Fullerene superconductivity by short-range order instability

For the fullerene-group (C₆₀ group) of metastable materials a novel model is conceptualized on the basis of a special dynamic clustering. This clustering is realized by a short-range instability through a collective, cooperative, and coherent displacement of the ions to seek for the most dense and most stable cluster formation. In the C₆₀ superconductivity, mediation by harmonic lattice vibrations (phonons) is replaced by a pairing mechanism with anharmonic collective and coherent cluster vibrations. The suggested model fits the experimental data surprisingly well.     

Preparation of Fe2O3/Al composite powders by homogeneous precipitation method

The Fe₂O₃/Al composite powders were prepared by homogeneous precipitation method. The influence of the concentration of Fe²⁺ and the molar ratio of raw materials on the preparation of Fe₂O₃/Al composite powders were investigated. X-ray diffractometer, scanning electron microscope, Fourier transform infrared spectroscopy and differential thermal analysis were used to analyze the morphology and structure of the Fe₂O₃/Al composite powders. The results show that the content of iron oxide in the composite powders could be effectively controlled by adjusting the concentration of Fe²⁺ and the molar ratio of raw materials in the plating solution. The surface of Al particle was coated with a layer of thick and dense iron oxide. The core-shell Fe₂O₃/Al composite powders with Fe₂O₃ content of 14.1% were produced, the coating efficiency of Fe₂O₃ reaches more than 77%. The iron oxide, which coated on the surface of the aluminium particle is flower-like cluster structure, each flower-like cluster is constituted by nano-flaky iron oxide.     

Electronic nature of vanadium nitride-carbon cluster composite materials obtained by the calcination of oxovanadylphthalocyanine

Calcination of oxovanadylphthalocyanine at 500-1000 °C under an argon atmosphere was performed. Elemental analyses, XRD and TEM measurements revealed that the calcined materials are composed of nano-sized vanadium nitride and carbon clusters. ESR spectral examinations suggested that the calcined materials have a photo-responsive charge separation feature. The decomposition of methylene blue and trimethylhydroquinone in the presence of the material calcined at 900 °C was accelerated by visible light irradiation. H₂ evolution was detected from a mixture of the calcined material and water under the visible light irradiation.     

Ultrahigh and Selective SO2 Uptake in Inorganic Anion‐Pillared Hybrid Porous Materials

The efficient capture of SO₂ is of great significance in gas‐purification processes including flue‐gas desulfurization and natural‐gas purification, but the design of porous materials with high adsorption capacity and selectivity of SO₂ remains very challenging. Herein, the selective recognition and dense packing of SO₂ clusters through multiple synergistic host–guest and guest–guest interactions by controlling the pore chemistry and size in inorganic anion (SiF₆^2?, SIFSIX) pillared metal–organic frameworks is reported. The binding sites of anions and aromatic rings in SIFSIX materials grasp every atom of SO₂ firmly via S^δ+···F^δ? electrostatic interactions and O^δ?···H^δ+ dipole–dipole interactions, while the guest–guest interactions between SO₂ molecules further promote gas trapping within the pore space, which is elucidated by first‐principles density functional theory calculations and powder X‐ray diffraction experiments. These interactions afford new benchmarks for the highly efficient removal of SO₂ from other gases, even if at a very low SO₂ concentration. Exceptionally high SO₂ capacity of 11.01 mmol g^?1 is achieved at atmosphere pressure by SIFSIX‐1‐Cu, and unprecedented low‐pressure SO₂ capacity is obtained in SIFSIX‐2‐Cu‐i (4.16 mmol g^?1 SO₂ at 0.01 bar and 2.31 mmol g^?1 at 0.002 bar). More importantly, record SO₂/CO₂ selectivity (86–89) and excellent SO₂/N₂ selectivity (1285–3145) are also achieved. Experimental breakthrough curves further demonstrate the excellent performance of these hybrid porous materials in removing low‐concentration SO₂.     

The polar cluster like behavior in Ti substituted BaZrO3 ceramics

In this paper we report the evolution of the polar cluster like behavior with the incorporation of Ti⁴⁺ ion in BaZrO₃ Ceramics. Dielectric behavior of BaZr_xTi_(1−x)O₃ (x = 1.00, 0.95, 0.90, 0.85) ceramics is studied in the temperature range from 300 to 30 K. Polar cluster like behavior becomes more prominent with the increase in content of Ti⁴⁺ ion. The dielectric relaxation is analyzed by Vogel–Fulcher relation and Arrhenius law. Frequency dependence of dielectric constant and low loss tangent of these materials can be useful for the potential applications at low temperature.     

Innovative aspects in thin film technologies for nanostructured materials in gas sensor devices

This work reports on the use of two innovative techniques in the field of gas sensors for preparing nano-structured materials: sol-gel and supersonic cluster beam deposition. By means of sol-gel, nano-structured In₂O₃ thin films have been prepared and deposited under different deposition parameters on silicon wafer. In this way the results have shown a good compatibility of the method with silicon technology, then potentially suitable to be used in the fabrication of integrated devices. The second technique has been applied for the preparation of nano-structured TiO₂ thin films showing its capability to be used in the fabrication of gas sensor devices, mainly when a good control of the grain dimension is required.     

Preparation and characterization of hollow silica nanocomposite functionalized with UV absorbable molybdenum cluster

The nanoparticle-based material technology has recently opened a new heat shielding material generation for window applications such as aerogel, vacuum insulation panel or nanospace materials. Aiming to prepare a nanospace-based heat insulation material functionalized with an ultraviolet (UV) absorbent, the Mo₆ cluster-deposited hollow silica nanoparticles (HSNs) were prepared by the vacuum impregnation process (VIP). The pore channels of the hollow silica wall filled with the Cs₂[Mo₆Iⁱ₈(OCOC₂F₅)^a₆] octahedral cluster (CMIF) were confirmed by an HR-TEM coupled EDX device, ICP-OES and BET analysis. The retention of the octahedral structure or the typical optical property of the Mo₆ cluster in the pores of the HSNs was demonstrated by ultraviolet (UV) light absorption and photoluminescence spectroscopes even though the powders were heated to 200 °C. The multi-functional CMIF@HSNs nanocomposite could adsorb the UV rays under 400 nm and scatter the NIR light through the pores of the silica wall in order to reduce the heat passing a window. For this purpose, the film preparation based on the CMIF@HSNs nanocomposite was performed by dip coating in the commercially available top coat suspension (TCS) on soda lime glass. Excellent mechanical and optical properties of the CMIF@HSNs-based thin film were visibly obtained with a relative transmittance. This study suggests a potential insulation material prepared by a high efficiency and simple method for reducing the air temperature in buildings.     

Cluster‐Assembled Nanocomposites: Functional Properties by Design

The unique functional properties of nanocomposites meet many of the material requirements sought after in numerous applications of today's high‐tech industry. This, in turn, inspires material scientists to devise new methods that can further expand the palette of available nanocomposites. Precise control over the chemistry, morphology, and microstructure of nanocomposites' constituents promises the eventual ability to design any composite material for any specific requirement. However, today's synthesis methods still lack the ability to simultaneously control all chemical, morphological, and microstructural features of nanocomposites in a one‐step process. Here, an alternative approach to fabricate fully tailorable nanocomposites under well‐defined conditions is described. In particular, this progress report focuses on the combination of cluster ion beam and thin‐film deposition technologies to fabricate cluster‐assembled nanocomposites via codeposition of cluster ions and matrix materials. Emphasis is given to the state‐of‐the‐art cluster deposition system, designed and built by our research group, as well as to its unique abilities. Moreover, case studies on two cluster‐assembled nanocomposite material systems (Fe/Ag_m and Fe/Cr_m) prepared with this method are presented. Finally, an outlook on research directions for cluster‐assembled nanocomposites is discussed.     

Advanced synthesis techniques and routes to new single-phase multiferroics

We review recent developments and advances in the synthesis of thin-film multiferroic and magnetoelectric heterostructures. Driven by the promise of new materials with built-in useful phenomena (i.e., electric field control of ferromagnetism), extensive research has been centered on the search for and characterization of new single-phase multiferroic materials. In this review we provide a brief overview of recent developments in the synthesis of thin film versions of these materials. Advances in modern film growth processes have provided access to high-quality materials for in-depth study. We highlight the use of epitaxial thin-film strain to stabilize metastable phases, drive multiferroic properties, and produce new structures and properties in materials including case studies of EuTiO₃ and BiFeO₃.     

Old and New Problems in Piezoelectric Materials Research and Materials with High Hydrostatic Sensitivity

The developments and future directions in the investigation and design of piezoelectric materials are analyzed. It is shown using concrete examples that, despite of clear signs of saturation in the search for new piezoelectric materials, this area continues to be the subject of intense attention. The current requirements for piezoelectrics, new classes of piezoelectric materials (Sn₂P₂S₆ films, SbSI-based materials, and adaptive systems), and advanced technologies (films, textures, and piezocomposites) are considered. The experimental data are summarized on piezoelectric materials based on lead metaniobate, lead titanate, antimony sulfoiodide, and Bi-containing layered perovskite-like phases and porous piezoceramics exhibiting high hydrostatic sensitivity.     

Preparation and luminescence of some [K2PtCl6] materials

The preparation of Cs₂TaOCl₅ and Cs₂TaSCl₅, new materials with the [K₂PtCl₆] structure, is described. Luminescence has been measured for these materials and other pure [K₂PtCl₆] materials.     

The effect of polysiloxane on the properties of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-NbC composite material produced by pyrolysis process

Recently, studies have been developed in order to obtain Al₂O₃-NbC composite materials. The reinforced materials have shown good potential to be used as cutting tool materials at high-speed cutting and high temperature as a substitute to WC-Co material. The main disadvantage to produce these alumina-reinforced materials is the necessity to use pressure assisted sintering or high sintering temperatures to produce dense bodies. Manufacturing of composite ceramic materials derived from polymer reactive filler has been intensively investigated. Polymer pyrolysis is a relatively new and very promising method for obtaining ceramic material in complex shapes and lower sintering temperatures. This work investigated a ceramic composite matrix based in SiC_xO_y and Al₂O₃ and reinforced with NbC obtained by means of the active fillers pyrolysis process. The results obtained in this work demonstrate that using a mixture of polysiloxanes produces a composite material with better properties when compared to others polymer materials.     

New 2D Carbon Nitride Organic Materials Synthesis with Huge‐Application Prospects in CN Photocatalyst

In recent years, 2D materials are attracting increased attention because of their excellent properties. In this paper, new 2D carbon nitride (CN) organic materials are successfully prepared on the basis of the organic synthesis theory, and the thickness is about 1.5 nm. This new 2D CN organic material further strengthens the 2D materials family. Meanwhile, their synthetic mechanism is theoretically speculated. Then CN photocatalysts of several structures are obtained by roasting 2D CN organic materials. Through the photocatalytic hydrogen production experiments, the results exhibit that these kinds of photocatalysts have good photocatalytic effects compared to common g‐C₃N₄.     

Superconductivity and magnetism in quaternary borocarbides

Quaternary borocarbide superconductors have attracted attention and are of current interest due to a variety of reasons. Some of them exhibit high T_c's for intermetallics, including the material which shows highest known T_c for intermetallics. Though the structure of RNi₂B₂C (R=Sc, Y, rare earth, Th, U) is effectively a layered structure like that of high T_c cuprates, rare earth ions influence the superconducting properties of these materials. Coexistence of superconductivity and magnetism has been found in these materials with magnetic ordering temperatures much higher than those of earlier known magnetic superconductors which implies stronger coupling of rare earth moment to conduction electrons. These features make quaternary borocarbides an altogether different class of materials. Being quaternary, and with the possibility of having more than one rare earth-carbon layer in the structure, this family offers the possibility of finding many new materials with wide ranging properties. Highlights of recent developments in this new subject of quaternary borocarbides are reviewed here.     

Laser processing of NiCrAlFe alloy: microstructural evolution

Laser surface treatments are an attractive alternative for the production of new materials with high mechanical and corrosion-resistance properties. This technique permits the production of materials with a high added value on low-cost materials. The present research is aimed at obtaining NiCrAl alloys on iron-based materials using a continuous CO₂ laser with 5–7 kW power. The microstructural characteristics and influence of iron on the type of phase in the new alloy is also analysed.     

Production of mortars using novel glass-ceramic porous spherical particles with chemical composition into SiO2-CaO-Al2O3-MgO quaternary system as replacement of sand aggregates

A novel production of new aggregate for mortars based on glass-ceramic porous spherical particles into SiO₂-CaO-Al₂O₃-MgO quaternary system is reported. Crystalline blast furnace slags (c-BFS) are transformed into new glass-ceramic porous spherical materials with lower density than their precursor. The conversion occurs by c-BFS projection into an oxygen/Liquefied Petroleum Gas (LPG) plume-flame. The aim of the present work is to evaluate these new materials as aggregates to replace the sand in conventional mortars formulations in order to indicate a potential way to reduce the use of this mineral resource and also how industrial wastes can be transformed in useful materials with direct application into the construction materials field. The characterization of the precursor and products were carried out by optical microscopy; scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and their densities were measured by Helium pycnometry. Additionally, the compressive strengths at different aging times (7, 14 and 28 days), from a control sample and diverse mortars based on glass-ceramic porous spherical particles were evaluated. Finally, thermal conductivities from all the specimens cured at 28 days were also measured.     

Two-dimensional metamaterials for epitaxial heterostructures

We review the use of two-dimensional psuedomorphic materials to accommodate an extraordinary range of misfit and allow novel new phases to be grown epitaxially. These materials assume the structure of the substrate and can thus be regarded as metamaterials. We illustrate these principles through a number of systems, including a detailed structural and spectroscopic study of epitaxial VO₂/NiO heterostructures. In this case the metamaterial is VO_1+x which is structurally and electronically distinct from the bulk of the VO₂ film. In the transition region the crystal structure adopts that of the NiO layer, while the oxidation state of vanadium increases from ∼3+ to ∼4+ with thickness, accompanied by increasing lattice disorder. The formation and evolution of this interfacial phase, VO_1+x, accommodates the change in crystal symmetry across the interface from the rock-salt structure of NiO to the rutile structure of VO₂. The use of two-dimensional metamaterials opens a wealth of new opportunities for the growth of new materials with novel properties.     

In vitro hemocompatibility testing of new materials for mechanical heart valves

Biomaterials with improved wear properties, high resistance towards breaking, and better availability in comparison to the conventional material (PyroCarbon) may result in heart valve prostheses with prolonged lifetime and improved quality of life (no required lifetime anticoagulation). TiN-coatings as well as ceramic materials such as ZrO₂, and alternative carbon surfaces are considered as potential new materials. In order to determine hemocompatibility properties of these materials, a new test set-up without blood-air-contact has been built and successfully tested according to ISO 10993-4 : 1993 (EN 30993) within a first study for a series of materials.     

Diphasic xerogels: I. Ceramic-metal composites

The sol-gel process has been extended to the preparation of new diphasic xerogels leading to new hybrid ceramic-metal materials. The final component compositions were Al₂O₃, SiO₂, ZrO₂ as oxides and Cu, Pt, Sn, and Ni as metals.The xerogels as examined by XRD, SEM, TEM, consisted or a noncrystalline (in a few cases, microcrystalline) ceramic matrix with small metallic islands (5–50 nm) and micro and macro pores. The fine structure of these materials can be controlled by both preparation steps: the gelation parameters and subsequent thermal treatment.