). A maximum CNC yield of 60% was achieved with pentanol-1 at a sulfuric acid concentration of 50%. The paper showed that in descending order of both the acid concentration corresponding to the maximum CNC yield and the yield itself, the alcohols studied can be arranged as follows: pentanol-1, hexanol-1, heptanol-1, and octanol-1. For 1-octanol, the maximum CNC yield was 20% at an acid concentration of 40%. The physicochemical properties of the isolated CNCs were studied. No surface alkylation of the synthesized CNCs was found to occur during cellulose alcoholysis in the media of the alcohols studied, as the properties of the CNCs, in general, were similar to those of CNCs obtained by standard sulfuric acid hydrolysis.

The lack of an alternative universal method for obtaining cellulose nanocrystals (CNCs), that would replace traditional sulfuric acid hydrolysis, encourages researchers to look for new methods and approaches. At the same time, alcoholysis of cellulose has long been known as a method of obtaining various alkyl glycosides and products of their further alcoholysis. In this paper, the authors propose to use controlled alcoholysis of cellulose in a medium of simple alcohols for CNC synthesis. Specifically, in this study, CNCs are prepared by controlled sulfuric acid alcoholysis of sulfate cellulose in a medium of four aliphatic alcohols (methanol, ethanol, propanol, and butanol-1). The paper also discusses the possible mechanism of cellulose alcoholysis during CNC preparation and shows that, in contrast to hydrolysis, cellulose alcoholysis can produce CNCs with a higher yield and under milder conditions (at a lower acid concentration). The physicochemical properties of the CNCs synthesized are studied. On the whole, the properties of the CNCs obtained by alcoholysis and hydrolysis are found out to be similar. However, alcoholysis is shown to produce CNC particles with a higher surface charge, which increases the colloidal stability of aqueous CNC suspensions and can be used to study their liquid crystal properties. Under the given conditions of CNC synthesis in alcoholic media (concentration of sulfate cellulose suspension of 0.025 g/mL, temperature of 50 °C, duration of 2 h), butanol-1 makes it possible to achieve the maximum possible CNC yield of 60%.

The results of the synthesis and study of Zn-containing clusters at the interface of a Si3N4/Si film implanted with 64Zn+ ions with a dose of 5 × 1016 cm–2 and an energy of 40 keV are presented. A Si3N4 film is preliminarily deposited onto a silicon substrate using the CVD-method. Then, the implanted samples of 10 × 10 mm are annealed in an oxidizing atmosphere (in air) with a step of 100°С for 1 h at each step in the temperature range from 400 to 800°С. The Rutherford backscattering method is used to study the profiles of zinc during annealing. The structure and composition of the film are studied using scanning electron microscopy in combination with energy-dispersive spectroscopy, as well as photoluminescence. After implantation, individual clusters of metallic zinc with a size of about 100 nm or less are recorded near the surface of the Si3N4 film. It is established that, during annealing, Zn clusters grow in the sample and the phase of metallic Zn gradually transforms into phases of its oxide ZnO and then, presumably, silicide Zn2SiO4. After annealing at a temperature of 700°С, which is the most optimal for obtaining the ZnO phase, zinc-oxide clusters with a size of about 100 nm are formed in the Si3N4 film. A peak appears in the photoluminescence spectrum at a wavelength of 370 nm due to exciton luminescence in zinc oxide. After annealing at 800°C, the ZnO phase degrades and, presumably, the zinc-silicide phase Zn2SiO4 is formed.

To enhance the redispersibility of dried nanocellulose, cellulose nanocrystal (CNC) cryogels were produced by freeze-drying CNC-stabilized cyclohexane-in-water Pickering emulsions. The CNC cryogels were easily redispersed in water and organic solvents; thus, the approach proposed made it possible to significantly improve CNC redispersibility in aqueous and nonaqueous media.

This article shows the new insights for stabilizing the p‐i‐n perovskite solar cells (PSCs) and modules based on double cation CsFAPbI3 absorber using CsCl additives. The presence of chlorine in the perovskite crystal structure results in the decrease of the lattice parameters by 0.6 ± 0.06%, in the increase of the bandgap value (+0.018 eV), and charge carrier lifetimes with respect to the undoped one. The champion PSCs based on the CsFAPbI3−xClx absorber show an increase in power conversation efficiency from 18.06% up to 20.13% after Cl doping. The light‐soaking stability of PSCs measured at maximum power point demonstrates impressive increase of the T80 from 1128 h for CsFAPbI3‐based devices to more than 3479 h for CsFAPbI3−xClx ones. It is found that the Cl doping suppresses the formation of lead iodide and pure CsPbI3 induced by decomposition and phase segregation processes only when the perovskite is covered with the C60/BCP electron‐transporting layer (ETL), while in the structure without ETL Cl additive is not effective. Finally, the high potential of Cl‐anion engineering for the perovskite modules (5 × 5 cm2) is demonstrated, which shows promising 17.08% of power conversation efficiency and light‐soaking stability for 1396 h.

The main drawback of cellulose nanocrystals (CNCs) obtained by conventional sulphuric acid hydrolysis is their low thermal stability in consequence of pyrolysis catalyzed by sulfo-groups on the CNC surface. Replacement of surface sulfo-groups by carboxyl groups as a result of oxi-dation allows the thermal stability of CNCs to be enhanced significantly. Although a great num-ber of studies have reported properties of polymer nanocomposites reinforced by CNCs, thermal properties of the composites compared to the neat polymers are discrepant and still poorly under-stood. In this work, CNCs were produced from microcrystalline cellulose by sulfuric acid hydroly-sis and (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidation. The CNC composites with water-soluble polymers ??? polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone and poly-acrylamide ??? were obtained. The composites were characterized by various methods, i.e. transmis-sion electron and scanning electron microscopies, energy-dispersive X-ray analysis, Fourier -transform infrared spectroscopy, X-ray diffraction and thermogravimetric analyses, differential scanning calorimetry, and tensile testing. A side-by-side comparison between the thermal and mechanical properties of the polymer composites reinforced by sulfuric acid-hydrolyzed and TEMPO-oxidized nanocellulose was conducted. Analysis of the thermal properties of CNC shows that the surface sulfonate groups replacement with carboxyl groups leads to significant increase of initial temperature of thermal degradation and temperature of the maximum decomposition rate of the CNC. However, the thermal behavior of the composites is much more complicated, and such thermal properties are discussed in detailed. The tensile properties analysis of the compo-sites demonstrates that an addition of TEMPO-oxidized nanocellulose does not improve signifi-cantly the tensile strength and Young???s modulus as compared with sulfuric acid-hydrolyzed one.

Sol–gel method has been employed for preparing porous carbon materials (xerogels and aerogels) using nanocrystalline cellulose (NCC) as a template. The method includes sol–gel synthesis of inorganic silica matrix (using tetraethoxysilane as SiO2 precursor) and carbonization of NCC under inert atmosphere followed by removal of SiO2 by refluxing in alkali solution. Factors affecting formation of porous carbon structure and resultant porous carbon materials have been studied.

We investigate the changes in structural and optical properties of perovskite crystals induced by e-beam irradiation with high flux (10 15 electrons per cm 2 , energy 5 MeV) and an extremely high dose (25 MRAD). The result clearly shows that MAPbBr crystals are stable for high energy applications.

ZnO single crystals are used for the fabrication of laser targets for high-energy electron irradiated UV laser cathode-ray tubes and homoepitaxial substrates for lasers. The technology of ZnO based UV LEDs imposes strict requirements to surface quality. Chemical-mechanical polishing delivers good surface quality but it is known that polishing of ZnO polar faces may yield different results. Surface-sensitive high-resolution X-ray diffraction (HRXRD) and X-ray reflectometry (XRR) methods have been used for studying the structure of (0001) and (000–1) polar faces of ZnO after chemical-mechanical polishing. Two double-sided polished (0001) ZnO substrates have been cut out from different hydrothermally grown ingots. The damage and density depth profiles for the Zn and O faces of the specimens have been retrieved from the X-ray diffraction curves and the specular reflection curves, respectively. Intensity distributions in the vicinity of the [0002] and [0000] reciprocal lattice sites have been taken on a D8 Discover X-ray diffractometer (Bruker-AXS, Germany) in a triple-crystal setup. For separating the coherent and incoherent scattering components, the intensity profiles have been analyzed along sections perpendicular to the diffraction vector and located at different distances from the reciprocal lattice sites. The HRXRD and XRR data have been compared with atomic force microscopy (AFM) data. The HRXRD method has revealed damaged layers at both faces of the specimens, with the layer thicknesses differing for the Zn and O faces, i.e., 5–7 nm for the Zn face and 10–11 nm for the O face. The XRR method has shown that both faces are sufficiently smooth. These results have been confirmed by AFM (RMS roughness ~ 0.23 ± 0.07 nm). However, the concentration of electrons in the superficial layers has been found to change. The layer thickness proves to be greater for the O face. We have hypothesized that the phenomena observed are caused by the difference in the chemical interaction of the Zn and O faces with the polishing agents.

Nanoclusters of metals and metal-oxide compounds in various solid-state matrices can find application in promising microelectronic devices. The results of studying memristors based on silicon-oxide films implanted with 64Zn+ ions (dose of 3 × 1016 cm–2 and energy of 40 keV) at room temperature and annealed at temperatures from 400 to 800°C in an oxidizing environment are presented. The concentration profiles of implanted zinc, as well as matrix elements, silicon and oxygen, are obtained via the Rutherford backscattering spectroscopy of He+ ions with an energy of 2 MeV. The surface topology is investigated using a scanning probe microscope in the atomic-force-microscopy mode and Kelvin mode. After implantation, sample-surface smoothing occurs due to sputtering. Further, during thermal annealing, the surface roughness increases and broadening of the roughness distribution is observed in comparison with the implanted sample. The images of the surface potential obtained in the Kelvin mode differ in terms of the sign of the signal: positive, for the initial sample, and negative, for the sample annealed at 800°C. The phase composition of the films is studied using X-ray diffraction analysis in the grazing geometry. It is found that crystalline phase of Zn was formed in the SiO2 film after implantation. After annealing at 800°C, the Zn phase is mainly transformed into the zinc silicide (willemite) Zn2SiO4 phase and partially into the ZnO phase. The analysis of small peaks in the diffraction patterns carried out using the EVA program indicates that the β-Zn2SiO4 and Zn1.95SiO4 phases are formed in the samples.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/polycaprolactone (PHBV/PCL) polymer mixtures reinforced by cellulose nanocrystals (CNCs) have been obtained. To improve the CNC compatibility with the hydrophobic PHBV/PCL matrix, the CNC surface was modified by amphiphilic polymers, i.e., polyvinylpyrrolidone (PVP) and polyacrylamide (PAM). The polymer composites were characterized by FTIR, DSC, TG, XRD, microscopy, BET surface area, and tensile testing. The morphological, sorption, thermal, and mechanical properties of the obtained composites have been studied. It was found out that with an increase in the CNC content in the composites, the porosity of the films increased, which was reflected in an increase in their specific surface areas and water sorption. An analysis of the IR spectra confirms that hydrogen bonds can be formed between the CNC hydroxyl- and the –CO– groups of PCL and PHBV. The thermal decomposition of CNC in the PHBV/PCL/CNC composites starts at a much higher temperature than the decomposition of pure CNC. It was revealed that CNCs can either induce crystallization and the polymer crystallite growth or act as a compatibilizer of a mixture of the polymers causing their amorphization. The CNC addition significantly reduces the elongation and strength of the composites, but changes Young’s modulus insignificantly, i.e., the mechanical properties of the composites are retained under conditions of small linear deformations. A molecular-dynamics simulation of several systems, starting from simplest binary (solvent-polymer) and finishing with multi-component (CNC—polymer mixture—solvent) systems, has been made. It is concluded that the surface modification of CNCs with amphiphilic polymers makes it possible to obtain the CNC composites with hydrophobic polymer matrices.

In this paper, physical adsorption of polyvinylpyrrolidone (PVP) was used as the method of surface modification of cellulose nanocrystals (CNCs). The work also considers the PVP molecular weight effect on dispersion of the surface-modified CNC in dichloromethane (DCM). The authors analyze the physicochemical properties of the composite with polycaprolactone (PCL) - CNC/PVP/PCL - prepared from a solution of PVP-modified CNCs in DCM, and conduct a molecular dynamics simulation of the interactions between the system (CNC, PVP, PCL) components in vacuum and in a solvent medium (water, DCM). According to the simulation results, the CNC/PVP/PCL composite has the following structure: PCL macromolecules have practically no direct contacts with the CNC surface but are located between the PVP macromolecules that, in their turn, are predominantly located near the CNC particle surface. (C) 2021 Elsevier B.V. All rights reserved.

In this work, we have developed methods of synthesis of cellulose nanocrystal (CNC) conjugates with chlorotriazine reactive dyes (RDs)—reactive violet, reactive-bright red and reactive bright-orange.) The prepared CNC-RD conjugates were characterized by a complex of techniques: UV–Vis, FTIR and solid-state 13C NMR spectroscopy, thermogravimetric and elemental analysis, particle size and zeta potential analysis, scanning electron and polarization optical microscopy. An analysis of the solid state 13C NMR spectra allowed us to conclude that the crystallinity index of the CNC-RD conjugates, compared to CNCs, did not change, i.e. RDs covalently bonded with the surface of the CNC particles and did not affect the CNC crystalline structure. The amount of the dye covalently bonded to the CNC particle surface was determined based on the elemental analysis data and using a square-cross-section model of the cellulose nanocrystal. The results obtained enabled us to make a conclusion that the RD covalent fixation was selective and occurred on one of the CNC ends (the so-called reducing end of the cellulose polymeric chain). Successful modification of the CNC surface was confirmed by UV–Vis spectroscopy. It was found that aqueous suspensions of the CNC-reactive violet dye conjugates possessed indicator properties. The size and charges of the CNC-RD particles in diluted aqueous suspensions were determined; the CNC-RD aqueous suspensions were found to have high colloidal stability. The stabilizing effect of the CNC-reactive violet dye conjugate for the formation of Pickering emulsions of the oil-in-water type was studied. It was shown that the CNC-reactive violet dye conjugate effectively stabilized n-decane emulsions in water.

Polymer-based magnetoelectric composite materials have attracted a lot of attention due to their high potential in various types of applications as magnetic field sensors, energy harvesting, and biomedical devices. Current researches are focused on the increase in the efficiency of magnetoelectric transformation. In this work, a new strategy of arrangement of clusters of magnetic nanoparticles by an external magnetic field in PVDF and PFVD-TrFE matrixes is proposed to increase the voltage coefficient (αME) of the magnetoelectric effect. Another strategy is the use of 3-component composites through the inclusion of piezoelectric BaTiO3 particles. Developed strategies allow us to increase the αME value from ~5 mV/cm·Oe for the composite of randomly distributed CoFe2O4 nanoparticles in PVDF matrix to ~18.5 mV/cm·Oe for a composite of magnetic particles in PVDF-TrFE matrix with 5%wt of piezoelectric particles. The applicability of such materials as bioactive surface is demonstrated on neural crest stem cell cultures.