Classement des porteurs de charge et conductivite du compose K8Na4Sb12O36 de structure KSbO3 cubique

Two structures have been reported for cubic KSbO₃ type. One has space group Pn3, where K⁺ ions are in an ordered state. The other has Im3 with K⁺ ions in a disordered state. These ions are weakly bound in large tunnels along 〈111〉 and are mobile along them three-dimensionally.The presence of two alkaline cations in these tunnels is in favour of the ordered state. Single-crystals of K₈Na₄Sb₁₂O₃₆ are obtained and crystallize in the space group Pn3, $\text{a}\text{= 9,515(3)}\text{A}\text{?}$. Using 563 independent reflections, the structure has been refined by full-matrix least squares, to factor R = 0,059.The comparison of the ionic conductivity of ordered (Pn3) and disordered (Im3) compounds is studied by the authors.     

Microstructure analysis of calcium phosphate formed in tendon

The surface of soft tendon tissue has been modified using calcium phosphate in order for the tendon to directly connect with hard bone and reconstruct an injured ligament. Calcium phosphate was coated onto the tendon in a soaking process using alternating a CaCl₂ (200 mM) and a Na₂HPO₄ (120 mM) solution. According to SEM/EDX observations, calcium phosphate was formed, not only on the tendon surface, but also inside the tendon tissue. When the tendon was treated with seven soaking cycles, calcium phosphate was detected between 0–500 m from the tendon surface. According to TEM observations, the crystal morphology of calcium phosphate depends on the distance from the surface. Hydroxyapatite crystals were observed near the surface, while octa-calcium phosphate crystals could be observed further from the surface, thus at initial soaking. The crystals were formed on collagen fibrils in spaces between the collagen fibrils with the c-axes of the crystals aligned parallel with the collagen fibrils. This finding suggests Ca²⁺ ions to interact with the tendon surface, most probably with the carboxyl functional groups of collagen, and subsequently forming nucleation centers for the crystals.     

Structure of medium temperature phase β-LaSc3(BO3)4 crystal

The compound β-LaSc₃(BO₃)₄ crystallizes in the rhombohedral with space group R32 and cell parameters a=9.819(3), c=7.987(1) Å, Z=3, V=666.5(3) Å³, Dc=3.80 g/cm³, λ(MoKα)=0.71067 Å, F(000)=708, final R=0.053. R_W=0.072 for 512 observed reflection with I≥3σ(I). The La atoms, Sc atoms and B atoms occupy trigonal prisms, octahedra and planar triangle of oxygen, respectively. The isolated LaO₆ trigonal prisms alternate along the c-axis with BO₃ triangle (B(1)) that are perpendicular to the c-axis. La³⁺ ions join by means of La-O-Sc(B)-O-La with the distance between La³⁺ ions being 6.263 Å. This structural characteristic will result in a weaker interaction between Nd³⁺ ions and a lower fluorescence concentration quenching effect.     

溶胶-凝胶法与射频磁控溅射法制备ZnO薄膜及其表征对比

分别对溶胶-凝胶法和磁控溅射法制备ZnO进行了详细的介绍,并借助X射线衍射、原子力显微镜、拉曼光谱分析、紫外吸收等检测手段对这两种方法生长的薄膜进行了分析比较.分析显示:相同石英基底,相同退火温度下生长ZnO薄膜,磁控溅射法生长的ZnO薄膜要比溶胶-凝胶法生长的ZnO薄膜有更优异的c轴取向特性,生长的薄膜结晶更加均匀、致密.     

Preparation and characterization of nano-sized Sr0.7Ca0.3TiO3 crystallines by low temperature aqueous synthesis method

Nano-sized calcium strontium titanate (Sr_0.7Ca_0.3TiO₃) particles were prepared by low temperature aqueous synthesis method at temperature as low as 90 °C and under ambient pressure. To improve the morphology and crystallinity of the particles, the hydrothermal treatment was used. The lattice structure, particle size, particle morphology, and hydroxyl defects of Sr_0.7Ca_0.3TiO₃ particles were investigated by using XRD, TEM, FE-SEM, TG and FT-IR measurements. The as-prepared particles with size about 100 nm were single cubic phase crystallines which consist of aggregates of small rounded nanocrystals about 10 nm in diameter. However, in as-prepared crystallines, a hydroxyl group was detected as a lattice defect. After the hydrothermal treatment, the hydroxyl groups in Sr_0.7Ca_0.3TiO₃ nanoparticles were partially released from the perovskite lattice. The morphology and crystallinity of the hydrothermally treated particles were observably improved.     

Effect of bovine serum albumin on the functionality and structure of catanionic surfactant at air–buffer interface

Interaction of bovine serum albumin (BSA) with the solvent spread monolayer of a catanionic surfactant, octadecyltrimethylammonium dodecylsulfate, (C₁₈TA⁺DS^?) at the air–buffer interface was investigated by measuring the surface pressure with time and change in surface area. Dipalmitoylphosphatidylcholine (DPPC) was used as reference. Kinetics of BSA desorption from the interface to the buffer subphase, that of C₁₈TA⁺DS^? and DPPC through their interaction with BSA, were also studied at different BSA concentrations (in the subphase) and surface pressures. Surface pressure (π)–area (A) isotherms (at pH = 5.4, μ = 0.01, T = 298 K) revealed that the coacervate/DPPC monolayer becomes expanded in the presence of BSA at low π while their protein bound species are released into the subphase at high π. Film morphology, studied by epifluorescence microscopy (EFM) and atomic force microscopy (AFM), reveals that the sizes of the domains of both DPPC and coacervate decrease in the presence of BSA. Presence of BSA in the coacervate and DPPC monolayer was supported from AFM data analysis.     

Probing Adsorption Behaviors of BSA onto Chiral Surfaces of Nanoparticles

Chiral properties of nanoscale materials are of importance as they dominate interactions with proteins in physiological environments; however, they have rarely been investigated. In this study, a systematic investigation is conducted for the adsorption behaviors of bovine serum albumin (BSA) onto the chiral surfaces of gold nanoparticles (AuNPs), involving multiple techniques and molecular dynamic (MD) simulation. The adsorption of BSA onto both L‐ and D‐chiral surfaces of AuNPs shows discernible differences involving thermodynamics, adsorption orientation, exposed charges, and affinity. As a powerful supplement, MD simulation provides a molecular‐level understanding of protein adsorption onto nanochiral surfaces. Salt bridge interaction is proposed as a major driving force at protein–nanochiral interface interaction. The spatial distribution features of functional groups (? COO^?, ? NH₃⁺, and ? CH₃) of chiral molecules on the nanosurface play a key role in the formation and location of salt bridges, which determine the BSA adsorption orientation and binding strength to chiral surfaces. Sequentially, BSA corona coated on nanochiral surfaces affects their uptake by cells. The results enhance the understanding of protein corona, which are important for biological effects of nanochirality in living organisms.     

Synthesis of silica-coated AgI nanoparticles and immobilization of proteins on them

This paper describes a method for preparing silica-coated silver iodide (AgI/SiO2) particles and immobilizing proteins on the AgI/SiO2 particles. Colloid solution of AgI particles was prepared by mixing AgClO4 aqueous solution and KI aqueous solution. Silica-coating of the AgI particles was performed by adding 3-mercaptopropyltrimethoxysilane, tetraethylorthosilicate/ethanol solution and NaOH aqueous solution successively to the AgI colloid solution. TEM observation revealed that the AgI nanoparticles were coated with uniform silica shell. The AgI/SiO2 particles were surface-modified with 3-aminopropyltrimethoxysilane and succinic anhydride. It was confirmed by XPS measurement that amino group or carboxyl group was introduced onto the AgI/SiO2 particles. Protein-immobilization was performed in aqueous solution with bovine serum albumin (BSA) in the presence of the surface-modified AgI/SiO2 particles. UV-VIS absorption spectroscopy revealed that the BSA was adsorbed on the surface-modified particles.     

Enhanced near-infrared quantum cutting in CaMoO4:Yb phosphors induced by doping with Li ions for improving solar cells efficiency

The near-infrared (NIR) quantum cutting (QC) CaMoO₄:Yb³⁺ phosphors co-doped with Li⁺ ions were synthesized by the sol–gel methods. The dependence of the structure, morphology, photoluminescence (PL) and downconversion (DC) quantum efficiency on the Li⁺ doping concentration have been investigated in details. It was demonstrated that the CaMoO₄:Yb³⁺ phosphors with appropriate concentration of the Li⁺ ions show improved crystallinity and remarkable increase of the NIR emission from the Yb³⁺ ions, if compared with the Li⁺-free samples. The enhancement of the NIR emission and DC quantum efficiency was suggested to be a consequence of the improved crystallinity and stronger absorption of the host due to the [MoO₄] tetrahedra distortion induced by the Li⁺ ions. Cooperative energy transfer (CET) from the host to the Yb³⁺ ions is discussed as a possible mechanism for the NIR emission enhancement. Excellent luminescence properties of the Li⁺ doped CaMoO₄:Yb³⁺ phosphor demonstrate its potential application as a better QC layer to increase the energy conversion efficiency of the Si-based solar cells.     

Deposition and characterization of c-axis oriented aluminum nitride films by radio frequency magnetron sputtering without external substrate heating

Aluminum nitride (AlN) films were deposited on a variety of substrates (glass, Si, oxidized Si, Al-SiO₂-Si, Cr-SiO₂-Si, and Au-Cr-SiO₂-Si) by radio frequency (RF) magnetron sputtering using an AlN target. The films were deposited without external substrate heating. The effect of RF power, ambient gas (Ar and Ar-N₂) and sputtering pressure on deposition rate and crystallinity were investigated. The structure and morphology of the films were studied by X-ray diffraction, scanning electron microscopy and atomic force microscopy techniques. These investigations revealed that the AlN films prepared in mixed gas ambient (Ar-N₂) were highly c-axis oriented with moderate surface roughness on all the substrate. A strong IR absorption band was observed around 670 cm^− 1 which confirms the presence of Al-N bond in the film. The dc resistivity of the films was measured to be in the range of 10¹¹ to 10¹² Ω-cm at moderate electric fields. The application of these films in piezoelectric based micro-electro-mechanical systems is discussed.     

Formation of Ni2Si silicide in Ni/Si bilayers by ion beam mixing

We have studied ion mixing in Ni-Si(1 1 1) bilayers using noble gas ions. Thin Ni films of 45 nm thickness, deposited on a Si (1 1 1) substrate, were irradiated with 175 keV Kr and 110 keV Ar ions at the same fluence of 4×10¹⁶ ions/cm² at room temperature. The formation of the mixing and the elemental depth profile were investigated by Rutherford backscattering spectrometry. In the Ar irradiated sample, there was no structural change. On the other hand, we have noted the formation of Ni₂Si for the sample irradiated with Kr ions. X-ray diffraction measurements confirmed the formation of the Ni₂Si phase. The surface morphology of the Kr irradiated sample was also studied by scanning electron microscopy.     

Evidences of Rubber Grafting on Activated Carbon Surfaces Containing Fullerene‐like Structures

Abstract

It is shown that graphite is converted into an high disordered carbon black by prolonged ball milling. The kinetics of this transformation has been followed by powder x‐ray diffraction, measurements of the crystallinity and of the surface area. Ball milling is able to introduce an high concentration of defective sites in the pristine graphite including the fullerene‐like structures. By mixing with natural rubber both the pristine and the ball‐milled graphite, it is shown by bound rubber measurements that the amount of rubber grafted (chemically linked) on the pristine graphite surface is negligible but reaches a very high level in the ball‐milled graphite. Similarly, ball‐milling of N660 carbon black causes a deep activation of its surface activity which can be measured by a significant increase in the bound rubber level and in the amount of grafted rubber in comparison to the pristine N660 sample. The bound rubber measurement has been performed also on a natural rubber masterbatch with extracted fullerene carbon black (EFCB). Also in this case extremely high levels of rubber grafting have been achieved in comparison to graphite. It is discussed and demonstrated that the fullerene‐like nanostructures in carbon blacks play a key role in the formation of bound rubber phenomenon and in grafting natural rubber on carbon black surface.     

Low temperature synthesis of Ba1?xSrxSnO3 (x = 0–1) from molten alkali hydroxide flux

Perovskite structured stannates (Ba_1−x Sr _x SnO₃, x = 0·0–1·0) powders have been synthesized for the first time by molten salt synthesis (MSS) method using KOH as the flux at lower temperature (400°C) compared to other methods. The phase formation was confirmed by FT-IR spectroscopy, powder X-ray diffraction (XRD) and the microstructure was analysed by scanning electron microscopy. XRD patterns reveal the formation of single phasic products for parent and substituted products with good crystallinity throughout the range (x = 0·0–1·0). The morphology of the particles of BaSnO₃ and SrSnO₃ is spherical and rod shaped, respectively. Effect of soaking periods on the grain growth is observed clearly in SrSnO₃. Ba_0·5Sr_0·5SnO₃ (BSS5) crystallizes in flake like morphology.     

A Superior Method for Constructing Electrical Percolation Network of Nanocomposite Fibers: In Situ Thermally Reduced Silver Nanoparticles

Nanocomposite fibers, composed of conductive nanoparticles and polymer matrix, are crucial for wearable electronics. However, the nanoparticle mixing approach results in aggregation and dispersion problems. A revolutionary synthesis method by premixing silver precursor ions (silver ammonium acetate) with polyvinyl alcohol is reported here. The solvation of ions‐prevented aggregation, and uniformly distributed silver nanoparticles (in situ AgNPs, 77 nm) are formed after thermal reduction (155 °C) without using additional reducing or dispersion agents. The conductive fiber is synthesized by the wet spinning technology. After careful optimization, flower‐shaped silver nanoparticles (AgNFs, 350–450 nm) are also employed as cofillers. The addition of in situ AgNPs (9.5 vol%) to AgNFs (30 vol%) increases electrical conductivity by 1434% (2090 to 32 064 S cm^?1) through the efficient construction of percolation networks. The in situ AgNPs provide significantly higher conductivity compared with other secondary nanoparticle fillers. The gaseous byproducts dramatically increase flexibility with a moderate compromise in tensile strength (55 MPa). The particle‐free ion‐level uniform mixing of silver precursors, followed by in situ reduction, would be a fundamental paradigm shift in nanocomposite synthesis.     

Ion release from three lead-free piezoelectric ceramics and their physical and cytotoxicity characteristics

The ions released from the polarized potassium sodium niobate (KNN), lithium-doped potassium sodium niobate (LKNN) and barium titanate (BT) specimens after soaking in a normal saline up to 28 days were monitored. The cytotoxicity of ion released products was evaluated. The cytotoxicity testing on these three lead-free piezoelectric ceramics exhibited low toxicity. However, the decrease of biaxial strength for KNN and the decrease of piezoelectric charge coefficient d₃₃ for LKNN were noted after soaking in saline solution. Such decreases can be related to the release of ions from the surface of the KNN and LKNN specimens during soaking in saline solution.     

SAW器件用金刚石基c轴取向LiNbO3压电薄膜的制备

采用脉冲激光沉积技术,在以c轴取向ZnO作为缓冲层的金刚石/硅基底上制备出了结晶良好的高c轴取向LiNbO3薄膜。利用X射线衍射对薄膜的结晶质量和c轴取向性进行了研究,结果表明制得的LiNbO3薄膜具有高度c轴取向且结晶质量良好。采用扫描电子显微镜和原子力显微镜对薄膜的表面形貌进行了分析,发现薄膜表面光滑,晶粒尺寸均匀,薄膜表面粗糙度约为20nm。     

Bioactivity of CaSiO<Subscript>3</Subscript>/poly-lactic acid (PLA) composites prepared by various surface loading methods of CaSiO<Subscript>3</Subscript> powder

Mixing bioactive ceramic powders with polymers is an effective method for generating bioactivity to the polymer-matrix composites but it is necessary to incorporate up to 40 vol% of bioactive ceramic powder. However, such a high mixing ratio offsets the advantages of the flexibility and formability of polymer matrix and it would be highly advantageous to lower the mixing ratio. Since surface loading of ceramic powders in the polymer is thought to be an effective way of reducing the mixing ratio of the ceramic powder while maintaining bioactive activity, CaSiO₃/poly-lactic acid (PLA) composites were prepared by three methods; (1) casting, (2) spin coating and (3) hot pressing. In methods (1) and (2), a suspension was prepared by dissolving PLA in chloroform and dispersing CaSiO₃ powder in it. The suspension was cast and dried to form a film in the case of method (1) while it was spin-coated on a PLA substrate in method (2). In method (3), CaSiO₃ powder was surface loaded on to a PLA substrate by hot-pressing. The bioactivity of these samples was investigated in vitro using simulated body fluid (SBF). Apatite formation was not observed in the samples prepared by method (1) but some apatite formation was achieved by mixing polyethylene glycol (PEG) with the PLA, producing a porous polymer matrix. In method (2), apatite was clearly observed after soaking for 7 days. Enhanced apatite formation was observed in method (3), the thickness of the resulting apatite layers becoming about 20 μm after soaking for 14 days. Since the amount of CaSiO₃ powder used in these samples was only ≤0.4 vol%, it is concluded that this preparation method is very effective in generating bioactivity in polymer-matrix composites by loading with only very small amounts of ceramic powder.     

Synthesis and dissolution behaviour of CaO/SrO-containing sol–gel-derived 58S glasses

The effect of the substitution of strontium for calcium in the tertiary the SiO₂–CaO–P₂O₅ sol–gel bioactive glass 58S (60SiO₂·36CaO·4P₂O₅, mol%) on its structure and its chemical durability on soaking in simulated body fluids was investigated. 58S was selected as a starting composition, and substitution for calcium was carried out from 0 to 100% with an increment of 25%. A novel phosphate source of diethylphosphatoethyltriethoxysilane, which consists of Si and P connected with ethylene group, was used in this work. XRD and FTIR showed that the gels obtained following drying at 130 °C had a typical sol–gel structure, where a continuous amorphous silica gel network and surface bound mineral salts of Ca(NO₃)₂ and Sr(NO₃)₂. Once the gels were heat stabilised to decompose nitrates and incorporate the cations into the network, samples containing Sr formed a strontium silicate crystalline phase. With increasing levels of Sr in the composition, the overall crystallinity of the glass–ceramic increased, while, at the maximum substitution of 100% SrO, macroscopic phase separation was observed, characterised by needle-like crystals of strontium apatite (Sr₅(PO₄)₃OH) and strontium silicate (Sr₂SiO₄) phases in addition to amorphous regions. Dissolution experiments in Tris-buffered solution showed Sr successfully released into the media even though it existed as a crystalline phase in the glass–ceramic. Further, the glass–ceramics induced nucleation and growth of carbonated hydroxyapatite (HA) on their surface suggesting potential bioactivity of the materials. At higher substitutions (75 and 100% SrO for CaO), HA nucleation was not found to occur this may have been due to low amount of phosphate released from the original glass–ceramic as a result of it being locked up in the strontium apatite phase.     

Templated biomineralization of Au nanoplates under bovine serum albumin Langmuir monolayers

Au nanoplates were generated by spontaneous reduction of chloroaurate ions (AuCl₄⁻) under bovine serum albumin (BSA) Langmuir monolayers at room temperature. The structure of the resulting Au particulates was analyzed by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), selected-area electron diffraction (SAED), and high resolution transmission electron microscopy (HRTEM). The results showed that BSA provided dual functions for both reducing Au³⁺ ions and directing anisotropic growth of Au particles into plate-like structure as well. Amorphous Au particulates were obtained firstly in a relatively short reaction time, and then anisotropic Au nanoparticles were generated at extended reaction durations. The triangular Au nanoplates oriented along (1 1 1) basal planes were obtained via the reduction of chloroaurate ions by BSA with a relatively longer reaction duration. The present research provides a biological route to produce single-crystalline gold nanoplates with a wide variety of applications, and it also verifies that the interaction between protein/peptide and gold ions/surface may be used advantageously for green chemical synthesis of nanogold. Hopefully, this would contribute to promote genuine green biomimetic synthesis of nanomaterials with prescribed geometrical features where rationally designed multifunctional peptides are preferred.     

Reinforcing effect of organo-modified layered silicates in high-density polyethylene

This study focuses on the understanding of the reinforcing effect given by organo-modified layered silicates to a high-density polyethylene and the influence on the crystallization properties of this polymer. The addition of organo-modified clay to high-density polyethylene resulted in an evident increase in the tensile and flexural Young's modulus of the material with respect to unfilled polymer. The morphology, crystallinity, and thermo-oxidative stability of such nanocomposites were investigated using X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, and oxidation induction time test. The materials obtained show tactoid as well as intercalated and exfoliated structures with different dominant states depending on the loading level and process conditions. It was observed that organic ions not only change mixing behavior but also influence material properties, including the degree of crystallinity and the stability to the thermo-oxidative phenomena.