Search

By introducing rare-earth metal-centered polyhedra to enhance the birefringence of non-π-conjugated sulfate systems, NaLa2(SO4)2F3 with a moderate birefringence (0.041 at 1064 nm) was successfully synthesized.

Herein, by introducing [AlO4] tetrahedra, a new aluminoborate was discovered. This work confirms that the introduction of [AlO4] tetrahedra can lead to the rearrangement of anionic framework of borate system and thereby enhance the birefringence.

The effect of spinning rates on mechanical properties and hydrogen absorption/desorption properties of Ti47Zr31Ni14Cr8 amorphous ribbons have been investigated in the present work. A fully amorphous structure was confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis of the ribbons obtained from spinning rates of 30 m s−1 to 45 m s−1. The uniformity of amorphous ribbons and their mechanical properties were improved with the increase in the spinning rate. Scanning electron microscopy (SEM) revealed that the fracture surface of amorphous ribbons had a cleavage feature and vein-like pattern when the spinning rates were 30 m s−1 and 45 m s−1, respectively. Because of the influence of flow units on the kinetic process of hydrogen absorption, the hydrogenation kinetics and hydrogen desorption capacity of amorphous ribbons were enhanced with the increased spinning rates. After the amorphous ribbons absorbed a large amount of hydrogen, ZrH2, TiH2, and (ZrTi)2Ni7 crystalline phases were formed from the amorphous matrix. Hydrogen promotes amorphous phase decomposition and the crystallinity of the new phases led to deterioration of the mechanical properties.

Pitting initiation and stable propagation behaviors of 2205 duplex stainless steel were investigated in the hot concentrated seawater under vacuum pressures by potentiostatic polarization. Both applied potentials and vacuum pressures greatly influence the pitting corrosion. Higher potentials lead to much faster stable pitting initiation and growth rates in both static (101.3 kPa) and dynamic (28.4 kPa) solutions. The pressure reduction can also accelerate the pitting initiation rate. However, the boiling of solution can influence the pitting propagation mechanism. The dynamic actions of boiling bubbles are unfavorable to the pit propagation and result in the formation of relatively smooth pit bottom without secondary pits.

As the core component of satellite navigation, the hydrogen maser needs a high vacuum environment to maintain the stability of the frequency signal. The getter pump, composed of various non-evaporable getters, plays an important role in maintaining the high vacuum. In this paper, the Zr100-xCux (x = 0, 2, 4, 6)/Zr56.97V35.85Cr7.18 getter was studied and the contradiction between sorption performance and mechanical properties was solved. The Zr-V-Cr getter, a better candidate for getter pump, exists for problems which will destroy the high vacuum and affect the service life of the hydrogen maser. To solve the problem of dropping powder from Zr-V-Cr getter, Zr-Cu films were coated on the surface of Zr-V-Cr matrix to obtain the pore gradient structure. After vacuum sintering, the interface showed gradient structure and network change in pore structure from Zr-Cu film to Zr-V-Cr matrix. These characteristic structures made Zr-V-Cr getter have good absorption properties, which is better than a similar product of SAES company and mechanical properties. Because the Zr-Cu film on Zr-V-Cr matrix effectively prevented dropping powders from the matrix, (Zr-Cu)/(Zr-V-Cr) getter solved the problem of dropping powder. The self-developed new getter with pore gradient structure is of great significance for maintaining the high vacuum of hydrogen maser in the future.

The superelastic behavior and elastocaloric effect of a [001]-textured Ni50Mn23Ga25Cu2 polycrystal have been investigated below room temperature (256–294 K). The adiabatic temperature change caused by rapid unloading of uniaxial stress reached −4.3 K at 259 K. A small stress hysteresis of 14 MPa was observed. Due to the low hysteresis energy loss (0.37 MJ m−3) stemming from the texture structure, the coefficient of performance (COPmat) of our alloy was calculated to be 18, indicating that it is a promising elastocaloric candidate for low-temperature refrigeration.

The effects of different sintering time on the microstructure and high-temperature magnetic properties of Sm(Co 0.79 Fe 0.09 Cu 0.09 Zr 0.03 ) 7.68 magnets were studied. As the sintering time increased from 0.5 to 2 h, the room temperature coercivity increased from 30.50 to 32.25 kOe, while the coercivity at 823 K decreased from 5.20 to 4.69 kOe. The microstructure and element distribution were analyzed by scanning electron microscope and transmission electron microscopy. The average grain size increased obviously from 17.86 to $71.21μm, which was beneficial to the increase in coercivity for less grain boundary regions. For solution-treated magnets, 1:7H, 2:17H, Zr 6 Co 23 , and minor 2:17R phases are formed in both magnets. More cubic Zr 6 Co 23 phase and 2:17H phase appeared as the sintering time increased. Cellular structure was observed in both magnets. Furthermore, more Cu content was distributed in the cell boundary phase due to higher density of lamellar phase in magnets with shorter sintering time. The change in Cu distribution altered the coercivity mechanism from repulsive pinning to attractive pinning, which could be the reason for the different high-temperature magnetic properties.

The chromatographic fingerprint of 14 batches of

The melt-spun ribbons of LaFe11.5Si1.5Cx (x = 0, 0.1, 0.2, 0.3) compounds are prepared by the melt fast-quenching method. The doping of C is beneficial to the nucleation and precipitation of the La (Fe, Si)13 phase, which is indicated by the microstructure observation and the elemental analysis. Subsequently, the ribbons of LaFe11.5Si1.5C0.2 are annealed at different times, and the phase composition, the microstructures, and the magnetic properties are investigated. The LaFe11.5Si1.5C0.2 ribbons annealed at 1273 K for 2 h achieved the best magnetic properties, and the maximum isothermal magnetic entropy change with a value of 9.45 J/(kg·K) upon an applied field of 1.5 T at an increased Curie temperature 255 K.

Due to cultivation position, climate, harvest times, storage conditions and processing method, the evaluation of intra- and inter- batches quality consistency of botanical drugs has always been a thorny problem since it concerns safety and efficacy. The combination of fingerprint based on instrumental analysis and chemometrics is a common evaluation method in recent years. The differences between groups can be judged intuitively and superficially through principal component analysis (PCA) multi-dimensional score plots, but there is a lack of scientific and quantitative index to quantify the differences between groups. How to quantify the difference between groups is basically a blank area of research. Based on traditional F-statistic, we proposed a new F

Elastic semiconductors are becoming more and more important to the development of flexible wearable electronic devices, which can be prepared by structural engineering design, blending, and the intrinsic elastification of organic semiconductors (intrinsically elastic organic semiconductor, IEOS). Compared with the elastic semiconductors prepared by structural engineering and blending, the IEOS prepared by organic synthesis has attracted numerous attentions for its solution processability and highly tunable chemical structures. For IEOSs, reasonable designs of synthetic routes and methods are the basis for realizing good mechanical and electrical properties. This brief review begins with a concise introduction of elastic semiconductors, then follows with several synthetic methods of IEOSs, and concludes the characteristics of each method, which provides guidance for the synthesis of IEOSs in the future. Furthermore, the properties of IEOSs are involved from the aspects of electrical, mechanical properties, and the applications of the IEOSs in elastic electronic devices. Finally, the challenge and an outlook which IEOSs are facing are presented in conclusion.

The Fe69.5–xNd7B21Nb2.5Gax (x = 0–1) permanent magnets in the form of rods were prepared by annealing the bulk amorphous alloys. The magnetic properties, phase evolution and microstructure of the alloys were investigated systematically. It is found that the glass forming ability (GFA), microstructure and magnetic properties are sensitive to Ga content for Fe69.5–xNd7B21Nb2.5Gax (x = 0–1) bulk alloys. The annealed alloys are mainly composed of soft α-Fe, hard Nd2Fe14B and nonmagnetic Nd1.1Fe4B4 phases. When x = 0.3, the optimally annealed magnets exhibit magnetic properties of the remanence Br = 0.63 T, intrinsic coercivity Hcj = 368.68 kA/m and maximum energy product (BH)max = 33.73 kJ/m3. Furthermore, magnetic field heat treatment at the temperature close to Curie temperature of Nd2Fe14B phase was applied to the annealed Fe69.2Nd7B21Nb2.5Ga0.3 magnet. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate that the magnetic field heat treatment can be beneficial for the precipitation of α-Fe. Thus, the Br, Hcj and (BH)max are enhanced by 8.7%, 6.3% and 16.3%, respectively.

In this work, we investigate the evolution with x of the microstructure and alternating current (AC) magnetic properties of FeCoNi(MnSi)x (0 ≤ x ≤ 0.4) high-entropy alloys (HEAs) with the motivation of exploring the potential applications of soft magnetic HEAs. The suitable addition of MnSi improves AC remanence (AC Br), AC coercivity (AC Hc) and especially specific total loss (Ps) while it suppresses amplitude permeability (μa) and AC maximum magnetic flux density (AC Bm), which suggests that the HEAs can be used as a new soft magnetic material with low Br and low Hc. Ps can be divided into two parts: hysteresis loss (Ph), eddy current loss (Pe), and further studies show that the Ph plays an important role at the frequency of 50 Hz, while the Pe is dominant in the total losses when the frequency is 950 Hz. This provides the direction of efforts to reduce the Ps. The XRD, SEM and TEM results show that these alloys contain simple FCC structure, but a new Mn6Ni16Si7 intermetallic compound appears when x ≥ 0.3, and it has a big influence on the AC magnetic properties of HEAs.

The FeCoNi(CuAl)0.8Ga0.06 high-entropy alloy (HEA) was prepared by the vacuum arc melt casting method, then annealed at different temperatures for 1 h. The microstructure, phase constitution, and magnetic and mechanical properties of the FeCoNi(CuAl)0.8Ga0.06 HEA during the phase transition were investigated. The experimental results showed that the as-cast alloy consisted of FCC and BCC duplex phases, and there were numerous nano-precipitates uniformly distributed in the BCC matrix. After annealing at different temperatures, the phase transformed from FCC to BCC. The relative volume fraction of the BCC phase increased, and the size of the nano-precipitates in the BCC matrix were larger after annealing than that of the as-cast sample. STEM-EDS images showed that there was a Cu-rich zone in the phase boundary region between FCC and BCC phases, and annealing may have significant influence on this region. Based on XRD, SEM, TEM and STEM-EDS results, a phase transition mechanism was proposed, which may have a close relationship with the Cu-rich nano-precipitates in the BCC matrix and the Cu-rich zone in the phase boundary region. In addition, it was found that the volume fraction of BCC (or FCC) phase can govern the magnetic properties. This study may help to deepen the fundamental understanding of the phase transition mechanism in HEAs.

Realizing improved strength–ductility synergy in eutectic alloys acting as in situ composite materials remains a challenge in conventional eutectic systems, which is why eutectic high-entropy alloys (EHEAs), a newly-emerging multi-principal-element eutectic category, may offer wider in situ composite possibilities. Here, we use an AlCoCrFeNi2.1 EHEA to engineer an ultrafine-grained duplex microstructure that deliberately inherits its composite lamellar nature by tailored thermo-mechanical processing to achieve property combinations which are not accessible to previously-reported reinforcement methodologies. The as-prepared samples exhibit hierarchically-structural heterogeneity due to phase decomposition, and the improved mechanical response during deformation is attributed to both a two-hierarchical constraint effect and a self-generated microcrack-arresting mechanism. This work provides a pathway for strengthening eutectic alloys and widens the design toolbox for high-performance materials based upon EHEAs., Producing in situ composite materials with superior strength and ductility has long been a challenge. Here, the authors use lamellar microstructure inherited from casting, rolling, and annealing to produce an ultrafine duplex eutectic high entropy alloy with outstanding properties.

In this paper, the effects of vanadium addition on the mechanical properties of Ti-Zr-Ni-Cr amorphous ribbons with high spinning speed were studied. It was found that the mechanical properties of samples were obvious promoted by adding vanadium into Ti-Zr-Ni-Cr amorphous alloys. The rapidly solidified Ti-Zr-Ni-Cr (V = 0, V = 0.1) ribbons at a speed of 45 m/s is an amorphous structure. But the amorphous structure of Ti-Zr-Ni-Cr-V alloys is even more uniform than that of the V-free alloys samples. In particular, Ti-Zr-Ni-Cr-V amorphous ribbons showed better mechanical properties that the tensile strength ( $$\sigma_{b}$$ ) of the amorphous ribbons samples that had been significantly increased from 542 MPa for V = 0–675 MPa for V = 0.1. The elongation (δ) exhibited a tiny increase from 1.1% for V = 0–1.29% for V = 0.1. The fractured surface of amorphous ribbons for V = 0 showed more cleavage features, it was the obviously brittle fracture. The fracture surface for amorphous ribbons for V = 0 were more vein-like patterns, they are attributed to a local change of viscosity. It’s likely that adding V into Ti-Zr-Ni-Cr amorphous alloys is beneficial to enhance rheological units and massive accumulation of free volume in ribbons. It contributes to mechanical properties, especially for the tensile strength and the plastic deformation of the amorphous ribbons.

The as-cast FeCoNi(CuAl)0.8Gax (0 ≤ x ≤ 0.08) high-entropy alloys (HEAs) were produced by vacuum arc melting. The correlation between the magnetic properties and phase constitution of the HEAs was thoroughly investigated. The results reveal that all samples contain BCC plus FCC duplex phases and the addition of Ga can promote the formation of BCC phases. Energy dispersive spectroscopy (EDS) results revealed that Cu and Ga elements are enriched in the BCC phases and they are more seriously in the phase boundary regions. Furthermore, the magnetic properties are closely related to the phase constitution of the as-cast FeCoNi(CuAl)0.8Gax (0 ≤ x ≤ 0.08) HEAs. The values of saturated magnetization (Ms), maximum magnetic flux density (Bm), remanence (Br), coercivity (Hc) and hysteresis losses (Pu) increase with the increase of the volume fraction of BCC phases, while the values of initial permeability (μi) and maximum permeability (μmax) increase with the increase of the volume fraction of FCC phases. In addition, the mechanical property of FeCoNi(CuAl)0.8Gax (0 ≤ x ≤ 0.08) HEAs was also discussed in the work.

An efficient, simple protocol has been established for convenient synthesis of novel 2,3-disubstituted thieno[2,3-d]pyrimidin-4(3H)-one derivatives in good to high yields through a one-pot, two-step and three-component reaction from 2H-thieno[2,3-d][1,3]oxazine-2,4(1H)-diones, aromatic aldehydes, and amines.

Long-term corrosion behavior of 2205 duplex stainless steel was investigated in the hot concentrated artificial seawater under intermittent vacuum boiling and atmosphere conditions during the immersion of more than one year by using electrochemical impedance spectroscopy (EIS). Compared to the atmosphere state, the passive film formed on specimen surface is thinner and the induction time for pitting corrosion decreases notably under intermittent vacuum boiling condition. However, the pit propagation is retarded by the lower dissolved oxygen content and violent boiling of solution. The vacuum boiling of solution has opposite effect on the initiation and stable growth processes of pitting corrosion.

Magnetic field annealing is an important method to enhance the magnetic properties of amorphous alloys. In this work, the effects of magnetic field annealing intensity on the magnetic properties, mechanical properties, and microstructure of Fe80Si9B11 amorphous ribbons were investigated. It can be seen from the results that the magnetic induction at 1600 A/m (B1600), maximum permeability (μm), coercivity (Hc), Elastic modulus (Er), and Hardness were improved with an increase of the magnetic field intensity. When the magnetic annealing intensity was 2.5 × 10−4 T, the B1600, μm, Hc, Er and Hardness of the sample were improved by 9%, 298%, 67%, 23% and 3%, respectively, compared with those of the as-spun sample. TEM results showed that there are some spherical symmetric clusters present in the 653 K × 2.5 × 10−4 T sample. This may be an important reason for the improvement of the magnetic properties. Compared with the 653 K × 1 T sample, the magnetic field intensity of the 653 K × 2.5 × 10−4 T sample was only 0.025%. However, the values of B1600, μm, Hc, Er and Hardness of the latter reached 96%, 82%, 115%, 90% and 94% of the former, respectively. It means that during the magnetic field annealing process, applying only a small magnetic field can obviously enhance the magnetic and mechanical properties of Fe80Si9B11 amorphous alloy. This provides a theoretical basis for the further improvement of the magnetic and mechanical properties of Fe80Si9B11 alloys, and in the energy saving. The reasons for the changes of magnetic and mechanical properties caused by different magnetic field intensities are discussed.

Magnetocaloric effect by employing direct measurements of the adiabatic temperature changes (ΔTad) with a low magnetic field change (ΔH) up to 1.2 T are investigated, for the Gd based alloys with Zn and Cd substituted for Gd individually or synchronously. A comparative study of the adiabatic temperature change (ΔTad) and magnetic entropy change (ΔSM) near room temperature has been reported in three different alloys of Gd1 − xZnx, Gd1 − yCdy and Gd0.95(Zn1 − zCdz)0.05. Effects of Zn and Cd content on magnetocaloric effect and the Curie temperature (Tc) are studied in different alloys. A direct correlation between phase structure and ΔTad, ΔSM, Tc was discussed in three different types alloys of Gd1 − xZnx, Gd1 − yCdy, and Gd0.95(Zn1 − zCdz)0.05. Mechanism of Zn improving the ΔTad and Cd increasing the Tc is revealed. It is expected that magnetic refrigeration near room temperature has a potential for superseding the traditional gas refrigeration. Keywords: Gd1 − xZnx, Gd1 − yCdy, Gd0.95(Zn1 − zCdz)0.05, Magnetocaloric effect

In the present work, (Nd 0.8 Ce 0.2 ) 2− x Fe 12 Co 2 B ( x = 0–0.6) permanent alloys are prepared by melt-spinning method. The hard magnetic properties of (Nd 0.8 Ce 0.2 ) 2− x Fe 12 Co 2 B ( x = 0–0.6) alloys annealed at optimum temperatures have been investigated systematically. Depending on the Nd, Ce concentration, the maximum energy product ( (BH) max ) and remanence ( B r ) increase gradually with x in the range of 0 ≤ x ≤ 0.4, whereas decrease gradually in the alloys with 0.4 x ≤ 0.6. It is found that the optimum magnetic properties are obtained at x = 0.4: H ci = 4.9 kOe, B r = 10.1 kG, (BH) max = 13.7 MGOe. Specifically, magnetic field heat treatment below the Curie temperature is applied for (Nd 0.8 Ce 0.2 ) 1.6 Fe 12 Co 2 B ( x = 0.4) annealed ribbons. The magnetic properties B r , (BH) max and squareness are all enhanced after the magnetic field heat treatment. The (BH) max shows a substantial increase from 13.7 MGOe to 16.0 MGOe after the heat treatment at 623 K with a magnetic field of 1 T, which gets 17% improvement compared with that of the sample without a magnetic field heat treatment. We demonstrate that the magnetic field heat treatment plays a certain role in the magnetization reversal behavior and can improve the microstructure of (Nd 0.8 Ce 0.2 ) 1.6 Fe 12 Co 2 B alloy.

Nonlinear optical materials are essential for the development of solid-state lasers. KBe2BO3F2 (KBBF) is a unique nonlinear optical material for generation of deep-ultraviolet coherent light; however, its industrial application is limited. Here, we report a new material NH4B4O6F, which exhibits a wide deep-ultraviolet transparent range and suitable birefringence that enables frequency doubling below 200 nm. NH4B4O6F possesses large nonlinear coefficients about 2.5 times that of KBBF. In addition, it is easy to grow bulk crystals and does not contain toxic elements.