Advanced Materials Research Vols. 560-561

Abstract: By cost-effective techniques of hydrothermal reaction and polymer-assisted deposition, Feather-like (CoFe2O4)0.3-(BaTiO3)0.7 (CFO-BTO) nanostructures have been synthesized. The nanostructures show an average diameter of 250 nm and lengths up to 5 μm, with CFO nanopillars embedded in BTO matrix. The three-dimensional microstructure and growth mechanism of the nanostructures have been investigated. A large magnetoelectric (ME) response at room-temperature and a strong phonon abnormality between 110 °C and 140 °C have been studied.

Abstract: By hydrothermal methods single-crystalline BiFeO3 (BFO) nanorods with diameters of 15-40nm and lengths of 100-400nm were synthesized. The rhombohedra phased nanorods grow along the [110] direction. The nanorods show weak ferromagnetism at room temperature and enhanced spin-glass type magnetism at low temperature. Around 100K, a strong spin-two-phonon coupling has been detected, confirming the spin-glass freezing behaviors. With emphasis on the size and morphology, the enhanced magnetism and the spin-glass freezing of the BFO nanorods have been discussed.

Abstract: Polycarbonate-based polyurethane nanocomposites were prepared using one step procedure by addition of either organically modified bentonite or montmorillonite (1 wt. %). All aliphatic components (polycarbonate diol, hexamethylene-diisocyanate and 1,4-butane diol) were used as reactants. The hard segment content of obtained thermoplastic polyurethanes was 30 wt. %. Scanning electron microscopy (SEM) was performed to investigate the morphology of obtained hybrid materials. The structure of synthesized elastomers was studied by Fourier transform infrared spectroscopy (FTIR). In order to obtain the degree of phase separation and investigate the hydrogen bonding constitution, deconvolution of –NH and –C=O IR regions was done, using Gaussian equations. It was determined that the degree of phase separation is not influenced by addition of organoclays, indicating uniform dispersion of silicate layers in the polyurethanes, which was also confirmed by SEM experiments.

Abstract: _{Subscript text}Feasible conditions to get flame retardant expandable graphite (EG) with low initiation expansion temperature and high dilatability were obtained through orthogonal test and single factor experiment. EG with initiation expansion temperature of 148 ±2 °C and expansion volume of 550 mL/g can be prepared according to the mass ratio of C : KMnO₄ : 98% H₂SO₄ : Na₄P₂O7 = 1.0 : 0.4 : 5.0 : 0.6 (H₂SO₄ should be diluted to th_{Subscript text}e mass concentration of 80% before intercalation reaction), the reaction time is 40 min at 40 °C. Addition of 30% of the prepared EG to Liner Low-Density Polyethylene (LLDPE) can improve its limiting oxygen index LOI from 17.5% to 29.4%, and the synergistic anti-flame LOI of 20% EG with 10 polyphosphate (APP II) can reach to 31.2%. TG and DTA analysis was completed to discuss the anti-flame mechanism.

Abstract: The medicinal mushroom Inonotus obliquus has been a folk remedy for a long time in East-European and Asian countries. It has been ascribed to a number of triterpenoids that show various biological activities. In this study, the response surface methodology was employed to optimise the medium composition for triterpenoids production by I. obliquus in shake flask culture. A fractional factorial design was used to evaluate the effects of different components in the medium. Glucose, peptone, yeast powder, and CaCl2 were important factors significantly affecting I. obliquus triterpenoids production. These selected variables were subsequently optimised using steepest ascent method, a central composite design, and response surface methodology. The optimal medium composition was (% w/v): glucose, 5.92; peptone, 0.23; CaCl2, 0.048; yeast powder, 0.12; KH2PO4, 0.1; MgSO4, 0.02. Under optimal conditions, triterpenoids production by I. obliquus reached 5.51%, representing an increase of 1.4-fold compared with that using the basal medium (3.98%).

Abstract: Micro-mesoporous titanium-silicon molecular sieve (MMTS) was synthesized through dual templates method. The physical characterization of MMTS was carried out by BET, FTIR, UV-Vis. The results showed that the MMTS samples synthesized by dual templates method possessed mainly micropores and some mesopores with pore size of 3.9 nm, but a portion of the titanium in the framework was removed as indicated from UV-Vis diffuse reflectance spectroscopy.

Abstract: A series of FeCoBM (M=Nb, Zr, Hf, Mo ,Ta, Ti)–Al2O3 films were prepared on glass and polymer substrates by means of RF magnetron co-sputtering. Effect of dopants on the soft magnetic properties and microwave magnetic characteristics of FeCoBM-Al2O3 Thin Films were studied. To further tailor the magnetic characteristics of the films, the (Fe40Co40B20)94.5Hf2.5–(Al2O3)3 film was annealed at 200 to 400°C for 60 min. As a consequence, the (Fe40Co40B20)94.5Hf2.5–(Al2O3)3 film annealed at 350°C exhibit excellent properties with high saturation magnetization of 1197 kA/m, high resonant frequency of 1.76 GHz, and the real part of permeability is about 600, which is maintained up to 1.5GHz. These results show that the presented films possesses potential in designing micro-magnetic devices for Monolithic Microwave Integrated Circuit (MMIC) and surface mount technology (SMT)industry.

Abstract: The paper presents the results of an analysis of the mechanics of contact between a rigid sphere and an elastic rigidly plastic two-layer half-space that imitates a surface covered with a hard strengthening coating. Analytical dependences are derived which relate the surface hardness to the base and coating hard¬nesses within the whole possible range of the coating thickness. A new physical interpretation of the mechanism of the deformation of a layered solid is proposed for the range of the indentation depth that commonly characterizes the domain of the existence of the composite hardness. The obtained theoretical solutions are used to determine the ranges of the thicknesses within which the composite and real hardnesses of a hardened surface exist.

Abstract: A large number of laminates have been used in marine structures, such as small boat hulls, superstructures and propellers, etc. In this study, the using of composites in large scale marine hatch cover and comparison of strength, weight and cost between the conventional marine hatch cover and the composite hatch cover are investigated. The results show that the composite hatch cover is feasible and has great potential for future use because of its higher strength, lighter weight, super-corrosion resistance and economic.

Abstract: Polycrystalline sample of PZT (52/48) was prepared by solid-state reaction method. X-ray analysis indicated the formation of single-phase. Electrical and impedance-spectroscopy plots were employed to analyze the electrical behavior of the sample, as a function of frequency, in the range of 0.01 Hz to 1 M Hz at different temperatures. Spectroscopic and complex plots indicated non-Debye dielectric relaxation. Detailed electrical studies revealed that the conduction is through hoping of electrons (extrinsic region) at lowers temperature and migration of oxygen vacancies at high temperature (intrinsic region). The results are explained using Euryod’s conduction model and confirmed with pyroelectric and ferroelectric data.