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New bromide compounds A2BIBIIIBr6 with a double perovskite structure provide variety and flexibility of optoelectronic properties, and some of them are of poor toxicity in comparison with such popular lead halides. The promising compound with a double perovskite structure was proposed recently for the ternary system of CsBr-CuBr-InBr3. Analysis of phase equilibria in the CsBr-CuBr-InBr3 ternary system showed stability of the quasi-binary section of CsCu2Br3–Cs3In2Br9. Formation of the estimated phase Cs2CuInBr6 by melt crystallization or solid-state sintering was not observed, most likely, as a result of higher thermodynamic stability of binary bromides CsCu2Br3 and Cs3In2Br9. The existence of three quasi-binary sections was observed, while no ternary bromide compounds were found.

Silver inverse opals have been prepared electrochemically using a number of water-ethanol acidic or alkaline electrolytes. Opal matrices made of polystyrene microspheres of 420 nm diameter were used as templates. Compositions of electrolytes and conditions of syntheses have been optimized according to cyclic voltammetry and stability window of silver complexes during the experiments. Samples with the most uniform structure have been deposited from the iodous electrolyte. At the same time, the list percentage of surface admixtures observed for the opals formed from the rhodanide electrolyte using X-ray photoelectron spectroscopy (XPS). Reflectance optical spectra of the silver inverse opals measured with angles of incidence of 8 - 64° have shown various plasmon excitation modes in a visible spectral range according to the Bragg effect making the silver opals attractive for the Surface-Enhanced Raman Spectroscopy (SERS).

A new organic-inorganic hybrid [{p-(CH3)2NH—C6H4—NH3}2Cl][BiI6] was synthesized and its crystal structure was established. The hybrid consists of an inorganic anion [BiI6]3− and an organic cation [{p-(CH3)2NH-C6H4-NH3}2Cl]3+. The [BiI6]3− anions are linked via non-covalent I...I interactions between axial atoms of neighboring anions to form chains running along the c axis of the tetragonal unit cell. In the cationic part, the Cl− anion is involved in four (N)H…Cl hydrogen bonds with hydrogen atoms of the p-(CH3)2NH—C6H4—NH32+ cation, forming a two-dimensional substructure. Alternating covalent and I...I halogen bonds in the anionic substructure and cation—anion hydrogen bonds provide the formation of a three-dimensional supramolecular structure with a band gap of 1.93 eV.

The double perovskite halides A2BIBIIIX6 provide flexibility for various formulation adjustments and are of less toxicity in comparison with well-discussed complex lead halide derivatives. Such type of structure can be formed by replacing two Pb2+ ions in the cubic lattice with a pair of non-toxic heterovalent (monovalent and trivalent) metal cations, such as silver and indium. The aim of this work is to briefly characterize the phase equilibria in the ternary system CsBr-AgBr-InBr3 and investigate the thermodynamic availability of synthesis of Cs2AgInBr6 double perovskite phase by solid-state sintering or melt crystallization. The results demonstrate the unfeasibility of the Cs2AgInBr6 phase but high stability of the corresponding binary bromides perspective for optoelectronics.

We report on solution-processed bismuth triiodide (BiI3) solar cells and their optoelectronic properties under different fabrication approaches. The BiI3 films crystallized by annealing under controlled solvent vapour conditions were found to have dominant effects on film morphology as well as the crystal growth. The photovoltaic device with BiI3 film followed by annealing under a chlorobenzene vapour atmosphere demonstrated the best power conversion efficiency of ∼1.01% with an open circuit voltage of 0.587 V in the inverted device configuration. This is attributed to the improvement in film quality comprising uniform morphology, increase in grain size, and hence mitigation of defect profile. Based on the material growth properties, and device analysis, our report provides insight into the correlation between film morphology, opto-physical properties, and defect profile in the BiI3 based device.

Hexamethylenetetramine (HMT) was used as a strong base for the preparation of new hybride iodobismuthates, (HMTH)2BiI5·(CH3)2C═O (1) and (HMTH)2BiI5 (2). They crystallize in the orthorhombic system...

Graphene oxide was reduced by aspartic acid, β-mercaptoethanol in the acidic mixture, hydrothermal method and by atomic hydrogen (deuterium and tritium). Raman spectroscopy and FTIR indicat...

The preparation of hydro- and aerogels based on reduced graphite oxide and gold nanoparticles obtained by the method of Turkevich is described. According to the transmission electron microscopy data, gold nanoparticles have a spherical shape and an average size of 16‒18 nm. Sorption of methylene blue dye from water solutions was used to characterize the obtained 3D structures. The sorption properties of hydro- and aerogels were compared; it was shown that aerogels sorb the dye more efficiently (>80%) than a composite based on hydrogel (~50%). The formed porous 3D structure of the aerogel efficiently sorbs the molecules of the dye, while the gold nanoparticles facilitate its destruction under the visible light. Sorption by aerogels of pure graphite oxide is most efficient at room temperature, in a neutral medium, and in the absence of additional reducing agents. Introduction of gold nanoparticles to aerogels led to an increase of the maximal sorption by 15%.

Golden inverse opals additionally decorated with 15.5 ± 1.5 nm gold nanoparticles are proposed as reusable substrates for surface-enhanced Raman spectroscopy (SERS). Gold nanoparticles are found to be uniformly distributed making an input of enhancement ability of spectral characteristics with the colloidal system by ten times. This technique is demonstrated to be efficient in spectral features tuning via a combination of different gold derivatives. Two lasers served for resonant, pre-resonance, and non-resonance signal analyses. Reusability of the Au-Au composite films is demonstrated for methylene blue as a stable dye deposited onto the SERS chips using a 632.8-nm resonant laser for exciting. The enhancement factor for methylene blue achieved 108 and for rohodamine 6G was of about 105. It was observed that rinsing of Au-Au nanocomposite SERS films with distilled water and heating up to 100 °C followed by dropping on a new portion of Au colloids onto the platform regenerates the substrates.

We report the synthesis, crystal structures, and optical properties of two new compounds, K18Bi8I42(I2)0.5·14H2O (1) and (NH4)7Bi3I16(I2)0.5·4.5H2O (2), as well as the electronic structure of the latter. They crystallize in tetragonal space group P4/mmm with the unit cell parameters a = 12.974(1) and c = 20.821(3) A for 1 and a = 13.061(3) and c = 15.162(7) A for 2. Though 1 and 2 are not isomorphous, their crystal structures display the same structural organization; namely, the BiI6 octahedra are linked by I2 units to form disordered layers in 1 and perfectly ordered chains in 2. The I–I bond distances in the thus formed I–I–I–I linear links are not uniform; the central bond is only slightly longer than in a standalone I2 molecule, whereas the peripheral bonds are significantly shorter than longer bonds typical for various polyiodides, which is confirmed by Raman spectroscopy. The analysis of the electronic structure shows that the atoms forming the I–I–I–I subunits transfer electron density from their o...

Mesoporous silver nanoparticles were easily synthesized through the bulk reduction of crystalline silver(I) oxide and used for the preparation of highly porous surface-enhanced Raman scattering (SERS)-active substrates. An analogous procedure was successfully performed for the production of mesoporous silver films by chemical reduction of oxidized silver films. The sponge-like silver blocks with high surface area and the in-situ-prepared mesoporous silver films are efficient as both analyte adsorbents and Raman signal enhancement mediators. The efficiency of silver reduction was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The developed substrates were applied for SERS detection of rhodamine 6G (enhancement factor of about 1–5 × 105) and an anti-ischemic mildronate drug (meldonium; enhancement factor of ≈102) that is known for its ability to increase the endurance performance of athletes.

Gold porous films with an 2D inverse opal structure were prepared via electrochemical deposition for further application as SERS-active substrates for the on-chip analysis of heme B derivatives. The thickness of the deposited film was controlled through deposition charge while the grain size was dependent significantly on electrolyte content. A semiquantitative surface analysis of film composition and phase analysis of the gold films were performed by XPS and XRD methods while the observed local, Mie and Bragg plasmon resonance modes were discussed based on UV–vis reflectance data.

ZnO inverse opal films were synthesized electrochemically using aqueous and non-aqueous zinc acetate electrolytes and ITO deposited polystyrene opal matrices. The following thermal oxidation in air was performed for further application in optoelectronics. The overall composition and deposition potentials varied to reach uniform porous films with opal structure. Most uniform photonic film of ZnO with zincite structure has been deposited from DMSO electrolyte. Photoluminescence spectra of the ZnO coverages showed more complex spectra for precipitates sedimented from aqueous baths than from DMSO. Less deficient films of opal ZnO films deposited from DMSO demonstrated lower scattering effect compared to coverages deposited from aqueous electrolytes. Magnetron sputtering was applied for Au/ZnO composite film formation. The optical spectra of the Au/ZnO composite coverages correlate to spectra of uniform Au opal films.

Air-stable caesium tin iodide (Cs2SnI6) double perovskite are highly desirable for substituting the lead-based halide perovskite solar cells. In this work, we have investigated the effect of A-site tailoring in Cs2SnI6 by adding monovalent cation (Rb and Ag) on film growth properties, (morphology, structural properties, opto-physical properties), optoelectronic properties, and device characteristics. The crystal analysis suggests that the A-site additives suppress CsI secondary phase in (Cs1-xAx)2SnI6 film for x 0.5 whereas multiple secondary phases occur in higher additive content. The opto-physical properties reveal a small change in bandgap energy for alloyed film and excellent thermal stability in ambient air. The inverted device structure ITO/CuI/Cs2SnI6-alloyed/PCBM/AZO/Ag, for the first time, demonstrated the improvement in device parameters (with VOC~ 0.38 V and efficiency of ~0.66%) for the alloyed films. The capacitance analysis reveals that the high defect density in bulk as well as at the interface (Nt > 1019 cm−3) has a deleterious effect on the device performance. In this work, we underline insight into the A-site tailoring of Cs2SnI6 double perovskite and the dominant limiting factors for getting high device performance.

The effect of pH on the growth pathways and final morphology of the plasmonic gold nanoparticles (AuNPs) synthesized using natural Citrus limon extract was in the spotlight. In acidic medium (pH 2.5–5), the growth of AuNPs is fast and involves an intermediate aggregation stage, whereas pH 7–9 results in much slower nucleation-growth route. The synthesis at pH 5 was shown to be the most appropriate for preparation of 8-nm gold nanospheres with narrow size distribution and amazingly bright surface plasmon resonance. The reported findings contribute to better understanding of the processes in “green” AuNP synthesis using C. limon extract and can promote its implementation in sustainable industry. Pronounced plasmonic properties and eco-friendly precursors of the AuNPs make them an essential material for biological tagging and cell visualization.

Carbon-based nanomaterials have piqued the interest of several researchers. At the same time, radioactive labeling is a powerful tool for studying processes in different systems, including biological and organic; however, the introduction of radioactive isotopes into carbon-based nanomaterial remains a great challenge. We have used the Langmuir hydrogen dissociation method to introduce tritium in single-walled carbon nanotubes and graphene oxide. The technique allows us to achieve a specific radioactivity of 107 and 27 Ci/g for single-layer graphene oxide and single-walled carbon nanotubes, respectively. Based on the analysis of characteristic Raman modes at 1350 and 1580 cm−1, a minimal amount of structural changes to the nanomaterials due to radiolabeling was observed. The availability of a simple, nondestructive, and economic technique for the introduction of radiolabels to single-walled carbon nanotubes and graphene oxide will ultimately expand the applicability of these materials.

Surface-enhanced Raman spectroscopy-active nanocomposites of silver and graphene oxide were obtained by ultrasonic aerosol spray pyrolysis of graphene oxide suspension in diamminesilver(I) hydroxide aqueous solution thus allowing one to tune silver nanoparticle load, size and an overall specific area of the nanocomposite.

Four iodobismuthates, LiBiI4·5H2O (1), MgBi2I8·8H2O (2), MnBi2I8·8H2O (3), and KBiI4·H2O (4), were prepared by a facile solution route and revealed thermal stability in air up to 120 °C. Crystal structures of compounds 1-4 were solved by a single crystal X-ray diffraction method. 1: space group C2/c, a = 12.535(2), b = 16.0294(18), c = 7.6214(9) Å, β = 107.189(11)°, Z = 4, R = 0.029. 2: space group P21/c, a = 7.559(2), b = 13.1225(15), c = 13.927(4) Å, β = 97.14(3)°, Z = 2, R = 0.031. 3: space group P21/c, a = 7.606(3), b = 13.137(3), c = 14.026(5) Å, β = 97.14(3)°, Z = 2, R = 0.056. 4: space group P21/n, a = 7.9050(16), b = 7.7718(16), c = 18.233(4) Å, β = 97.45(3)°, Z = 4, R = 0.043. All solid state structures feature one-dimensional (BiI4)(-) anionic chains built of [BiI6] octahedra that share two opposite edges in such a fashion that two iodine atoms in cis-positions remain terminal. The calculated electronic structures and observed optical properties confirmed that compounds 1-4 are semiconductors with direct band gaps of 1.70-1.76 eV, which correspond to their intense red color. It was shown that the cations do not affect the optical properties, and the optical absorption is primarily associated with the charge transfer from the I 5p orbitals at the top of the valence band to the Bi 6p orbitals at the bottom of the conduction band. Based on their properties and facile synthesis, the title compounds are proposed as promising light-harvesting materials for all-solid solar cells.

Solvothermal reduction of graphene oxide performed up to a sp2/sp3 ratio of 20 was demonstrated. The presence of chemical and structural defects was minimized by varying the treatment conditions and reduction agents to reduce their impact on electronic and optical properties. Using the interphase deposition technique both graphene oxide and reduced graphene oxide films were transferred onto ITO-coated glass substrates or SITAL for further analysis. The analysis of the electric characteristics of the reduced graphene oxide films showed high sheet resistance originated from grain boundary resistance. The optical transmittance of the films reached 30% for the most uniform coatings.

The aim of this study is to examine the technological challenge of the electrochemical formation of zinc oxide and Al-doped ZnO films (ZnO:Al, AZO) as transparent conductive oxide coatings with complex architectures for solar cell photoanode materials. A cathodic electrodeposition of AZO was performed using aqueous nitrate electrolytes at 25°C. A significant positive deviation in aluminum percentage in the films was demonstrated by the LAES, EDX, and XPS methods, which originates from aluminum hydroxide sedimentation. The photoluminescent characteristics of the ZnO films reveal low band intensities related to intrinsic defects, while the samples with 1 at.% of aluminum show a strong and wide PL band at 600±80 nm and increase in conductivity.

This article is devoted to studying the kinetics of formation of individual nanoparticles of noble metals and composites based on them. The effect of the concentration of the reducing agent and temperature on the rate of formation of nanoparticles of noble metals is studied. In order to characterize the morphology, phase composition, and optical properties of the synthesized nanomaterials, X-ray diffraction, transmission electron microscopy, UV–visible spectroscopy, and Raman scattering (RS) are used. It is shown that the formation of nanoparticles of noble metals and composites based on them is a three-step process consisting of an induction period, the process of nucleation, and the particle growth stage (which has an autocatalytic character). The formed nanoparticles of noble metals catalyze the further process of reduction of ions remaining in the solution. It has been confirmed that an important factor for amplifying the signal from the analyte molecules in Raman spectroscopy is the resonance absorption by nanoparticles of noble metals in a wavelength range close to the wavelength of the excitation laser.

The refinement of the Bi2O3–Fe2O3–Sb2O5 system phase diagram has been performed and the existence of the two ternary compounds has been confirmed. The first one with a pyrochlore-type structure (sp. gr. Fd 3m) exists in the wide solid solution region, (Bi2−xFex)Fe1+ySb1−yO7±δ, where x=0.1–0.4 and y=−0.13–0.11. The second one, Bi3FeSb2O11, corresponds to the cubic KSbO3-type structure (sp. gr. Pn 3) with unit cell parameter a=9.51521(2) A. The Rietveld structure refinement showed that this compound is characterized by disordered structure. The Bi3FeSb2O11 factor group analysis has been carried out and a Raman spectrum has been investigated. According to magnetization measurements performed at the temperature range 2–300 K it may be concluded that the Bi3FeSb2O11 magnetic properties can be substantially described as a superposition of strong short-range antiferromagnetic exchange interactions realizing inside the [(FeSb2)O9] 3D-framework via different pathways.

We report the synthesis, crystal structures, and optical properties of two new compounds, K

A new reactive ink based on a silver citrate complex is proposed for a photochemical route to surface-enhanced Raman spectroscopy active substrates with controllable extinction spectra. The drop-cast test of the ink reveals homogeneous nucleation of silver and colloid particle growth originating directly from photochemical in situ reduction in droplets, while the following evaporation of the deposited ink produces small nano- and micron-size particles. The prepared nanostructures and substrates were accurately characterized by electron microscopy methods and optical extinction spectroscopy. Varying the duration of UV irradiation allows tuning the morphology of individual silver nanoparticles forming hierarchical ring structures with numerous “hot spots” for most efficient Raman enhancement. Raman measurements of probe molecules of rhodamine 6G and methylene blue reached the largest signal enhancement of 106 by the resonance effects.

A new two-step chimie douce method of substrate preparation for Surface-Enhanced-Raman-Spectroscopy (SERS) is suggested. The Ultrasonic Silver Rain (USR) approach includes a simple thermochemical transformation of a nutrient layer of Ag 2 O interlacing rings ultrasonically deposited from aqueous diaminsilver oxide complexes. Solid state decomposition of Ag 2 O under mild preparation conditions below 300 °C and for less than 5 min gives hierarchic nanostructures highly suitable for studies of living erythrocytes and some important analytes.

Four iodobismuthates, LiBiI4·5H2O (1), MgBi2I8·8H2O (2), MnBi2I8·8H2O (3), and KBiI4·H2O (4), were prepared by a facile solution route and revealed thermal stability in air up to 120 °C. Crystal structures of compounds 1–4 were solved by a single crystal X-ray diffraction method. 1: space group C2/c, a = 12.535(2), b = 16.0294(18), c = 7.6214(9) A, β = 107.189(11)°, Z = 4, R = 0.029. 2: space group P21/c, a = 7.559(2), b = 13.1225(15), c = 13.927(4) A, β = 97.14(3)°, Z = 2, R = 0.031. 3: space group P21/c, a = 7.606(3), b = 13.137(3), c = 14.026(5) A, β = 97.14(3)°, Z = 2, R = 0.056. 4: space group P21/n, a = 7.9050(16), b = 7.7718(16), c = 18.233(4) A, β = 97.45(3)°, Z = 4, R = 0.043. All solid state structures feature one-dimensional (BiI4)− anionic chains built of [BiI6] octahedra that share two opposite edges in such a fashion that two iodine atoms in cis-positions remain terminal. The calculated electronic structures and observed optical properties confirmed that compounds 1–4 are semiconductors with...

α-MnO2 nanorods were obtained by a fast redox transformation of aqueous solution of potassium permanganate. The formation mechanism of 1D nanocrystals proceeds via a first pH- and temperature sensitive stage followed by cation/anion control of the nanorod growth. A high surface area and nanostructuring allowed to achieve superb catalytic activity in a CO oxidation process compared to a conventionally prepared manganese dioxide.

ZnO films have been prepared by cathodic electrodeposition at room temperature using aqueous and non-aqueous zinc acetate electrolytes with a complexing agent for further application in optoelectronic devices. Influence of electrodeposition conditions on homogeneity and continuity of the films is discussed including the role of Trilon B as a complexing agent in grain size decrease and ensure adherence to ITO glass substrates. The annealing temperature has been optimised according to TG-DTA MS and XRD data. All ZnO opals have wurtzite-type structure and morphology of closed-packed round-shaped particles or very thin flakes forming porous sponge-like architecture. ZnO opal films with artificial microporous architecture have been synthesised using a polystyrene opal matrices as templates. Photoluminescence spectra of the ZnO coverages have shown more complex spectra for precipitates sedimented from aqueous baths than from DMSO electrolytes, most likely, because of different characteristic intrinsic defects.

High frequency (60 GHz) electron spin resonance (ESR) and magnetic susceptibility were studied for VO x multi-walled nanotubes (VOx-NTs) in the range of 4.2–300 K. It is found that apart from technological impurities, the magnetism of VOx-NTs is controlled by (i) antiferromagnetic V4+ noninteracting dimmers and (ii) V4+ quasi-free spins, which at T < 50 K form a disorder driven quantum critical state. From concentration estimates, we argue the V4+ dimers are an essential element of the VO x -NTs structure.

Microwave cavity perturbation technique was used to measure high-frequency (60 GHz) conductivity of VOx multi-walled nanotubes in a wide temperature range of 4.2–80 K. We found that conductivity of VOx nanotubes monotonically increases with temperature. Furthermore, two contributions to high-frequency conductivity can be distinguished: quasi-metallic linear term and thermally activated conductivity with the activation energy EA=150 ± 10 K.

Vanadium oxide nanorods were prepared by a hydrothermal route and then tested as a transducer for a resistive-type gas sensor. The importance of control of pH and pressure during the synthesis of 1D crystals of vanadium oxide was demonstrated for the V 2 O 5 /ethanol mixture, which served as a precursor. As a gas sensor element, the nanorods demonstrated a stable response to triethylamine and weak sensor response to carbon monoxide with a short response time (as low as 32 s).

Nanotubes, nanorods and nanopowders of hydrated titanium dioxide were studied with respect to their catalytic activity in a model reaction of CO oxidation. It was found that it is the nanotubular form characterized by distorted layered structure that demonstrates outstanding results in catalysis compared to all other forms.

The magnetic properties of nanomaterials based on vanadium oxide (multiwall nanotubes, nanorods, and nanolayers) have been investigated in the temperature range of 1.8–220 K by high-frequency (60-GHz) EPR. A transition from a ferromagnetic temperature dependence to an antiferromagnetic temperature dependence has been observed in nanorods and nanotubes with a decrease in the temperature. The FM-AFM crossover observed near TC ∼ 110 K is accompanied by a low-temperature increase in the Curie constant by a factor of 2.7–7. The comparison of the experimental data for various VOx nanoparticles indicates that the most probable cause of the change in the type of magnetic interaction is a change in the concentration of V4+ magnetic ions.

Catalytic activity of TiO 2 nanotubes and titania-supported platinum catalysts was examined for carbon monoxide oxidation process. It is shown that titania nanotubes modified with 1.5 wt.% of 1–5 nm platinum clusters reveal notable catalytic activity already at room temperature contrary to titania or platinum itself. The catalyst behavior was analyzed using TEM, XRD and XPS techniques to find out if structural peculiarities of titania nanotubes may contribute to the catalysis at low temperatures.

We report the first direct experimental evidence of the presence of antiferromagnetic dimers in VOx nanotubes based on the high frequency (60 GHz) electron spin resonance study carried out in the temperature range of 4.2-200 K. Arguments favouring a possible observation of the low temperature quantum critical phenomena in VOx nanotubes are provided.

Vanadium oxide nanotubes are synthesized by the hydrothermal method with the use of polycrystalline vanadium oxide V2O5 and 1-hexadecylamine as a structural template. The structure of the vanadium oxide nanotubes is investigated using small-angle X-ray diffraction and transmission electron microscopy. It is demonstrated that the structure of the vanadium oxide nanotubes is characterized by a combination of fragments with different interlayer distances associated with the twisting of oxide layers in the form of “nanorolls.” The thermal stability, morphology, and surface properties of the nanotubes, as well as the role of the organic template in the formation of their structure, are discussed.

Vanadium(V) oxide xerogels with an ordered laminar structure are of considerable interest in modern inorganic chemistry [1]. They combine the ease of intercalation of inorganic ions [2] or organic molecules [3] into the interlayer space and the presence of a transition metal ions with variable oxidation states, giving rise to nonlinear electrical and, in some cases, magnetic characteristics. Hybrid inorganic‐organic materials based on xerogels of vanadium(V) oxide and its nanotubular forms [4] attract considerable attention due to their unique physical and unusual physicochemical and rheological properties, which enable their use as cathode materials for lithium batteries [5], chemical sensors [6], electrochromic materials [7], and catalysts [8]. Vanadium(V) oxide xerogels can be prepared by hydrolysis of organic derivatives of vanadic acid, by polycondensation of vanadates in an aqueous solution in an acid medium, and by decomposition of peroxovanadium(V) compounds upon dissolution of the crystalline oxide in hydrogen peroxide [1, 9, 11]. The mechanisms of these processes are essentially different; therefore, it is important to elucidate the structural features of the xerogels as a function of the preparation method. Small-angle X-ray scattering, which is a standard method for measuring the kinetics of gel condensation in solutions [10], can also be used rather efficiently to study the structural features of xerogels. This study reveals the correlation between the chemical prehistory and the structural organization of samples obtained. Complex analysis of small-angle X-ray scattering (SAXS) patterns of xerogel films synthesized by different methods was carried out for the first time and possible models for description of their structure were considered. Colloid solutions of vanadium(V) oxide for the formation of xerogel films were prepared by three procedures (table). According to method A, analytical grade crystalline V 2 O 5 (0.5 g) was dissolved in 15% H 2 O 2 (30 mL) by slow addition of V 2 O 5 powder to the hydrogen peroxide solution [11]. After the oxygen evolution ceased, the solution became yellow. Heating the solution to ~40°C gave a dark red solution, which was kept under ambient conditions for 7 days until a xerogel film formed. According to method B, the gel was obtained by hydrolysis of tert -butyl metavanadate VO(OC(CH 3 ) 3 ) 3 . The ester was synthesized [11] by refluxing a mixture of calcined vanadium(V) oxide with excess tert -butyl alcohol in the presence of a desiccant (silica gel) for 7 h. The resulting mixture was separated by distillation at 81°C . Hydrolysis was carried out by mixing the ester with an equal volume of water (an excess) for the preparation of bulk samples or under ambient conditions. In method C, polycondensation of V took place in an aqueous solution of sodium vanadate on acidification. A colloid solution of V 2 O 5 · n H 2 O was obtained by

Na x MnO 2 · n H 2 O birnessite was used to yield one-dimensional nanostructures of manganese dioxide and effect of its chemical composition on electrochemical performance in lithium cells was studied.

Basing on the high frequency (60 GHz) electron spin resonance study of the VOx multiwall nanotubes (VOx -NTs) carried out in the temperature range 4.2–200 K we report: (i) the first direct experimental evidence of the presence of the antiferromagnetic dimers in VOx -NTs and (ii) the observation of an anomalous low temperature growth of the magnetic susceptibility for quasi-free spins, which obey the power law χ (T)∼1/T α with the exponent α ≈ 0.6 in a wide temperature range 4.2–50 K. We argue that the observed departures from the Curie–Weiss behaviour manifest the onset of the quantum critical regime and formation of the Griffiths phase as a magnetic ground state of these spin species. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Graphoepitaxial crystallization of amino acids in anisotropically shaped droplets is studied on silicon substrates with striped and chiral microreliefs to simulate the formation of ordered planar biological structures and films.

A conventional hydrothermal method widely used for the preparation of titania-based nanotubes still generates many unsolved questions. One of them is definitely connected with the influence of a posthydrothermal treatment of titania nanotubes on their micromorphology, structure, and adsorption characteristics. Here, it was analyzed systematically by a group of methods including nitrogen adsorption and temperature-programmed desorption of ammonia and carbon dioxide. It is proved that adsorption characteristics and the surface state of titania nanotubes correlate with a sodium content, since sodium ions act as Lewis acid sites and shield Ti4+acid sites of the nanotubes. To obey a balance between chemical and heat treatments of the nanotubes to design their functional properties has been suggested.