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In this work, we investigated the structure, mechanical properties and corrosion resistance of Ti50Ni50 and Ti16.667Zr16.667A16.667Ni25Cu25 (A = Hf, Nb, Co, Cr and Ga) shape memory alloys (SMAs) fabricated by using melt-spinning method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses reveal that the alloy ribbons are partially crystallized with B19' martensitic structure in the added alloys. The crystalline phase formation and the atomic size difference (δ = 4.33 - 10.25%) significantly affect the hardness, tensile strength, tensile strain, elastic modulus and corrosion resistance of the alloys. The hardness of the alloy gradually increases from 583 HV to 873 HV when adding elements in the order of Hf, Nb, Co, Cr and Ga. Tensile strength, tensile strain and elastic modulus simultaneously reach their maximum of 669.2 MPa, 0.899% and 28.82 GPa, respectively, when Hf is added to the alloy. Ga enhances the corrosion resistance of the alloy ribbons more than other additional elements.

Các màng mỏng đa lớp [Co/Pd] có cấu trúc antidots phún xạ trên các đế xốp nano Al2O3 và TiO2 với kích thước lỗ xốp 30 nm và 50 nm được chế tạo bằng phương pháp phún xạ DC magnetron. Ảnh hưởng của hình thái bề mặt lên đặc trưng cấu trúc và tính chất từ trong các màng đa lớp đã chế tạo được khảo sát một cách kỹ lưỡng. Kết quả nghiên cứu chỉ ra rằng, tương tự như trong các màng phẳng [Co/Pd], các màng xốp cũng có dị hướng từ vuông góc lớn ở nhiệt độ phòng. Tuy nhiên, lực kháng từ HC trong các màng xốp có sự tăng cường đáng kể so với các màng phẳng, HC lớn nhất đạt được là 2220 Oe với mẫu màng xốp TiO2-[Co/Pd], lần lượt cao gấp 1,28 và 3,15 lần so với màng Al2O3-[Co/Pd] và màng phẳng SiO2-[Co/Pd], là do sự hình thành pha từ mềm tại gờ các lỗ xốp. Có thể nói tính chất từ trong các màng xốp hoàn toàn có thể được điều biến thông qua việc điều chỉnh các thông số cấu trúc của đế xốp như kích thước lỗ xốp và độ nhám bề mặt.

Despite the utilization of external magnetic field (MF) in promoting the intrinsic unique features of magnetic nanomaterials in many different applications has been reported, however the origin of MF-dependent electrochemical behaviors as well as the electrochemical response of analytes at the electrode in sensor applications is still not clear. In this report, the influence of MF on the electrolyte's physicochemical properties (polarization, mass transport, charge/electron transfer) and electrode's properties (conductivity, morphology, surface area, interaction, adsorption capability, electrocatalytic ability) was thoroughly investigated. Herein, the working electrode surface was modified with carbon spheres (CSs), magnetic nanoparticles (Fe

Rutile TiO2 was synthesized by sol–gel method. Vanadium-doped rutile TiO2 nanoparticle was obtained by reactive grinding method. The photocatalytic activity was evaluated by the degradation of methylene blue (MB) under solar light at room temperature. The results show that after 4 h of milling the particle size of rutile decreased from 130 to 14 nm and the Brunauer–Emmet–Teller (BET) specific surface area increased from 7.18 to 15.12 m2 g−1. The vanadium doping promoted the particle growth and the particle size of vanadium-modified rutile TiO2 obtained by 4 h of milling is about 22 nm, but the BET specific surface area increased from 15.12 m2 g−1 for TiO2 to 20.8 m2 g−1 for vanadium-doped TiO2 under the same conditions. The 5% vanadium-doped rutile possessed better absorption ability of solar light; the calculated band gap energy value is 2.7 eV. The degradation rate of MB on vanadium-doped rutile TiO2 was higher than that of pure rutile obtained after the same time of milling.

In this report we present low-field magnetoresistance (LFMR) of (1 − x)La0.7Ca0.3MnO3 + xLa1.5Sr0.5NiO4 (x­ =0–0.3) nanocomposites at temperatures ranging from 30 to 300 K. These materials were synthesized by reactive mechanical ball milling combined with the heat treatment. Experimental results have revealed that the Curie temperature is almost independent of x, while the metal–insulator transition temperature shifts from 254 K for x = 0.0 to 65 K for x = 0.2. Particularly, the samples with x ≥ 0.25 exhibit insulating properties. Magnetoresistance (MR) of all the samples is observed at an applied magnetic field of 3 kOe. In order to explore their MR nature at changing temperature, we analyzed carefully the obtained data basing on the phenomenological model related to the spin polarized transport (SPT) of conduction electrons at grain boundaries.

In this paper we present the results of study on the magnetic and magnetocaloric properties of LaFe11?xCoxSi2 (x?=?0, 1, 2, 3 and 4) ribbons prepared by using melt-spinning method. The results show that the glass forming ability (GFA) of the alloy is considerably influenced by the addition of Co. With increasing Co-concentration of the alloy, Curie temperature (TC) increases from ?220?K (for x?=?0) to ?500?K (for x?=?4). The maximum magnetic entropy change |?SM|max of the alloy, which is achieved near TC, is larger than 1.2?J?kg?1?K?1 (under magnetic change ?H?=?12?kOe) for all the concentrations of Co. This has a significant meaning for magnetic refrigeration applications.

The magnetocaloric effect of Ni50Mn50?xSnx ribbons (x?=?11?15) prepared by using melt-spinning and subsequent annealing has been investigated. The x-ray diffraction data of specimens show that all the samples are partially crystallized with Ni2MnSn phase. The magnetic transitions of these ribbons strongly depend on Sn-concentration and annealing process. Particularly, the antiferromagnetic?ferromagnetic transition is just observed at a narrow range of the Sn-concentration (x?=?12?14). The positive magnetic entropy changes occurring at the transition temperature of the antiferromagnetic phase are quite large, |?Sm|max?=?5.7?J?kg?1?K?1 (for x?=?13) with external magnetic field change ?H?=?12?kOe. Besides that, the negative magnetic entropy changes take place near Curie temperature and their magnitude is also large, |?Sm|max?=?1.9?J?kg?1?K?1 (for x?=?13). The obtained results indicate that Ni50Mn50?xSnx ribbons are good candidates for magnetic refrigeration application at room temperature.

A multiferroic sample of La1.5Sr0.5NiO4+δ was prepared by conventional solid-state reaction. X-ray diffraction study revealed La1.5Sr0.5NiO4+δ exhibiting a single phase with a tetragonal structure (F4K2Ni-perovskite-type structure, and space group of I4/mmm). An iodometric titration method was used to determine non-stoichiometric oxygen concentrations (δ) in the La1.5Sr0.5NiO4+δ ceramic. We found δ = −0.017, which corresponds to a doping level of nh = x + 2δ = 0.466 (with x being Sr2+ content). The field-cooled (FC) magnetization curve indicated that there was a strong increase in spin ordering (SO) at temperature TSO ∼ 100 K. Below TSR ∼ 50 K, spins undergo a spin reorientation (SR) turning away from the stripe direction on cooling. Its dielectric constant e (ω , T) = e′(ω,T) − ie ″(ω,T) was estimated by basing on capacitance and conductance curves measured at different temperatures and frequencies. Dielectric relaxations of charge-ordered La1.5Sr0.5NiO4+δ ceramic were investigated in a broad temperature range. The giant dielectric constant (104–106) with a low dielectric loss of 10−2–10−1 was also found.

TiO2 nanocrystal doped with Cu has been fabricated by wet chemical processing. The obtained results of x-ray diffraction, optical absorption in the UV–Vis bands and luminescence spectra have shown that Cu has substituted Ti in the structure of TiO2 anatase phase when the Cu concentration is about 8 at%. In the case of larger Cu concentrations the copper oxide appeared and increased with increasing Cu concentration. The samples doped with Cu strongly absorb the visible light (400–900 nm) and their absorption edge shifts to the longer wavelength in dependence on the Cu concentration. The absorption in the visible light band is attributed to transitions between the impurities levels of Cu created in the energy band gap of TiO2. In addition, an absorption shoulder above 800 nm is observed and supposed to be related with the absorption of CuO. The experimental results prove that the TiO2 anatase doped with Cu is suitable for hydrogen generation by photocatalytic water splitting under sunlight.

Nd 10.5 Fe 83.5−x Ga x B 6 (x=1.5, 3 and 4.5) ribbons were prepared by melt-spinning method with various wheel speeds from 5 to 40 m s −1. Strong crystallographic texture with c-axis of Nd 2 Fe 14 B crystallites along normal of the ribbon surface was observed. The texture degree can be enhanced by decreasing the quenching rate during solidification of the melt and by increasing the concentration of Ga. Preferred orientation of the nanocrystallites with their size of 10–30 nm is obtained not only by controlling the quenching rate of the melt during solidification but also by appropriately annealing the over-quenched ribbons. The texture of microstructure clearly affects magnetic anisotropy of the ribbons. With increasing concentration of Ga, the magnetic anisotropy of the ribbons is considerably increased. The coercivity above 6.5 kOe and maximum energy products larger than 15 MGOe can be achieved on the ribbons with Ga-concentration of 1.5%.